Add Natvis visualizations for the Url type

.github/workflows/main.yml

@@ -25,8 +25,6 @@ jobs:
             rust: beta
           - os: macos-latest
             rust: nightly
-          - os: windows-latest
-            rust: nightly
 
     runs-on: ${{ matrix.os }}
 
@@ -41,10 +39,27 @@ jobs:
         with:
           command: build
           args: --all-targets
-      - uses: actions-rs/cargo@v1
+        # Run tests
+      - name: Run tests
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+        # Run tests enabling the serde feature
+      - name: Run tests with the serde feature
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --features "url/serde"
+      # The #[debugger_visualizer] attribute is currently gated behind an unstable feature flag.
+      # In order to test the visualizers for the url crate, they have to be tested on a nightly build.
+      - name: Run debugger_visualizer tests
+        if: |
+          matrix.os == 'windows-latest' &&
+          matrix.rust == 'nightly'
+        uses: actions-rs/cargo@v1
         with:
           command: test
-          args: --all-features
+          args: --test debugger_visualizer --features "url/serde,url/debugger_visualizer" -- --test-threads=1
 
   WASM:
     runs-on: ubuntu-latest

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 `url`
+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 `url` 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 `url` 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 `url` crate via `debug_metadata/url.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/url.natvis

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8"?>
+<AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
+  <Type Name="url::Url">
+    <Intrinsic Name="ptr" Expression="serialization.vec.buf.ptr.pointer.pointer" />
+    <DisplayString>{serialization}</DisplayString>
+    <Expand>
+      <Synthetic Name="[scheme]">
+        <DisplayString>{(char*)(ptr()),[scheme_end]s8}</DisplayString>
+      </Synthetic>
+      <Synthetic Name="[username]" Condition="username_end > (scheme_end + 3)">
+        <!-- Add 3 to the scheme end to account for the scheme separator which is '://' -->
+        <DisplayString>{(char*)(ptr()+(scheme_end + 3)),[((username_end)-(scheme_end + 3))]s8}</DisplayString>
+      </Synthetic>
+      <Synthetic Name="[host]" Condition="host.tag != 0">
+        <DisplayString>{(char*)(ptr()+host_start),[host_end-host_start]s8}</DisplayString>
+      </Synthetic>
+      <Synthetic Name="[port]" Condition="port.tag == 1">
+        <DisplayString>{port.variant1.value.__0,d}</DisplayString>
+      </Synthetic>
+      <Synthetic Name="[path]">
+        <DisplayString Condition="query_start.tag == 0 &amp;&amp; fragment_start.tag == 0">{(char*)(ptr()+path_start),[(serialization.vec.len-path_start)]s8}</DisplayString>
+        <DisplayString Condition="query_start.tag == 1">{(char*)(ptr()+path_start),[(query_start.variant1.value.__0-path_start)]s8}</DisplayString>
+        <DisplayString Condition="fragment_start.tag == 1">{(char*)(ptr()+path_start),[(fragment_start.variant1.value.__0-path_start)]s8}</DisplayString>
+      </Synthetic>
+      <Synthetic Name="[query]" Condition="query_start.tag == 1">
+        <DisplayString Condition="fragment_start.tag == 0">{(char*)(ptr()+query_start.variant1.value.__0+1),[((serialization.vec.len)-(query_start.variant1.value.__0+1))]s8}</DisplayString>
+        <DisplayString Condition="fragment_start.tag == 1">{(char*)(ptr()+query_start.variant1.value.__0+1),[((fragment_start.variant1.value.__0)-(query_start.variant1.value.__0+1))]s8}</DisplayString>
+      </Synthetic>
+      <Synthetic Name="[fragment]" Condition="fragment_start.tag == 1">
+        <DisplayString>{(char*)(ptr()+fragment_start.variant1.value.__0+1),[(serialization.vec.len-fragment_start.variant1.value.__0-1)]s8}</DisplayString>
+      </Synthetic>
+    </Expand>
+  </Type>
+</AutoVisualizer>

url/Cargo.toml

@@ -23,6 +23,9 @@ appveyor = { repository = "Manishearth/rust-url" }
 [dev-dependencies]
 serde_json = "1.0"
 bencher = "0.1"
+# To test debugger visualizers defined for the url crate such as url.natvis
+debugger_test = "0.1"
+debugger_test_parser = "0.1"
 
 [dependencies]
 form_urlencoded = { version = "1.0.0", path = "../form_urlencoded" }
@@ -32,8 +35,17 @@ serde = {version = "1.0", optional = true, features = ["derive"]}
 
 [features]
 default = ["idna"]
+# UNSTABLE FEATURES (requires Rust nightly)
+# Enable to use the #[debugger_visualizer] attribute.
+debugger_visualizer = []
 
 [[bench]]
 name = "parse_url"
 path = "benches/parse_url.rs"
 harness = false
+
+[[test]]
+name = "debugger_visualizer"
+path = "tests/debugger_visualizer.rs"
+required-features = ["debugger_visualizer"]
+test = false

url/src/lib.rs

@@ -131,6 +131,11 @@ url = { version = "2", default-features = false }
 */
 
 #![doc(html_root_url = "https://docs.rs/url/2.2.2")]
+#![cfg_attr(
+    feature = "debugger_visualizer",
+    feature(debugger_visualizer),
+    debugger_visualizer(natvis_file = "../../debug_metadata/url.natvis")
+)]
 
 pub use form_urlencoded;
 

url/tests/debugger_visualizer.rs

@@ -0,0 +1,102 @@
+use debugger_test::debugger_test;
+use url::Url;
+
+#[inline(never)]
+fn __break() {}
+
+#[debugger_test(
+    debugger = "cdb",
+    commands = "
+    .nvlist
+
+    dx base_url
+
+    dx url_with_non_special_scheme
+
+    dx url_with_user_pass_port_query_fragments
+
+    dx url_blob
+
+    dx url_with_base
+
+    dx url_with_base_replaced
+
+    dx url_with_comma",
+    expected_statements = r#"
+    pattern:debugger_visualizer-.*\.exe \(embedded NatVis ".*-[0-9]+\.natvis"\)
+
+    base_url         : "http://example.org/foo/bar" [Type: url::Url]
+    [<Raw View>]     [Type: url::Url]
+    [scheme]         : "http"
+    [host]           : "example.org"
+    [path]           : "/foo/bar"
+
+    url_with_non_special_scheme : "non-special://test/x" [Type: url::Url]
+    [<Raw View>]     [Type: url::Url]
+    [scheme]         : "non-special"
+    [host]           : "test"
+    [path]           : "/x"
+
+    url_with_user_pass_port_query_fragments : "http://user:pass@foo:21/bar;par?b#c" [Type: url::Url]
+    [<Raw View>]     [Type: url::Url]
+    [scheme]         : "http"
+    [username]       : "user"
+    [host]           : "foo"
+    [port]           : 21
+    [path]           : "/bar;par"
+    [query]          : "b"
+    [fragment]       : "c"
+
+    url_blob         : "blob:https://example.com:443/" [Type: url::Url]
+    [<Raw View>]     [Type: url::Url]
+    [scheme]         : "blob"
+    [path]           : "https://example.com:443/"
+
+    url_with_base    : "http://example.org/a%2fc" [Type: url::Url]
+    [<Raw View>]     [Type: url::Url]
+    [scheme]         : "http"
+    [host]           : "example.org"
+    [path]           : "/a%2fc"
+
+    url_with_base_replaced : "http://[::7f00:1]/" [Type: url::Url]
+    [<Raw View>]     [Type: url::Url]
+    [scheme]         : "http"
+    [host]           : "[::7f00:1]"
+    [path]           : "/"
+
+    url_with_comma   : "data:text/html,test#test" [Type: url::Url]
+    [<Raw View>]     [Type: url::Url]
+    [scheme]         : "data"
+    [path]           : "text/html,test"
+    [fragment]       : "test"
+    "#
+)]
+fn test_url_visualizer() {
+    // Copied from https://github.com/web-platform-tests/wpt/blob/master/url/
+    let base_url = Url::parse("http://example.org/foo/bar").unwrap();
+    assert_eq!(base_url.as_str(), "http://example.org/foo/bar");
+
+    let url_with_non_special_scheme = Url::parse("non-special://:@test/x").unwrap();
+    assert_eq!(url_with_non_special_scheme.as_str(), "non-special://test/x");
+
+    let url_with_user_pass_port_query_fragments =
+        Url::parse("http://user:pass@foo:21/bar;par?b#c").unwrap();
+    assert_eq!(
+        url_with_user_pass_port_query_fragments.as_str(),
+        "http://user:pass@foo:21/bar;par?b#c"
+    );
+
+    let url_blob = Url::parse("blob:https://example.com:443/").unwrap();
+    assert_eq!(url_blob.as_str(), "blob:https://example.com:443/");
+
+    let url_with_base = base_url.join("/a%2fc").unwrap();
+    assert_eq!(url_with_base.as_str(), "http://example.org/a%2fc");
+
+    let url_with_base_replaced = base_url.join("http://[::127.0.0.1]").unwrap();
+    assert_eq!(url_with_base_replaced.as_str(), "http://[::7f00:1]/");
+
+    let url_with_comma = base_url.join("data:text/html,test#test").unwrap();
+    assert_eq!(url_with_comma.as_str(), "data:text/html,test#test");
+
+    __break();
+}