1 # =============================================================================
2 # http://www.gnu.org/software/autoconf-archive/ax_compiler_flags_ldflags.html
3 # =============================================================================
7 # AX_COMPILER_FLAGS_LDFLAGS([VARIABLE], [IS-RELEASE], [EXTRA-BASE-FLAGS], [EXTRA-MINIMUM-FLAGS], [EXTRA-YES-FLAGS], [EXTRA-MAXIMUM-FLAGS], [EXTRA-ERROR-FLAGS])
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.
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.
21 # Copyright (c) 2014, 2015 Philip Withnall <philip@tecnocode.co.uk>
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
30 AC_DEFUN([AX_COMPILER_FLAGS_LDFLAGS],[
31 AX_REQUIRE_DEFINED([AX_APPEND_COMPILE_FLAGS])
32 AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
33 AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG])
36 m4_define(ax_warn_ldflags_variable,
37 [m4_normalize(ifelse([$1],,[WARN_LDFLAGS],[$1]))])
39 # Always pass -Werror=unknown-warning-option to get Clang to fail on bad
40 # flags, otherwise they are always appended to the warn_ldflags variable,
41 # and Clang warns on them for every compilation unit.
42 # If this is passed to GCC, it will explode, so the flag must be enabled
44 AX_CHECK_COMPILE_FLAG([-Werror=unknown-warning-option],[
45 ax_compiler_flags_test="-Werror=unknown-warning-option"
47 ax_compiler_flags_test=""
51 AX_APPEND_COMPILE_FLAGS([ dnl
52 -Wl,--no-as-needed dnl
54 ],ax_warn_ldflags_variable,[$ax_compiler_flags_test])
56 AS_IF([test "$ax_enable_compile_warnings" != "no"],[
58 AX_APPEND_COMPILE_FLAGS([$4],
59 ax_warn_ldflags_variable,
60 [$ax_compiler_flags_test])
62 AS_IF([test "$ax_enable_compile_warnings" != "no" -a \
63 "$ax_enable_compile_warnings" != "minimum"],[
65 AX_APPEND_COMPILE_FLAGS([$5],
66 ax_warn_ldflags_variable,
67 [$ax_compiler_flags_test])
69 AS_IF([test "$ax_enable_compile_warnings" = "maximum" -o \
70 "$ax_enable_compile_warnings" = "error"],[
72 AX_APPEND_COMPILE_FLAGS([$6],
73 ax_warn_ldflags_variable,
74 [$ax_compiler_flags_test])
76 AS_IF([test "$ax_enable_compile_warnings" = "error"],[
77 # "error" flags; -Werror has to be appended unconditionally because
78 # it’s not possible to test for
80 # suggest-attribute=format is disabled because it gives too many false
82 AX_APPEND_COMPILE_FLAGS([ dnl
83 -Wl,--fatal-warnings dnl
85 ],ax_warn_ldflags_variable,[$ax_compiler_flags_test])
88 # Substitute the variables
89 AC_SUBST(ax_warn_ldflags_variable)
90 ])dnl AX_COMPILER_FLAGS