Merge pull request #21374 from Jefffrey/excuse-non-camel-case-repr-c

fix: don't fire `non_camel_case_types` lint for structs/enums marked with `repr(C)`

Author: ChayimFriedman2

crates/hir-def/src/signatures.rs

@@ -185,6 +185,9 @@ impl UnionSignature {
 bitflags! {
     #[derive(Debug, Copy, Clone, PartialEq, Eq)]
     pub struct EnumFlags: u8 {
+        /// Indicates whether this enum has `#[repr]`.
+        const HAS_REPR = 1 << 0;
+        /// Indicates whether the enum has a `#[rustc_has_incoherent_inherent_impls]` attribute.
         const RUSTC_HAS_INCOHERENT_INHERENT_IMPLS  = 1 << 1;
     }
 }
@@ -205,6 +208,9 @@ impl EnumSignature {
         if attrs.contains(AttrFlags::RUSTC_HAS_INCOHERENT_INHERENT_IMPLS) {
             flags |= EnumFlags::RUSTC_HAS_INCOHERENT_INHERENT_IMPLS;
         }
+        if attrs.contains(AttrFlags::HAS_REPR) {
+            flags |= EnumFlags::HAS_REPR;
+        }
 
         let InFile { file_id, value: source } = loc.source(db);
         let (store, generic_params, source_map) = lower_generic_params(
@@ -233,6 +239,11 @@ impl EnumSignature {
             _ => IntegerType::Pointer(true),
         }
     }
+
+    #[inline]
+    pub fn repr(&self, db: &dyn DefDatabase, id: EnumId) -> Option<ReprOptions> {
+        if self.flags.contains(EnumFlags::HAS_REPR) { AttrFlags::repr(db, id.into()) } else { None }
+    }
 }
 bitflags::bitflags! {
     #[derive(Debug, Clone, Copy, Eq, PartialEq, Default)]

crates/hir-ty/src/diagnostics/decl_check.rs

@@ -293,12 +293,18 @@ impl<'a> DeclValidator<'a> {
     fn validate_struct(&mut self, struct_id: StructId) {
         // Check the structure name.
         let data = self.db.struct_signature(struct_id);
-        self.create_incorrect_case_diagnostic_for_item_name(
-            struct_id,
-            &data.name,
-            CaseType::UpperCamelCase,
-            IdentType::Structure,
-        );
+
+        // rustc implementation excuses repr(C) since C structs predominantly don't
+        // use camel case.
+        let has_repr_c = data.repr(self.db, struct_id).is_some_and(|repr| repr.c());
+        if !has_repr_c {
+            self.create_incorrect_case_diagnostic_for_item_name(
+                struct_id,
+                &data.name,
+                CaseType::UpperCamelCase,
+                IdentType::Structure,
+            );
+        }
 
         // Check the field names.
         self.validate_struct_fields(struct_id);
@@ -378,15 +384,20 @@ impl<'a> DeclValidator<'a> {
     }
 
     fn validate_enum(&mut self, enum_id: EnumId) {
+        // Check the enum name.
         let data = self.db.enum_signature(enum_id);
 
-        // Check the enum name.
-        self.create_incorrect_case_diagnostic_for_item_name(
-            enum_id,
-            &data.name,
-            CaseType::UpperCamelCase,
-            IdentType::Enum,
-        );
+        // rustc implementation excuses repr(C) since C structs predominantly don't
+        // use camel case.
+        let has_repr_c = data.repr(self.db, enum_id).is_some_and(|repr| repr.c());
+        if !has_repr_c {
+            self.create_incorrect_case_diagnostic_for_item_name(
+                enum_id,
+                &data.name,
+                CaseType::UpperCamelCase,
+                IdentType::Enum,
+            );
+        }
 
         // Check the variant names.
         self.validate_enum_variants(enum_id)

crates/ide-diagnostics/src/handlers/incorrect_case.rs

@@ -1059,4 +1059,19 @@ fn foo(_HelloWorld: ()) {}
         "#,
         );
     }
+
+    #[test]
+    fn allow_with_repr_c() {
+        check_diagnostics(
+            r#"
+#[repr(C)]
+struct FFI_Struct;
+
+#[repr(C)]
+enum FFI_Enum {
+    Field,
+}
+        "#,
+        );
+    }
 }

crates/ide-diagnostics/src/lib.rs

@@ -108,7 +108,6 @@ use syntax::{
     ast::{self, AstNode},
 };
 
-// FIXME: Make this an enum
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
 pub enum DiagnosticCode {
     RustcHardError(&'static str),