[clang] [Basic] Enable __has_feature(leak_sanitizer)

[mgorny]

Summary

Add a 'leak_sanitizer' feature akin to existing '*_sanitizer' features
to let programmers switch code paths accounting for leak sanitizers
being enabled.

[krytarowski]

Looks good to me but I will leave the final decision to someone else.

[phosek]

LGTM

[phosek]

Actually, can you please add a test akin to https://github.com/llvm/llvm-project/blob/master/clang/test/Lexer/has_feature_memory_sanitizer.cpp?

[mgorny]

Test added. Thanks for the suggestion!

[phosek]

LGTM

clang/include/clang/Basic/Features.def

 
 #ifndef EXTENSION
 #define EXTENSION(Name, Predicate)
 #endif
 
 FEATURE(address_sanitizer,
         LangOpts.Sanitize.hasOneOf(SanitizerKind::Address |
                                    SanitizerKind::KernelAddress))
+FEATURE(leak_sanitizer,
+        LangOpts.Sanitize.has(SanitizerKind::Leak))
 FEATURE(hwaddress_sanitizer,
         LangOpts.Sanitize.hasOneOf(SanitizerKind::HWAddress |
                                    SanitizerKind::KernelHWAddress))
 FEATURE(memtag_sanitizer, LangOpts.Sanitize.has(SanitizerKind::MemTag))
 FEATURE(xray_instrument, LangOpts.XRayInstrument)
 FEATURE(undefined_behavior_sanitizer,
         LangOpts.Sanitize.hasOneOf(SanitizerKind::Undefined))
 FEATURE(assume_nonnull, true)