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70 lines
2.3 KiB
Plaintext
70 lines
2.3 KiB
Plaintext
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# SYNOPSIS
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#
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# AX_GCC_STMT_ATTRIBUTE(ATTRIBUTE)
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#
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# DESCRIPTION
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#
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# This macro checks if the compiler supports one of GCC's statement
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# attributes; many other compilers also provide statement attributes with the
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# same syntax. Compiler warnings are used to detect supported attributes as
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# unsupported ones are ignored by default so quieting warnings when using
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# this macro will yield false positives.
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#
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# The ATTRIBUTE parameter holds the name of the attribute to be checked.
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#
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# If ATTRIBUTE is supported define HAVE_STMT_ATTRIBUTE_<ATTRIBUTE>.
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#
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# The macro caches its result in the ax_cv_have_stmt_attribute_<attribute>
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# variable.
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#
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# The macro currently supports the following variable attributes:
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#
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# fallthrough (added 11 Sep 2017, Serval Project)
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#
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# LICENSE
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#
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# Copyright (c) 2017 Flinders University
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#
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# Copying and distribution of this file, with or without modification, are
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# permitted in any medium without royalty provided the copyright notice
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# and this notice are preserved. This file is offered as-is, without any
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# warranty.
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#serial 3
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AC_DEFUN([AX_GCC_STMT_ATTRIBUTE], [
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AS_VAR_PUSHDEF([ac_var], [ax_cv_have_stmt_attribute_$1])
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AC_CACHE_CHECK([for __attribute__(($1))], [ac_var], [
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AC_LINK_IFELSE([AC_LANG_PROGRAM([], [
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m4_case([$1],
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[fallthrough], [
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int x = 1;
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switch (x) {
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case 0: __attribute__(($1));
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case 1: break;
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}
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], [
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m4_warn([syntax], [Unsupported attribute "$1", the test may fail])
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int x = 1;
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++x __attribute__(($1));
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]
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)])
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],
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dnl GCC doesn't exit with an error if an unknown attribute is
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dnl provided but only outputs a warning, so accept the attribute
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dnl only if no warning were issued.
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[AS_IF([test -s conftest.err],
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[AS_VAR_SET([ac_var], [no])],
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[AS_VAR_SET([ac_var], [yes])])],
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[AS_VAR_SET([ac_var], [no])
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])
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])
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AS_IF([test yes = AS_VAR_GET([ac_var])],
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[AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_STMT_ATTRIBUTE_$1), 1,
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[Define to 1 if the system has the `$1' statement attribute])], [])
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AS_VAR_POPDEF([ac_var])
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])
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