clang requires quotes around strings in attributes

[llvmbot]

Bugzilla Link	38584
Version	unspecified
OS	Windows NT
Reporter	LLVM Bugzilla Contributor
CC	@AaronBallman,@DougGregor

Extended Description

See following PR for discussion:
microsoft/GSL#703

The issue prevents platform-independent suppression of static analysis warnings from CppCoreCheck, for example, i have to define the following macro to use as suppression:

#if defined(_MSC_VER)
#define GSL_SUPPRESS(x) [[gsl::suppress(x)]] 
#else
#if defined(__clang__) 
#define GSL_SUPPRESS(x) [[gsl::suppress("x")]] 
#endif // __clang__

[AaronBallman]

That's an unfortunate discrepancy. I think it arose because the documentation is a bit loose about the syntax (all specific examples in prose use quotes which sort of suggested that tags are quoted) and this form of attribute argument is more novel than a string literal. Bummer.

Our attribute support doesn't have a way to specify an attribute that can take an arbitrary number of tokens as a single argument, which is needed to support constructs like [[gsl::suppress(Rh-public) or gsl::suppress(type.4). And we'd still need to support the quoted version so we don't break code.

Do you know if there are other surprises here, such as whitespace within the attribute argument list? e.g., are these equivalent? [[gsl::suppress(Rh - public)]], [[gsl::suppress(Rh-public)]], and [[gsl::suppress( R h - p u b l i c )]]?

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: None (llvmbot)

| | | | --- | --- | | Bugzilla Link | [38584](https://llvm.org/bz38584) | | Version | unspecified | | OS | Windows NT | | Reporter | LLVM Bugzilla Contributor | | CC | @AaronBallman,@DougGregor |

Extended Description

See following PR for discussion:
microsoft/GSL#703

The issue prevents platform-independent suppression of static analysis warnings from CppCoreCheck, for example, i have to define the following macro to use as suppression:

#if defined(_MSC_VER)
#define GSL_SUPPRESS(x) [[gsl::suppress(x)]] 
#else
#if defined(__clang__) 
#define GSL_SUPPRESS(x) [[gsl::suppress("x")]] 
#endif // __clang__

[shafik]

CC @erichkeane