[PATCH] D147626: [clang] Do not crash when initializing union with flexible array member

[Mariya Podchishchaeva via Phabricator via cfe-commits]

Fznamznon created this revision.
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Due to missing check on union, there was a null expression added to init
list that caused crash later.

Fixes https://github.com/llvm/llvm-project/issues/61746


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D147626

Files:
  clang/lib/Sema/SemaInit.cpp
  clang/test/Sema/init.c


Index: clang/test/Sema/init.c
===================================================================
--- clang/test/Sema/init.c
+++ clang/test/Sema/init.c
@@ -164,3 +164,6 @@
 
 typedef struct { uintptr_t x : 2; } StructWithBitfield;
 StructWithBitfield bitfieldvar = { (uintptr_t)&bitfieldvar }; // expected-error {{initializer element is not a compile-time constant}}
+
+// GH61746
+union { char x[]; } r = {0}; // expected-error {{flexible array member 'x' in a union is not allowed}}
Index: clang/lib/Sema/SemaInit.cpp
===================================================================
--- clang/lib/Sema/SemaInit.cpp
+++ clang/lib/Sema/SemaInit.cpp
@@ -805,7 +805,7 @@
       // order to leave them uninitialized, the ILE is expanded and the extra
       // fields are then filled with NoInitExpr.
       unsigned NumElems = numStructUnionElements(ILE->getType());
-      if (RDecl->hasFlexibleArrayMember())
+      if (!RDecl->isUnion() && RDecl->hasFlexibleArrayMember())
         ++NumElems;
       if (!VerifyOnly && ILE->getNumInits() < NumElems)
         ILE->resizeInits(SemaRef.Context, NumElems);


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