From 8608a3f637871c157b030f5661231f8261ca9797 Mon Sep 17 00:00:00 2001
From: Eric Huss <eric@huss.org>
Date: Sat, 26 Apr 2025 14:08:36 -0700
Subject: [PATCH 1/2] lint-docs: Don't hard-code the valid editions

This removes the hard-coded list of edition support in the lint-docs
tool, and instead just assumes the edition attribute is something valid.
There isn't a real reason to have this, as rustc will error if given a
wrong number. This should be easier to maintain going forward.
---
 src/tools/lint-docs/src/lib.rs | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/src/tools/lint-docs/src/lib.rs b/src/tools/lint-docs/src/lib.rs
index 9fd33e23204..7e00697a0bd 100644
--- a/src/tools/lint-docs/src/lib.rs
+++ b/src/tools/lint-docs/src/lib.rs
@@ -444,21 +444,15 @@ impl<'a> LintExtractor<'a> {
         fs::write(&tempfile, source)
             .map_err(|e| format!("failed to write {}: {}", tempfile.display(), e))?;
         let mut cmd = Command::new(self.rustc_path);
-        if options.contains(&"edition2024") {
-            cmd.arg("--edition=2024");
-            cmd.arg("-Zunstable-options");
-        } else if options.contains(&"edition2021") {
-            cmd.arg("--edition=2021");
-        } else if options.contains(&"edition2018") {
-            cmd.arg("--edition=2018");
-        } else if options.contains(&"edition2015") {
-            cmd.arg("--edition=2015");
-        } else if options.contains(&"edition") {
-            panic!("lint-docs: unknown edition");
-        } else {
+        let edition = options
+            .iter()
+            .filter_map(|opt| opt.strip_prefix("edition"))
+            .next()
             // defaults to latest edition
-            cmd.arg("--edition=2021");
-        }
+            .unwrap_or("2021");
+        cmd.arg(format!("--edition={edition}"));
+        // Just in case this is an unstable edition.
+        cmd.arg("-Zunstable-options");
         cmd.arg("--error-format=json");
         cmd.arg("--target").arg(self.rustc_target);
         if let Some(target_linker) = self.rustc_linker {

From 1f108fe08a906b49026cd0aa324b3f9381c052c1 Mon Sep 17 00:00:00 2001
From: Eric Huss <eric@huss.org>
Date: Sat, 26 Apr 2025 14:08:58 -0700
Subject: [PATCH 2/2] Update lint-docs to default to Rust 2024

This updates the lint-docs tool to default to the 2024 edition. The lint
docs are supposed to illustrate the code with the latest edition, and I
just forgot to update this in
https://github.com/rust-lang/rust/pull/133349.

Some docs needed to add the `edition` attribute since they were assuming
a particular edition, but were missing the explicit annotation.
---
 compiler/rustc_lint/src/builtin.rs                 | 2 +-
 compiler/rustc_lint/src/impl_trait_overcaptures.rs | 2 +-
 compiler/rustc_lint_defs/src/builtin.rs            | 4 ++--
 src/tools/lint-docs/src/lib.rs                     | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index e65f4beab24..41b43f64798 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -948,7 +948,7 @@ declare_lint! {
     ///
     /// ### Example
     ///
-    /// ```rust,compile_fail
+    /// ```rust,compile_fail,edition2021
     /// #[no_mangle]
     /// const FOO: i32 = 5;
     /// ```
diff --git a/compiler/rustc_lint/src/impl_trait_overcaptures.rs b/compiler/rustc_lint/src/impl_trait_overcaptures.rs
index f1dc420aa3c..7f4789ad0d9 100644
--- a/compiler/rustc_lint/src/impl_trait_overcaptures.rs
+++ b/compiler/rustc_lint/src/impl_trait_overcaptures.rs
@@ -41,7 +41,7 @@ declare_lint! {
     ///
     /// ### Example
     ///
-    /// ```rust,compile_fail
+    /// ```rust,compile_fail,edition2021
     /// # #![deny(impl_trait_overcaptures)]
     /// # use std::fmt::Display;
     /// let mut x = vec![];
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 17d501c5730..03b8112938c 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -1424,7 +1424,7 @@ declare_lint! {
     ///
     /// ### Example
     ///
-    /// ```rust,compile_fail
+    /// ```rust,compile_fail,edition2021
     /// macro_rules! foo {
     ///    () => {};
     ///    ($name) => { };
@@ -4128,7 +4128,7 @@ declare_lint! {
     ///
     /// ### Example
     ///
-    /// ```rust,compile_fail
+    /// ```rust,compile_fail,edition2021
     /// #![deny(dependency_on_unit_never_type_fallback)]
     /// fn main() {
     ///     if true {
diff --git a/src/tools/lint-docs/src/lib.rs b/src/tools/lint-docs/src/lib.rs
index 7e00697a0bd..d6c69d39e17 100644
--- a/src/tools/lint-docs/src/lib.rs
+++ b/src/tools/lint-docs/src/lib.rs
@@ -449,7 +449,7 @@ impl<'a> LintExtractor<'a> {
             .filter_map(|opt| opt.strip_prefix("edition"))
             .next()
             // defaults to latest edition
-            .unwrap_or("2021");
+            .unwrap_or("2024");
         cmd.arg(format!("--edition={edition}"));
         // Just in case this is an unstable edition.
         cmd.arg("-Zunstable-options");