diff options
Diffstat (limited to 'macros/texinfo/texinfo/gnulib/lib/verify.h')
-rw-r--r-- | macros/texinfo/texinfo/gnulib/lib/verify.h | 73 |
1 files changed, 48 insertions, 25 deletions
diff --git a/macros/texinfo/texinfo/gnulib/lib/verify.h b/macros/texinfo/texinfo/gnulib/lib/verify.h index afdc1ad81f..65514c34b9 100644 --- a/macros/texinfo/texinfo/gnulib/lib/verify.h +++ b/macros/texinfo/texinfo/gnulib/lib/verify.h @@ -1,6 +1,6 @@ /* Compile-time assert-like macros. - Copyright (C) 2005-2006, 2009-2019 Free Software Foundation, Inc. + Copyright (C) 2005-2006, 2009-2021 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -22,12 +22,10 @@ /* Define _GL_HAVE__STATIC_ASSERT to 1 if _Static_assert (R, DIAGNOSTIC) - works as per C11. This is supported by GCC 4.6.0 and later, in C - mode. + works as per C11. This is supported by GCC 4.6.0+ and by clang 4+. Define _GL_HAVE__STATIC_ASSERT1 to 1 if _Static_assert (R) works as - per C2X, and define _GL_HAVE_STATIC_ASSERT1 if static_assert (R) - works as per C++17. This is supported by GCC 9.1 and later. + per C2X. This is supported by GCC 9.1+. Support compilers claiming conformance to the relevant standard, and also support GCC when not pedantic. If we were willing to slow @@ -35,17 +33,14 @@ since this affects only the quality of diagnostics, why bother? */ #ifndef __cplusplus # if (201112L <= __STDC_VERSION__ \ - || (!defined __STRICT_ANSI__ && 4 < __GNUC__ + (6 <= __GNUC_MINOR__))) + || (!defined __STRICT_ANSI__ \ + && (4 < __GNUC__ + (6 <= __GNUC_MINOR__) || 4 <= __clang_major__))) # define _GL_HAVE__STATIC_ASSERT 1 # endif # if (202000L <= __STDC_VERSION__ \ || (!defined __STRICT_ANSI__ && 9 <= __GNUC__)) # define _GL_HAVE__STATIC_ASSERT1 1 # endif -#else -# if 201703L <= __cplusplus || 9 <= __GNUC__ -# define _GL_HAVE_STATIC_ASSERT1 1 -# endif #endif /* FreeBSD 9.1 <sys/cdefs.h>, included by <stddef.h> and lots of other @@ -212,7 +207,9 @@ template <int w> Unfortunately, unlike C11, this implementation must appear as an ordinary declaration, and cannot appear inside struct { ... }. */ -#if defined _GL_HAVE__STATIC_ASSERT +#if 200410 <= __cpp_static_assert +# define _GL_VERIFY(R, DIAGNOSTIC, ...) static_assert (R, DIAGNOSTIC) +#elif defined _GL_HAVE__STATIC_ASSERT # define _GL_VERIFY(R, DIAGNOSTIC, ...) _Static_assert (R, DIAGNOSTIC) #else # define _GL_VERIFY(R, DIAGNOSTIC, ...) \ @@ -226,13 +223,29 @@ template <int w> # define _Static_assert(...) \ _GL_VERIFY (__VA_ARGS__, "static assertion failed", -) # endif -# if !defined _GL_HAVE_STATIC_ASSERT1 && !defined static_assert +# if __cpp_static_assert < 201411 && !defined static_assert # define static_assert _Static_assert /* C11 requires this #define. */ # endif #endif /* @assert.h omit start@ */ +#if 3 < __GNUC__ + (3 < __GNUC_MINOR__ + (4 <= __GNUC_PATCHLEVEL__)) +# define _GL_HAS_BUILTIN_TRAP 1 +#elif defined __has_builtin +# define _GL_HAS_BUILTIN_TRAP __has_builtin (__builtin_trap) +#else +# define _GL_HAS_BUILTIN_TRAP 0 +#endif + +#if 4 < __GNUC__ + (5 <= __GNUC_MINOR__) +# define _GL_HAS_BUILTIN_UNREACHABLE 1 +#elif defined __has_builtin +# define _GL_HAS_BUILTIN_UNREACHABLE __has_builtin (__builtin_unreachable) +#else +# define _GL_HAS_BUILTIN_UNREACHABLE 0 +#endif + /* Each of these macros verifies that its argument R is nonzero. To be portable, R should be an integer constant expression. Unlike assert (R), there is no run-time overhead. @@ -260,24 +273,34 @@ template <int w> # define verify(R) _GL_VERIFY (R, "verify (" #R ")", -) #endif -#ifndef __has_builtin -# define __has_builtin(x) 0 -#endif - /* Assume that R always holds. Behavior is undefined if R is false, - fails to evaluate, or has side effects. Although assuming R can - help a compiler generate better code or diagnostics, performance - can suffer if R uses hard-to-optimize features such as function - calls not inlined by the compiler. */ + fails to evaluate, or has side effects. + + 'assume (R)' is a directive from the programmer telling the + compiler that R is true so the compiler needn't generate code to + test R. This is why 'assume' is in verify.h: it's related to + static checking (in this case, static checking done by the + programmer), not dynamic checking. + + 'assume (R)' can affect compilation of all the code, not just code + that happens to be executed after the assume (R) is "executed". + For example, if the code mistakenly does 'assert (R); assume (R);' + the compiler is entitled to optimize away the 'assert (R)'. + + Although assuming R can help a compiler generate better code or + diagnostics, performance can suffer if R uses hard-to-optimize + features such as function calls not inlined by the compiler. + + Avoid Clang's __builtin_assume, as it breaks GNU Emacs master + as of 2020-08-23T21:09:49Z!eggert@cs.ucla.edu; see + <https://bugs.gnu.org/43152#71>. It's not known whether this breakage + is a Clang bug or an Emacs bug; play it safe for now. */ -#if (__has_builtin (__builtin_unreachable) \ - || 4 < __GNUC__ + (5 <= __GNUC_MINOR__)) +#if _GL_HAS_BUILTIN_UNREACHABLE # define assume(R) ((R) ? (void) 0 : __builtin_unreachable ()) #elif 1200 <= _MSC_VER # define assume(R) __assume (R) -#elif ((defined GCC_LINT || defined lint) \ - && (__has_builtin (__builtin_trap) \ - || 3 < __GNUC__ + (3 < __GNUC_MINOR__ + (4 <= __GNUC_PATCHLEVEL__)))) +#elif (defined GCC_LINT || defined lint) && _GL_HAS_BUILTIN_TRAP /* Doing it this way helps various packages when configured with --enable-gcc-warnings, which compiles with -Dlint. It's nicer when 'assume' silences warnings even with older GCCs. */ |