Fix sign of wide character literals in preprocessor conditions

[rcraik]

Summary

Set the correct sign of wide character literals based on the underlying type of wchar_t

Fix for PR 19649

[• fraggamuffin]

We have reviewed this internally in IBM and it looks fine. We like to have someone externally review it as well. Thanks.

[hfinkel]

LGTM.

[• fraggamuffin]

Thanks, I will commit this on behalf of Rachel.

[• fraggamuffin]

Commit
D:\llvmtrunk\tools\clang\lib\Lex\PPExpressions.cpp
D:\llvmtrunk\tools\clang\test\Preprocessor\pr19649-signed-wchar_t.c
D:\llvmtrunk\tools\clang\test\Preprocessor\pr19649-unsigned-wchar_t.c
At revision: 230333

lib/Lex/PPExpressions.cpp

case tok::utf32_char_constant: {  // U'x'
     else
       NumBits = TI.getCharWidth();
 
     // Set the width.
     llvm::APSInt Val(NumBits);
     // Set the value.
     Val = Literal.getValue();
     // Set the signedness. UTF-16 and UTF-32 are always unsigned
-    if (!Literal.isUTF16() && !Literal.isUTF32())
+    if (Literal.isWide())
+      Val.setIsUnsigned(!TargetInfo::isTypeSigned(TI.getWCharType()));
+    else if (!Literal.isUTF16() && !Literal.isUTF32())
       Val.setIsUnsigned(!PP.getLangOpts().CharIsSigned);
 
     if (Result.Val.getBitWidth() > Val.getBitWidth()) {
       Result.Val = Val.extend(Result.Val.getBitWidth());
     } else {
       assert(Result.Val.getBitWidth() == Val.getBitWidth() &&
              "intmax_t smaller than char/wchar_t?");
       Result.Val = Val;

test/Preprocessor/pr19649-signed-wchar_t.c

+// RUN: %clang_cc1 -triple powerpc64-unknown-linux-gnu -E -x c %s
+// RUN: %clang_cc1 -triple powerpc64-unknown-linux-gnu -E -fno-signed-char -x c %s
+
+#if (L'\0' - 1 > 0)
+# error "Unexpected expression evaluation result"
+#endif

test/Preprocessor/pr19649-unsigned-wchar_t.c

+// RUN: %clang_cc1 -triple i386-pc-cygwin -E -x c %s
+// RUN: %clang_cc1 -triple powerpc64-unknown-linux-gnu -E -fshort-wchar -x c %s
+
+#if (L'\0' - 1 < 0)
+# error "Unexpected expression evaluation result"
+#endif