[constexpr] Fix ICE when memcpy() is given a pointer to an incomplete array

Fix code for constant evaluation of __builtin_memcpy() and
__builtin_memmove() that would attempt to divide by zero when given two
pointers to an incomplete array.

Differential Revision: https://reviews.llvm.org/D51855

llvm-svn: 343761

1 files changed, 4 insertions, 0 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index a34940e53ad..c012fc377fb 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -6239,6 +6239,10 @@ bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
       Info.FFDiag(E, diag::note_constexpr_memcpy_type_pun) << Move << SrcT << T;
       return false;
     }
+    if (T->isIncompleteType()) {
+      Info.FFDiag(E, diag::note_constexpr_memcpy_incomplete_type) << Move << T;
+      return false;
+    }
     if (!T.isTriviallyCopyableType(Info.Ctx)) {
       Info.FFDiag(E, diag::note_constexpr_memcpy_nontrivial) << Move << T;
       return false;