Add Natvis visualizations for ArrayVec and ArrayString types

.github/workflows/ci.yml

@@ -12,10 +12,10 @@ env:
 
 jobs:
   tests:
-    runs-on: ubuntu-latest
     continue-on-error: ${{ matrix.experimental }}
     strategy:
       matrix:
+        os: [ubuntu-latest]
         include:
           - rust: 1.51.0 # MSRV
             features: serde
@@ -29,6 +29,12 @@ jobs:
           - rust: nightly
             features: serde
             experimental: false
+          - rust: nightly
+            features: debugger_visualizer
+            os: windows-latest
+            experimental: false
+
+    runs-on: ${{ matrix.os }}
 
     steps:
       - uses: actions/checkout@v2
@@ -43,6 +49,9 @@ jobs:
           cargo doc --verbose --features "${{ matrix.features }}" --no-deps
           cargo test --verbose --features "${{ matrix.features }}"
           cargo test --release --verbose --features "${{ matrix.features }}"
+      - name: Test debugger visualizer
+        if: matrix.features == 'debugger_visualizer'
+        run: cargo test --release --verbose --features "${{ matrix.features }}" --test debugger_visualizer -- --test-threads=1
       - name: Test run benchmarks
         if: matrix.bench != ''
         run: cargo test -v --benches

Cargo.toml

@@ -25,6 +25,8 @@ version = "1.0"
 [dev-dependencies]
 matches = { version = "0.1" }
 bencher = "0.1.4"
+debugger_test = "0.1"
+debugger_test_parser = "0.1"
 
 [[bench]]
 name = "extend"
@@ -34,10 +36,25 @@ harness = false
 name = "arraystring"
 harness = false
 
+[[test]]
+name = "debugger_visualizer"
+path = "tests/debugger_visualizer.rs"
+required-features = ["debugger_visualizer"]
+# Do not run these tests by default. These tests need to
+# be run with the additional rustc flag `--test-threads=1`
+# since each test causes a debugger to attach to the current
+# test process. If multiple debuggers try to attach at the same
+# time, the test will fail.
+test = false
+
 [features]
 default = ["std"]
 std = []
 
+# UNSTABLE FEATURES (requires Rust nightly)
+# Enable to use the #[debugger_visualizer] attribute.
+debugger_visualizer = []
+
 [profile.bench]
 debug = true
 [profile.release]

debug_metadata/README.md

@@ -0,0 +1,111 @@
+## Debugger Visualizers
+
+Many languages and debuggers enable developers to control how a type is
+displayed in a debugger. These are called "debugger visualizations" or "debugger
+views".
+
+The Windows debuggers (WinDbg\CDB) support defining custom debugger visualizations using
+the `Natvis` framework. To use Natvis, developers write XML documents using the natvis
+schema that describe how debugger types should be displayed with the `.natvis` extension.
+(See: https://docs.microsoft.com/en-us/visualstudio/debugger/create-custom-views-of-native-objects?view=vs-2019)
+The Natvis files provide patterns which match type names a description of how to display
+those types.
+
+The Natvis schema can be found either online (See: https://code.visualstudio.com/docs/cpp/natvis#_schema)
+or locally at `<VS Installation Folder>\Xml\Schemas\1033\natvis.xsd`.
+
+The GNU debugger (GDB) supports defining custom debugger views using Pretty Printers.
+Pretty printers are written as python scripts that describe how a type should be displayed
+when loaded up in GDB/LLDB. (See: https://sourceware.org/gdb/onlinedocs/gdb/Pretty-Printing.html#Pretty-Printing)
+The pretty printers provide patterns, which match type names, and for matching
+types, descibe how to display those types. (For writing a pretty printer, see: https://sourceware.org/gdb/onlinedocs/gdb/Writing-a-Pretty_002dPrinter.html#Writing-a-Pretty_002dPrinter).
+
+### Embedding Visualizers
+
+Through the use of the currently unstable `#[debugger_visualizer]` attribute, the `arrayvec`
+crate can embed debugger visualizers into the crate metadata.
+
+Currently the two types of visualizers supported are Natvis and Pretty printers.
+
+For Natvis files, when linking an executable with a crate that includes Natvis files,
+the MSVC linker will embed the contents of all Natvis files into the generated `PDB`.
+
+For pretty printers, the compiler will encode the contents of the pretty printer
+in the `.debug_gdb_scripts` section of the `ELF` generated.
+
+### Testing Visualizers
+
+The `arrayvec` crate supports testing debugger visualizers defined for this crate. The entry point for
+these tests are `tests/debugger_visualizer.rs`. These tests are defined using the `debugger_test` and
+`debugger_test_parser` crates. The `debugger_test` crate is a proc macro crate which defines a
+single proc macro attribute, `#[debugger_test]`. For more detailed information about this crate,
+see https://crates.io/crates/debugger_test. The CI pipeline for the `arrayvec` crate has been updated
+to run the debugger visualizer tests to ensure debugger visualizers do not become broken/stale.
+
+The `#[debugger_test]` proc macro attribute may only be used on test functions and will run the
+function under the debugger specified by the `debugger` meta item.
+
+This proc macro attribute has 3 required values:
+
+1. The first required meta item, `debugger`, takes a string value which specifies the debugger to launch.
+2. The second required meta item, `commands`, takes a string of new line (`\n`) separated list of debugger
+commands to run.
+3. The third required meta item, `expected_statements`, takes a string of new line (`\n`) separated list of
+statements that must exist in the debugger output. Pattern matching through regular expressions is also
+supported by using the `pattern:` prefix for each expected statement.
+
+#### Example:
+
+```rust
+#[debugger_test(
+    debugger = "cdb",
+    commands = "command1\ncommand2\ncommand3",
+    expected_statements = "statement1\nstatement2\nstatement3")]
+fn test() {
+
+}
+```
+
+Using a multiline string is also supported, with a single debugger command/expected statement per line:
+
+```rust
+#[debugger_test(
+    debugger = "cdb",
+    commands = "
+command1
+command2
+command3",
+    expected_statements = "
+statement1
+pattern:statement[0-9]+
+statement3")]
+fn test() {
+
+}
+```
+
+In the example above, the second expected statement uses pattern matching through a regular expression
+by using the `pattern:` prefix.
+
+#### Testing Locally
+
+Currently, only Natvis visualizations have been defined for the `arrayvec` crate via `debug_metadata/arrayvec.natvis`,
+which means the `tests/debugger_visualizer.rs` tests need to be run on Windows using the `*-pc-windows-msvc` targets.
+To run these tests locally, first ensure the debugging tools for Windows are installed or install them following
+the steps listed here, [Debugging Tools for Windows](https://docs.microsoft.com/en-us/windows-hardware/drivers/debugger/).
+Once the debugging tools have been installed, the tests can be run in the same manner as they are in the CI
+pipeline.
+
+#### Note
+
+When running the debugger visualizer tests, `tests/debugger_visualizer.rs`, they need to be run consecutively
+and not in parallel. This can be achieved by passing the flag `--test-threads=1` to rustc. This is due to
+how the debugger tests are run. Each test marked with the `#[debugger_test]` attribute launches a debugger
+and attaches it to the current test process. If tests are running in parallel, the test will try to attach
+a debugger to the current process which may already have a debugger attached causing the test to fail.
+
+For example:
+
+```
+cargo test --test debugger_visualizer --features debugger_visualizer -- --test-threads=1
+```

debug_metadata/arrayvec.natvis

@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="utf-8"?>
+<AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
+  <Type Name="arrayvec::array_string::ArrayString&lt;*&gt;">
+    <DisplayString>{xs,[len]s8}</DisplayString>
+    <StringView>{xs,[len]s8}</StringView>
+    <Expand>
+      <Item Name="[len]" ExcludeView="simple">len</Item>
+      <Item Name="[capacity]" ExcludeView="simple">$T1</Item>
+      <CustomListItems>
+        <Variable Name="i" InitialValue="0" />
+        <Size>len</Size>
+        <Loop>
+          <Item>(char)xs[i].value.value</Item>
+          <Exec>i++</Exec>
+        </Loop>
+      </CustomListItems>
+    </Expand>
+  </Type>
+
+  <Type Name="arrayvec::arrayvec::ArrayVec&lt;*,*&gt;">
+    <DisplayString>{{ len={len} }}</DisplayString>
+    <Expand>
+      <Item Name="[len]" ExcludeView="simple">len</Item>
+      <Item Name="[capacity]" ExcludeView="simple">$T2</Item>
+      <CustomListItems>
+        <Variable Name="i" InitialValue="0" />
+        <Size>len</Size>
+        <Loop>
+          <Item>($T1)xs[i].value.value</Item>
+          <Exec>i++</Exec>
+        </Loop>
+      </CustomListItems>
+    </Expand>
+  </Type>
+</AutoVisualizer>

src/lib.rs

@@ -17,6 +17,11 @@
 //!
 #![doc(html_root_url="https://docs.rs/arrayvec/0.7/")]
 #![cfg_attr(not(feature="std"), no_std)]
+#![cfg_attr(
+    feature="debugger_visualizer",
+    feature(debugger_visualizer),
+    debugger_visualizer(natvis_file = "../debug_metadata/arrayvec.natvis")
+)]
 
 #[cfg(feature="serde")]
 extern crate serde;

tests/debugger_visualizer.rs

@@ -0,0 +1,82 @@
+use arrayvec::ArrayString;
+use arrayvec::ArrayVec;
+use debugger_test::debugger_test;
+
+#[inline(never)]
+fn __break() {
+    println!("Breakpoint hit");
+}
+
+#[debugger_test(
+    debugger = "cdb",
+    commands = r#"
+.nvlist
+dv
+
+dx array
+dx string
+
+g
+
+dx string
+"#,
+    expected_statements = r#"
+array            : { len=0xa } [Type: arrayvec::arrayvec::ArrayVec<i32,10>]
+    [<Raw View>]     [Type: arrayvec::arrayvec::ArrayVec<i32,10>]
+    [len]            : 0xa [Type: unsigned int]
+    [capacity]       : 10
+    [0x0]            : 1 [Type: i32]
+    [0x1]            : 2 [Type: i32]
+    [0x2]            : 3 [Type: i32]
+    [0x3]            : 4 [Type: i32]
+    [0x4]            : 5 [Type: i32]
+    [0x5]            : 6 [Type: i32]
+    [0x6]            : 7 [Type: i32]
+    [0x7]            : 8 [Type: i32]
+    [0x8]            : 9 [Type: i32]
+    [0x9]            : 10 [Type: i32]
+
+string           : "foo" [Type: arrayvec::array_string::ArrayString<10>]
+    [<Raw View>]     [Type: arrayvec::array_string::ArrayString<10>]
+    [len]            : 0x3 [Type: unsigned int]
+    [capacity]       : 10
+    [0x0]            : 102 'f' [Type: char]
+    [0x1]            : 111 'o' [Type: char]
+    [0x2]            : 111 'o' [Type: char]
+
+string           : "foo-bar" [Type: arrayvec::array_string::ArrayString<10>]
+    [<Raw View>]     [Type: arrayvec::array_string::ArrayString<10>]
+    [len]            : 0x7 [Type: unsigned int]
+    [capacity]       : 10
+    [0x0]            : 102 'f' [Type: char]
+    [0x1]            : 111 'o' [Type: char]
+    [0x2]            : 111 'o' [Type: char]
+    [0x3]            : 45 '-' [Type: char]
+    [0x4]            : 98 'b' [Type: char]
+    [0x5]            : 97 'a' [Type: char]
+    [0x6]            : 114 'r' [Type: char]
+"#
+)]
+#[inline(never)]
+fn test_debugger_visualizer() {
+    let mut array = ArrayVec::<i32, 10>::new();
+    for i in 0..10 {
+        array.push(i + 1);
+    }
+    assert_eq!(&array[..], &[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+    assert_eq!(array.capacity(), 10);
+
+    let mut string = ArrayString::<10>::new();
+    string.push_str("foo");
+    assert_eq!(&string[..], "foo");
+    assert_eq!(string.capacity(), 10);
+    __break();
+
+    string.push_str("-bar");
+    assert_eq!(&string[..], "foo-bar");
+    assert_eq!(string.capacity(), 10);
+
+    let result = string.to_string();
+    assert_eq!(String::from("foo-bar"), result);
+    __break();
+}