1# warnings.m4 serial 16
2dnl Copyright (C) 2008-2020 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 Simon Josefsson
8
9# gl_AS_VAR_APPEND(VAR, VALUE)
10# ----------------------------
11# Provide the functionality of AS_VAR_APPEND if Autoconf does not have it.
12m4_ifdef([AS_VAR_APPEND],
13[m4_copy([AS_VAR_APPEND], [gl_AS_VAR_APPEND])],
14[m4_define([gl_AS_VAR_APPEND],
15[AS_VAR_SET([$1], [AS_VAR_GET([$1])$2])])])
16
17
18# gl_COMPILER_OPTION_IF(OPTION, [IF-SUPPORTED], [IF-NOT-SUPPORTED],
19#                       [PROGRAM = AC_LANG_PROGRAM()])
20# -----------------------------------------------------------------
21# Check if the compiler supports OPTION when compiling PROGRAM.
22#
23# The effects of this macro depend on the current language (_AC_LANG).
24AC_DEFUN([gl_COMPILER_OPTION_IF],
25[
26AS_VAR_PUSHDEF([gl_Warn], [gl_cv_warn_[]_AC_LANG_ABBREV[]_$1])dnl
27AS_VAR_PUSHDEF([gl_Flags], [_AC_LANG_PREFIX[]FLAGS])dnl
28AS_LITERAL_IF([$1],
29  [m4_pushdef([gl_Positive], m4_bpatsubst([$1], [^-Wno-], [-W]))],
30  [gl_positive="$1"
31case $gl_positive in
32  -Wno-*) gl_positive=-W`expr "X$gl_positive" : 'X-Wno-\(.*\)'` ;;
33esac
34m4_pushdef([gl_Positive], [$gl_positive])])dnl
35AC_CACHE_CHECK([whether _AC_LANG compiler handles $1], [gl_Warn], [
36  gl_save_compiler_FLAGS="$gl_Flags"
37  gl_AS_VAR_APPEND(m4_defn([gl_Flags]),
38    [" $gl_unknown_warnings_are_errors ]m4_defn([gl_Positive])["])
39  AC_LINK_IFELSE([m4_default([$4], [AC_LANG_PROGRAM([[]])])],
40                 [AS_VAR_SET([gl_Warn], [yes])],
41                 [AS_VAR_SET([gl_Warn], [no])])
42  gl_Flags="$gl_save_compiler_FLAGS"
43])
44AS_VAR_IF(gl_Warn, [yes], [$2], [$3])
45m4_popdef([gl_Positive])dnl
46AS_VAR_POPDEF([gl_Flags])dnl
47AS_VAR_POPDEF([gl_Warn])dnl
48])
49
50# gl_UNKNOWN_WARNINGS_ARE_ERRORS
51# ------------------------------
52# Clang doesn't complain about unknown warning options unless one also
53# specifies -Wunknown-warning-option -Werror.  Detect this.
54#
55# The effects of this macro depend on the current language (_AC_LANG).
56AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS],
57[_AC_LANG_DISPATCH([$0], _AC_LANG, $@)])
58
59# Specialization for _AC_LANG = C. This macro can be AC_REQUIREd.
60AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C)],
61[
62  AC_LANG_PUSH([C])
63  gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL
64  AC_LANG_POP([C])
65])
66
67# Specialization for _AC_LANG = C++. This macro can be AC_REQUIREd.
68AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C++)],
69[
70  AC_LANG_PUSH([C++])
71  gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL
72  AC_LANG_POP([C++])
73])
74
75# Specialization for _AC_LANG = Objective C. This macro can be AC_REQUIREd.
76AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(Objective C)],
77[
78  AC_LANG_PUSH([Objective C])
79  gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL
80  AC_LANG_POP([Objective C])
81])
82
83AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL],
84[gl_COMPILER_OPTION_IF([-Werror -Wunknown-warning-option],
85   [gl_unknown_warnings_are_errors='-Wunknown-warning-option -Werror'],
86   [gl_unknown_warnings_are_errors=])])
87
88# gl_WARN_ADD(OPTION, [VARIABLE = WARN_CFLAGS/WARN_CXXFLAGS],
89#             [PROGRAM = AC_LANG_PROGRAM()])
90# -----------------------------------------------------------
91# Adds parameter to WARN_CFLAGS/WARN_CXXFLAGS if the compiler supports it
92# when compiling PROGRAM.  For example, gl_WARN_ADD([-Wparentheses]).
93#
94# If VARIABLE is a variable name, AC_SUBST it.
95#
96# The effects of this macro depend on the current language (_AC_LANG).
97AC_DEFUN([gl_WARN_ADD],
98[AC_REQUIRE([gl_UNKNOWN_WARNINGS_ARE_ERRORS(]_AC_LANG[)])
99gl_COMPILER_OPTION_IF([$1],
100  [gl_AS_VAR_APPEND(m4_if([$2], [], [[WARN_]_AC_LANG_PREFIX[FLAGS]], [[$2]]), [" $1"])],
101  [],
102  [$3])
103m4_ifval([$2],
104         [AS_LITERAL_IF([$2], [AC_SUBST([$2])])],
105         [AC_SUBST([WARN_]_AC_LANG_PREFIX[FLAGS])])dnl
106])
107
108# Local Variables:
109# mode: autoconf
110# End:
111