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Diffstat (limited to 'm4/include_next.m4')
| -rw-r--r-- | m4/include_next.m4 | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/m4/include_next.m4 b/m4/include_next.m4 new file mode 100644 index 00000000..e37eb056 --- /dev/null +++ b/m4/include_next.m4 @@ -0,0 +1,217 @@ +# include_next.m4 serial 16 +dnl Copyright (C) 2006-2010 Free Software Foundation, Inc. +dnl This file is free software; the Free Software Foundation +dnl gives unlimited permission to copy and/or distribute it, +dnl with or without modifications, as long as this notice is preserved. + +dnl From Paul Eggert and Derek Price. + +dnl Sets INCLUDE_NEXT and PRAGMA_SYSTEM_HEADER. +dnl +dnl INCLUDE_NEXT expands to 'include_next' if the compiler supports it, or to +dnl 'include' otherwise. +dnl +dnl INCLUDE_NEXT_AS_FIRST_DIRECTIVE expands to 'include_next' if the compiler +dnl supports it in the special case that it is the first include directive in +dnl the given file, or to 'include' otherwise. +dnl +dnl PRAGMA_SYSTEM_HEADER can be used in files that contain #include_next, +dnl so as to avoid GCC warnings when the gcc option -pedantic is used. +dnl '#pragma GCC system_header' has the same effect as if the file was found +dnl through the include search path specified with '-isystem' options (as +dnl opposed to the search path specified with '-I' options). Namely, gcc +dnl does not warn about some things, and on some systems (Solaris and Interix) +dnl __STDC__ evaluates to 0 instead of to 1. The latter is an undesired side +dnl effect; we are therefore careful to use 'defined __STDC__' or '1' instead +dnl of plain '__STDC__'. +dnl +dnl PRAGMA_COLUMNS can be used in files that override system header files, so +dnl as to avoid compilation errors on HP NonStop systems when the gnulib file +dnl is included by a system header file that does a "#pragma COLUMNS 80" (which +dnl has the effect of truncating the lines of that file and all files that it +dnl includes to 80 columns) and the gnulib file has lines longer than 80 +dnl columns. + +AC_DEFUN([gl_INCLUDE_NEXT], +[ + AC_LANG_PREPROC_REQUIRE() + AC_CACHE_CHECK([whether the preprocessor supports include_next], + [gl_cv_have_include_next], + [rm -rf conftestd1a conftestd1b conftestd2 + mkdir conftestd1a conftestd1b conftestd2 + dnl IBM C 9.0, 10.1 (original versions, prior to the 2009-01 updates) on + dnl AIX 6.1 support include_next when used as first preprocessor directive + dnl in a file, but not when preceded by another include directive. Check + dnl for this bug by including <stdio.h>. + dnl Additionally, with this same compiler, include_next is a no-op when + dnl used in a header file that was included by specifying its absolute + dnl file name. Despite these two bugs, include_next is used in the + dnl compiler's <math.h>. By virtue of the second bug, we need to use + dnl include_next as well in this case. + cat <<EOF > conftestd1a/conftest.h +#define DEFINED_IN_CONFTESTD1 +#include_next <conftest.h> +#ifdef DEFINED_IN_CONFTESTD2 +int foo; +#else +#error "include_next doesn't work" +#endif +EOF + cat <<EOF > conftestd1b/conftest.h +#define DEFINED_IN_CONFTESTD1 +#include <stdio.h> +#include_next <conftest.h> +#ifdef DEFINED_IN_CONFTESTD2 +int foo; +#else +#error "include_next doesn't work" +#endif +EOF + cat <<EOF > conftestd2/conftest.h +#ifndef DEFINED_IN_CONFTESTD1 +#error "include_next test doesn't work" +#endif +#define DEFINED_IN_CONFTESTD2 +EOF + gl_save_CPPFLAGS="$CPPFLAGS" + CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1b -Iconftestd2" +dnl We intentionally avoid using AC_LANG_SOURCE here. + AC_COMPILE_IFELSE([AC_LANG_DEFINES_PROVIDED[#include <conftest.h>]], + [gl_cv_have_include_next=yes], + [CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1a -Iconftestd2" + AC_COMPILE_IFELSE([AC_LANG_DEFINES_PROVIDED[#include <conftest.h>]], + [gl_cv_have_include_next=buggy], + [gl_cv_have_include_next=no]) + ]) + CPPFLAGS="$gl_save_CPPFLAGS" + rm -rf conftestd1a conftestd1b conftestd2 + ]) + PRAGMA_SYSTEM_HEADER= + if test $gl_cv_have_include_next = yes; then + INCLUDE_NEXT=include_next + INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next + if test -n "$GCC"; then + PRAGMA_SYSTEM_HEADER='#pragma GCC system_header' + fi + else + if test $gl_cv_have_include_next = buggy; then + INCLUDE_NEXT=include + INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next + else + INCLUDE_NEXT=include + INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include + fi + fi + AC_SUBST([INCLUDE_NEXT]) + AC_SUBST([INCLUDE_NEXT_AS_FIRST_DIRECTIVE]) + AC_SUBST([PRAGMA_SYSTEM_HEADER]) + AC_CACHE_CHECK([whether system header files limit the line length], + [gl_cv_pragma_columns], + [dnl HP NonStop systems, which define __TANDEM, have this misfeature. + AC_EGREP_CPP([choke me], + [ +#ifdef __TANDEM +choke me +#endif + ], + [gl_cv_pragma_columns=yes], + [gl_cv_pragma_columns=no]) + ]) + if test $gl_cv_pragma_columns = yes; then + PRAGMA_COLUMNS="#pragma COLUMNS 10000" + else + PRAGMA_COLUMNS= + fi + AC_SUBST([PRAGMA_COLUMNS]) +]) + +# gl_CHECK_NEXT_HEADERS(HEADER1 HEADER2 ...) +# ------------------------------------------ +# For each arg foo.h, if #include_next works, define NEXT_FOO_H to be +# '<foo.h>'; otherwise define it to be +# '"///usr/include/foo.h"', or whatever other absolute file name is suitable. +# Also, if #include_next works as first preprocessing directive in a file, +# define NEXT_AS_FIRST_DIRECTIVE_FOO_H to be '<foo.h>'; otherwise define it to +# be +# '"///usr/include/foo.h"', or whatever other absolute file name is suitable. +# That way, a header file with the following line: +# #@INCLUDE_NEXT@ @NEXT_FOO_H@ +# or +# #@INCLUDE_NEXT_AS_FIRST_DIRECTIVE@ @NEXT_AS_FIRST_DIRECTIVE_FOO_H@ +# behaves (after sed substitution) as if it contained +# #include_next <foo.h> +# even if the compiler does not support include_next. +# The three "///" are to pacify Sun C 5.8, which otherwise would say +# "warning: #include of /usr/include/... may be non-portable". +# Use `""', not `<>', so that the /// cannot be confused with a C99 comment. +# Note: This macro assumes that the header file is not empty after +# preprocessing, i.e. it does not only define preprocessor macros but also +# provides some type/enum definitions or function/variable declarations. +AC_DEFUN([gl_CHECK_NEXT_HEADERS], +[ + AC_REQUIRE([gl_INCLUDE_NEXT]) + AC_REQUIRE([AC_CANONICAL_HOST]) + AC_CHECK_HEADERS_ONCE([$1]) + + m4_foreach_w([gl_HEADER_NAME], [$1], + [AS_VAR_PUSHDEF([gl_next_header], + [gl_cv_next_]m4_defn([gl_HEADER_NAME])) + if test $gl_cv_have_include_next = yes; then + AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>']) + else + AC_CACHE_CHECK( + [absolute name of <]m4_defn([gl_HEADER_NAME])[>], + m4_defn([gl_next_header]), + [AS_VAR_PUSHDEF([gl_header_exists], + [ac_cv_header_]m4_defn([gl_HEADER_NAME])) + if test AS_VAR_GET(gl_header_exists) = yes; then + AC_LANG_CONFTEST( + [AC_LANG_SOURCE( + [[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]] + )]) + dnl AIX "xlc -E" and "cc -E" omit #line directives for header files + dnl that contain only a #include of other header files and no + dnl non-comment tokens of their own. This leads to a failure to + dnl detect the absolute name of <dirent.h>, <signal.h>, <poll.h> + dnl and others. The workaround is to force preservation of comments + dnl through option -C. This ensures all necessary #line directives + dnl are present. GCC supports option -C as well. + case "$host_os" in + aix*) gl_absname_cpp="$ac_cpp -C" ;; + *) gl_absname_cpp="$ac_cpp" ;; + esac + dnl eval is necessary to expand gl_absname_cpp. + dnl Ultrix and Pyramid sh refuse to redirect output of eval, + dnl so use subshell. + AS_VAR_SET([gl_next_header], + ['"'`(eval "$gl_absname_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD | + sed -n '\#/]m4_defn([gl_HEADER_NAME])[#{ + s#.*"\(.*/]m4_defn([gl_HEADER_NAME])[\)".*#\1# + s#^/[^/]#//&# + p + q + }'`'"']) + else + AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>']) + fi + AS_VAR_POPDEF([gl_header_exists])]) + fi + AC_SUBST( + AS_TR_CPP([NEXT_]m4_defn([gl_HEADER_NAME])), + [AS_VAR_GET([gl_next_header])]) + if test $gl_cv_have_include_next = yes || test $gl_cv_have_include_next = buggy; then + # INCLUDE_NEXT_AS_FIRST_DIRECTIVE='include_next' + gl_next_as_first_directive='<'gl_HEADER_NAME'>' + else + # INCLUDE_NEXT_AS_FIRST_DIRECTIVE='include' + gl_next_as_first_directive=AS_VAR_GET([gl_next_header]) + fi + AC_SUBST( + AS_TR_CPP([NEXT_AS_FIRST_DIRECTIVE_]m4_defn([gl_HEADER_NAME])), + [$gl_next_as_first_directive]) + AS_VAR_POPDEF([gl_next_header])]) +]) + +# Autoconf 2.68 added warnings for our use of AC_COMPILE_IFELSE; +# this fallback is safe for all earlier autoconf versions. +m4_define_default([AC_LANG_DEFINES_PROVIDED]) |