| 1 | # include_next.m4 serial 23
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| 2 | dnl Copyright (C) 2006-2012 Free Software Foundation, Inc.
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| 3 | dnl This file is free software; the Free Software Foundation
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| 4 | dnl gives unlimited permission to copy and/or distribute it,
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| 5 | dnl with or without modifications, as long as this notice is preserved.
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| 6 |
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| 7 | dnl From Paul Eggert and Derek Price.
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| 8 |
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| 9 | dnl Sets INCLUDE_NEXT and PRAGMA_SYSTEM_HEADER.
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| 10 | dnl
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| 11 | dnl INCLUDE_NEXT expands to 'include_next' if the compiler supports it, or to
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| 12 | dnl 'include' otherwise.
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| 13 | dnl
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| 14 | dnl INCLUDE_NEXT_AS_FIRST_DIRECTIVE expands to 'include_next' if the compiler
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| 15 | dnl supports it in the special case that it is the first include directive in
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| 16 | dnl the given file, or to 'include' otherwise.
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| 17 | dnl
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| 18 | dnl PRAGMA_SYSTEM_HEADER can be used in files that contain #include_next,
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| 19 | dnl so as to avoid GCC warnings when the gcc option -pedantic is used.
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| 20 | dnl '#pragma GCC system_header' has the same effect as if the file was found
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| 21 | dnl through the include search path specified with '-isystem' options (as
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| 22 | dnl opposed to the search path specified with '-I' options). Namely, gcc
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| 23 | dnl does not warn about some things, and on some systems (Solaris and Interix)
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| 24 | dnl __STDC__ evaluates to 0 instead of to 1. The latter is an undesired side
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| 25 | dnl effect; we are therefore careful to use 'defined __STDC__' or '1' instead
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| 26 | dnl of plain '__STDC__'.
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| 27 | dnl
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| 28 | dnl PRAGMA_COLUMNS can be used in files that override system header files, so
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| 29 | dnl as to avoid compilation errors on HP NonStop systems when the gnulib file
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| 30 | dnl is included by a system header file that does a "#pragma COLUMNS 80" (which
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| 31 | dnl has the effect of truncating the lines of that file and all files that it
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| 32 | dnl includes to 80 columns) and the gnulib file has lines longer than 80
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| 33 | dnl columns.
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| 34 |
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| 35 | AC_DEFUN([gl_INCLUDE_NEXT],
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| 36 | [
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| 37 | AC_LANG_PREPROC_REQUIRE()
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| 38 | AC_CACHE_CHECK([whether the preprocessor supports include_next],
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| 39 | [gl_cv_have_include_next],
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| 40 | [rm -rf conftestd1a conftestd1b conftestd2
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| 41 | mkdir conftestd1a conftestd1b conftestd2
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| 42 | dnl IBM C 9.0, 10.1 (original versions, prior to the 2009-01 updates) on
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| 43 | dnl AIX 6.1 support include_next when used as first preprocessor directive
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| 44 | dnl in a file, but not when preceded by another include directive. Check
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| 45 | dnl for this bug by including <stdio.h>.
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| 46 | dnl Additionally, with this same compiler, include_next is a no-op when
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| 47 | dnl used in a header file that was included by specifying its absolute
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| 48 | dnl file name. Despite these two bugs, include_next is used in the
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| 49 | dnl compiler's <math.h>. By virtue of the second bug, we need to use
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| 50 | dnl include_next as well in this case.
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| 51 | cat <<EOF > conftestd1a/conftest.h
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| 52 | #define DEFINED_IN_CONFTESTD1
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| 53 | #include_next <conftest.h>
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| 54 | #ifdef DEFINED_IN_CONFTESTD2
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| 55 | int foo;
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| 56 | #else
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| 57 | #error "include_next doesn't work"
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| 58 | #endif
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| 59 | EOF
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| 60 | cat <<EOF > conftestd1b/conftest.h
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| 61 | #define DEFINED_IN_CONFTESTD1
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| 62 | #include <stdio.h>
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| 63 | #include_next <conftest.h>
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| 64 | #ifdef DEFINED_IN_CONFTESTD2
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| 65 | int foo;
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| 66 | #else
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| 67 | #error "include_next doesn't work"
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| 68 | #endif
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| 69 | EOF
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| 70 | cat <<EOF > conftestd2/conftest.h
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| 71 | #ifndef DEFINED_IN_CONFTESTD1
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| 72 | #error "include_next test doesn't work"
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| 73 | #endif
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| 74 | #define DEFINED_IN_CONFTESTD2
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| 75 | EOF
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| 76 | gl_save_CPPFLAGS="$CPPFLAGS"
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| 77 | CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1b -Iconftestd2"
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| 78 | dnl We intentionally avoid using AC_LANG_SOURCE here.
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| 79 | AC_COMPILE_IFELSE([AC_LANG_DEFINES_PROVIDED[#include <conftest.h>]],
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| 80 | [gl_cv_have_include_next=yes],
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| 81 | [CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1a -Iconftestd2"
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| 82 | AC_COMPILE_IFELSE([AC_LANG_DEFINES_PROVIDED[#include <conftest.h>]],
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| 83 | [gl_cv_have_include_next=buggy],
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| 84 | [gl_cv_have_include_next=no])
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| 85 | ])
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| 86 | CPPFLAGS="$gl_save_CPPFLAGS"
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| 87 | rm -rf conftestd1a conftestd1b conftestd2
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| 88 | ])
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| 89 | PRAGMA_SYSTEM_HEADER=
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| 90 | if test $gl_cv_have_include_next = yes; then
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| 91 | INCLUDE_NEXT=include_next
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| 92 | INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next
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| 93 | if test -n "$GCC"; then
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| 94 | PRAGMA_SYSTEM_HEADER='#pragma GCC system_header'
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| 95 | fi
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| 96 | else
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| 97 | if test $gl_cv_have_include_next = buggy; then
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| 98 | INCLUDE_NEXT=include
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| 99 | INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next
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| 100 | else
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| 101 | INCLUDE_NEXT=include
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| 102 | INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include
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| 103 | fi
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| 104 | fi
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| 105 | AC_SUBST([INCLUDE_NEXT])
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| 106 | AC_SUBST([INCLUDE_NEXT_AS_FIRST_DIRECTIVE])
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| 107 | AC_SUBST([PRAGMA_SYSTEM_HEADER])
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| 108 | AC_CACHE_CHECK([whether system header files limit the line length],
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| 109 | [gl_cv_pragma_columns],
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| 110 | [dnl HP NonStop systems, which define __TANDEM, have this misfeature.
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| 111 | AC_EGREP_CPP([choke me],
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| 112 | [
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| 113 | #ifdef __TANDEM
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| 114 | choke me
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| 115 | #endif
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| 116 | ],
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| 117 | [gl_cv_pragma_columns=yes],
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| 118 | [gl_cv_pragma_columns=no])
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| 119 | ])
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| 120 | if test $gl_cv_pragma_columns = yes; then
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| 121 | PRAGMA_COLUMNS="#pragma COLUMNS 10000"
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| 122 | else
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| 123 | PRAGMA_COLUMNS=
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| 124 | fi
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| 125 | AC_SUBST([PRAGMA_COLUMNS])
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| 126 | ])
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| 127 |
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| 128 | # gl_CHECK_NEXT_HEADERS(HEADER1 HEADER2 ...)
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| 129 | # ------------------------------------------
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| 130 | # For each arg foo.h, if #include_next works, define NEXT_FOO_H to be
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| 131 | # '<foo.h>'; otherwise define it to be
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| 132 | # '"///usr/include/foo.h"', or whatever other absolute file name is suitable.
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| 133 | # Also, if #include_next works as first preprocessing directive in a file,
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| 134 | # define NEXT_AS_FIRST_DIRECTIVE_FOO_H to be '<foo.h>'; otherwise define it to
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| 135 | # be
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| 136 | # '"///usr/include/foo.h"', or whatever other absolute file name is suitable.
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| 137 | # That way, a header file with the following line:
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| 138 | # #@INCLUDE_NEXT@ @NEXT_FOO_H@
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| 139 | # or
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| 140 | # #@INCLUDE_NEXT_AS_FIRST_DIRECTIVE@ @NEXT_AS_FIRST_DIRECTIVE_FOO_H@
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| 141 | # behaves (after sed substitution) as if it contained
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| 142 | # #include_next <foo.h>
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| 143 | # even if the compiler does not support include_next.
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| 144 | # The three "///" are to pacify Sun C 5.8, which otherwise would say
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| 145 | # "warning: #include of /usr/include/... may be non-portable".
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| 146 | # Use '""', not '<>', so that the /// cannot be confused with a C99 comment.
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| 147 | # Note: This macro assumes that the header file is not empty after
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| 148 | # preprocessing, i.e. it does not only define preprocessor macros but also
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| 149 | # provides some type/enum definitions or function/variable declarations.
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| 150 | #
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| 151 | # This macro also checks whether each header exists, by invoking
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| 152 | # AC_CHECK_HEADERS_ONCE or AC_CHECK_HEADERS on each argument.
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| 153 | AC_DEFUN([gl_CHECK_NEXT_HEADERS],
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| 154 | [
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| 155 | gl_NEXT_HEADERS_INTERNAL([$1], [check])
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| 156 | ])
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| 157 |
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| 158 | # gl_NEXT_HEADERS(HEADER1 HEADER2 ...)
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| 159 | # ------------------------------------
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| 160 | # Like gl_CHECK_NEXT_HEADERS, except do not check whether the headers exist.
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| 161 | # This is suitable for headers like <stddef.h> that are standardized by C89
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| 162 | # and therefore can be assumed to exist.
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| 163 | AC_DEFUN([gl_NEXT_HEADERS],
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| 164 | [
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| 165 | gl_NEXT_HEADERS_INTERNAL([$1], [assume])
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| 166 | ])
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| 167 |
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| 168 | # The guts of gl_CHECK_NEXT_HEADERS and gl_NEXT_HEADERS.
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| 169 | AC_DEFUN([gl_NEXT_HEADERS_INTERNAL],
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| 170 | [
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| 171 | AC_REQUIRE([gl_INCLUDE_NEXT])
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| 172 | AC_REQUIRE([AC_CANONICAL_HOST])
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| 173 |
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| 174 | m4_if([$2], [check],
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| 175 | [AC_CHECK_HEADERS_ONCE([$1])
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| 176 | ])
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| 177 |
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| 178 | dnl FIXME: gl_next_header and gl_header_exists must be used unquoted
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| 179 | dnl until we can assume autoconf 2.64 or newer.
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| 180 | m4_foreach_w([gl_HEADER_NAME], [$1],
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| 181 | [AS_VAR_PUSHDEF([gl_next_header],
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| 182 | [gl_cv_next_]m4_defn([gl_HEADER_NAME]))
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| 183 | if test $gl_cv_have_include_next = yes; then
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| 184 | AS_VAR_SET(gl_next_header, ['<'gl_HEADER_NAME'>'])
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| 185 | else
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| 186 | AC_CACHE_CHECK(
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| 187 | [absolute name of <]m4_defn([gl_HEADER_NAME])[>],
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| 188 | m4_defn([gl_next_header]),
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| 189 | [m4_if([$2], [check],
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| 190 | [AS_VAR_PUSHDEF([gl_header_exists],
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| 191 | [ac_cv_header_]m4_defn([gl_HEADER_NAME]))
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| 192 | if test AS_VAR_GET(gl_header_exists) = yes; then
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| 193 | AS_VAR_POPDEF([gl_header_exists])
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| 194 | ])
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| 195 | AC_LANG_CONFTEST(
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| 196 | [AC_LANG_SOURCE(
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| 197 | [[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]]
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| 198 | )])
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| 199 | dnl AIX "xlc -E" and "cc -E" omit #line directives for header
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| 200 | dnl files that contain only a #include of other header files and
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| 201 | dnl no non-comment tokens of their own. This leads to a failure
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| 202 | dnl to detect the absolute name of <dirent.h>, <signal.h>,
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| 203 | dnl <poll.h> and others. The workaround is to force preservation
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| 204 | dnl of comments through option -C. This ensures all necessary
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| 205 | dnl #line directives are present. GCC supports option -C as well.
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| 206 | case "$host_os" in
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| 207 | aix*) gl_absname_cpp="$ac_cpp -C" ;;
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| 208 | *) gl_absname_cpp="$ac_cpp" ;;
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| 209 | esac
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| 210 | changequote(,)
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| 211 | case "$host_os" in
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| 212 | mingw*)
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| 213 | dnl For the sake of native Windows compilers (excluding gcc),
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| 214 | dnl treat backslash as a directory separator, like /.
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| 215 | dnl Actually, these compilers use a double-backslash as
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| 216 | dnl directory separator, inside the
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| 217 | dnl # line "filename"
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| 218 | dnl directives.
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| 219 | gl_dirsep_regex='[/\\]'
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| 220 | ;;
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| 221 | *)
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| 222 | gl_dirsep_regex='\/'
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| 223 | ;;
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| 224 | esac
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| 225 | dnl A sed expression that turns a string into a basic regular
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| 226 | dnl expression, for use within "/.../".
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| 227 | gl_make_literal_regex_sed='s,[]$^\\.*/[],\\&,g'
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| 228 | changequote([,])
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| 229 | gl_header_literal_regex=`echo ']m4_defn([gl_HEADER_NAME])[' \
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| 230 | | sed -e "$gl_make_literal_regex_sed"`
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| 231 | gl_absolute_header_sed="/${gl_dirsep_regex}${gl_header_literal_regex}/"'{
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| 232 | s/.*"\(.*'"${gl_dirsep_regex}${gl_header_literal_regex}"'\)".*/\1/
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| 233 | changequote(,)dnl
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| 234 | s|^/[^/]|//&|
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| 235 | changequote([,])dnl
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| 236 | p
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| 237 | q
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| 238 | }'
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| 239 | dnl eval is necessary to expand gl_absname_cpp.
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| 240 | dnl Ultrix and Pyramid sh refuse to redirect output of eval,
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| 241 | dnl so use subshell.
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| 242 | AS_VAR_SET(gl_next_header,
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| 243 | ['"'`(eval "$gl_absname_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
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| 244 | sed -n "$gl_absolute_header_sed"`'"'])
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| 245 | m4_if([$2], [check],
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| 246 | [else
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| 247 | AS_VAR_SET(gl_next_header, ['<'gl_HEADER_NAME'>'])
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| 248 | fi
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| 249 | ])
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| 250 | ])
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| 251 | fi
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| 252 | AC_SUBST(
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| 253 | AS_TR_CPP([NEXT_]m4_defn([gl_HEADER_NAME])),
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| 254 | [AS_VAR_GET(gl_next_header)])
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| 255 | if test $gl_cv_have_include_next = yes || test $gl_cv_have_include_next = buggy; then
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| 256 | # INCLUDE_NEXT_AS_FIRST_DIRECTIVE='include_next'
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| 257 | gl_next_as_first_directive='<'gl_HEADER_NAME'>'
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| 258 | else
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| 259 | # INCLUDE_NEXT_AS_FIRST_DIRECTIVE='include'
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| 260 | gl_next_as_first_directive=AS_VAR_GET(gl_next_header)
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| 261 | fi
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| 262 | AC_SUBST(
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| 263 | AS_TR_CPP([NEXT_AS_FIRST_DIRECTIVE_]m4_defn([gl_HEADER_NAME])),
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| 264 | [$gl_next_as_first_directive])
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| 265 | AS_VAR_POPDEF([gl_next_header])])
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| 266 | ])
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| 267 |
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| 268 | # Autoconf 2.68 added warnings for our use of AC_COMPILE_IFELSE;
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| 269 | # this fallback is safe for all earlier autoconf versions.
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| 270 | m4_define_default([AC_LANG_DEFINES_PROVIDED])
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