Auto merge of #118924 - Urgau:check-cfg-exclude-well-known-from-diag, r=petrochenkov

Exclude well known names from showing a suggestion in check-cfg

This PR adds an exclusion for well known names from showing in suggestions of check-cfg/`unexpected_cfgs`.

Follow-up to https://github.com/rust-lang/rust/pull/118213 and fixes https://github.com/rust-lang/rust/pull/118213#issuecomment-1854189934.

r? `@petrochenkov`

1 files changed, 5 insertions, 2 deletions

diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 20bea153793..fe1166457ba 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -1380,6 +1380,8 @@ pub struct CheckCfg {
     pub exhaustive_values: bool,
     /// All the expected values for a config name
     pub expecteds: FxHashMap<Symbol, ExpectedValues<Symbol>>,
+    /// Well known names (only used for diagnostics purposes)
+    pub well_known_names: FxHashSet<Symbol>,
 }
 
 pub enum ExpectedValues<T> {
@@ -1432,9 +1434,10 @@ impl CheckCfg {
         };
 
         macro_rules! ins {
-            ($name:expr, $values:expr) => {
+            ($name:expr, $values:expr) => {{
+                self.well_known_names.insert($name);
                 self.expecteds.entry($name).or_insert_with($values)
-            };
+            }};
         }
 
         // Symbols are inserted in alphabetical order as much as possible.