__has_include should not error if unevaluated

[kyuupichan]

If /tmp/unreadable.cpp is unreadable (e.g. because chmod a-r) then clang gives a fatal error on this conditional. GCC gets this right and is silent only because the __has_include is unevaluated.

#if 0 && __has_include("/tmp/unreadable.cpp")
#endif

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Neil Booth (kyuupichan)

If /tmp/unreadable.cpp is unreadable (e.g. because chmod a-r) then clang gives a fatal error on this conditional. GCC gets this right and is silent only because the __has_include is unevaluated.

#if 0 && __has_include("/tmp/unreadable.cpp")
#endif

[Agent-Hellboy]

Hey, I am exploring llvm these days and i want to try this issue.

[kyuupichan]

It might be tricky as I think the problem is that the processing of _has_include isn't taking place in the context of the expression evaluator (which is where it should be, IMO).

[Agent-Hellboy]

It might be tricky as I think the problem is that the processing of _has_include isn't taking place in the context of the expression evaluator (which is where it should be, IMO).

No problem, I can at least try.