refactor: simplify downcasting logic with std::mem::transmute (#20)

Simplified the downcasting implementations by replacing pointer casting
logic with `std::mem::transmute`, ensuring type safety after matching.
Added tests to validate various downcasting behaviors for both owned and
trait-object error scenarios, improving overall reliability and test
coverage.

.github/dependabot.yml

@@ -0,0 +1,7 @@
+version: 2
+updates:
+- package-ecosystem: cargo
+  directory: "/"
+  schedule:
+    interval: daily
+  open-pull-requests-limit: 10

.github/workflows/coverage.yml

@@ -0,0 +1,38 @@
+name: coverage
+
+on:
+  # Trigger the workflow on push or pull request,
+  # but only for the master branch
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+  release:
+    types:
+      - created
+
+
+jobs:
+  coverage:
+    runs-on: ubuntu-latest
+    env:
+      CARGO_TERM_COLOR: always
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          target: x86_64-unknown-linux-gnu
+          toolchain: nightly
+          components: llvm-tools-preview
+      - name: Install cargo-llvm-cov
+        uses: taiki-e/install-action@cargo-llvm-cov
+      - name: Generate code coverage
+        run: cargo +nightly llvm-cov --all-features --workspace --codecov --doctests --output-path codecov.json
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v3
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }} # not required for public repos
+          files: codecov.json
+          fail_ci_if_error: true

.github/workflows/gh-pages.yml

@@ -0,0 +1,30 @@
+name: github pages
+
+on:
+  push:
+    tags:
+      - '*'
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Build mdbook
+        run: cargo install mdbook
+
+      - name: Build cargo-readme
+        run: cargo install cargo-readme
+
+      - name: Build README.md
+        run: cargo readme > README.md
+
+      - name: Build
+        run: mdbook build
+
+      - name: Deploy
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          deploy_key: ${{ secrets.ACTIONS_DEPLOY_KEY }}
+          publish_dir: ./book

.github/workflows/rust.yml

@@ -0,0 +1,72 @@
+name: Rust
+
+on:
+  # Trigger the workflow on push or pull request,
+  # but only for the master branch
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+  release:
+    types:
+      - created
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        version:
+          - 1.54.0
+          - stable
+          - beta
+          - nightly
+    steps:
+      - uses: actions/checkout@v1
+      - name: Install toolchain
+        uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: ${{ matrix.version }}
+          profile: minimal
+      - name: Build
+        run: cargo build --verbose
+      - name: Run tests
+        run: cargo test --verbose
+      - name: Build --all-features
+        run: cargo build --verbose --all-features
+      - name: Run tests --all-features
+        run: cargo test --verbose --all-features
+
+  fmt:
+    name: cargo fmt
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          components: rustfmt
+          toolchain: stable
+          profile: minimal
+          override: true
+      - uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+
+  clippy:
+    name: cargo clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          components: clippy
+          toolchain: stable
+          profile: minimal
+          override: true
+      - uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+          args: -- -D warnings

.travis.yml

@@ -1,22 +0,0 @@
-language: rust
-
-branches:
-  except:
-    - gh-pages
-
-rust:
-- stable
-- nightly
-
-os:
-- linux
-- windows
-
-script:
-- cargo build --all
-- cargo test --all
-
-matrix:
-  allow_failures:
-  - rust: nightly
-  fast_finish: true

Cargo.toml

@@ -1,9 +1,9 @@
 [package]
 name = "chainerror"
-version = "0.4.3"
+version = "1.0.0"
 authors = ["Harald Hoyer <harald@redhat.com>"]
 edition = "2018"
-license = "MIT/Apache-2.0"
+license = "MIT OR Apache-2.0"
 documentation = "https://docs.rs/chainerror"
 homepage = "https://haraldh.github.io/chainerror/"
 repository = "https://github.com/haraldh/chainerror"
@@ -16,10 +16,11 @@ exclude = [ ".gitignore", "examples/*", "booksrc/*", "book.toml",
             "theme/*", "git-deploy-branch.sh", ".travis.yml" ]
 
 [badges]
-travis-ci = { repository = "haraldh/chainerror" }
+# See https://doc.rust-lang.org/cargo/reference/manifest.html#the-badges-section
+github = { repository = "haraldh/chainerror", workflow = "Rust" }
+maintenance = { status = "actively-developed" }
+is-it-maintained-issue-resolution = { repository = "haraldh/chainerror" }
+is-it-maintained-open-issues = { repository = "haraldh/chainerror" }
 
-[features]
-default = [ ]
-no-fileline = []
-display-cause = []
-no-debug-cause = []
+[package.metadata.docs.rs]
+cargo-args = ["-Zunstable-options", "-Zrustdoc-scrape-examples"]

README.md

@@ -1,129 +1,186 @@
-# chainerror
-
-[![Build Status](https://travis-ci.org/haraldh/chainerror.svg?branch=master)](https://travis-ci.org/haraldh/chainerror)
 [![Crate](https://img.shields.io/crates/v/chainerror.svg)](https://crates.io/crates/chainerror)
 [![Rust Documentation](https://img.shields.io/badge/api-rustdoc-blue.svg)](https://docs.rs/chainerror/)
+[![Coverage Status](https://codecov.io/gh/haraldh/chainerror/branch/master/graph/badge.svg?token=HGLJFGA11B)](https://codecov.io/gh/haraldh/chainerror)
+![Maintenance](https://img.shields.io/badge/maintenance-activly--developed-brightgreen.svg)
 
-`chainerror` provides an error backtrace like `failure` without doing a real backtrace, so even after you `strip` your
+# chainerror
+
+`chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
 binaries, you still have the error backtrace.
 
-`chainerror` has no dependencies!
+Having nested function returning errors, the output doesn't tell where the error originates from.
 
-`chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
-It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
+```rust
+use std::path::PathBuf;
 
-Along with the `ChainError<T>` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
-
-Debug information is worth it!
-
-Now continue reading the
-[Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
-
-## Example:
-Output:
-
-~~~
-$ cargo run -q --example example
-Main Error Report: func1 error calling func2
-
-Error reported by Func2Error: func2 error: calling func3
-
-The root cause was: std::io::Error: Kind(
-    NotFound
-)
-
-Debug Error:
-examples/example.rs:45: func1 error calling func2
-Caused by:
-examples/example.rs:20: Func2Error(func2 error: calling func3)
-Caused by:
-examples/example.rs:13: Error reading 'foo.txt'
-Caused by:
-Kind(NotFound)
-~~~
-
-~~~rust,ignore
-use chainerror::*;
-use std::error::Error;
-use std::io;
-use std::result::Result;
-
-fn do_some_io() -> Result<(), Box<Error>> {
-    Err(io::Error::from(io::ErrorKind::NotFound))?;
+type BoxedError = Box<dyn std::error::Error + Send + Sync>;
+fn read_config_file(path: PathBuf) -> Result<(), BoxedError> {
+    // do stuff, return other errors
+    let _buf = std::fs::read_to_string(&path)?;
+    // do stuff, return other errors
     Ok(())
 }
 
-fn func3() -> Result<(), Box<Error>> {
-    let filename = "foo.txt";
-    do_some_io().map_err(mstrerr!("Error reading '{}'", filename))?;
-    Ok(())
-}
-
-derive_str_cherr!(Func2Error);
-
-fn func2() -> ChainResult<(), Func2Error> {
-    func3().map_err(mstrerr!(Func2Error, "func2 error: calling func3"))?;
-    Ok(())
-}
-
-enum Func1Error {
-    Func2,
-    IO(String),
-}
-
-impl ::std::fmt::Display for Func1Error {
-    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
-        match self {
-            Func1Error::Func2 => write!(f, "func1 error calling func2"),
-            Func1Error::IO(filename) => write!(f, "Error reading '{}'", filename),
-        }
-    }
-}
-
-impl ::std::fmt::Debug for Func1Error {
-    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
-        write!(f, "{}", self)
-    }
-}
-
-fn func1() -> ChainResult<(), Func1Error> {
-    func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
-    let filename = String::from("bar.txt");
-    do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
+fn process_config_file() -> Result<(), BoxedError> {
+    // do stuff, return other errors
+    let _buf = read_config_file("foo.txt".into())?;
+    // do stuff, return other errors
     Ok(())
 }
 
 fn main() {
-    if let Err(e) = func1() {
-        match e.kind() {
-            Func1Error::Func2 => eprintln!("Main Error Report: func1 error calling func2"),
-            Func1Error::IO(filename) => {
-                eprintln!("Main Error Report: func1 error reading '{}'", filename)
-            }
-        }
-
-        if let Some(e) = e.find_chain_cause::<Func2Error>() {
-            eprintln!("\nError reported by Func2Error: {}", e)
-        }
-
-        if let Some(e) = e.root_cause() {
-            let ioerror = e.downcast_ref::<io::Error>().unwrap();
-            eprintln!("\nThe root cause was: std::io::Error: {:#?}", ioerror);
-        }
-
-        eprintln!("\nDebug Error:\n{:?}", e);
+    if let Err(e) = process_config_file() {
+        eprintln!("Error:\n{:?}", e);
     }
 }
+```
 
-~~~
+This gives the output:
+```console
+Error:
+Os { code: 2, kind: NotFound, message: "No such file or directory" }
+```
+and you have no idea where it comes from.
 
-## Features
 
-`no-fileline`
-: completely turn off storing filename and line
+With `chainerror`, you can supply a context and get a nice error backtrace:
 
-`display-cause`
-: turn on printing a backtrace of the errors in `Display`
+```rust
+use chainerror::Context as _;
+use std::path::PathBuf;
 
-`no-debug-cause`
-: turn off printing a backtrace of the errors in `Debug`
+type BoxedError = Box<dyn std::error::Error + Send + Sync>;
+fn read_config_file(path: PathBuf) -> Result<(), BoxedError> {
+    // do stuff, return other errors
+    let _buf = std::fs::read_to_string(&path).context(format!("Reading file: {:?}", &path))?;
+    // do stuff, return other errors
+    Ok(())
+}
+
+fn process_config_file() -> Result<(), BoxedError> {
+    // do stuff, return other errors
+    let _buf = read_config_file("foo.txt".into()).context("read the config file")?;
+    // do stuff, return other errors
+    Ok(())
+}
+
+fn main() {
+    if let Err(e) = process_config_file() {
+        eprintln!("Error:\n{:?}", e);
+    }
+}
+```
+
+with the output:
+```console
+Error:
+examples/simple.rs:14:51: read the config file
+Caused by:
+examples/simple.rs:7:47: Reading file: "foo.txt"
+Caused by:
+Os { code: 2, kind: NotFound, message: "No such file or directory" }
+```
+
+`chainerror` uses `.source()` of `std::error::Error` along with `#[track_caller]` and `Location` to provide a nice debug error backtrace.
+It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
+
+Along with the `Error<T>` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
+
+`chainerror` has no dependencies!
+
+Debug information is worth it!
+
+## Multiple Output Formats
+
+`chainerror` supports multiple output formats, which can be selected with the different format specifiers:
+
+* `{}`: Display
+```console
+func1 error calling func2
+```
+
+* `{:#}`: Alternative Display
+```console
+func1 error calling func2
+Caused by:
+  func2 error: calling func3
+Caused by:
+  (passed error)
+Caused by:
+  Error reading 'foo.txt'
+Caused by:
+  entity not found
+```
+
+* `{:?}`: Debug
+```console
+examples/example.rs:50:13: func1 error calling func2
+Caused by:
+examples/example.rs:25:13: Func2Error(func2 error: calling func3)
+Caused by:
+examples/example.rs:18:13: (passed error)
+Caused by:
+examples/example.rs:13:18: Error reading 'foo.txt'
+Caused by:
+Kind(NotFound)
+
+```
+
+* `{:#?}`: Alternative Debug
+```console
+Error<example::Func1Error> {
+    occurrence: Some(
+        "examples/example.rs:50:13",
+    ),
+    kind: func1 error calling func2,
+    source: Some(
+        Error<example::Func2Error> {
+            occurrence: Some(
+                "examples/example.rs:25:13",
+            ),
+            kind: Func2Error(func2 error: calling func3),
+            source: Some(
+                Error<chainerror::AnnotatedError> {
+                    occurrence: Some(
+                        "examples/example.rs:18:13",
+                    ),
+                    kind: (passed error),
+                    source: Some(
+                        Error<alloc::string::String> {
+                            occurrence: Some(
+                                "examples/example.rs:13:18",
+                            ),
+                            kind: "Error reading 'foo.txt'",
+                            source: Some(
+                                Kind(
+                                    NotFound,
+                                ),
+                            ),
+                        },
+                    ),
+                },
+            ),
+        },
+    ),
+}
+```
+
+## Tutorial
+
+Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
+
+## License
+
+Licensed under either of
+
+* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or <https://www.apache.org/licenses/LICENSE-2.0>)
+* MIT license ([LICENSE-MIT](LICENSE-MIT) or <https://opensource.org/licenses/MIT>)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally
+submitted for inclusion in the work by you, as defined in the Apache-2.0
+license, shall be dual licensed as above, without any additional terms or
+conditions.

booksrc/LICENSE-APACHE

@@ -0,0 +1 @@
+../LICENSE-APACHE

booksrc/LICENSE-MIT

@@ -0,0 +1 @@
+../LICENSE-MIT

booksrc/SUMMARY.md

@@ -5,7 +5,7 @@
 - [Simple String Errors](tutorial1.md)
 - [Simple Chained String Errors](tutorial2.md)
 - [Mapping Errors](tutorial3.md)
-- [Saving coding chars](tutorial4.md)
+- [More Information](tutorial4.md)
 - [The source() of Errors](tutorial5.md)
 - [Downcast the Errors](tutorial6.md)
 - [The root cause of all Errors](tutorial7.md)
@@ -15,5 +15,6 @@
 - [Debug for the ErrorKind](tutorial11.md)
 - [Deref for the ErrorKind](tutorial12.md)
 - [Writing a library](tutorial13.md)
+- [Going back to std](tutorial14.md)
 
 [The End](end.md)

booksrc/tutorial1.md

@@ -9,7 +9,7 @@ this only
 prints out the last `Error`.
 
 ~~~
-Error: StringError("func1 error")
+Error: "func1 error"
 ~~~
 
 The next chapters of this tutorial show how `chainerror` adds more information
@@ -17,7 +17,7 @@ and improves inspecting the sources of an error.
 
 You can also run the tutorial examples in the checked out 
 [chainerror git repo](https://github.com/haraldh/chainerror).
-~~~
+~~~console
 $ cargo run -q --example tutorial1
 ~~~
 

booksrc/tutorial10.md

@@ -1,25 +1,21 @@
 # ErrorKind to the rescue
 
-To cope with different kind of errors, we introduce the kind of an error `Func1ErrorKind` with an enum.
+To cope with different kind of errors, we introduce the `kind` of an error `Func1ErrorKind` with an enum.
 
 Because we derive `Debug` and implement `Display` our `Func1ErrorKind` enum, this enum can be used as
 a `std::error::Error`.
 
-Not using `String` errors anymore, the `cherr!()` macro seen in the beginning of
-the tutorial has to be used again.
-
-Only returning `Func1ErrorKind` in `func1()` now let us get rid of `Result<(), Box<Error>>` and we can
+Only returning `Func1ErrorKind` in `func1()` now let us get rid of `Result<(), Box<Error + Send + Sync>>` and we can
 use `ChainResult<(), Func1ErrorKind>`.
 
-In `main` we can now directly use the methods of `ChainError<T>` without downcasting the error first.
+In `main` we can now directly use the methods of `chainerror::Error<T>` without downcasting the error first.
 
-Also a nice `match` on `ChainError<T>.kind()` is now possible, which returns `&T`, meaning 
-`&Func1ErrorKind` here.
+Also, a nice `match` on `chainerror::Error<T>.kind()` is now possible, which returns `&T`, meaning `&Func1ErrorKind` here.
 
 ~~~rust
 {{#include ../examples/tutorial10.rs}}
 # #[allow(dead_code)]
 # mod chainerror {
-{{#includecomment ../src/lib.rs}}
+{{#rustdoc_include ../src/lib.rs:-1}}
 # }
 ~~~

booksrc/tutorial11.md

@@ -1,6 +1,6 @@
 # Debug for the ErrorKind
 
-One small improvement at the end of the tutorial is to fix the debug output of
+One small improvement is to fix the debug output of
 `Func1ErrorKind`. As you probably noticed, the output doesn't say much of the enum.
 
 ~~~
@@ -21,13 +21,13 @@ which gives us a lot more detail.
 
 To create your own Errors, you might find [crates](https://crates.io) which create enum `Display+Debug` via derive macros.
 
-Also noteworthy is [custom_error](https://crates.io/crates/custom_error) to define your custom errors,
+Also, noteworthy is [custom_error](https://crates.io/crates/custom_error) to define your custom errors,
 which can then be used with `chainerror`.
 
 ~~~rust
 {{#include ../examples/tutorial11.rs}}
 # #[allow(dead_code)]
 # mod chainerror {
-{{#includecomment ../src/lib.rs}}
+{{#rustdoc_include ../src/lib.rs:-1}}
 # }
 ~~~

booksrc/tutorial12.md

@@ -1,11 +1,11 @@
 # Deref for the ErrorKind
 
-Because ChainError<T> implements Deref to &T, we can also match on `*e` instead of `e.kind()`
+Because chainerror::Error<T> implements Deref to &T, we can also match on `*e` instead of `e.kind()`
 or call a function with `&e`
 ~~~rust
 {{#include ../examples/tutorial12.rs}}
 # #[allow(dead_code)]
 # mod chainerror {
-{{#includecomment ../src/lib.rs}}
+{{#rustdoc_include ../src/lib.rs:-1}}
 # }
 ~~~

booksrc/tutorial13.md

@@ -1,6 +1,6 @@
 # Writing a library
 
-I would advise to only expose an `mycrate::ErrorKind` and type alias `mycrate::Error` to `ChainError<mycrate::ErrorKind>`
+I would advise to only expose an `mycrate::ErrorKind` and type alias `mycrate::Error` to `chainerror::Error<mycrate::ErrorKind>`
 so you can tell your library users to use the `.kind()` method as `std::io::Error` does.
 
 If you later decide to make your own `Error` implementation, your library users don't
@@ -10,7 +10,7 @@ have to change much or anything.
 # #[allow(dead_code)]
 # #[macro_use]
 # pub mod chainerror {
-{{#includecomment ../src/lib.rs}}
+{{#rustdoc_include ../src/lib.rs:-1}}
 # }
 pub mod mycrate {
     use crate::chainerror::*; // omit the `crate::` part

booksrc/tutorial14.md

@@ -0,0 +1,9 @@
+# Going back to std
+
+Not using `chainerror` and going full `std` would look like this:
+
+Btw, the code size is bigger than using `chainerror` :-)
+
+~~~rust
+{{#include ../examples/tutorial14.rs}}
+~~~

booksrc/tutorial2.md

@@ -1,7 +1,7 @@
 # Simple Chained String Errors
 
-With relatively small changes and the help of the `cherr!` macro of the `chainerror` crate
-the `String` errors are now chained together.
+With relatively small changes and the help of the `context()` method of the `chainerror` crate
+the `&str` errors are now chained together.
 
 Press the play button in the upper right corner and see the nice debug output.
 
@@ -9,7 +9,7 @@ Press the play button in the upper right corner and see the nice debug output.
 {{#include ../examples/tutorial2.rs}}
 # #[allow(dead_code)]
 # mod chainerror {
-{{#includecomment ../src/lib.rs}}
+{{#rustdoc_include ../src/lib.rs:-1}}
 # }
 ~~~
 
@@ -19,14 +19,13 @@ Press the play button in the upper right corner and see the nice debug output.
 {{#include ../examples/tutorial2.rs:13:15}}
 ~~~
 
-The macro `cherr!(olderror, newerror)` stores `olderror` as the source/cause of `newerror` 
-along with the filename (`file!()`) and line number (`line!()`)
-and returns `newerror`.
+The function `context(newerror)` stores `olderror` as the source/cause of `newerror` 
+along with the `Location` of the `context()` call and returns `Err(newerror)`.
 
-`Err()?` then returns the inner error applying `.into()`, so that we
-again have a `Err(Box<Error>)` as a result.
+`?` then returns the inner error applying `.into()`, so that we
+again have a `Err(Box<Error + Send + Sync>)` as a result.
 
-The `Debug` implementation of `ChainError<T>` (which is returned by `cherr!()`)
+The `Debug` implementation of `chainerror::Error<T>` (which is returned by `context()`)
 prints the `Debug` of `T` prefixed with the stored filename and line number.
 
-`ChainError<T>` in our case is `ChainError<String>`.
+`chainerror::Error<T>` in our case is `chainerror::Error<&str>`.

booksrc/tutorial3.md

@@ -1,12 +1,12 @@
 # Mapping Errors
 
-Now let's get more rust idiomatic by using `.map_err()`.
+Now let's get more rust idiomatic by using `.context()` directly on the previous `Result`.
 
 ~~~rust
 {{#include ../examples/tutorial3.rs}}
 # #[allow(dead_code)]
 # mod chainerror {
-{{#includecomment ../src/lib.rs}}
+{{#rustdoc_include ../src/lib.rs:-1}}
 # }
 ~~~
 
@@ -14,13 +14,13 @@ If you compare the output to the previous example, you will see,
 that:
 
 ~~~
-Error: src/main.rs:19: "func1 error"
+Error: examples/tutorial2.rs:20:16: func1 error
 ~~~
 
 changed to just:
 
 ~~~
-src/main.rs:16: "func1 error"
+examples/tutorial3.rs:17:13: func1 error
 ~~~
 
 This is, because we caught the error of `func1()` in `main()` and print it out ourselves.

booksrc/tutorial4.md

@@ -1,17 +1,12 @@
-# Saving coding chars
+# More information
 
-Because decorating an error with more information should not
-let you jump through hoops, `chainerror` has a quick macro for that.
-
-`mstrerror!()` fits right into `.map_err()` letting you quickly add
-more debug strings.
-
-`mstrerror!()` even understands `format!()` syntax like `println!()`.
+To give more context to the error, you want to use `format!`
+to extend the information in the context string.
 
 ~~~rust
 {{#include ../examples/tutorial4.rs}}
 # #[allow(dead_code)]
 # mod chainerror {
-{{#includecomment ../src/lib.rs}}
+{{#rustdoc_include ../src/lib.rs:-1}}
 # }
 ~~~

booksrc/tutorial5.md

@@ -7,12 +7,11 @@ Sometimes you want to inspect the `source()` of an `Error`.
 {{#include ../examples/tutorial5.rs}}
 # #[allow(dead_code)]
 # mod chainerror {
-{{#includecomment ../src/lib.rs}}
+{{#rustdoc_include ../src/lib.rs:-1}}
 # }
 ~~~
 
 Note, that because we changed the output of the error in `main()` from 
 `Debug` to `Display`, we don't see the error backtrace with filename and line number.
 
-To enable the `Display` backtrace, you have to enable the feature `display-cause` for `chainerror`.
- 
+To use the `Display` backtrace, you have to use the alternative display format output `{:#}`.

booksrc/tutorial6.md

@@ -14,6 +14,6 @@ This is how it looks like, when using those:
 {{#include ../examples/tutorial6.rs}}
 # #[allow(dead_code)]
 # mod chainerror {
-{{#includecomment ../src/lib.rs}}
+{{#rustdoc_include ../src/lib.rs:-1}}
 # }
 ~~~

booksrc/tutorial7.md

@@ -4,15 +4,15 @@
 
 ~~~rust,ignore
 fn is_chain<T: 'static + Display + Debug>(&self) -> bool
-fn downcast_chain_ref<T: 'static + Display + Debug>(&self) -> Option<&ChainError<T>>
-fn downcast_chain_mut<T: 'static + Display + Debug>(&mut self) -> Option<&mut ChainError<T>>
+fn downcast_chain_ref<T: 'static + Display + Debug>(&self) -> Option<&chainerror::Error<T>>
+fn downcast_chain_mut<T: 'static + Display + Debug>(&mut self) -> Option<&mut chainerror::Error<T>>
 fn root_cause(&self) -> Option<&(dyn Error + 'static)>
 fn find_cause<U: Error + 'static>(&self) -> Option<&U>
-fn find_chain_cause<U: Error + 'static>(&self) -> Option<&ChainError<U>>
+fn find_chain_cause<U: Error + 'static>(&self) -> Option<&chainerror::Error<U>>
 fn kind<'a>(&'a self) -> &'a T
 ~~~
 
-Using `downcast_chain_ref::<String>()` gives a `ChainError<String>`, which can be used
+Using `downcast_chain_ref::<String>()` gives a `chainerror::Error<String>`, which can be used
 to call `.find_cause::<io::Error>()`. 
 
 ~~~rust,ignore
@@ -30,6 +30,6 @@ or to use `.root_cause()`, which of course can be of any type implementing `std:
 {{#include ../examples/tutorial7.rs}}
 # #[allow(dead_code)]
 # mod chainerror {
-{{#includecomment ../src/lib.rs}}
+{{#rustdoc_include ../src/lib.rs:-1}}
 # }
 ~~~

booksrc/tutorial8.md

@@ -1,14 +1,14 @@
 # Finding an Error cause
 
-To distinguish the errors occuring in various places, we can define named string errors with the
+To distinguish the errors occurring in various places, we can define named string errors with the
 "new type" pattern.
 
 ~~~rust,ignore
-derive_str_cherr!(Func2Error);
-derive_str_cherr!(Func1Error);
+chainerror::str_context!(Func2Error);
+chainerror::str_context!(Func1Error);
 ~~~
 
-Instead of `ChainError<String>` we now have `struct Func1Error(String)` and `ChainError<Func1Error>`.
+Instead of `chainerror::Error<String>` we now have `struct Func1Error(String)` and `chainerror::Error<Func1Error>`.
 
 In the `main` function you can see, how we can match the different errors.
 
@@ -18,14 +18,14 @@ Also see:
 ~~~
 as a shortcut to
 ~~~rust,ignore
-            if let Some(f2err) = f1err.find_cause::<ChainError<Func2Error>>() {
+            if let Some(f2err) = f1err.find_cause::<chainerror::Error<Func2Error>>() {
 ~~~
-hiding the `ChainError<T>` implementation detail.
+hiding the `chainerror::Error<T>` implementation detail.
 
 ~~~rust
 {{#include ../examples/tutorial8.rs}}
 # #[allow(dead_code)]
 # mod chainerror {
-{{#includecomment ../src/lib.rs}}
+{{#rustdoc_include ../src/lib.rs:-1}}
 # }
 ~~~

booksrc/tutorial9.md

@@ -7,7 +7,7 @@ In this example `func1()` can return either `Func1ErrorFunc2` or `Func1ErrorIO`.
 We might want to `match` on `func1()` with something like:
 
 ~~~rust,ignore
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<Error + Send + Sync>> {
     match func1() {
         Err(e) if let Some(s) = e.downcast_chain_ref::<Func1ErrorIO>() =>
         eprintln!("Func1ErrorIO:\n{:?}", s),
@@ -28,6 +28,6 @@ In the next chapter, we will see, how to solve this more elegantly.
 {{#include ../examples/tutorial9.rs}}
 # #[allow(dead_code)]
 # mod chainerror {
-{{#includecomment ../src/lib.rs}}
+{{#rustdoc_include ../src/lib.rs:-1}}
 # }
 ~~~

examples/example.rs

@@ -1,23 +1,28 @@
-use chainerror::*;
+use chainerror::Context as _;
 use std::error::Error;
+use std::fmt;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-fn func3() -> Result<(), Box<Error>> {
+fn func4() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
-    do_some_io().map_err(mstrerr!("Error reading '{}'", filename))?;
+    do_some_io().context(format!("Error reading '{}'", filename))?;
     Ok(())
 }
 
-derive_str_cherr!(Func2Error);
+fn func3() -> Result<(), Box<dyn Error + Send + Sync>> {
+    func4().annotate()?;
+    Ok(())
+}
 
-fn func2() -> ChainResult<(), Func2Error> {
-    func3().map_err(mstrerr!(Func2Error, "func2 error: calling func3"))?;
+chainerror::str_context!(Func2Error);
+
+fn func2() -> chainerror::Result<(), Func2Error> {
+    func3().context(Func2Error::new("func2 error: calling func3"))?;
     Ok(())
 }
 
@@ -26,8 +31,8 @@ enum Func1Error {
     IO(String),
 }
 
-impl ::std::fmt::Display for Func1Error {
-    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+impl fmt::Display for Func1Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             Func1Error::Func2 => write!(f, "func1 error calling func2"),
             Func1Error::IO(filename) => write!(f, "Error reading '{}'", filename),
@@ -35,21 +40,29 @@ impl ::std::fmt::Display for Func1Error {
     }
 }
 
-impl ::std::fmt::Debug for Func1Error {
-    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+impl fmt::Debug for Func1Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "{}", self)
     }
 }
 
-fn func1() -> ChainResult<(), Func1Error> {
-    func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
+fn func1() -> chainerror::Result<(), Func1Error> {
+    func2().context(Func1Error::Func2)?;
     let filename = String::from("bar.txt");
-    do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
+    do_some_io().context(Func1Error::IO(filename))?;
     Ok(())
 }
 
 fn main() {
     if let Err(e) = func1() {
+        eprintln!("\nDisplay Error {{}}:\n{}", e);
+
+        eprintln!("\nAlternative Display Error {{:#}}:\n{:#}", e);
+
+        eprintln!("\nDebug Error {{:?}}:\n{:?}", e);
+
+        eprintln!("\nAlternative Debug Error {{:#?}}:\n{:#?}\n", e);
+
         match e.kind() {
             Func1Error::Func2 => eprintln!("Main Error Report: func1 error calling func2"),
             Func1Error::IO(filename) => {
@@ -65,7 +78,5 @@ fn main() {
             let ioerror = e.downcast_ref::<io::Error>().unwrap();
             eprintln!("\nThe root cause was: std::io::Error: {:#?}", ioerror);
         }
-
-        eprintln!("\nDebug Error:\n{:?}", e);
     }
 }

examples/tutorial1.rs

@@ -1,26 +1,28 @@
+#![allow(clippy::single_match)]
+#![allow(clippy::redundant_pattern_matching)]
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-fn func2() -> Result<(), Box<Error>> {
+fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(_) = do_some_io() {
         Err("func2 error")?;
     }
     Ok(())
 }
 
-fn func1() -> Result<(), Box<Error>> {
+fn func1() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(_) = func2() {
         Err("func1 error")?;
     }
     Ok(())
 }
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     func1()
 }

examples/tutorial10.rs

@@ -1,18 +1,18 @@
-use chainerror::*;
+use chainerror::Context as _;
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-derive_str_cherr!(Func2Error);
+chainerror::str_context!(Func2Error);
 
-fn func2() -> Result<(), Box<Error>> {
+fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
-    do_some_io().map_err(mstrerr!(Func2Error, "Error reading '{}'", filename))?;
+    do_some_io().context(Func2Error(format!("Error reading '{}'", filename)))?;
     Ok(())
 }
 
@@ -32,14 +32,14 @@ impl ::std::fmt::Display for Func1ErrorKind {
 }
 impl ::std::error::Error for Func1ErrorKind {}
 
-fn func1() -> ChainResult<(), Func1ErrorKind> {
-    func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
+fn func1() -> chainerror::Result<(), Func1ErrorKind> {
+    func2().context(Func1ErrorKind::Func2)?;
     let filename = String::from("bar.txt");
-    do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(filename)))?;
+    do_some_io().context(Func1ErrorKind::IO(filename))?;
     Ok(())
 }
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func1() {
         match e.kind() {
             Func1ErrorKind::Func2 => eprintln!("Main Error Report: func1 error calling func2"),
@@ -53,6 +53,8 @@ fn main() -> Result<(), Box<Error>> {
         }
 
         eprintln!("\nDebug Error:\n{:?}", e);
+
+        std::process::exit(1);
     }
     Ok(())
 }

examples/tutorial11.rs

@@ -1,18 +1,18 @@
-use chainerror::*;
+use chainerror::Context as _;
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-derive_str_cherr!(Func2Error);
+chainerror::str_context!(Func2Error);
 
-fn func2() -> Result<(), Box<Error>> {
+fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
-    do_some_io().map_err(mstrerr!(Func2Error, "Error reading '{}'", filename))?;
+    do_some_io().context(Func2Error(format!("Error reading '{}'", filename)))?;
     Ok(())
 }
 
@@ -38,14 +38,14 @@ impl ::std::fmt::Debug for Func1ErrorKind {
 
 impl ::std::error::Error for Func1ErrorKind {}
 
-fn func1() -> ChainResult<(), Func1ErrorKind> {
-    func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
+fn func1() -> chainerror::Result<(), Func1ErrorKind> {
+    func2().context(Func1ErrorKind::Func2)?;
     let filename = String::from("bar.txt");
-    do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(filename)))?;
+    do_some_io().context(Func1ErrorKind::IO(filename))?;
     Ok(())
 }
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func1() {
         match e.kind() {
             Func1ErrorKind::Func2 => eprintln!("Main Error Report: func1 error calling func2"),
@@ -59,6 +59,8 @@ fn main() -> Result<(), Box<Error>> {
         }
 
         eprintln!("\nDebug Error:\n{:?}", e);
+
+        std::process::exit(1);
     }
     Ok(())
 }

examples/tutorial12.rs

@@ -1,18 +1,18 @@
-use chainerror::*;
+use chainerror::Context as _;
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-derive_str_cherr!(Func2Error);
+chainerror::str_context!(Func2Error);
 
-fn func2() -> Result<(), Box<Error>> {
+fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
-    do_some_io().map_err(mstrerr!(Func2Error, "Error reading '{}'", filename))?;
+    do_some_io().context(Func2Error(format!("Error reading '{}'", filename)))?;
     Ok(())
 }
 
@@ -38,10 +38,10 @@ impl ::std::fmt::Debug for Func1ErrorKind {
 
 impl ::std::error::Error for Func1ErrorKind {}
 
-fn func1() -> ChainResult<(), Func1ErrorKind> {
-    func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
+fn func1() -> chainerror::Result<(), Func1ErrorKind> {
+    func2().context(Func1ErrorKind::Func2)?;
     let filename = String::from("bar.txt");
-    do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(filename)))?;
+    do_some_io().context(Func1ErrorKind::IO(filename))?;
     Ok(())
 }
 
@@ -54,7 +54,7 @@ fn handle_func1errorkind(e: &Func1ErrorKind) {
     }
 }
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func1() {
         match *e {
             Func1ErrorKind::Func2 => eprintln!("Main Error Report: func1 error calling func2"),
@@ -70,6 +70,8 @@ fn main() -> Result<(), Box<Error>> {
         }
 
         eprintln!("\nDebug Error:\n{:?}", e);
+
+        std::process::exit(1);
     }
     Ok(())
 }

examples/tutorial13.rs

@@ -1,31 +1,36 @@
+#![allow(clippy::single_match)]
+#![allow(clippy::redundant_pattern_matching)]
+
 pub mod mycrate {
-    use chainerror::*;
+    use chainerror::Context as _;
+
     use std::io;
 
-    fn do_some_io() -> std::result::Result<(), Box<std::error::Error>> {
+    fn do_some_io() -> std::result::Result<(), Box<dyn std::error::Error + Send + Sync>> {
         Err(io::Error::from(io::ErrorKind::NotFound))?;
         Ok(())
     }
 
-    derive_str_cherr!(Func2Error);
+    chainerror::str_context!(Func2Error);
 
-    fn func2() -> std::result::Result<(), Box<std::error::Error>> {
+    fn func2() -> std::result::Result<(), Box<dyn std::error::Error + Send + Sync>> {
         let filename = "foo.txt";
-        do_some_io().map_err(mstrerr!(Func2Error, "Error reading '{}'", filename))?;
+        do_some_io().context(Func2Error(format!("Error reading '{}'", filename)))?;
         Ok(())
     }
 
-    #[derive(Debug)]
+    #[derive(Debug, Clone)]
     pub enum ErrorKind {
         Func2,
         IO(String),
     }
 
-    pub type Error = ChainError<ErrorKind>;
+    chainerror::err_kind!(Error, ErrorKind);
+
     pub type Result<T> = std::result::Result<T, Error>;
 
-    impl ::std::fmt::Display for ErrorKind {
-        fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+    impl std::fmt::Display for ErrorKind {
+        fn fmt(&self, f: &mut ::std::fmt::Formatter) -> std::fmt::Result {
             match self {
                 ErrorKind::Func2 => write!(f, "func1 error calling func2"),
                 ErrorKind::IO(filename) => write!(f, "Error reading '{}'", filename),
@@ -34,14 +39,14 @@ pub mod mycrate {
     }
 
     pub fn func1() -> Result<()> {
-        func2().map_err(|e| cherr!(e, ErrorKind::Func2))?;
+        func2().context(ErrorKind::Func2)?;
         let filename = String::from("bar.txt");
-        do_some_io().map_err(|e| cherr!(e, ErrorKind::IO(filename)))?;
+        do_some_io().context(ErrorKind::IO(filename))?;
         Ok(())
     }
 }
 
-fn main() -> Result<(), Box<std::error::Error>> {
+fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
     use mycrate::func1;
     use mycrate::ErrorKind;
     use std::error::Error;
@@ -56,7 +61,7 @@ fn main() -> Result<(), Box<std::error::Error>> {
         }
 
         eprintln!();
-        let mut s : &Error = &e;
+        let mut s: &dyn Error = &e;
         while let Some(c) = s.source() {
             if let Some(ioerror) = c.downcast_ref::<io::Error>() {
                 eprintln!("caused by: std::io::Error: {}", ioerror);
@@ -71,6 +76,8 @@ fn main() -> Result<(), Box<std::error::Error>> {
         }
 
         eprintln!("\nDebug Error:\n{:?}", e);
+
+        std::process::exit(1);
     }
     Ok(())
 }

examples/tutorial14.rs

@@ -0,0 +1,222 @@
+#![allow(clippy::single_match)]
+#![allow(clippy::redundant_pattern_matching)]
+
+pub mod mycrate {
+    use std::error::Error as StdError;
+
+    use self::func2mod::{do_some_io, func2};
+
+    pub mod func2mod {
+        use std::error::Error as StdError;
+        use std::io;
+
+        pub enum ErrorKind {
+            IO(String),
+        }
+
+        impl std::fmt::Display for ErrorKind {
+            fn fmt(&self, f: &mut ::std::fmt::Formatter) -> std::fmt::Result {
+                match self {
+                    ErrorKind::IO(s) => std::fmt::Display::fmt(s, f),
+                }
+            }
+        }
+
+        impl std::fmt::Debug for ErrorKind {
+            fn fmt(&self, f: &mut ::std::fmt::Formatter) -> std::fmt::Result {
+                match self {
+                    ErrorKind::IO(s) => std::fmt::Display::fmt(s, f),
+                }
+            }
+        }
+
+        macro_rules! mcontext {
+            ( $k:expr ) => {{
+                |e| {
+                    Error(
+                        $k,
+                        Some(Box::from(e)),
+                        Some(concat!(file!(), ":", line!(), ": ")),
+                    )
+                }
+            }};
+        }
+
+        pub struct Error(
+            ErrorKind,
+            Option<Box<dyn std::error::Error + 'static>>,
+            Option<&'static str>,
+        );
+
+        impl Error {
+            pub fn kind(&self) -> &ErrorKind {
+                &self.0
+            }
+        }
+
+        impl From<ErrorKind> for Error {
+            fn from(e: ErrorKind) -> Self {
+                Error(e, None, None)
+            }
+        }
+
+        impl std::error::Error for Error {
+            fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+                self.1.as_ref().map(|e| e.as_ref())
+            }
+        }
+
+        impl std::fmt::Display for Error {
+            fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+                std::fmt::Display::fmt(&self.0, f)
+            }
+        }
+
+        impl std::fmt::Debug for Error {
+            fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+                if let Some(ref o) = self.2 {
+                    std::fmt::Display::fmt(o, f)?;
+                }
+
+                std::fmt::Debug::fmt(&self.0, f)?;
+
+                if let Some(e) = self.source() {
+                    std::fmt::Display::fmt("\nCaused by:\n", f)?;
+                    std::fmt::Debug::fmt(&e, f)?;
+                }
+                Ok(())
+            }
+        }
+
+        pub fn do_some_io() -> std::result::Result<(), Box<dyn std::error::Error>> {
+            Err(io::Error::from(io::ErrorKind::NotFound))?;
+            Ok(())
+        }
+
+        pub fn func2() -> std::result::Result<(), Error> {
+            let filename = "foo.txt";
+            do_some_io().map_err(mcontext!(ErrorKind::IO(format!(
+                "Error reading '{}'",
+                filename
+            ))))?;
+            Ok(())
+        }
+    }
+
+    #[derive(Debug)]
+    pub enum ErrorKind {
+        Func2,
+        IO(String),
+    }
+
+    impl std::fmt::Display for ErrorKind {
+        fn fmt(&self, f: &mut ::std::fmt::Formatter) -> std::fmt::Result {
+            match self {
+                ErrorKind::Func2 => write!(f, "func1 error calling func2"),
+                ErrorKind::IO(filename) => write!(f, "Error reading '{}'", filename),
+            }
+        }
+    }
+
+    macro_rules! mcontext {
+        ( $k:expr ) => {{
+            |e| {
+                Error(
+                    $k,
+                    Some(Box::from(e)),
+                    Some(concat!(file!(), ":", line!(), ": ")),
+                )
+            }
+        }};
+    }
+
+    pub struct Error(
+        ErrorKind,
+        Option<Box<dyn std::error::Error + 'static>>,
+        Option<&'static str>,
+    );
+
+    impl Error {
+        pub fn kind(&self) -> &ErrorKind {
+            &self.0
+        }
+    }
+
+    impl From<ErrorKind> for Error {
+        fn from(e: ErrorKind) -> Self {
+            Error(e, None, None)
+        }
+    }
+
+    impl std::error::Error for Error {
+        fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+            self.1.as_ref().map(|e| e.as_ref())
+        }
+    }
+
+    impl std::fmt::Display for Error {
+        fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+            std::fmt::Display::fmt(&self.0, f)
+        }
+    }
+
+    impl std::fmt::Debug for Error {
+        fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+            if let Some(ref o) = self.2 {
+                std::fmt::Display::fmt(o, f)?;
+            }
+
+            std::fmt::Debug::fmt(&self.0, f)?;
+            if let Some(e) = self.source() {
+                std::fmt::Display::fmt("\nCaused by:\n", f)?;
+                std::fmt::Debug::fmt(&e, f)?;
+            }
+            Ok(())
+        }
+    }
+
+    pub type Result<T> = std::result::Result<T, Error>;
+
+    pub fn func1() -> Result<()> {
+        func2().map_err(mcontext!(ErrorKind::Func2))?;
+        let filename = String::from("bar.txt");
+        do_some_io().map_err(mcontext!(ErrorKind::IO(filename)))?;
+        Ok(())
+    }
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
+    use mycrate::func1;
+    use mycrate::ErrorKind;
+    use std::error::Error;
+    use std::io;
+
+    if let Err(e) = func1() {
+        match e.kind() {
+            ErrorKind::Func2 => eprintln!("Main Error Report: func1 error calling func2"),
+            ErrorKind::IO(ref filename) => {
+                eprintln!("Main Error Report: func1 error reading '{}'", filename)
+            }
+        }
+
+        eprintln!();
+        let mut s: &dyn Error = &e;
+        while let Some(c) = s.source() {
+            if let Some(ioerror) = c.downcast_ref::<io::Error>() {
+                eprintln!("caused by: std::io::Error: {}", ioerror);
+                match ioerror.kind() {
+                    io::ErrorKind::NotFound => eprintln!("of kind: std::io::ErrorKind::NotFound"),
+                    _ => {}
+                }
+            } else {
+                eprintln!("caused by: {}", c);
+            }
+            s = c;
+        }
+
+        eprintln!("\nDebug Error:\n{:?}", e);
+
+        std::process::exit(1);
+    }
+    Ok(())
+}

examples/tutorial15.rs

@@ -0,0 +1,140 @@
+#![allow(clippy::single_match)]
+#![allow(clippy::redundant_pattern_matching)]
+
+pub mod mycrate {
+    use chainerror::{Context as _, ErrorDown as _};
+
+    use std::io;
+
+    fn do_some_io(_f: &str) -> std::result::Result<(), io::Error> {
+        Err(io::Error::from(io::ErrorKind::NotFound))?;
+        Ok(())
+    }
+
+    chainerror::str_context!(Func2Error);
+
+    fn func2() -> std::result::Result<(), Box<dyn std::error::Error + Send + Sync>> {
+        let filename = "foo.txt";
+        do_some_io(filename).context(Func2Error(format!("Error reading '{}'", filename)))?;
+        Ok(())
+    }
+
+    #[derive(Debug, Clone)]
+    pub enum ErrorKind {
+        Func2,
+        IO(String),
+        FatalError(String),
+        Unknown,
+    }
+
+    chainerror::err_kind!(Error, ErrorKind);
+    pub type Result<T> = std::result::Result<T, Error>;
+
+    impl std::fmt::Display for ErrorKind {
+        fn fmt(&self, f: &mut ::std::fmt::Formatter) -> std::fmt::Result {
+            match self {
+                ErrorKind::FatalError(e) => write!(f, "fatal error {}", e),
+                ErrorKind::Unknown => write!(f, "unknown error"),
+                ErrorKind::Func2 => write!(f, "func1 error calling func2"),
+                ErrorKind::IO(filename) => write!(f, "Error reading '{}'", filename),
+            }
+        }
+    }
+
+    impl ErrorKind {
+        fn from_io_error(e: &io::Error, f: String) -> Self {
+            match e.kind() {
+                io::ErrorKind::BrokenPipe => panic!("Should not happen"),
+                io::ErrorKind::ConnectionReset => {
+                    ErrorKind::FatalError(format!("While reading `{}`: {}", f, e))
+                }
+                _ => ErrorKind::IO(f),
+            }
+        }
+    }
+
+    impl From<&(dyn std::error::Error + 'static + Send + Sync)> for ErrorKind {
+        fn from(e: &(dyn std::error::Error + 'static + Send + Sync)) -> Self {
+            if let Some(_) = e.downcast_ref::<io::Error>() {
+                ErrorKind::IO(String::from("Unknown filename"))
+            } else if let Some(_) = e.downcast_inner_ref::<Func2Error>() {
+                ErrorKind::Func2
+            } else {
+                ErrorKind::Unknown
+            }
+        }
+    }
+
+    impl From<&std::boxed::Box<dyn std::error::Error + 'static + Send + Sync>> for ErrorKind {
+        fn from(e: &std::boxed::Box<dyn std::error::Error + 'static + Send + Sync>) -> Self {
+            Self::from(&**e)
+        }
+    }
+
+    impl From<&Func2Error> for ErrorKind {
+        fn from(_: &Func2Error) -> Self {
+            ErrorKind::Func2
+        }
+    }
+
+    impl From<&io::Error> for ErrorKind {
+        fn from(e: &io::Error) -> Self {
+            ErrorKind::IO(format!("{}", e))
+        }
+    }
+
+    pub fn func1() -> Result<()> {
+        func2().map_err(|e| ErrorKind::from(&e))?;
+
+        let filename = "bar.txt";
+
+        do_some_io(filename).map_context(|e| ErrorKind::from_io_error(e, filename.into()))?;
+        do_some_io(filename).map_context(|_| ErrorKind::IO(filename.into()))?;
+        do_some_io(filename).map_context(|e| ErrorKind::from(e))?;
+
+        Ok(())
+    }
+
+    pub fn super_func1() -> Result<()> {
+        func1().map_context(|e| ErrorKind::from(e))?;
+        Ok(())
+    }
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
+    use mycrate::super_func1;
+    use mycrate::ErrorKind;
+    use std::error::Error;
+    use std::io;
+
+    if let Err(e) = super_func1() {
+        match e.kind() {
+            ErrorKind::FatalError(f) => eprintln!("Main Error Report: Fatal Error: {}", f),
+            ErrorKind::Unknown => eprintln!("Main Error Report: Unknown error occurred"),
+            ErrorKind::Func2 => eprintln!("Main Error Report: func1 error calling func2"),
+            ErrorKind::IO(ref filename) => {
+                eprintln!("Main Error Report: func1 error reading '{}'", filename)
+            }
+        }
+
+        eprintln!();
+        let mut s: &dyn Error = &e;
+        while let Some(c) = s.source() {
+            if let Some(ioerror) = c.downcast_ref::<io::Error>() {
+                eprintln!("caused by: std::io::Error: {}", ioerror);
+                match ioerror.kind() {
+                    io::ErrorKind::NotFound => eprintln!("of kind: std::io::ErrorKind::NotFound"),
+                    _ => {}
+                }
+            } else {
+                eprintln!("caused by: {}", c);
+            }
+            s = c;
+        }
+
+        eprintln!("\nDebug Error:\n{:?}", e);
+
+        std::process::exit(1);
+    }
+    Ok(())
+}

examples/tutorial2.rs

@@ -1,28 +1,27 @@
-use chainerror::*;
+use chainerror::Context as _;
 
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-fn func2() -> Result<(), Box<Error>> {
+fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = do_some_io() {
-        Err(cherr!(e, "func2 error"))?;
+        Err(e).context("func2 error")?;
     }
     Ok(())
 }
 
-fn func1() -> Result<(), Box<Error>> {
+fn func1() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func2() {
-        Err(cherr!(e, "func1 error"))?;
+        Err(e).context("func1 error")?;
     }
     Ok(())
 }
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     func1()
 }

examples/tutorial3.rs

@@ -1,27 +1,27 @@
-use chainerror::*;
+use chainerror::Context as _;
 
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-fn func2() -> Result<(), Box<Error>> {
-    do_some_io().map_err(|e| cherr!(e, "func2 error"))?;
+fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
+    do_some_io().context("func2 error")?;
     Ok(())
 }
 
-fn func1() -> Result<(), Box<Error>> {
-    func2().map_err(|e| cherr!(e, "func1 error"))?;
+fn func1() -> Result<(), Box<dyn Error + Send + Sync>> {
+    func2().context("func1 error")?;
     Ok(())
 }
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func1() {
         eprintln!("{:?}", e);
+        std::process::exit(1);
     }
     Ok(())
 }

examples/tutorial4.rs

@@ -1,27 +1,28 @@
-use chainerror::*;
+use chainerror::Context as _;
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-fn func2() -> Result<(), Box<Error>> {
+fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
-    do_some_io().map_err(mstrerr!("Error reading '{}'", filename))?;
+    do_some_io().context(format!("Error reading '{}'", filename))?;
     Ok(())
 }
 
-fn func1() -> Result<(), Box<Error>> {
-    func2().map_err(mstrerr!("func1 error"))?;
+fn func1() -> Result<(), Box<dyn Error + Send + Sync>> {
+    func2().context("func1 error")?;
     Ok(())
 }
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func1() {
         eprintln!("{:?}", e);
+        std::process::exit(1);
     }
     Ok(())
 }

examples/tutorial5.rs

@@ -1,32 +1,33 @@
-use chainerror::*;
+use chainerror::Context as _;
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-fn func2() -> Result<(), Box<Error>> {
+fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
-    do_some_io().map_err(mstrerr!("Error reading '{}'", filename))?;
+    do_some_io().context(format!("Error reading '{}'", filename))?;
     Ok(())
 }
 
-fn func1() -> Result<(), Box<Error>> {
+fn func1() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func2() {
         if let Some(s) = e.source() {
             eprintln!("func2 failed because of '{}'", s);
-            Err(e).map_err(mstrerr!("func1 error"))?;
+            Err(e).context("func1 error")?;
         }
     }
     Ok(())
 }
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func1() {
         eprintln!("{}", e);
+        std::process::exit(1);
     }
     Ok(())
 }

examples/tutorial6.rs

@@ -1,28 +1,31 @@
-use chainerror::*;
+#![allow(clippy::single_match)]
+#![allow(clippy::redundant_pattern_matching)]
+
+use chainerror::Context as _;
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-fn func2() -> Result<(), Box<Error>> {
+fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
-    do_some_io().map_err(mstrerr!("Error reading '{}'", filename))?;
+    do_some_io().context(format!("Error reading '{}'", filename))?;
     Ok(())
 }
 
-fn func1() -> Result<(), Box<Error>> {
-    func2().map_err(mstrerr!("func1 error"))?;
+fn func1() -> Result<(), Box<dyn Error + Send + Sync>> {
+    func2().context("func1 error")?;
     Ok(())
 }
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func1() {
         eprintln!("Error: {}", e);
-        let mut s = e.as_ref();
+        let mut s: &(dyn Error) = e.as_ref();
         while let Some(c) = s.source() {
             if let Some(ioerror) = c.downcast_ref::<io::Error>() {
                 eprintln!("caused by: std::io::Error: {}", ioerror);
@@ -35,6 +38,7 @@ fn main() -> Result<(), Box<Error>> {
             }
             s = c;
         }
+        std::process::exit(1);
     }
     Ok(())
 }

examples/tutorial7.rs

@@ -1,25 +1,28 @@
-use chainerror::*;
+#![allow(clippy::single_match)]
+#![allow(clippy::redundant_pattern_matching)]
+
+use chainerror::{Context as _, ErrorDown as _};
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-fn func2() -> Result<(), Box<Error>> {
+fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
-    do_some_io().map_err(mstrerr!("Error reading '{}'", filename))?;
+    do_some_io().context(format!("Error reading '{}'", filename))?;
     Ok(())
 }
 
-fn func1() -> Result<(), Box<Error>> {
-    func2().map_err(mstrerr!("func1 error"))?;
+fn func1() -> Result<(), Box<dyn Error + Send + Sync>> {
+    func2().context("func1 error")?;
     Ok(())
 }
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func1() {
         eprintln!("Error: {}", e);
         if let Some(s) = e.downcast_chain_ref::<String>() {
@@ -36,6 +39,7 @@ fn main() -> Result<(), Box<Error>> {
                 eprintln!("The root cause was: std::io::Error: {:#?}", ioerror);
             }
         }
+        std::process::exit(1);
     }
     Ok(())
 }

examples/tutorial8.rs

@@ -1,34 +1,34 @@
-use chainerror::*;
+use chainerror::{Context as _, ErrorDown as _};
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-derive_str_cherr!(Func2Error);
+chainerror::str_context!(Func2Error);
 
-fn func2() -> Result<(), Box<Error>> {
+fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
-    do_some_io().map_err(mstrerr!(Func2Error, "Error reading '{}'", filename))?;
+    do_some_io().context(Func2Error(format!("Error reading '{}'", filename)))?;
     Ok(())
 }
 
-derive_str_cherr!(Func1Error);
+chainerror::str_context!(Func1Error);
 
-fn func1() -> Result<(), Box<Error>> {
-    func2().map_err(mstrerr!(Func1Error, "func1 error"))?;
+fn func1() -> Result<(), Box<dyn Error + Send + Sync>> {
+    func2().context(Func1Error::new("func1 error"))?;
     Ok(())
 }
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func1() {
         if let Some(f1err) = e.downcast_chain_ref::<Func1Error>() {
             eprintln!("Func1Error: {}", f1err);
 
-            if let Some(f2err) = f1err.find_cause::<ChainError<Func2Error>>() {
+            if let Some(f2err) = f1err.find_cause::<chainerror::Error<Func2Error>>() {
                 eprintln!("Func2Error: {}", f2err);
             }
 
@@ -36,6 +36,7 @@ fn main() -> Result<(), Box<Error>> {
                 eprintln!("Debug Func2Error:\n{:?}", f2err);
             }
         }
+        std::process::exit(1);
     }
     Ok(())
 }

examples/tutorial9.rs

@@ -1,40 +1,41 @@
-use chainerror::*;
+use chainerror::{Context as _, ErrorDown};
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
-fn do_some_io() -> Result<(), Box<Error>> {
+fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-derive_str_cherr!(Func2Error);
+chainerror::str_context!(Func2Error);
 
-fn func2() -> Result<(), Box<Error>> {
+fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
-    do_some_io().map_err(mstrerr!(Func2Error, "Error reading '{}'", filename))?;
+    do_some_io().context(Func2Error(format!("Error reading '{}'", filename)))?;
     Ok(())
 }
 
-derive_str_cherr!(Func1ErrorFunc2);
-derive_str_cherr!(Func1ErrorIO);
+chainerror::str_context!(Func1ErrorFunc2);
+chainerror::str_context!(Func1ErrorIO);
 
-fn func1() -> Result<(), Box<Error>> {
-    func2().map_err(mstrerr!(Func1ErrorFunc2, "func1 error calling func2"))?;
+fn func1() -> Result<(), Box<dyn Error + Send + Sync>> {
+    func2().context(Func1ErrorFunc2::new("func1 error calling func2"))?;
     let filename = "bar.txt";
-    do_some_io().map_err(mstrerr!(Func1ErrorIO, "Error reading '{}'", filename))?;
+    do_some_io().context(Func1ErrorIO(format!("Error reading '{}'", filename)))?;
     Ok(())
 }
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func1() {
-        if let Some(s) = e.downcast_ref::<ChainError<Func1ErrorIO>>() {
+        if let Some(s) = e.downcast_ref::<chainerror::Error<Func1ErrorIO>>() {
             eprintln!("Func1ErrorIO:\n{:?}", s);
         }
 
         if let Some(s) = e.downcast_chain_ref::<Func1ErrorFunc2>() {
             eprintln!("Func1ErrorFunc2:\n{:?}", s);
         }
+        std::process::exit(1);
     }
     Ok(())
 }

tests/test_basic.rs

@@ -0,0 +1,33 @@
+use chainerror::Context;
+
+#[test]
+fn test_basic() {
+    use std::path::PathBuf;
+    type BoxedError = Box<dyn std::error::Error + Send + Sync>;
+    fn read_config_file(path: PathBuf) -> Result<(), BoxedError> {
+        // do stuff, return other errors
+        let _buf = std::fs::read_to_string(&path).context(format!("Reading file: {:?}", &path))?;
+        // do stuff, return other errors
+        Ok(())
+    }
+    fn process_config_file() -> Result<(), BoxedError> {
+        // do stuff, return other errors
+        read_config_file("_non_existent.txt".into()).context("read the config file")?;
+        // do stuff, return other errors
+        Ok(())
+    }
+
+    if let Err(e) = process_config_file() {
+        let os_notfound_error = std::io::Error::from_raw_os_error(2);
+        let s = format!("{:?}", e);
+        let lines = s.lines().collect::<Vec<_>>();
+        assert_eq!(lines.len(), 5);
+        assert!(lines[0].starts_with("tests/test_basic.rs:"));
+        assert_eq!(lines[1], "Caused by:");
+        assert!(lines[2].starts_with("tests/test_basic.rs:"));
+        assert_eq!(lines[3], "Caused by:");
+        assert_eq!(lines[4], format!("{:?}", os_notfound_error));
+    } else {
+        panic!();
+    }
+}

tests/test_iter.rs

@@ -1,28 +1,29 @@
-use chainerror::*;
+use chainerror::Context;
 use std::error::Error;
-use std::fmt::Write;
 use std::io;
 
 #[test]
-fn test_iter() -> Result<(), Box<Error>> {
-    let err = io::Error::from(io::ErrorKind::NotFound);
-    let err = cherr!(err, "1");
-    let err = cherr!(err, "2");
-    let err = cherr!(err, "3");
-    let err = cherr!(err, "4");
-    let err = cherr!(err, "5");
-    let err = cherr!(err, "6");
+fn test_iter() -> Result<(), Box<dyn Error + Send + Sync>> {
+    use std::fmt::Write;
+    let err: Result<(), _> = Err(io::Error::from(io::ErrorKind::NotFound));
+    let err = err.context("1");
+    let err = err.context("2");
+    let err = err.context("3");
+    let err = err.context("4");
+    let err = err.context("5");
+    let err = err.context("6");
+    let err = err.err().unwrap();
 
     let mut res = String::new();
 
     for e in err.iter() {
-        write!(res, "{}", e.to_string())?;
+        write!(res, "{}", e)?;
     }
     assert_eq!(res, "654321entity not found");
 
     let io_error: Option<&io::Error> = err
         .iter()
-        .filter_map(Error::downcast_ref::<io::Error>)
+        .filter_map(<dyn Error>::downcast_ref::<io::Error>)
         .next();
 
     assert_eq!(io_error.unwrap().kind(), io::ErrorKind::NotFound);
@@ -31,14 +32,40 @@ fn test_iter() -> Result<(), Box<Error>> {
 }
 
 #[test]
-fn test_find_cause() -> Result<(), Box<Error>> {
-    let err = io::Error::from(io::ErrorKind::NotFound);
-    let err = cherr!(err, "1");
-    let err = cherr!(err, "2");
-    let err = cherr!(err, "3");
-    let err = cherr!(err, "4");
-    let err = cherr!(err, "5");
-    let err = cherr!(err, "6");
+fn test_iter_alternate() -> Result<(), Box<dyn Error + Send + Sync>> {
+    let err: Result<(), _> = Err(io::Error::from(io::ErrorKind::NotFound));
+    let err = err.context("1");
+    let err = err.context("2");
+    let err = err.context("3");
+    let err = err.context("4");
+    let err = err.context("5");
+    let err = err.context("6");
+    let err = err.err().unwrap();
+
+    let res = format!("{:#}", err);
+
+    assert_eq!(res, format!("6\nCaused by:\n  5\nCaused by:\n  4\nCaused by:\n  3\nCaused by:\n  2\nCaused by:\n  1\nCaused by:\n  {:#}", io::Error::from(io::ErrorKind::NotFound)));
+
+    let io_error: Option<&io::Error> = err
+        .iter()
+        .filter_map(<dyn Error>::downcast_ref::<io::Error>)
+        .next();
+
+    assert_eq!(io_error.unwrap().kind(), io::ErrorKind::NotFound);
+
+    Ok(())
+}
+
+#[test]
+fn test_find_cause() -> Result<(), Box<dyn Error + Send + Sync>> {
+    let err: Result<(), _> = Err(io::Error::from(io::ErrorKind::NotFound));
+    let err = err.context("1");
+    let err = err.context("2");
+    let err = err.context("3");
+    let err = err.context("4");
+    let err = err.context("5");
+    let err = err.context("6");
+    let err = err.err().unwrap();
 
     let io_error: Option<&io::Error> = err.find_cause::<io::Error>();
 
@@ -48,17 +75,18 @@ fn test_find_cause() -> Result<(), Box<Error>> {
 }
 
 #[test]
-fn test_root_cause() -> Result<(), Box<Error>> {
-    let err = io::Error::from(io::ErrorKind::NotFound);
-    let err = cherr!(err, "1");
-    let err = cherr!(err, "2");
-    let err = cherr!(err, "3");
-    let err = cherr!(err, "4");
-    let err = cherr!(err, "5");
-    let err = cherr!(err, "6");
+fn test_root_cause() -> Result<(), Box<dyn Error + Send + Sync>> {
+    let err: Result<(), _> = Err(io::Error::from(io::ErrorKind::NotFound));
+    let err = err.context("1");
+    let err = err.context("2");
+    let err = err.context("3");
+    let err = err.context("4");
+    let err = err.context("5");
+    let err = err.context("6");
+    let err = err.err().unwrap();
 
     let err: Option<&(dyn std::error::Error + 'static)> = err.root_cause();
-    let io_error: Option<&io::Error> = err.and_then(Error::downcast_ref::<io::Error>);
+    let io_error: Option<&io::Error> = err.and_then(<dyn Error>::downcast_ref::<io::Error>);
 
     assert_eq!(io_error.unwrap().kind(), io::ErrorKind::NotFound);
 

theme/book.js

@@ -1,611 +0,0 @@
-"use strict";
-
-// Fix back button cache problem
-window.onunload = function () { };
-
-// Global variable, shared between modules
-function playpen_text(playpen) {
-    let code_block = playpen.querySelector("code");
-
-    if (window.ace && code_block.classList.contains("editable")) {
-        let editor = window.ace.edit(code_block);
-        return editor.getValue();
-    } else {
-        return code_block.textContent;
-    }
-}
-
-(function codeSnippets() {
-    // Hide Rust code lines prepended with a specific character
-    var hiding_character = "#";
-
-    function fetch_with_timeout(url, options, timeout = 6000) {
-        return Promise.race([
-            fetch(url, options),
-            new Promise((_, reject) => setTimeout(() => reject(new Error('timeout')), timeout))
-        ]);
-    }
-
-    var playpens = Array.from(document.querySelectorAll(".playpen"));
-    if (playpens.length > 0) {
-        fetch_with_timeout("https://play.rust-lang.org/meta/crates", {
-            headers: {
-                'Content-Type': "application/json",
-            },
-            method: 'POST',
-            mode: 'cors',
-        })
-        .then(response => response.json())
-        .then(response => {
-            // get list of crates available in the rust playground
-            let playground_crates = response.crates.map(item => item["id"]);
-            playpens.forEach(block => handle_crate_list_update(block, playground_crates));
-        });
-    }
-
-    function handle_crate_list_update(playpen_block, playground_crates) {
-        // update the play buttons after receiving the response
-        update_play_button(playpen_block, playground_crates);
-
-        // and install on change listener to dynamically update ACE editors
-        if (window.ace) {
-            let code_block = playpen_block.querySelector("code");
-            if (code_block.classList.contains("editable")) {
-                let editor = window.ace.edit(code_block);
-                editor.addEventListener("change", function (e) {
-                    update_play_button(playpen_block, playground_crates);
-                });
-            }
-        }
-    }
-
-    // updates the visibility of play button based on `no_run` class and
-    // used crates vs ones available on http://play.rust-lang.org
-    function update_play_button(pre_block, playground_crates) {
-        var play_button = pre_block.querySelector(".play-button");
-
-        // skip if code is `no_run`
-        if (pre_block.querySelector('code').classList.contains("no_run")) {
-            play_button.classList.add("hidden");
-            return;
-        }
-
-        // get list of `extern crate`'s from snippet
-        var txt = playpen_text(pre_block);
-        var re = /extern\s+crate\s+([a-zA-Z_0-9]+)\s*;/g;
-        var snippet_crates = [];
-        var item;
-        while (item = re.exec(txt)) {
-            snippet_crates.push(item[1]);
-        }
-
-        // check if all used crates are available on play.rust-lang.org
-        var all_available = snippet_crates.every(function (elem) {
-            return playground_crates.indexOf(elem) > -1;
-        });
-
-        if (all_available) {
-            play_button.classList.remove("hidden");
-        } else {
-            play_button.classList.add("hidden");
-        }
-    }
-
-    function run_rust_code(code_block) {
-        var result_block = code_block.querySelector(".result");
-        if (!result_block) {
-            result_block = document.createElement('code');
-            result_block.className = 'result hljs language-bash';
-
-            code_block.append(result_block);
-        }
-
-        let text = playpen_text(code_block);
-
-        var params = {
-            channel: "stable",
-            mode: "debug",
-            edition: "2018",
-            crateType: "bin",
-            tests: false,
-            code: text
-        };
-
-        if (text.indexOf("#![feature") !== -1) {
-            params.channel = "nightly";
-        }
-
-        if (text.indexOf("#[test]") !== -1) {
-            params.tests = "true";
-        }
-
-        if (text.indexOf("#![crate_type=\"lib\"]") !== -1) {
-            params.crateType = "lib";
-        }
-
-        result_block.innerText = "Running...";
-
-        fetch_with_timeout("https://play.rust-lang.org/execute", {
-            headers: {
-                'Content-Type': "application/json",
-            },
-            method: 'POST',
-            mode: 'cors',
-            body: JSON.stringify(params)
-        })
-        .then(response => response.json())
-        .then(response => result_block.innerText = response.stderr + "\n\n" + response.stdout)
-        .catch(error => result_block.innerText = "Playground Communication: " + error.message);
-    }
-
-    // Syntax highlighting Configuration
-    hljs.configure({
-        tabReplace: '    ', // 4 spaces
-        languages: [],      // Languages used for auto-detection
-    });
-
-    if (window.ace) {
-        // language-rust class needs to be removed for editable
-        // blocks or highlightjs will capture events
-        Array
-            .from(document.querySelectorAll('code.editable'))
-            .forEach(function (block) { block.classList.remove('language-rust'); });
-
-        Array
-            .from(document.querySelectorAll('code:not(.editable)'))
-            .forEach(function (block) { hljs.highlightBlock(block); });
-    } else {
-        Array
-            .from(document.querySelectorAll('code'))
-            .forEach(function (block) { hljs.highlightBlock(block); });
-    }
-
-    // Adding the hljs class gives code blocks the color css
-    // even if highlighting doesn't apply
-    Array
-        .from(document.querySelectorAll('code'))
-        .forEach(function (block) { block.classList.add('hljs'); });
-
-    Array.from(document.querySelectorAll("code.language-rust")).forEach(function (block) {
-
-        var code_block = block;
-        var pre_block = block.parentNode;
-        // hide lines
-        var lines = code_block.innerHTML.split("\n");
-        var first_non_hidden_line = false;
-        var lines_hidden = false;
-        var trimmed_line = "";
-
-        for (var n = 0; n < lines.length; n++) {
-            trimmed_line = lines[n].trim();
-            if (trimmed_line[0] == hiding_character && trimmed_line[1] != hiding_character) {
-                if (first_non_hidden_line) {
-                    lines[n] = "<span class=\"hidden\">" + "\n" + lines[n].replace(/(\s*)# ?/, "$1") + "</span>";
-                }
-                else {
-                    lines[n] = "<span class=\"hidden\">" + lines[n].replace(/(\s*)# ?/, "$1") + "\n" + "</span>";
-                }
-                lines_hidden = true;
-            }
-            else if (first_non_hidden_line) {
-                lines[n] = "\n" + lines[n];
-            }
-            else {
-                first_non_hidden_line = true;
-            }
-            if (trimmed_line[0] == hiding_character && trimmed_line[1] == hiding_character) {
-                lines[n] = lines[n].replace("##", "#")
-            }
-        }
-        code_block.innerHTML = lines.join("");
-
-        // If no lines were hidden, return
-        if (!lines_hidden) { return; }
-
-        var buttons = document.createElement('div');
-        buttons.className = 'buttons';
-        buttons.innerHTML = "<button class=\"fa fa-expand\" title=\"Show hidden lines\" aria-label=\"Show hidden lines\"></button>";
-
-        // add expand button
-        pre_block.insertBefore(buttons, pre_block.firstChild);
-
-        pre_block.querySelector('.buttons').addEventListener('click', function (e) {
-            if (e.target.classList.contains('fa-expand')) {
-                var lines = pre_block.querySelectorAll('span.hidden');
-
-                e.target.classList.remove('fa-expand');
-                e.target.classList.add('fa-compress');
-                e.target.title = 'Hide lines';
-                e.target.setAttribute('aria-label', e.target.title);
-
-                Array.from(lines).forEach(function (line) {
-                    line.classList.remove('hidden');
-                    line.classList.add('unhidden');
-                });
-            } else if (e.target.classList.contains('fa-compress')) {
-                var lines = pre_block.querySelectorAll('span.unhidden');
-
-                e.target.classList.remove('fa-compress');
-                e.target.classList.add('fa-expand');
-                e.target.title = 'Show hidden lines';
-                e.target.setAttribute('aria-label', e.target.title);
-
-                Array.from(lines).forEach(function (line) {
-                    line.classList.remove('unhidden');
-                    line.classList.add('hidden');
-                });
-            }
-        });
-    });
-
-    Array.from(document.querySelectorAll('pre code')).forEach(function (block) {
-        var pre_block = block.parentNode;
-        if (!pre_block.classList.contains('playpen')) {
-            var buttons = pre_block.querySelector(".buttons");
-            if (!buttons) {
-                buttons = document.createElement('div');
-                buttons.className = 'buttons';
-                pre_block.insertBefore(buttons, pre_block.firstChild);
-            }
-
-            var clipButton = document.createElement('button');
-            clipButton.className = 'fa fa-copy clip-button';
-            clipButton.title = 'Copy to clipboard';
-            clipButton.setAttribute('aria-label', clipButton.title);
-            clipButton.innerHTML = '<i class=\"tooltiptext\"></i>';
-
-            buttons.insertBefore(clipButton, buttons.firstChild);
-        }
-    });
-
-    // Process playpen code blocks
-    Array.from(document.querySelectorAll(".playpen")).forEach(function (pre_block) {
-        // Add play button
-        var buttons = pre_block.querySelector(".buttons");
-        if (!buttons) {
-            buttons = document.createElement('div');
-            buttons.className = 'buttons';
-            pre_block.insertBefore(buttons, pre_block.firstChild);
-        }
-
-        var runCodeButton = document.createElement('button');
-        runCodeButton.className = 'fa fa-play play-button';
-        runCodeButton.hidden = true;
-        runCodeButton.title = 'Run this code';
-        runCodeButton.setAttribute('aria-label', runCodeButton.title);
-
-        var copyCodeClipboardButton = document.createElement('button');
-        copyCodeClipboardButton.className = 'fa fa-copy clip-button';
-        copyCodeClipboardButton.innerHTML = '<i class="tooltiptext"></i>';
-        copyCodeClipboardButton.title = 'Copy to clipboard';
-        copyCodeClipboardButton.setAttribute('aria-label', copyCodeClipboardButton.title);
-
-        buttons.insertBefore(runCodeButton, buttons.firstChild);
-        buttons.insertBefore(copyCodeClipboardButton, buttons.firstChild);
-
-        runCodeButton.addEventListener('click', function (e) {
-            run_rust_code(pre_block);
-        });
-
-        let code_block = pre_block.querySelector("code");
-        if (window.ace && code_block.classList.contains("editable")) {
-            var undoChangesButton = document.createElement('button');
-            undoChangesButton.className = 'fa fa-history reset-button';
-            undoChangesButton.title = 'Undo changes';
-            undoChangesButton.setAttribute('aria-label', undoChangesButton.title);
-
-            buttons.insertBefore(undoChangesButton, buttons.firstChild);
-
-            undoChangesButton.addEventListener('click', function () {
-                let editor = window.ace.edit(code_block);
-                editor.setValue(editor.originalCode);
-                editor.clearSelection();
-            });
-        }
-    });
-})();
-
-(function themes() {
-    var html = document.querySelector('html');
-    var themeToggleButton = document.getElementById('theme-toggle');
-    var themePopup = document.getElementById('theme-list');
-    var themeColorMetaTag = document.querySelector('meta[name="theme-color"]');
-    var stylesheets = {
-        ayuHighlight: document.querySelector("[href$='ayu-highlight.css']"),
-        tomorrowNight: document.querySelector("[href$='tomorrow-night.css']"),
-        highlight: document.querySelector("[href$='highlight.css']"),
-    };
-
-    function showThemes() {
-        themePopup.style.display = 'block';
-        themeToggleButton.setAttribute('aria-expanded', true);
-        themePopup.querySelector("button#" + document.body.className).focus();
-    }
-
-    function hideThemes() {
-        themePopup.style.display = 'none';
-        themeToggleButton.setAttribute('aria-expanded', false);
-        themeToggleButton.focus();
-    }
-
-    function set_theme(theme) {
-        let ace_theme;
-
-        if (theme == 'coal' || theme == 'navy') {
-            stylesheets.ayuHighlight.disabled = true;
-            stylesheets.tomorrowNight.disabled = false;
-            stylesheets.highlight.disabled = true;
-
-            ace_theme = "ace/theme/tomorrow_night";
-        } else if (theme == 'ayu') {
-            stylesheets.ayuHighlight.disabled = false;
-            stylesheets.tomorrowNight.disabled = true;
-            stylesheets.highlight.disabled = true;
-
-            ace_theme = "ace/theme/tomorrow_night";
-        } else {
-            stylesheets.ayuHighlight.disabled = true;
-            stylesheets.tomorrowNight.disabled = true;
-            stylesheets.highlight.disabled = false;
-
-            ace_theme = "ace/theme/dawn";
-        }
-
-        setTimeout(function () {
-            themeColorMetaTag.content = getComputedStyle(document.body).backgroundColor;
-        }, 1);
-
-        if (window.ace && window.editors) {
-            window.editors.forEach(function (editor) {
-                editor.setTheme(ace_theme);
-            });
-        }
-
-        var previousTheme;
-        try { previousTheme = localStorage.getItem('mdbook-theme'); } catch (e) { }
-        if (previousTheme === null || previousTheme === undefined) { previousTheme = default_theme; }
-
-        try { localStorage.setItem('mdbook-theme', theme); } catch (e) { }
-
-        document.body.className = theme;
-        html.classList.remove(previousTheme);
-        html.classList.add(theme);
-    }
-
-    // Set theme
-    var theme;
-    try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
-    if (theme === null || theme === undefined) { theme = default_theme; }
-
-    set_theme(theme);
-
-    themeToggleButton.addEventListener('click', function () {
-        if (themePopup.style.display === 'block') {
-            hideThemes();
-        } else {
-            showThemes();
-        }
-    });
-
-    themePopup.addEventListener('click', function (e) {
-        var theme = e.target.id || e.target.parentElement.id;
-        set_theme(theme);
-    });
-
-    themePopup.addEventListener('focusout', function(e) {
-        // e.relatedTarget is null in Safari and Firefox on macOS (see workaround below)
-        if (!!e.relatedTarget && !themeToggleButton.contains(e.relatedTarget) && !themePopup.contains(e.relatedTarget)) {
-            hideThemes();
-        }
-    });
-
-    // Should not be needed, but it works around an issue on macOS & iOS: https://github.com/rust-lang-nursery/mdBook/issues/628
-    document.addEventListener('click', function(e) {
-        if (themePopup.style.display === 'block' && !themeToggleButton.contains(e.target) && !themePopup.contains(e.target)) {
-            hideThemes();
-        }
-    });
-
-    document.addEventListener('keydown', function (e) {
-        if (e.altKey || e.ctrlKey || e.metaKey || e.shiftKey) { return; }
-        if (!themePopup.contains(e.target)) { return; }
-
-        switch (e.key) {
-            case 'Escape':
-                e.preventDefault();
-                hideThemes();
-                break;
-            case 'ArrowUp':
-                e.preventDefault();
-                var li = document.activeElement.parentElement;
-                if (li && li.previousElementSibling) {
-                    li.previousElementSibling.querySelector('button').focus();
-                }
-                break;
-            case 'ArrowDown':
-                e.preventDefault();
-                var li = document.activeElement.parentElement;
-                if (li && li.nextElementSibling) {
-                    li.nextElementSibling.querySelector('button').focus();
-                }
-                break;
-            case 'Home':
-                e.preventDefault();
-                themePopup.querySelector('li:first-child button').focus();
-                break;
-            case 'End':
-                e.preventDefault();
-                themePopup.querySelector('li:last-child button').focus();
-                break;
-        }
-    });
-})();
-
-(function sidebar() {
-    var html = document.querySelector("html");
-    var sidebar = document.getElementById("sidebar");
-    var sidebarLinks = document.querySelectorAll('#sidebar a');
-    var sidebarToggleButton = document.getElementById("sidebar-toggle");
-    var firstContact = null;
-
-    function showSidebar() {
-        html.classList.remove('sidebar-hidden')
-        html.classList.add('sidebar-visible');
-        Array.from(sidebarLinks).forEach(function (link) {
-            link.setAttribute('tabIndex', 0);
-        });
-        sidebarToggleButton.setAttribute('aria-expanded', true);
-        sidebar.setAttribute('aria-hidden', false);
-        try { localStorage.setItem('mdbook-sidebar', 'visible'); } catch (e) { }
-    }
-
-    function hideSidebar() {
-        html.classList.remove('sidebar-visible')
-        html.classList.add('sidebar-hidden');
-        Array.from(sidebarLinks).forEach(function (link) {
-            link.setAttribute('tabIndex', -1);
-        });
-        sidebarToggleButton.setAttribute('aria-expanded', false);
-        sidebar.setAttribute('aria-hidden', true);
-        try { localStorage.setItem('mdbook-sidebar', 'hidden'); } catch (e) { }
-    }
-
-    // Toggle sidebar
-    sidebarToggleButton.addEventListener('click', function sidebarToggle() {
-        if (html.classList.contains("sidebar-hidden")) {
-            showSidebar();
-        } else if (html.classList.contains("sidebar-visible")) {
-            hideSidebar();
-        } else {
-            if (getComputedStyle(sidebar)['transform'] === 'none') {
-                hideSidebar();
-            } else {
-                showSidebar();
-            }
-        }
-    });
-
-    document.addEventListener('touchstart', function (e) {
-        firstContact = {
-            x: e.touches[0].clientX,
-            time: Date.now()
-        };
-    }, { passive: true });
-
-    document.addEventListener('touchmove', function (e) {
-        if (!firstContact)
-            return;
-
-        var curX = e.touches[0].clientX;
-        var xDiff = curX - firstContact.x,
-            tDiff = Date.now() - firstContact.time;
-
-        if (tDiff < 250 && Math.abs(xDiff) >= 150) {
-            if (xDiff >= 0 && firstContact.x < Math.min(document.body.clientWidth * 0.25, 300))
-                showSidebar();
-            else if (xDiff < 0 && curX < 300)
-                hideSidebar();
-
-            firstContact = null;
-        }
-    }, { passive: true });
-
-    // Scroll sidebar to current active section
-    var activeSection = sidebar.querySelector(".active");
-    if (activeSection) {
-        sidebar.scrollTop = activeSection.offsetTop;
-    }
-})();
-
-(function chapterNavigation() {
-    document.addEventListener('keydown', function (e) {
-        if (e.altKey || e.ctrlKey || e.metaKey || e.shiftKey) { return; }
-        if (window.search && window.search.hasFocus()) { return; }
-
-        switch (e.key) {
-            case 'ArrowRight':
-                e.preventDefault();
-                var nextButton = document.querySelector('.nav-chapters.next');
-                if (nextButton) {
-                    window.location.href = nextButton.href;
-                }
-                break;
-            case 'ArrowLeft':
-                e.preventDefault();
-                var previousButton = document.querySelector('.nav-chapters.previous');
-                if (previousButton) {
-                    window.location.href = previousButton.href;
-                }
-                break;
-        }
-    });
-})();
-
-(function clipboard() {
-    var clipButtons = document.querySelectorAll('.clip-button');
-
-    function hideTooltip(elem) {
-        elem.firstChild.innerText = "";
-        elem.className = 'fa fa-copy clip-button';
-    }
-
-    function showTooltip(elem, msg) {
-        elem.firstChild.innerText = msg;
-        elem.className = 'fa fa-copy tooltipped';
-    }
-
-    var clipboardSnippets = new Clipboard('.clip-button', {
-        text: function (trigger) {
-            hideTooltip(trigger);
-            let playpen = trigger.closest("pre");
-            return playpen_text(playpen);
-        }
-    });
-
-    Array.from(clipButtons).forEach(function (clipButton) {
-        clipButton.addEventListener('mouseout', function (e) {
-            hideTooltip(e.currentTarget);
-        });
-    });
-
-    clipboardSnippets.on('success', function (e) {
-        e.clearSelection();
-        showTooltip(e.trigger, "Copied!");
-    });
-
-    clipboardSnippets.on('error', function (e) {
-        showTooltip(e.trigger, "Clipboard error!");
-    });
-})();
-
-(function scrollToTop () {
-    var menuTitle = document.querySelector('.menu-title');
-
-    menuTitle.addEventListener('click', function () {
-        document.scrollingElement.scrollTo({ top: 0, behavior: 'smooth' });
-    });
-})();
-
-(function autoHideMenu() {
-    var menu = document.getElementById('menu-bar');
-
-    var previousScrollTop = document.scrollingElement.scrollTop;
-
-    document.addEventListener('scroll', function () {
-        if (menu.classList.contains('folded') && document.scrollingElement.scrollTop < previousScrollTop) {
-            menu.classList.remove('folded');
-        } else if (!menu.classList.contains('folded') && document.scrollingElement.scrollTop > previousScrollTop) {
-            menu.classList.add('folded');
-        }
-
-        if (!menu.classList.contains('bordered') && document.scrollingElement.scrollTop > 0) {
-            menu.classList.add('bordered');
-        }
-
-        if (menu.classList.contains('bordered') && document.scrollingElement.scrollTop === 0) {
-            menu.classList.remove('bordered');
-        }
-
-        previousScrollTop = document.scrollingElement.scrollTop;
-    }, { passive: true });
-})();