[PATCH] Gracefully (and correctly) handle init of multiple union members

[Eli Friedman]

On Tue, Sep 24, 2013 at 8:04 AM, Matthew Curtis <mcurtis at codeaurora.org>wrote:

> We now emit warnings when doing so and code generation is consistent
> with GCC. Note that the C99 spec is unclear as to the precise
> behavior.
>
> See also ...
> Bug:
>   http://llvm.org/bugs/show_bug.**cgi?id=16644<http://llvm.org/bugs/show_bug.cgi?id=16644>and
>
> cfe-dev discussion:
> http://lists.cs.uiuc.edu/**pipermail/cfe-dev/2013-**September/031918.html<http://lists.cs.uiuc.edu/pipermail/cfe-dev/2013-September/031918.html>
>
>
>
+    FieldDecl *CFD = ArrayFillerOrUnionFieldInit.dyn_cast<FieldDecl *>();
+    assert((FD == 0 || CFD == 0 || CFD == FD)
+           && "Only one field of a union may be initiazed at a time!");

This will cause an unused variable warning in release builds.  Also,
spelling.

diff --git a/test/Sema/designated-initializers.c
b/test/Sema/designated-initializers.c
index 36fa559..be365a0 100644
--- a/test/Sema/designated-initializers.c
+++ b/test/Sema/designated-initializers.c
@@ -1,5 +1,8 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -triple x86_64-unknown-unknown %s
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -DCHECK_CODEGEN=1 \
+// RUN:   -S -emit-llvm -o - 2>&1 | FileCheck %s

Please put a separate code generation test into test/CodeGen.  It's okay if
you duplicate the test code.

The approach looks fine.

-Eli
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