Basic support for flexible array members in constant evaluation.

We don't allow runtime-sized flexible array members, nor initialization
of flexible array members, but it seems reasonable to support the most
basic case where the flexible array member is empty.

1 files changed, 11 insertions, 1 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index a4dc0cc..d20c238 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -9929,8 +9929,18 @@ namespace {
     bool ZeroInitialization(const Expr *E) {
       const ConstantArrayType *CAT =
           Info.Ctx.getAsConstantArrayType(E->getType());
-      if (!CAT)
+      if (!CAT) {
+        if (const IncompleteArrayType *IAT =
+                Info.Ctx.getAsIncompleteArrayType(E->getType())) {
+          // We can be asked to zero-initialize a flexible array member; this
+          // is represented as an ImplicitValueInitExpr of incomplete array
+          // type. In this case, the array has zero elements.
+          Result = APValue(APValue::UninitArray(), 0, 0);
+          return true;
+        }
+        // FIXME: We could handle VLAs here.
         return Error(E);
+      }
 
       Result = APValue(APValue::UninitArray(), 0,
                        CAT->getSize().getZExtValue());