[clang] Add getUnsignedPointerDiffType method
C11 standard refers to the unsigned counterpart of the type ptrdiff_t
in the paragraph 7.21.6.1p7 where it defines the format specifier %tu.
In Clang (in PrintfFormatString.cpp, lines 508-510) there is a FIXME for this case,
in particular, Clang didn't diagnose %tu issues at all, i.e.
it didn't emit any warnings on the code printf("%tu", 3.14).
In this diff we add a method getUnsignedPointerDiffType for getting the corresponding type
similarly to how it's already done in the other analogous cases (size_t, ssize_t, ptrdiff_t etc)
and fix -Wformat diagnostics for %tu plus the emitted fix-it as well.
Test plan: make check-all
Differential revision: https://reviews.llvm.org/D38270
llvm-svn: 314470
diff --git a/clang/lib/Analysis/ScanfFormatString.cpp b/clang/lib/Analysis/ScanfFormatString.cpp
index 734dc75..8398a4b 100644
--- a/clang/lib/Analysis/ScanfFormatString.cpp
+++ b/clang/lib/Analysis/ScanfFormatString.cpp
@@ -291,8 +291,8 @@
case LengthModifier::AsSizeT:
return ArgType::PtrTo(ArgType(Ctx.getSizeType(), "size_t"));
case LengthModifier::AsPtrDiff:
- // FIXME: Unsigned version of ptrdiff_t?
- return ArgType();
+ return ArgType::PtrTo(
+ ArgType(Ctx.getUnsignedPointerDiffType(), "unsigned ptrdiff_t"));
case LengthModifier::AsLongDouble:
// GNU extension.
return ArgType::PtrTo(Ctx.UnsignedLongLongTy);