[yelp/wip/kill-gnome-common: 10/13] Use AX_COMPILER_FLAGS

From: David King <davidk src gnome org>
To: commits-list gnome org
Cc:
Subject: [yelp/wip/kill-gnome-common: 10/13] Use AX_COMPILER_FLAGS
Date: Thu, 5 Feb 2015 16:53:08 +0000 (UTC)
commit dc4e521d3d5d34306d2b677cafa24bb5d0ecc036
Author: David King <amigadave amigadave com>
Date:   Thu Feb 5 16:08:44 2015 +0000

    Use AX_COMPILER_FLAGS
    
    Additionally, remove unused DEPRECATION_FLAGS.
    
    https://wiki.gnome.org/Projects/GnomeCommon/Migration

 configure.ac                     |   21 ++-----
 m4/ax_append_compile_flags.m4    |   65 +++++++++++++++++++
 m4/ax_append_flag.m4             |   71 +++++++++++++++++++++
 m4/ax_check_compile_flag.m4      |   74 ++++++++++++++++++++++
 m4/ax_compiler_flags.m4          |  107 ++++++++++++++++++++++++++++++++
 m4/ax_compiler_flags_cflags.m4   |  127 ++++++++++++++++++++++++++++++++++++++
 m4/ax_compiler_flags_cxxflags.m4 |  126 +++++++++++++++++++++++++++++++++++++
 m4/ax_compiler_flags_gir.m4      |   68 ++++++++++++++++++++
 m4/ax_compiler_flags_ldflags.m4  |   90 +++++++++++++++++++++++++++
 src/Makefile.am                  |    2 +-
 tests/Makefile.am                |    1 +
 11 files changed, 736 insertions(+), 16 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index edf9ae8..a630c75 100644
--- a/configure.ac
+++ b/configure.ac
@@ -17,10 +17,6 @@ AC_PROG_CC
 AC_PROG_CC_C_O
 AC_PROG_LN_S
 
-# Initialize libtool
-LT_PREREQ([2.2.6])
-LT_INIT
-
 AC_PATH_PROGS(SED, gsed sed)
 
 AM_PATH_GLIB_2_0
@@ -43,16 +39,11 @@ PKG_CHECK_MODULES(YELP,
 AC_SUBST([YELP_CFLAGS])
 AC_SUBST([YELP_LIBS])
 
+AX_COMPILER_FLAGS
 
-GNOME_COMPILE_WARNINGS([maximum])
-
-MORE_WARN_FLAGS=
-
-dnl NOTE : it appears that some systems do not like it when you use line
-dnl        continuation charactes to split CFLAGS into readable chunks
-if test "x$GCC" = "xyes"; then
-   AM_CFLAGS="$AM_CFLAGS -Wall -Wno-uninitialized -Wmissing-prototypes -Wnested-externs -Wpointer-arith 
-Wno-sign-compare"
-fi
+# Initialize libtool
+LT_PREREQ([2.2.6])
+LT_INIT
 
 # i18n stuff
 AX_REQUIRE_DEFINED([IT_PROG_INTLTOOL])
@@ -155,8 +146,8 @@ AC_SUBST(GLIB_GENMARSHAL)
 
 
 # Set flags
-AM_CPPFLAGS="$AM_CPPFLAGS $DEPRECATION_FLAGS"
-AM_CFLAGS="$AM_CFLAGS $WARN_CFLAGS $MORE_WARN_FLAGS"
+AM_CPPFLAGS="$AM_CPPFLAGS"
+AM_CFLAGS="$AM_CFLAGS $WARN_CFLAGS"
 
 
 AC_SUBST([AM_CPPFLAGS])
diff --git a/m4/ax_append_compile_flags.m4 b/m4/ax_append_compile_flags.m4
new file mode 100644
index 0000000..dc7b866
--- /dev/null
+++ b/m4/ax_append_compile_flags.m4
@@ -0,0 +1,65 @@
+# ===========================================================================
+#  http://www.gnu.org/software/autoconf-archive/ax_append_compile_flags.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_APPEND_COMPILE_FLAGS([FLAG1 FLAG2 ...], [FLAGS-VARIABLE], [EXTRA-FLAGS])
+#
+# DESCRIPTION
+#
+#   For every FLAG1, FLAG2 it is checked whether the compiler works with the
+#   flag.  If it does, the flag is added FLAGS-VARIABLE
+#
+#   If FLAGS-VARIABLE is not specified, the current language's flags (e.g.
+#   CFLAGS) is used.  During the check the flag is always added to the
+#   current language's flags.
+#
+#   If EXTRA-FLAGS is defined, it is added to the current language's default
+#   flags (e.g. CFLAGS) when the check is done.  The check is thus made with
+#   the flags: "CFLAGS EXTRA-FLAGS FLAG".  This can for example be used to
+#   force the compiler to issue an error when a bad flag is given.
+#
+#   NOTE: This macro depends on the AX_APPEND_FLAG and
+#   AX_CHECK_COMPILE_FLAG. Please keep this macro in sync with
+#   AX_APPEND_LINK_FLAGS.
+#
+# LICENSE
+#
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans gmail com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 4
+
+AC_DEFUN([AX_APPEND_COMPILE_FLAGS],
+[AX_REQUIRE_DEFINED([AX_CHECK_COMPILE_FLAG])
+AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
+for flag in $1; do
+  AX_CHECK_COMPILE_FLAG([$flag], [AX_APPEND_FLAG([$flag], [$2])], [], [$3])
+done
+])dnl AX_APPEND_COMPILE_FLAGS
diff --git a/m4/ax_append_flag.m4 b/m4/ax_append_flag.m4
new file mode 100644
index 0000000..d26286c
--- /dev/null
+++ b/m4/ax_append_flag.m4
@@ -0,0 +1,71 @@
+# ===========================================================================
+#      http://www.gnu.org/software/autoconf-archive/ax_append_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_APPEND_FLAG(FLAG, [FLAGS-VARIABLE])
+#
+# DESCRIPTION
+#
+#   FLAG is appended to the FLAGS-VARIABLE shell variable, with a space
+#   added in between.
+#
+#   If FLAGS-VARIABLE is not specified, the current language's flags (e.g.
+#   CFLAGS) is used.  FLAGS-VARIABLE is not changed if it already contains
+#   FLAG.  If FLAGS-VARIABLE is unset in the shell, it is set to exactly
+#   FLAG.
+#
+#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Guido U. Draheim <guidod gmx de>
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans gmail com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 4
+
+AC_DEFUN([AX_APPEND_FLAG],
+[dnl
+AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_SET_IF
+AS_VAR_PUSHDEF([FLAGS], [m4_default($2,_AC_LANG_PREFIX[FLAGS])])
+AS_VAR_SET_IF(FLAGS,[
+  AS_CASE([AS_VAR_GET(FLAGS)],
+    ["* $1 *|*$1"],[AC_RUN_LOG([: FLAGS already contains $1])],
+    [
+     AS_VAR_APPEND(FLAGS," $1")
+     AC_RUN_LOG([: FLAGS="$FLAGS"])
+    ])
+  ],
+  [
+  AS_VAR_SET(FLAGS,[$1])
+  AC_RUN_LOG([: FLAGS="$FLAGS"])
+  ])
+AS_VAR_POPDEF([FLAGS])dnl
+])dnl AX_APPEND_FLAG
diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4
new file mode 100644
index 0000000..ca36397
--- /dev/null
+++ b/m4/ax_check_compile_flag.m4
@@ -0,0 +1,74 @@
+# ===========================================================================
+#   http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
+#
+# DESCRIPTION
+#
+#   Check whether the given FLAG works with the current language's compiler
+#   or gives an error.  (Warnings, however, are ignored)
+#
+#   ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
+#   success/failure.
+#
+#   If EXTRA-FLAGS is defined, it is added to the current language's default
+#   flags (e.g. CFLAGS) when the check is done.  The check is thus made with
+#   the flags: "CFLAGS EXTRA-FLAGS FLAG".  This can for example be used to
+#   force the compiler to issue an error when a bad flag is given.
+#
+#   INPUT gives an alternative input source to AC_COMPILE_IFELSE.
+#
+#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
+#   macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Guido U. Draheim <guidod gmx de>
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans gmail com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 4
+
+AC_DEFUN([AX_CHECK_COMPILE_FLAG],
+[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
+AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
+AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
+  ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
+  _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
+  AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
+    [AS_VAR_SET(CACHEVAR,[yes])],
+    [AS_VAR_SET(CACHEVAR,[no])])
+  _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
+AS_VAR_IF(CACHEVAR,yes,
+  [m4_default([$2], :)],
+  [m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_COMPILE_FLAGS
diff --git a/m4/ax_compiler_flags.m4 b/m4/ax_compiler_flags.m4
new file mode 100644
index 0000000..1781b40
--- /dev/null
+++ b/m4/ax_compiler_flags.m4
@@ -0,0 +1,107 @@
+# ===========================================================================
+#     http://www.gnu.org/software/autoconf-archive/ax_compiler_flags.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_COMPILER_FLAGS([CFLAGS-VARIABLE], [LDFLAGS-VARIABLE], [IS-RELEASE], [EXTRA-BASE-CFLAGS], 
[EXTRA-MINIMUM-CFLAGS], [EXTRA-YES-CFLAGS], [EXTRA-MAXIMUM-CFLAGS], [EXTRA-ERROR-CFLAGS], 
[EXTRA-BASE-LDFLAGS], [EXTRA-MINIMUM-LDFLAGS], [EXTRA-YES-LDFLAGS], [EXTRA-MAXIMUM-LDFLAGS], 
[EXTRA-ERROR-LDFLAGS])
+#
+# DESCRIPTION
+#
+#   Check for the presence of an --enable-compile-warnings option to
+#   configure, defaulting to "error" in normal operation, or "yes" if
+#   IS-RELEASE is equal to "yes".  Return the value in the variable
+#   $ax_enable_compile_warnings.
+#
+#   Depending on the value of --enable-compile-warnings, different compiler
+#   warnings are checked to see if they work with the current compiler and,
+#   if so, are appended to CFLAGS-VARIABLE and LDFLAGS-VARIABLE.  This
+#   allows a consistent set of baseline compiler warnings to be used across
+#   a code base, irrespective of any warnings enabled locally by individual
+#   developers.  By standardising the warnings used by all developers of a
+#   project, the project can commit to a zero-warnings policy, using -Werror
+#   to prevent compilation if new warnings are introduced.  This makes
+#   catching bugs which are flagged by warnings a lot easier.
+#
+#   By providing a consistent --enable-compile-warnings argument across all
+#   projects using this macro, continuous integration systems can easily be
+#   configured the same for all projects.
+#
+#   --enable-compile-warnings can take the values:
+#
+#    * no:      Base compiler warnings only; not even -Wall.
+#    * minimum: The above, plus minimal extra warnings such as -Wall.
+#    * yes:     The above, plus a broad range of useful warnings.
+#    * maximum: The above, plus additional warnings which enforce a particular
+#               coding style
+#    * error:   The above, plus -Werror so that all warnings are fatal.
+#
+#   The set of flags enabled at each level can be augmented using the
+#   EXTRA-*-CFLAGS and EXTRA-*-LDFLAGS variables.  Flags should not be
+#   disabled using these arguments, as the entire point of AX_COMPILER_FLAGS
+#   is to enforce a consistent set of useful compiler warnings on code,
+#   using warnings which have been chosen for low false positive rates.  If
+#   a compiler emits false positives for a warning, a #pragma should be used
+#   in the code to disable the warning locally. See:
+#
+#     https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/Diagnostic-Pragmas.html#Diagnostic-Pragmas
+#
+#   IS-RELEASE can be used to disable -Werror when making a release, which
+#   is useful for those hairy moments when you just want to get the release
+#   done as quickly as possible.  Set it to "yes" to disable -Werror.
+#
+#   CFLAGS-VARIABLE defaults to WARN_CFLAGS, and LDFLAGS-VARIABLE defaults
+#   to WARN_LDFLAGS.  Both variables are AC_SUBST-ed by this macro, but must
+#   be manually added to the CFLAGS and LDFLAGS variables for each target in
+#   the code base.
+#
+#   Warning flags for the C++ compiler are AC_SUBST-ed as WARN_CXXFLAGS, and
+#   must be manually added to the CXXFLAGS variables for each target in the
+#   code base. EXTRA-*-CFLAGS can be used to augment the flags enabled at
+#   each level.
+#
+#   Warning flags for g-ir-scanner (from GObject Introspection) are
+#   AC_SUBST-ed as WARN_SCANNERFLAGS.  This variable must be manually added
+#   to the SCANNERFLAGS variable for each GIR target in the code base.  If
+#   extra g-ir-scanner flags need to be enabled, the AX_COMPILER_FLAGS_GIR
+#   macro must be invoked manually.
+#
+#   AX_COMPILER_FLAGS may add support for other tools in future, in addition
+#   to the compiler and linker.  No extra EXTRA-* variables will be added
+#   for those tools, and all extra support will still use the single
+#   --enable-compile-warnings configure option.  For finer grained control
+#   over the flags for individual tools, use AX_COMPILER_FLAGS_CFLAGS,
+#   AX_COMPILER_FLAGS_LDFLAGS and AX_COMPILER_FLAGS_* for new tools.
+#
+# LICENSE
+#
+#   Copyright (c) 2014, 2015 Philip Withnall <philip tecnocode co uk>
+#   Copyright (c) 2015 David King <amigadave amigadave com>
+#
+#   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 7
+
+AC_DEFUN([AX_COMPILER_FLAGS],[
+    AX_REQUIRE_DEFINED([AX_COMPILER_FLAGS_CFLAGS])
+    AX_REQUIRE_DEFINED([AX_COMPILER_FLAGS_CXXFLAGS])
+    AX_REQUIRE_DEFINED([AX_COMPILER_FLAGS_LDFLAGS])
+
+    AC_ARG_ENABLE([compile-warnings],
+                  AS_HELP_STRING([--enable-compile-warnings=@<:@no/minimum/yes/maximum/error@:>@],
+                                 [Enable different levels of compiler warnings]),,
+                  [AS_IF([test "$3" = "yes"],
+                         [enable_compile_warnings="yes"],
+                         [enable_compile_warnings="error"])])
+
+    # Return the user’s chosen warning level
+    ax_enable_compile_warnings=$enable_compile_warnings
+
+    AX_COMPILER_FLAGS_CFLAGS([$1],[$3],[$4],[$5],[$6],[$7],[$8])
+    AX_COMPILER_FLAGS_CXXFLAGS([WARN_CXXFLAGS],[$3],[$4],[$5],[$6],[$7],[$8])
+    AX_COMPILER_FLAGS_LDFLAGS([$2],[$3],[$9],[$10],[$11],[$12],[$13])
+    AX_COMPILER_FLAGS_GIR([WARN_SCANNERFLAGS],[$3])
+])dnl AX_COMPILER_FLAGS
diff --git a/m4/ax_compiler_flags_cflags.m4 b/m4/ax_compiler_flags_cflags.m4
new file mode 100644
index 0000000..1f8ef1f
--- /dev/null
+++ b/m4/ax_compiler_flags_cflags.m4
@@ -0,0 +1,127 @@
+# ============================================================================
+#  http://www.gnu.org/software/autoconf-archive/ax_compiler_flags_cflags.html
+# ============================================================================
+#
+# SYNOPSIS
+#
+#   AX_COMPILER_FLAGS_CFLAGS([VARIABLE], [IS-RELEASE], [EXTRA-BASE-FLAGS], [EXTRA-MINIMUM-FLAGS], 
[EXTRA-YES-FLAGS], [EXTRA-MAXIMUM-FLAGS], [EXTRA-ERROR-FLAGS])
+#
+# DESCRIPTION
+#
+#   Add warning flags for the C compiler to VARIABLE, which defaults to
+#   WARN_CFLAGS.  VARIABLE is AC_SUBST-ed by this macro, but must be
+#   manually added to the CFLAGS 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 3
+
+AC_DEFUN([AX_COMPILER_FLAGS_CFLAGS],[
+    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_cflags_variable,
+              [m4_normalize(ifelse([$1],,[WARN_CFLAGS],[$1]))])
+
+    # Always pass -Werror=unknown-warning-option to get Clang to fail on bad
+    # flags, otherwise they are always appended to the warn_cflags 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
+        -fno-strict-aliasing dnl
+        $3 dnl
+    ],ax_warn_cflags_variable,[$ax_compiler_flags_test])
+
+    AS_IF([test "$ax_enable_compile_warnings" != "no"],[
+        # "minimum" flags
+        AX_APPEND_COMPILE_FLAGS([ dnl
+            -Wall dnl
+            $4 dnl
+        ],ax_warn_cflags_variable,[$ax_compiler_flags_test])
+    ])
+    AS_IF([test "$ax_enable_compile_warnings" != "no" -a \
+                "$ax_enable_compile_warnings" != "minimum"],[
+        # "yes" flags
+        AX_APPEND_COMPILE_FLAGS([ dnl
+            -Wextra dnl
+            -Wundef dnl
+            -Wnested-externs dnl
+            -Wwrite-strings dnl
+            -Wpointer-arith dnl
+            -Wmissing-declarations dnl
+            -Wmissing-prototypes dnl
+            -Wstrict-prototypes dnl
+            -Wredundant-decls dnl
+            -Wno-unused-parameter dnl
+            -Wno-missing-field-initializers dnl
+            -Wdeclaration-after-statement dnl
+            -Wformat=2 dnl
+            -Wold-style-definition dnl
+            -Wcast-align dnl
+            -Wformat-nonliteral dnl
+            -Wformat-security dnl
+            -Wsign-compare dnl
+            -Wstrict-aliasing dnl
+            -Wshadow dnl
+            -Winline dnl
+            -Wpacked dnl
+            -Wmissing-format-attribute dnl
+            -Wmissing-noreturn dnl
+            -Winit-self dnl
+            -Wredundant-decls dnl
+            -Wmissing-include-dirs dnl
+            -Wunused-but-set-variable dnl
+            -Warray-bounds dnl
+            -Wimplicit-function-declaration dnl
+            -Wreturn-type dnl
+            $5 dnl
+        ],ax_warn_cflags_variable,[$ax_compiler_flags_test])
+    ])
+    AS_IF([test "$ax_enable_compile_warnings" = "maximum" -o \
+                "$ax_enable_compile_warnings" = "error"],[
+        # "maximum" flags
+        AX_APPEND_COMPILE_FLAGS([ dnl
+            -Wswitch-enum dnl
+            -Wswitch-default dnl
+            -Waggregate-return dnl
+            $6 dnl
+        ],ax_warn_cflags_variable,[$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_FLAG([-Werror],ax_warn_cflags_variable)
+
+        AX_APPEND_COMPILE_FLAGS([ dnl
+            -Wno-suggest-attribute=format dnl
+            $7 dnl
+        ],ax_warn_cflags_variable,[$ax_compiler_flags_test])
+    ])
+
+    # Substitute the variables
+    AC_SUBST(ax_warn_cflags_variable)
+])dnl AX_COMPILER_FLAGS
diff --git a/m4/ax_compiler_flags_cxxflags.m4 b/m4/ax_compiler_flags_cxxflags.m4
new file mode 100644
index 0000000..8f9c1a2
--- /dev/null
+++ b/m4/ax_compiler_flags_cxxflags.m4
@@ -0,0 +1,126 @@
+# ==============================================================================
+#  http://www.gnu.org/software/autoconf-archive/ax_compiler_flags_cxxflags.html
+# ==============================================================================
+#
+# SYNOPSIS
+#
+#   AX_COMPILER_FLAGS_CXXFLAGS([VARIABLE], [IS-RELEASE], [EXTRA-BASE-FLAGS], [EXTRA-MINIMUM-FLAGS], 
[EXTRA-YES-FLAGS], [EXTRA-MAXIMUM-FLAGS], [EXTRA-ERROR-FLAGS])
+#
+# DESCRIPTION
+#
+#   Add warning flags for the C++ compiler to VARIABLE, which defaults to
+#   WARN_CXXFLAGS.  VARIABLE is AC_SUBST-ed by this macro, but must be
+#   manually added to the CXXFLAGS 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) 2015 David King <amigadave amigadave com>
+#
+#   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 1
+
+AC_DEFUN([AX_COMPILER_FLAGS_CXXFLAGS],[
+    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_cxxflags_variable,
+              [m4_normalize(ifelse([$1],,[WARN_CXXFLAGS],[$1]))])
+
+    AC_LANG_PUSH([C++])
+
+    # Always pass -Werror=unknown-warning-option to get Clang to fail on bad
+    # flags, otherwise they are always appended to the warn_cxxflags 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
+        -fno-strict-aliasing dnl
+        $3 dnl
+    ],ax_warn_cxxflags_variable,[$ax_compiler_flags_test])
+
+    AS_IF([test "$ax_enable_compile_warnings" != "no"],[
+        # "minimum" flags
+        AX_APPEND_COMPILE_FLAGS([ dnl
+            -Wall dnl
+            $4 dnl
+        ],ax_warn_cxxflags_variable,[$ax_compiler_flags_test])
+    ])
+    AS_IF([test "$ax_enable_compile_warnings" != "no" -a \
+                "$ax_enable_compile_warnings" != "minimum"],[
+        # "yes" flags
+        AX_APPEND_COMPILE_FLAGS([ dnl
+            -Wextra dnl
+            -Wundef dnl
+            -Wwrite-strings dnl
+            -Wpointer-arith dnl
+            -Wmissing-declarations dnl
+            -Wredundant-decls dnl
+            -Wno-unused-parameter dnl
+            -Wno-missing-field-initializers dnl
+            -Wformat=2 dnl
+            -Wcast-align dnl
+            -Wformat-nonliteral dnl
+            -Wformat-security dnl
+            -Wsign-compare dnl
+            -Wstrict-aliasing dnl
+            -Wshadow dnl
+            -Winline dnl
+            -Wpacked dnl
+            -Wmissing-format-attribute dnl
+            -Wmissing-noreturn dnl
+            -Winit-self dnl
+            -Wredundant-decls dnl
+            -Wmissing-include-dirs dnl
+            -Wunused-but-set-variable dnl
+            -Warray-bounds dnl
+            -Wreturn-type dnl
+            -Wno-overloaded-virtual dnl
+            $5 dnl
+        ],ax_warn_cxxflags_variable,[$ax_compiler_flags_test])
+    ])
+    AS_IF([test "$ax_enable_compile_warnings" = "maximum" -o \
+                "$ax_enable_compile_warnings" = "error"],[
+        # "maximum" flags
+        AX_APPEND_COMPILE_FLAGS([ dnl
+            -Wswitch-enum dnl
+            -Wswitch-default dnl
+            $6 dnl
+        ],ax_warn_cxxflags_variable,[$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_FLAG([-Werror],ax_warn_cxxflags_variable)
+
+        AX_APPEND_COMPILE_FLAGS([ dnl
+            -Wno-suggest-attribute=format dnl
+            $7 dnl
+        ],ax_warn_cxxflags_variable,[$ax_compiler_flags_test])
+    ])
+
+    AC_LANG_POP([C++])
+
+    # Substitute the variables
+    AC_SUBST(ax_warn_cxxflags_variable)
+])dnl AX_COMPILER_FLAGS_CXXFLAGS
diff --git a/m4/ax_compiler_flags_gir.m4 b/m4/ax_compiler_flags_gir.m4
new file mode 100644
index 0000000..f26a8d2
--- /dev/null
+++ b/m4/ax_compiler_flags_gir.m4
@@ -0,0 +1,68 @@
+# ===========================================================================
+#   http://www.gnu.org/software/autoconf-archive/ax_compiler_flags_gir.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_COMPILER_FLAGS_GIR([VARIABLE], [IS-RELEASE], [EXTRA-BASE-FLAGS], [EXTRA-MINIMUM-FLAGS], 
[EXTRA-YES-FLAGS], [EXTRA-MAXIMUM-FLAGS], [EXTRA-ERROR-FLAGS])
+#
+# DESCRIPTION
+#
+#   Add warning flags for the g-ir-scanner (from GObject Introspection) to
+#   VARIABLE, which defaults to WARN_SCANNERFLAGS.  VARIABLE is AC_SUBST-ed
+#   by this macro, but must be manually added to the SCANNERFLAGS variable
+#   for each GIR 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) 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 2
+
+AC_DEFUN([AX_COMPILER_FLAGS_GIR],[
+    AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
+
+    # Variable names
+    m4_define(ax_warn_scannerflags_variable,
+              [m4_normalize(ifelse([$1],,[WARN_SCANNERFLAGS],[$1]))])
+
+    # Base flags
+    AX_APPEND_FLAG([$3],ax_warn_scannerflags_variable)
+
+    AS_IF([test "$ax_enable_compile_warnings" != "no"],[
+        # "minimum" flags
+        AX_APPEND_FLAG([ dnl
+            --warn-all dnl
+            $4 dnl
+        ],ax_warn_scannerflags_variable)
+    ]) 
+    AS_IF([test "$ax_enable_compile_warnings" != "no" -a \
+                "$ax_enable_compile_warnings" != "minimum"],[
+        # "yes" flags
+        AX_APPEND_FLAG([$5],ax_warn_scannerflags_variable)
+    ])
+    AS_IF([test "$ax_enable_compile_warnings" = "maximum" -o \
+                "$ax_enable_compile_warnings" = "error"],[
+        # "maximum" flags
+        AX_APPEND_FLAG([$6],ax_warn_scannerflags_variable)
+    ])
+    AS_IF([test "$ax_enable_compile_warnings" = "error"],[
+        # "error" flags
+        AX_APPEND_FLAG([ dnl
+            --warn-error dnl
+            $7 dnl
+        ],ax_warn_scannerflags_variable)
+    ])
+
+    # Substitute the variables
+    AC_SUBST(ax_warn_scannerflags_variable)
+])dnl AX_COMPILER_FLAGS
diff --git a/m4/ax_compiler_flags_ldflags.m4 b/m4/ax_compiler_flags_ldflags.m4
new file mode 100644
index 0000000..ad845c6
--- /dev/null
+++ b/m4/ax_compiler_flags_ldflags.m4
@@ -0,0 +1,90 @@
+# =============================================================================
+#  http://www.gnu.org/software/autoconf-archive/ax_compiler_flags_ldflags.html
+# =============================================================================
+#
+# SYNOPSIS
+#
+#   AX_COMPILER_FLAGS_LDFLAGS([VARIABLE], [IS-RELEASE], [EXTRA-BASE-FLAGS], [EXTRA-MINIMUM-FLAGS], 
[EXTRA-YES-FLAGS], [EXTRA-MAXIMUM-FLAGS], [EXTRA-ERROR-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 2
+
+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"],[
+        # "minimum" flags
+        AX_APPEND_COMPILE_FLAGS([$4],
+                                ax_warn_ldflags_variable,
+                                [$ax_compiler_flags_test])
+    ])
+    AS_IF([test "$ax_enable_compile_warnings" != "no" -a \
+                "$ax_enable_compile_warnings" != "minimum"],[
+        # "yes" flags
+        AX_APPEND_COMPILE_FLAGS([$5],
+                                ax_warn_ldflags_variable,
+                                [$ax_compiler_flags_test])
+    ])
+    AS_IF([test "$ax_enable_compile_warnings" = "maximum" -o \
+                "$ax_enable_compile_warnings" = "error"],[
+        # "maximum" flags
+        AX_APPEND_COMPILE_FLAGS([$6],
+                                ax_warn_ldflags_variable,
+                                [$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
+            $7 dnl
+        ],ax_warn_ldflags_variable,[$ax_compiler_flags_test])
+    ])
+
+    # Substitute the variables
+    AC_SUBST(ax_warn_ldflags_variable)
+])dnl AX_COMPILER_FLAGS
diff --git a/src/Makefile.am b/src/Makefile.am
index 4667c92..2ce1993 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -29,7 +29,7 @@ yelp_LDADD =                                  \
        $(YELP_LIBS)                            \
        $(POPT_LIBS)
 
-yelp_LDFLAGS = $(AM_LDFLAGS)
+yelp_LDFLAGS = $(WARN_LDFLAGS)
 
 install-exec-hook:
        rm -f $(DESTDIR)$(bindir)/gnome-help && \
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 7da92f1..8398f9e 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -6,6 +6,7 @@ YELP_COMMON_CFLAGS =                            \
        -I$(top_srcdir)/libyelp
 YELP_COMMON_LDADD =                            \
        $(YELP_LIBS)                            \
+       $(WARN_LDFLAGS)                         \
        $(top_builddir)/libyelp/libyelp.la
 
 check_PROGRAMS =                               \
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