1# absolute-header.m4 serial 17
2dnl Copyright (C) 2006-2022 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7dnl From Derek Price.
8
9# gl_ABSOLUTE_HEADER(HEADER1 HEADER2 ...)
10# ---------------------------------------
11# Find the absolute name of a header file, testing first if the header exists.
12# If the header were sys/inttypes.h, this macro would define
13# ABSOLUTE_SYS_INTTYPES_H to the '""' quoted absolute name of sys/inttypes.h
14# in config.h
15# (e.g. '#define ABSOLUTE_SYS_INTTYPES_H "///usr/include/sys/inttypes.h"').
16# The three "///" are to pacify Sun C 5.8, which otherwise would say
17# "warning: #include of /usr/include/... may be non-portable".
18# Use '""', not '<>', so that the /// cannot be confused with a C99 comment.
19# Note: This macro assumes that the header file is not empty after
20# preprocessing, i.e. it does not only define preprocessor macros but also
21# provides some type/enum definitions or function/variable declarations.
22AC_DEFUN([gl_ABSOLUTE_HEADER],
23[AC_REQUIRE([AC_CANONICAL_HOST])
24AC_LANG_PREPROC_REQUIRE()dnl
25m4_foreach_w([gl_HEADER_NAME], [$1],
26  [AS_VAR_PUSHDEF([gl_absolute_header],
27                  [gl_cv_absolute_]m4_defn([gl_HEADER_NAME]))dnl
28  AC_CACHE_CHECK([absolute name of <]m4_defn([gl_HEADER_NAME])[>],
29    [gl_absolute_header],
30    [AS_VAR_PUSHDEF([ac_header_exists],
31                    [ac_cv_header_]m4_defn([gl_HEADER_NAME]))dnl
32    AC_CHECK_HEADERS_ONCE(m4_defn([gl_HEADER_NAME]))dnl
33    if test AS_VAR_GET([ac_header_exists]) = yes; then
34      gl_ABSOLUTE_HEADER_ONE(m4_defn([gl_HEADER_NAME]))
35    fi
36    AS_VAR_POPDEF([ac_header_exists])dnl
37    ])dnl
38  AC_DEFINE_UNQUOTED(AS_TR_CPP([ABSOLUTE_]m4_defn([gl_HEADER_NAME])),
39                     ["AS_VAR_GET([gl_absolute_header])"],
40                     [Define this to an absolute name of <]m4_defn([gl_HEADER_NAME])[>.])
41  AS_VAR_POPDEF([gl_absolute_header])dnl
42])dnl
43])# gl_ABSOLUTE_HEADER
44
45# gl_ABSOLUTE_HEADER_ONE(HEADER)
46# ------------------------------
47# Like gl_ABSOLUTE_HEADER, except that:
48#   - it assumes that the header exists,
49#   - it uses the current CPPFLAGS,
50#   - it does not cache the result,
51#   - it is silent.
52AC_DEFUN([gl_ABSOLUTE_HEADER_ONE],
53[
54  AC_REQUIRE([AC_CANONICAL_HOST])
55  AC_LANG_CONFTEST([AC_LANG_SOURCE([[#include <]]m4_dquote([$1])[[>]])])
56  dnl AIX "xlc -E" and "cc -E" omit #line directives for header files
57  dnl that contain only a #include of other header files and no
58  dnl non-comment tokens of their own. This leads to a failure to
59  dnl detect the absolute name of <dirent.h>, <signal.h>, <poll.h>
60  dnl and others. The workaround is to force preservation of comments
61  dnl through option -C. This ensures all necessary #line directives
62  dnl are present. GCC supports option -C as well.
63  case "$host_os" in
64    aix*) gl_absname_cpp="$ac_cpp -C" ;;
65    *)    gl_absname_cpp="$ac_cpp" ;;
66  esac
67changequote(,)
68  case "$host_os" in
69    mingw*)
70      dnl For the sake of native Windows compilers (excluding gcc),
71      dnl treat backslash as a directory separator, like /.
72      dnl Actually, these compilers use a double-backslash as
73      dnl directory separator, inside the
74      dnl   # line "filename"
75      dnl directives.
76      gl_dirsep_regex='[/\\]'
77      ;;
78    *)
79      gl_dirsep_regex='\/'
80      ;;
81  esac
82  dnl A sed expression that turns a string into a basic regular
83  dnl expression, for use within "/.../".
84  gl_make_literal_regex_sed='s,[]$^\\.*/[],\\&,g'
85  gl_header_literal_regex=`echo '$1' \
86                           | sed -e "$gl_make_literal_regex_sed"`
87  gl_absolute_header_sed="/${gl_dirsep_regex}${gl_header_literal_regex}/"'{
88      s/.*"\(.*'"${gl_dirsep_regex}${gl_header_literal_regex}"'\)".*/\1/
89      s|^/[^/]|//&|
90      p
91      q
92    }'
93changequote([,])
94  dnl eval is necessary to expand gl_absname_cpp.
95  dnl Ultrix and Pyramid sh refuse to redirect output of eval,
96  dnl so use subshell.
97  AS_VAR_SET([gl_cv_absolute_]AS_TR_SH([[$1]]),
98[`(eval "$gl_absname_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
99  sed -n "$gl_absolute_header_sed"`])
100])
101