gcc/libcody/internal.hh
Jonathan Wakely 4e42f6ebf4 libcody: Fix build for older GCC versions
Before CWG DR 1955 the controlling expression for an #elif must be
syntactically correct, meaning this won't compile with C++11 compilers
such as gcc 4.8:

The solution is to define __has_include(X) as 0 for compilers that don't
support it.

The second problem is that when <source_location> is found, it is used
without the std:: qualification.

libcody/ChangeLog:

	* internal.hh: Define fallback macros for __has_builtin and
	__has_include. Use __has_builtin for __builtin_FILE and
	__builtin_LINE. Define alias for std::source_location.
2020-12-16 14:33:26 +00:00

137 lines
3.2 KiB
C++

// CODYlib -*- mode:c++ -*-
// Copyright (C) 2020 Nathan Sidwell, nathan@acm.org
// License: Apache v2.0
#include "cody.hh"
#ifndef __has_builtin
#define __has_builtin(X) 0
#endif
#ifndef __has_include
#define __has_include(X) 0
#endif
// C++
#if __has_builtin(__builtin_FILE) && __has_builtin(__builtin_LINE)
#define CODY_LOC_BUILTIN 1
#elif __has_include (<source_location>)
#include <source_location>
#ifdef __cpp_lib_source_location
#define CODY_LOC_SOURCE 1
#endif
#endif
// C
#include <cstdio>
namespace Cody {
// Location is needed regardless of checking, to make the fatal
// handler simpler
class Location
{
protected:
char const *file;
unsigned line;
public:
constexpr Location (char const *file_
#if CODY_LOC_BUILTIN
= __builtin_FILE ()
#elif !CODY_LOC_SOURCE
= nullptr
#endif
, unsigned line_
#if CODY_LOC_BUILTIN
= __builtin_LINE ()
#elif !CODY_LOC_SOURCE
= 0
#endif
)
:file (file_), line (line_)
{
}
#if !CODY_LOC_BUILTIN && CODY_LOC_SOURCE
using source_location = std::source_location;
constexpr Location (source_location loc = source_location::current ())
: Location (loc.file (), loc.line ())
{
}
#endif
public:
constexpr char const *File () const
{
return file;
}
constexpr unsigned Line () const
{
return line;
}
};
void HCF [[noreturn]]
(
char const *msg
#if NMS_CHECKING
, Location const = Location ()
#if !CODY_LOC_BUILTIN && !CODY_LOC_SOURCE
#define HCF(M) HCF ((M), Cody::Location (__FILE__, __LINE__))
#endif
#endif
) noexcept;
#if NMS_CHECKING
void AssertFailed [[noreturn]] (Location loc = Location ()) noexcept;
void Unreachable [[noreturn]] (Location loc = Location ()) noexcept;
#if !CODY_LOC_BUILTIN && !CODY_LOC_SOURCE
#define AssertFailed() AssertFailed (Cody::Location (__FILE__, __LINE__))
#define Unreachable() Unreachable (Cody::Location (__FILE__, __LINE__))
#endif
// Do we have __VA_OPT__, alas no specific feature macro for it :(
// From stack overflow
// https://stackoverflow.com/questions/48045470/portably-detect-va-opt-support
// Relies on having variadic macros, but they're a C++11 thing, so
// we're good
#define HAVE_ARG_3(a,b,c,...) c
#define HAVE_VA_OPT_(...) HAVE_ARG_3(__VA_OPT__(,),true,false,)
#define HAVE_VA_OPT HAVE_VA_OPT_(?)
// Oh, for lazily evaluated function parameters
#if HAVE_VA_OPT
// Assert is variadic, so you can write Assert (TPL<A,B>(C)) without
// extraneous parens. I don't think we need that though.
#define Assert(EXPR, ...) \
(__builtin_expect (bool (EXPR __VA_OPT__ (, __VA_ARGS__)), true) \
? (void)0 : AssertFailed ())
#else
// If you don't have the GNU ,##__VA_ARGS__ pasting extension, we'll
// need another fallback
#define Assert(EXPR, ...) \
(__builtin_expect (bool (EXPR, ##__VA_ARGS__), true) \
? (void)0 : AssertFailed ())
#endif
#else
// Not asserting, use EXPR in an unevaluated context
#if HAVE_VA_OPT
#define Assert(EXPR, ...) \
((void)sizeof (bool (EXPR __VA_OPT__ (, __VA_ARGS__))), (void)0)
#else
#define Assert(EXPR, ...) \
((void)sizeof (bool (EXPR, ##__VA_ARGS__)), (void)0)
#endif
inline void Unreachable () noexcept
{
__builtin_unreachable ();
}
#endif
// FIXME: This should be user visible in some way
void BuildNote (FILE *stream) noexcept;
}