[clang] 95b2dab - [Sema] Fix a miscompile by retaining array qualifiers when folding VLAs to constant arrays

[Erik Pilkington via cfe-commits]

Author: Erik Pilkington
Date: 2020-12-16T10:01:24-05:00
New Revision: 95b2dab199100f5a86d3f73a995afea879886d65

URL: https://github.com/llvm/llvm-project/commit/95b2dab199100f5a86d3f73a995afea879886d65
DIFF: https://github.com/llvm/llvm-project/commit/95b2dab199100f5a86d3f73a995afea879886d65.diff

LOG: [Sema] Fix a miscompile by retaining array qualifiers when folding VLAs to constant arrays

rdar://72243125

Differential revision: https://reviews.llvm.org/D93247

Added: 
    

Modified: 
    clang/lib/Sema/SemaDecl.cpp
    clang/test/SemaObjC/arc.m

Removed: 
    


################################################################################
diff  --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 0031f874c05a..6c438f319991 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -5965,8 +5965,9 @@ static QualType TryToFixInvalidVariablyModifiedType(QualType T,
     return QualType();
   }
 
-  return Context.getConstantArrayType(ElemTy, Res, VLATy->getSizeExpr(),
-                                      ArrayType::Normal, 0);
+  QualType FoldedArrayType = Context.getConstantArrayType(
+      ElemTy, Res, VLATy->getSizeExpr(), ArrayType::Normal, 0);
+  return Qs.apply(Context, FoldedArrayType);
 }
 
 static void

diff  --git a/clang/test/SemaObjC/arc.m b/clang/test/SemaObjC/arc.m
index fe5db9ce5384..bcd2f995622c 100644
--- a/clang/test/SemaObjC/arc.m
+++ b/clang/test/SemaObjC/arc.m
@@ -839,3 +839,15 @@ void block_capture_autoreleasing(A * __autoreleasing *a,
     (void)*l;
   }();
 }
+
+void test_vla_fold_keeps_strong(void) {
+  const unsigned bounds = 1;
+
+  static id array[bounds]; // expected-warning {{variable length array folded to constant array as an extension}}
+  typedef __typeof__(array) array_type;
+  typedef id __strong array_type[1];
+
+  static id weak_array[bounds] __weak; // expected-warning {{variable length array folded to constant array as an extension}}
+  typedef __typeof__(weak_array) weak_array_type;
+  typedef id __weak weak_array_type[1];
+}