From 7e1aa5b7ac70bf6030d0a6727c979dd9d6781053 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Fri, 14 Oct 2011 20:34:19 +0000
Subject: [PATCH] Don't try to diagnose anything when we're passing incomplete
 types through varargs. This only happens when we're in an unevaluated
 context, where we don't want to trigger an error anyway. Fixes PR11131 /
 <rdar://problem/10288375>.

llvm-svn: 141986
---
 clang/lib/Sema/SemaExpr.cpp                       |  5 ++++-
 clang/test/CXX/expr/expr.post/expr.call/p7-0x.cpp | 13 +++++++++++++
 clang/test/SemaCXX/vararg-non-pod.cpp             |  1 -
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 97060772b0a1..41fcf7299dbe 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -523,7 +523,10 @@ ExprResult Sema::DefaultVariadicArgumentPromotion(Expr *E, VariadicCallType CT,
                           << E->getType() << CT))
     return ExprError();
 
-  if (!E->getType().isPODType(Context)) {
+  // Complain about passing non-POD types through varargs. However, don't
+  // perform this check for incomplete types, which we can get here when we're
+  // in an unevaluated context.
+  if (!E->getType()->isIncompleteType() && !E->getType().isPODType(Context)) {
     // C++0x [expr.call]p7:
     //   Passing a potentially-evaluated argument of class type (Clause 9) 
     //   having a non-trivial copy constructor, a non-trivial move constructor,
diff --git a/clang/test/CXX/expr/expr.post/expr.call/p7-0x.cpp b/clang/test/CXX/expr/expr.post/expr.call/p7-0x.cpp
index e6ffebc8d84f..d51ba09835d2 100644
--- a/clang/test/CXX/expr/expr.post/expr.call/p7-0x.cpp
+++ b/clang/test/CXX/expr/expr.post/expr.call/p7-0x.cpp
@@ -15,3 +15,16 @@ void f(X1 x1, X2 x2) {
   vararg(x1); // okay
   vararg(x2); // expected-error{{cannot pass object of non-trivial type 'X2' through variadic function; call will abort at runtime}}
 }
+
+
+namespace PR11131 {
+  struct S;
+
+  S &getS();
+
+  void f(...);
+
+  void g() {
+    (void)sizeof(f(getS()));
+  }
+}
diff --git a/clang/test/SemaCXX/vararg-non-pod.cpp b/clang/test/SemaCXX/vararg-non-pod.cpp
index 3ca07b0215c3..42c27fb30e1b 100644
--- a/clang/test/SemaCXX/vararg-non-pod.cpp
+++ b/clang/test/SemaCXX/vararg-non-pod.cpp
@@ -118,4 +118,3 @@ void t8(int n, ...) {
   (void)__builtin_va_arg(list, Abstract); // expected-error{{second argument to 'va_arg' is of abstract type 'Abstract'}}
   __builtin_va_end(list);
 }
-
-- 
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