Reland r326766 (with a slightly modified test)

The original revert was done in r326869, since reverting r326602 broke
the test added by this.

The new test should be less dependent on r326602.

llvm-svn: 326872

2 files changed, 21 insertions, 1 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 45df133ad57..c3e41658c29 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -133,7 +133,11 @@ namespace {
 
     E = E->IgnoreParens();
     // If we're doing a variable assignment from e.g. malloc(N), there will
-    // probably be a cast of some kind. Ignore it.
+    // probably be a cast of some kind. In exotic cases, we might also see a
+    // top-level ExprWithCleanups. Ignore them either way.
+    if (const auto *EC = dyn_cast<ExprWithCleanups>(E))
+      E = EC->getSubExpr()->IgnoreParens();
+
     if (const auto *Cast = dyn_cast<CastExpr>(E))
       E = Cast->getSubExpr()->IgnoreParens();
 
diff --git a/clang/test/CodeGenCXX/alloc-size.cpp b/clang/test/CodeGenCXX/alloc-size.cpp
index ac53ea8f8ea..34892b8abc2 100644
--- a/clang/test/CodeGenCXX/alloc-size.cpp
+++ b/clang/test/CodeGenCXX/alloc-size.cpp
@@ -70,3 +70,19 @@ int testIt() {
          __builtin_object_size(dependent_calloc2<int, 9>(), 0);
 }
 } // namespace templated_alloc_size
+
+// Be sure that an ExprWithCleanups doesn't deter us.
+namespace alloc_size_with_cleanups {
+struct Foo {
+  ~Foo();
+};
+
+void *my_malloc(const Foo &, int N) __attribute__((alloc_size(2)));
+
+// CHECK-LABEL: define i32 lalala
+int testIt() {
+  int *const p = (int *)my_malloc(Foo{}, 3);
+  // CHECK: ret i32 3
+  return __builtin_object_size(p, 0);
+}
+} // namespace alloc_size_with_cleanups