1# absolute-header.m4 serial 16
2dnl Copyright (C) 2006-2020 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
25dnl FIXME: gl_absolute_header and ac_header_exists must be used unquoted
26dnl until we can assume autoconf 2.64 or newer.
27m4_foreach_w([gl_HEADER_NAME], [$1],
28  [AS_VAR_PUSHDEF([gl_absolute_header],
29                  [gl_cv_absolute_]m4_defn([gl_HEADER_NAME]))dnl
30  AC_CACHE_CHECK([absolute name of <]m4_defn([gl_HEADER_NAME])[>],
31    m4_defn([gl_absolute_header]),
32    [AS_VAR_PUSHDEF([ac_header_exists],
33                    [ac_cv_header_]m4_defn([gl_HEADER_NAME]))dnl
34    AC_CHECK_HEADERS_ONCE(m4_defn([gl_HEADER_NAME]))dnl
35    if test AS_VAR_GET(ac_header_exists) = yes; then
36      gl_ABSOLUTE_HEADER_ONE(m4_defn([gl_HEADER_NAME]))
37    fi
38    AS_VAR_POPDEF([ac_header_exists])dnl
39    ])dnl
40  AC_DEFINE_UNQUOTED(AS_TR_CPP([ABSOLUTE_]m4_defn([gl_HEADER_NAME])),
41                     ["AS_VAR_GET(gl_absolute_header)"],
42                     [Define this to an absolute name of <]m4_defn([gl_HEADER_NAME])[>.])
43  AS_VAR_POPDEF([gl_absolute_header])dnl
44])dnl
45])# gl_ABSOLUTE_HEADER
46
47# gl_ABSOLUTE_HEADER_ONE(HEADER)
48# ------------------------------
49# Like gl_ABSOLUTE_HEADER, except that:
50#   - it assumes that the header exists,
51#   - it uses the current CPPFLAGS,
52#   - it does not cache the result,
53#   - it is silent.
54AC_DEFUN([gl_ABSOLUTE_HEADER_ONE],
55[
56  AC_REQUIRE([AC_CANONICAL_HOST])
57  AC_LANG_CONFTEST([AC_LANG_SOURCE([[#include <]]m4_dquote([$1])[[>]])])
58  dnl AIX "xlc -E" and "cc -E" omit #line directives for header files
59  dnl that contain only a #include of other header files and no
60  dnl non-comment tokens of their own. This leads to a failure to
61  dnl detect the absolute name of <dirent.h>, <signal.h>, <poll.h>
62  dnl and others. The workaround is to force preservation of comments
63  dnl through option -C. This ensures all necessary #line directives
64  dnl are present. GCC supports option -C as well.
65  case "$host_os" in
66    aix*) gl_absname_cpp="$ac_cpp -C" ;;
67    *)    gl_absname_cpp="$ac_cpp" ;;
68  esac
69changequote(,)
70  case "$host_os" in
71    mingw*)
72      dnl For the sake of native Windows compilers (excluding gcc),
73      dnl treat backslash as a directory separator, like /.
74      dnl Actually, these compilers use a double-backslash as
75      dnl directory separator, inside the
76      dnl   # line "filename"
77      dnl directives.
78      gl_dirsep_regex='[/\\]'
79      ;;
80    *)
81      gl_dirsep_regex='\/'
82      ;;
83  esac
84  dnl A sed expression that turns a string into a basic regular
85  dnl expression, for use within "/.../".
86  gl_make_literal_regex_sed='s,[]$^\\.*/[],\\&,g'
87  gl_header_literal_regex=`echo '$1' \
88                           | sed -e "$gl_make_literal_regex_sed"`
89  gl_absolute_header_sed="/${gl_dirsep_regex}${gl_header_literal_regex}/"'{
90      s/.*"\(.*'"${gl_dirsep_regex}${gl_header_literal_regex}"'\)".*/\1/
91      s|^/[^/]|//&|
92      p
93      q
94    }'
95changequote([,])
96  dnl eval is necessary to expand gl_absname_cpp.
97  dnl Ultrix and Pyramid sh refuse to redirect output of eval,
98  dnl so use subshell.
99  AS_VAR_SET([gl_cv_absolute_]AS_TR_SH([[$1]]),
100[`(eval "$gl_absname_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
101  sed -n "$gl_absolute_header_sed"`])
102])
103