Stabilize debugger_visualizer feature (#855)

* Stabilize debugger_visualizer feature

* Run debugger_visualizer on  more rustc versions

Author: lucacasonato

.github/workflows/main.yml

@@ -49,12 +49,12 @@ jobs:
         # Run tests enabling the serde feature
       - name: Run tests with the serde feature
         run: cargo test --features "url/serde,url/expose_internals"
-      # 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.
+      # The #[debugger_visualizer] attribute is currently gated behind a feature flag until #[debugger_visualizer]
+      # is available in all rustc versions past our MSRV. As such, we only run the tests on newer rustc versions.
       - name: Run debugger_visualizer tests
         if: |
           matrix.os == 'windows-latest' &&
-          matrix.rust == 'nightly'
+          matrix.rust != '1.56.0'
         run: cargo test --test debugger_visualizer --features "url/debugger_visualizer,url_debug_tests/debugger_visualizer" -- --test-threads=1
       - name: Test `no_std` support
         run: cargo test --no-default-features --features=alloc,no_std_net

debug_metadata/README.md

@@ -22,8 +22,8 @@ types, descibe how to display those types. (For writing a pretty printer, see: h
 
 ### Embedding Visualizers
 
-Through the use of the currently unstable `#[debugger_visualizer]` attribute, the `url`
-crate can embed debugger visualizers into the crate metadata.
+Through the use of the `#[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.
 

url/Cargo.toml

@@ -32,13 +32,13 @@ no-std-net = { version = "0.6.0", default-features = false, optional = true }
 default = ["std"]
 std = ["idna/std", "percent-encoding/std", "form_urlencoded/std", "alloc"]
 alloc = []
-# UNSTABLE FEATURES (requires Rust nightly)
-# Enable to use the #[debugger_visualizer] attribute.
+# Enable to use the #[debugger_visualizer] attribute. This feature requires Rust >= 1.71.
 debugger_visualizer = []
 # Expose internal offsets of the URL.
 expose_internals = []
 # For no_std: Allow the use of no_std_net instead of nightly
 no_std_net = ["no-std-net"]
+# UNSTABLE FEATURES (requires Rust nightly)
 # For no_std: Use errors_in_core and net_in_core
 unstable = ["idna/unstable"]
 

url/src/lib.rs

@@ -119,13 +119,25 @@ See [serde documentation](https://serde.rs) for more information.
 url = { version = "2", features = ["serde"] }
 ```
 
+# Feature: `debugger_visualizer`
+
+If you enable the `debugger_visualizer` feature, the `url` crate will include
+a [natvis file](https://docs.microsoft.com/en-us/visualstudio/debugger/create-custom-views-of-native-objects)
+for [Visual Studio](https://www.visualstudio.com/) that allows you to view
+[`Url`](struct.Url.html) objects in the debugger.
+
+This feature requires Rust 1.71 or later.
+
+```toml
+url = { version = "2", features = ["debugger_visualizer"] }
+```
+
 */
 
 #![no_std]
 #![doc(html_root_url = "https://docs.rs/url/2.4.0")]
 #![cfg_attr(
     feature = "debugger_visualizer",
-    feature(debugger_visualizer),
     debugger_visualizer(natvis_file = "../../debug_metadata/url.natvis")
 )]
 #![cfg_attr(