# =============================================================================
# http://www.gnu.org/software/autoconf-archive/ax_compiler_flags_ldflags.html
# =============================================================================
#
# SYNOPSIS
#
# AX_COMPILER_FLAGS_LDFLAGS([VARIABLE], [IS-RELEASE], [EXTRA-BASE-FLAGS], [EXTRA-YES-FLAGS])
#
# DESCRIPTION
#
# Add warning flags for the linker to VARIABLE, which defaults to
# WARN_LDFLAGS. VARIABLE is AC_SUBST-ed by this macro, but must be
# manually added to the LDFLAGS variable for each target in the code base.
#
# This macro depends on the environment set up by AX_COMPILER_FLAGS.
# Specifically, it uses the value of $ax_enable_compile_warnings to decide
# which flags to enable.
#
# LICENSE
#
# Copyright (c) 2014, 2015 Philip Withnall <philip@tecnocode.co.uk>
#
# Copying and distribution of this file, with or without modification, are
# permitted in any medium without royalty provided the copyright notice
# and this notice are preserved. This file is offered as-is, without any
# warranty.
#serial 4
AC_DEFUN([AX_COMPILER_FLAGS_LDFLAGS],[
AX_REQUIRE_DEFINED([AX_APPEND_COMPILE_FLAGS])
AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG])
# Variable names
m4_define(ax_warn_ldflags_variable,
[m4_normalize(ifelse([$1],,[WARN_LDFLAGS],[$1]))])
# Always pass -Werror=unknown-warning-option to get Clang to fail on bad
# flags, otherwise they are always appended to the warn_ldflags variable,
# and Clang warns on them for every compilation unit.
# If this is passed to GCC, it will explode, so the flag must be enabled
# conditionally.
AX_CHECK_COMPILE_FLAG([-Werror=unknown-warning-option],[
ax_compiler_flags_test="-Werror=unknown-warning-option"
],[
ax_compiler_flags_test=""
])
# Base flags
AX_APPEND_COMPILE_FLAGS([ dnl
-Wl,--no-as-needed dnl
$3 dnl
],ax_warn_ldflags_variable,[$ax_compiler_flags_test])
AS_IF([test "$ax_enable_compile_warnings" != "no"],[
# "yes" flags
AX_APPEND_COMPILE_FLAGS([$4 $5 $6 $7],
ax_warn_ldflags_variable,
[$ax_compiler_flags_test])
])
AS_IF([test "$ax_enable_compile_warnings" = "error"],[
# "error" flags; -Werror has to be appended unconditionally because
# it's not possible to test for
#
# suggest-attribute=format is disabled because it gives too many false
# positives
AX_APPEND_COMPILE_FLAGS([ dnl
-Wl,--fatal-warnings dnl
],ax_warn_ldflags_variable,[$ax_compiler_flags_test])
])
# Substitute the variables
AC_SUBST(ax_warn_ldflags_variable)
])dnl AX_COMPILER_FLAGS