Format strings: offer a cast to 'unichar' for %C in Objective-C contexts.

For most cases where a conversion specifier doesn't match an argument,
we usually guess that the conversion specifier is wrong. However, if
the argument is an integer type and the specifier is %C, it's likely
the user really did mean to print the integer as a character.

(This is more common than %c because there is no way to specify a unichar
literal -- you have to write an integer literal, such as '0x2603',
and then cast it to unichar.)

This does not change the behavior of %S, since there are fewer cases
where printing a literal Unicode *string* is necessary, but this could
easily be changed in the future.

<rdar://problem/11982013>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@169400 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 3 deletions

diff --git a/lib/Analysis/PrintfFormatString.cpp b/lib/Analysis/PrintfFormatString.cpp
index 08207910b8..176aaedeaa 100644
--- a/lib/Analysis/PrintfFormatString.cpp
+++ b/lib/Analysis/PrintfFormatString.cpp
@@ -359,17 +359,19 @@ ArgType PrintfSpecifier::getArgType(ASTContext &Ctx,
     case ConversionSpecifier::sArg:
       if (LM.getKind() == LengthModifier::AsWideChar) {
         if (IsObjCLiteral)
-          return Ctx.getPointerType(Ctx.UnsignedShortTy.withConst());
+          return ArgType(Ctx.getPointerType(Ctx.UnsignedShortTy.withConst()),
+                         "const unichar *");
         return ArgType(ArgType::WCStrTy, "wchar_t *");
       }
       return ArgType::CStrTy;
     case ConversionSpecifier::SArg:
       if (IsObjCLiteral)
-        return Ctx.getPointerType(Ctx.UnsignedShortTy.withConst());
+        return ArgType(Ctx.getPointerType(Ctx.UnsignedShortTy.withConst()),
+                       "const unichar *");
       return ArgType(ArgType::WCStrTy, "wchar_t *");
     case ConversionSpecifier::CArg:
       if (IsObjCLiteral)
-        return Ctx.UnsignedShortTy;
+        return ArgType(Ctx.UnsignedShortTy, "unichar");
       return ArgType(Ctx.WCharTy, "wchar_t");
     case ConversionSpecifier::pArg:
       return ArgType::CPointerTy;