fix PR10384: C++ allows external arrays of incomplete type as well.

Many thanks to Eli for reducing this great testcase.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@135752 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 14 insertions, 0 deletions

diff --git a/lib/CodeGen/CodeGenTypes.cpp b/lib/CodeGen/CodeGenTypes.cpp
index ee629ec9b0..87b3da5000 100644
--- a/lib/CodeGen/CodeGenTypes.cpp
+++ b/lib/CodeGen/CodeGenTypes.cpp
@@ -419,6 +419,14 @@ llvm::Type *CodeGenTypes::ConvertType(QualType T) {
   case Type::ConstantArray: {
     const ConstantArrayType *A = cast<ConstantArrayType>(Ty);
     llvm::Type *EltTy = ConvertTypeForMem(A->getElementType());
+    
+    // Lower arrays of undefined struct type to arrays of i8 just to have a 
+    // concrete type.
+    if (!EltTy->isSized()) {
+      SkippedLayout = true;
+      EltTy = llvm::Type::getInt8Ty(getLLVMContext());
+    }
+
     ResultType = llvm::ArrayType::get(EltTy, A->getSize().getZExtValue());
     break;
   }
diff --git a/test/CodeGenCXX/incomplete-types.cpp b/test/CodeGenCXX/incomplete-types.cpp
index 4f37eeb975..1d4f430e5c 100644
--- a/test/CodeGenCXX/incomplete-types.cpp
+++ b/test/CodeGenCXX/incomplete-types.cpp
@@ -35,3 +35,9 @@ namespace PR10395 {
   extern T x[];
   T* f() { return x; }
 }
+
+namespace PR10384 {
+  struct X;
+  extern X x[1];
+  X* f() { return x; }
+}