--- /dev/null
+# ===========================================================================
+# https://www.gnu.org/software/autoconf-archive/ax_compiler_flags.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+# AX_COMPILER_FLAGS([CFLAGS-VARIABLE], [LDFLAGS-VARIABLE], [IS-RELEASE], [EXTRA-BASE-CFLAGS], [EXTRA-YES-CFLAGS], [UNUSED], [UNUSED], [UNUSED], [EXTRA-BASE-LDFLAGS], [EXTRA-YES-LDFLAGS], [UNUSED], [UNUSED], [UNUSED])
+#
+# 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. Automated systems or build
+# systems aimed at beginners may want to pass the --disable-Werror
+# argument to unconditionally prevent warnings being fatal.
+#
+# --enable-compile-warnings can take the values:
+#
+# * no: Base compiler warnings only; not even -Wall.
+# * yes: The above, plus a broad range of useful warnings.
+# * error: The above, plus -Werror so that all warnings are fatal.
+# Use --disable-Werror to override this and disable fatal
+# warnings.
+#
+# The set of base and enabled flags can be augmented using the
+# EXTRA-*-CFLAGS and EXTRA-*-LDFLAGS variables, which are tested and
+# appended to the output variable if --enable-compile-warnings is not
+# "no". 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
+#
+# The EXTRA-* variables should only be used to supply extra warning flags,
+# and not general purpose compiler flags, as they are controlled by
+# configure options such as --disable-Werror.
+#
+# 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. By
+# default, it uses the value of $ax_is_release, so if you are using the
+# AX_IS_RELEASE macro, there is no need to pass this parameter. For
+# example:
+#
+# AX_IS_RELEASE([git-directory])
+# AX_COMPILER_FLAGS()
+#
+# 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.
+#
+# If C++ language support is enabled with AC_PROG_CXX, which must occur
+# before this macro in configure.ac, 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 base and enabled flags.
+#
+# 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.
+#
+# The UNUSED variables date from a previous version of this macro, and are
+# automatically appended to the preceding non-UNUSED variable. They should
+# be left empty in new uses of the macro.
+#
+# 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 14
+
+# _AX_COMPILER_FLAGS_LANG([LANGNAME])
+m4_defun([_AX_COMPILER_FLAGS_LANG],
+[m4_ifdef([_AX_COMPILER_FLAGS_LANG_]$1[_enabled], [],
+ [m4_define([_AX_COMPILER_FLAGS_LANG_]$1[_enabled], [])dnl
+ AX_REQUIRE_DEFINED([AX_COMPILER_FLAGS_]$1[FLAGS])])dnl
+])
+
+AC_DEFUN([AX_COMPILER_FLAGS],[
+ # C support is enabled by default.
+ _AX_COMPILER_FLAGS_LANG([C])
+ # Only enable C++ support if AC_PROG_CXX is called. The redefinition of
+ # AC_PROG_CXX is so that a fatal error is emitted if this macro is called
+ # before AC_PROG_CXX, which would otherwise cause no C++ warnings to be
+ # checked.
+ AC_PROVIDE_IFELSE([AC_PROG_CXX],
+ [_AX_COMPILER_FLAGS_LANG([CXX])],
+ [m4_define([AC_PROG_CXX], defn([AC_PROG_CXX])[_AX_COMPILER_FLAGS_LANG([CXX])])])
+ AX_REQUIRE_DEFINED([AX_COMPILER_FLAGS_LDFLAGS])
+
+ # Default value for IS-RELEASE is $ax_is_release
+ ax_compiler_flags_is_release=m4_tolower(m4_normalize(ifelse([$3],,
+ [$ax_is_release],
+ [$3])))
+
+ AC_ARG_ENABLE([compile-warnings],
+ AS_HELP_STRING([--enable-compile-warnings=@<:@no/yes/error@:>@],
+ [Enable compiler warnings and errors]),,
+ [AS_IF([test "$ax_compiler_flags_is_release" = "yes"],
+ [enable_compile_warnings="yes"],
+ [enable_compile_warnings="error"])])
+ AC_ARG_ENABLE([Werror],
+ AS_HELP_STRING([--disable-Werror],
+ [Unconditionally make all compiler warnings non-fatal]),,
+ [enable_Werror=maybe])
+
+ # Return the user's chosen warning level
+ AS_IF([test "$enable_Werror" = "no" -a \
+ "$enable_compile_warnings" = "error"],[
+ enable_compile_warnings="yes"
+ ])
+
+ ax_enable_compile_warnings=$enable_compile_warnings
+
+ AX_COMPILER_FLAGS_CFLAGS([$1],[$ax_compiler_flags_is_release],
+ [$4],[$5 $6 $7 $8])
+ m4_ifdef([_AX_COMPILER_FLAGS_LANG_CXX_enabled],
+ [AX_COMPILER_FLAGS_CXXFLAGS([WARN_CXXFLAGS],
+ [$ax_compiler_flags_is_release],
+ [$4],[$5 $6 $7 $8])])
+ AX_COMPILER_FLAGS_LDFLAGS([$2],[$ax_compiler_flags_is_release],
+ [$9],[$10 $11 $12 $13])
+ AX_COMPILER_FLAGS_GIR([WARN_SCANNERFLAGS],[$ax_compiler_flags_is_release])
+])dnl AX_COMPILER_FLAGS
projects / babeltrace.git / blobdiff