From e1ffd49165485a7485fd4ae2c52606d7ae2b753a Mon Sep 17 00:00:00 2001
From: Eli Friedman <eli.friedman@gmail.com>
Date: Thu, 2 Feb 2012 00:40:20 +0000
Subject: [PATCH] Change the check for constant-conversion with width-1
 bitfields so it doesn't suppress quite as many cases.  Based off a testcase
 in the gcc testsuite.

llvm-svn: 149572
---
 clang/lib/Sema/SemaChecking.cpp       | 4 ++--
 clang/test/Sema/constant-conversion.c | 6 ++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index ee0446303739..9dbee1b2b3c6 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -3758,8 +3758,8 @@ static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
     return false;
 
   // Special-case bitfields of width 1: booleans are naturally 0/1, and
-  // therefore don't strictly fit into a bitfield of width 1.
-  if (FieldWidth == 1 && Value.getBoolValue() == TruncatedValue.getBoolValue())
+  // therefore don't strictly fit into a signed bitfield of width 1.
+  if (FieldWidth == 1 && Value == 1)
     return false;
 
   std::string PrettyValue = Value.toString(10);
diff --git a/clang/test/Sema/constant-conversion.c b/clang/test/Sema/constant-conversion.c
index e3097f8be30e..137633396712 100644
--- a/clang/test/Sema/constant-conversion.c
+++ b/clang/test/Sema/constant-conversion.c
@@ -74,3 +74,9 @@ void test7() {
 	f.twoBits1 &= ~1; // no-warning
 	f.twoBits2 &= ~2; // no-warning
 }
+
+void test8() {
+  enum E { A, B, C };
+  struct { enum E x : 1; } f;
+  f.x = C; // expected-warning {{implicit truncation from 'int' to bitfield changes value from 2 to 0}}
+}
-- 
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