[Sema] -Wformat-pedantic only for NSInteger/NSUInteger %tu/%td on Darwin
The '%tu'/'%td' as formatting specifiers have been used to print out the
NSInteger/NSUInteger values for a long time. Typically their ABI matches, but that's
not the case on watchOS. The ABI difference boils down to the following:
- Regular 32-bit darwin targets (like armv7) use 'ptrdiff_t' of type 'int',
which matches 'NSInteger'.
- WatchOS arm target (armv7k) uses 'ptrdiff_t' of type 'long', which doesn't
match 'NSInteger' of type 'int'.
Because of this ABI difference these specifiers trigger -Wformat warnings only
for watchOS builds, which is really inconvenient for cross-platform code.
This patch avoids this -Wformat warning for '%tu'/'%td' and NS[U]Integer only,
and instead uses the new -Wformat-pedantic warning that JF introduced in
https://reviews.llvm.org/D47290. This is acceptable because Darwin guarantees that,
despite the watchOS ABI differences, sizeof(ptrdiff_t) == sizeof(NS[U]Integer),
and alignof(ptrdiff_t) == alignof(NS[U]Integer) so the warning is therefore noisy
for pedantic reasons.
I'll update public documentation to ensure that this behaviour is properly
communicated.
rdar://41739204
Differential Revision: https://reviews.llvm.org/D48852
llvm-svn: 336396
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 98aeb61..cd2aabb 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -6894,10 +6894,11 @@
QualType CastTy;
std::tie(CastTy, CastTyName) = shouldNotPrintDirectly(S.Context, IntendedTy, E);
if (!CastTy.isNull()) {
- // %zi/%zu are OK to use for NSInteger/NSUInteger of type int
+ // %zi/%zu and %td/%tu are OK to use for NSInteger/NSUInteger of type int
// (long in ASTContext). Only complain to pedants.
if ((CastTyName == "NSInteger" || CastTyName == "NSUInteger") &&
- AT.isSizeT() && AT.matchesType(S.Context, CastTy))
+ (AT.isSizeT() || AT.isPtrdiffT()) &&
+ AT.matchesType(S.Context, CastTy))
Pedantic = true;
IntendedTy = CastTy;
ShouldNotPrintDirectly = true;