1 files changed, 18 insertions, 2 deletions
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 5bf95f878d4..9bcd9a01649 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -2595,8 +2595,24 @@ static bool isSameEntity(NamedDecl *X, NamedDecl *Y) {
   // Variables with the same type and linkage match.
   if (VarDecl *VarX = dyn_cast<VarDecl>(X)) {
     VarDecl *VarY = cast<VarDecl>(Y);
-    return (VarX->getLinkageInternal() == VarY->getLinkageInternal()) &&
-      VarX->getASTContext().hasSameType(VarX->getType(), VarY->getType());
+    if (VarX->getLinkageInternal() == VarY->getLinkageInternal()) {
+      ASTContext &C = VarX->getASTContext();
+      if (C.hasSameType(VarX->getType(), VarY->getType()))
+        return true;
+
+      // We can get decls with different types on the redecl chain. Eg.
+      // template <typename T> struct S { static T Var[]; }; // #1
+      // template <typename T> T S<T>::Var[sizeof(T)]; // #2
+      // Only? happens when completing an incomplete array type. In this case
+      // when comparing #1 and #2 we should go through their elements types.
+      const ArrayType *VarXTy = C.getAsArrayType(VarX->getType());
+      const ArrayType *VarYTy = C.getAsArrayType(VarY->getType());
+      if (!VarXTy || !VarYTy)
+        return false;
+      if (VarXTy->isIncompleteArrayType() || VarYTy->isIncompleteArrayType())
+        return C.hasSameType(VarXTy->getElementType(), VarYTy->getElementType());
+    }
+    return false;
   }
 
   // Namespaces with the same name and inlinedness match.