1# =============================================================================
2#  http://www.gnu.org/software/autoconf-archive/ax_compiler_flags_ldflags.html
3# =============================================================================
4#
5# SYNOPSIS
6#
7#   AX_COMPILER_FLAGS_LDFLAGS([VARIABLE], [IS-RELEASE], [EXTRA-BASE-FLAGS], [EXTRA-YES-FLAGS])
8#
9# DESCRIPTION
10#
11#   Add warning flags for the linker to VARIABLE, which defaults to
12#   WARN_LDFLAGS.  VARIABLE is AC_SUBST-ed by this macro, but must be
13#   manually added to the LDFLAGS variable for each target in the code base.
14#
15#   This macro depends on the environment set up by AX_COMPILER_FLAGS.
16#   Specifically, it uses the value of $ax_enable_compile_warnings to decide
17#   which flags to enable.
18#
19# LICENSE
20#
21#   Copyright (c) 2014, 2015 Philip Withnall <philip@tecnocode.co.uk>
22#
23#   Copying and distribution of this file, with or without modification, are
24#   permitted in any medium without royalty provided the copyright notice
25#   and this notice are preserved.  This file is offered as-is, without any
26#   warranty.
27
28#serial 5
29
30AC_DEFUN([AX_COMPILER_FLAGS_LDFLAGS],[
31    AX_REQUIRE_DEFINED([AX_APPEND_LINK_FLAGS])
32    AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
33    AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG])
34
35    # Variable names
36    m4_define(ax_warn_ldflags_variable,
37              [m4_normalize(ifelse([$1],,[WARN_LDFLAGS],[$1]))])
38
39    # Always pass -Werror=unknown-warning-option to get Clang to fail on bad
40    # flags, otherwise they are always appended to the warn_ldflags variable,
41    # and Clang warns on them for every compilation unit.
42    # If this is passed to GCC, it will explode, so the flag must be enabled
43    # conditionally.
44    AX_CHECK_COMPILE_FLAG([-Werror=unknown-warning-option],[
45        ax_compiler_flags_test="-Werror=unknown-warning-option"
46    ],[
47        ax_compiler_flags_test=""
48    ])
49
50    # Base flags
51    AX_APPEND_LINK_FLAGS([ dnl
52        -Wl,--no-as-needed dnl
53        $3 dnl
54    ],ax_warn_ldflags_variable,[$ax_compiler_flags_test])
55
56    AS_IF([test "$ax_enable_compile_warnings" != "no"],[
57        # "yes" flags
58        AX_APPEND_LINK_FLAGS([$4 $5 $6 $7],
59                                ax_warn_ldflags_variable,
60                                [$ax_compiler_flags_test])
61    ])
62    AS_IF([test "$ax_enable_compile_warnings" = "error"],[
63        # "error" flags; -Werror has to be appended unconditionally because
64        # it's not possible to test for
65        #
66        # suggest-attribute=format is disabled because it gives too many false
67        # positives
68        AX_APPEND_LINK_FLAGS([ dnl
69            -Wl,--fatal-warnings dnl
70        ],ax_warn_ldflags_variable,[$ax_compiler_flags_test])
71    ])
72
73    # Substitute the variables
74    AC_SUBST(ax_warn_ldflags_variable)
75])dnl AX_COMPILER_FLAGS
76