[PATCH] D99661: [SemaObjC] Fix a -Wbridge-cast false-positive

[Erik Pilkington via Phabricator via cfe-commits]

erik.pilkington created this revision.
erik.pilkington added reviewers: arphaman, ahatanak.
erik.pilkington requested review of this revision.

Clang used to emit a bad -Wbridge-cast diagnostic on the cast in the attached test. This was because, after 09abecef7 <https://reviews.llvm.org/rG09abecef7bbfda18d34f046954eaa4d491062839>, `struct __CFString` was not added to lookup, so the `objc_bridge` attribute wasn't getting duplicated onto the most recent declaration, causing us to fail to find it in `getObjCBridgeAttr`. This patch fixes this by instead walking through the redeclarations to find an appropriate bridge attribute.

rdar://72823399


https://reviews.llvm.org/D99661

Files:
  clang/lib/Sema/SemaExprObjC.cpp
  clang/test/SemaObjCXX/bridge-cast-redecl.mm


Index: clang/test/SemaObjCXX/bridge-cast-redecl.mm
===================================================================
--- /dev/null
+++ clang/test/SemaObjCXX/bridge-cast-redecl.mm
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -std=gnu++17 -verify %s
+
+// expected-no-diagnostics
+
+typedef const struct __CFString * CFStringRef;
+
+extern "C" {
+  typedef const struct __attribute__((objc_bridge(NSString))) __CFString * CFStringRef;
+  typedef struct __attribute__((objc_bridge_mutable(NSMutableString))) __CFString * CFMutableStringRef;
+}
+
+ at interface NSString @end
+ at interface NSMutableString : NSString @end
+
+void CFStringGetLength(CFStringRef theString);
+
+int main() {
+  CFStringGetLength((__bridge CFStringRef)(NSString *)0);
+}
Index: clang/lib/Sema/SemaExprObjC.cpp
===================================================================
--- clang/lib/Sema/SemaExprObjC.cpp
+++ clang/lib/Sema/SemaExprObjC.cpp
@@ -3847,9 +3847,12 @@
   QualType QT = TDNDecl->getUnderlyingType();
   if (QT->isPointerType()) {
     QT = QT->getPointeeType();
-    if (const RecordType *RT = QT->getAs<RecordType>())
-      if (RecordDecl *RD = RT->getDecl()->getMostRecentDecl())
-        return RD->getAttr<T>();
+    if (const RecordType *RT = QT->getAs<RecordType>()) {
+      for (auto *Redecl : RT->getDecl()->redecls()) {
+        if (auto *attr = Redecl->getAttr<T>())
+          return attr;
+      }
+    }
   }
   return nullptr;
 }


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