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Diffstat (limited to 'm4/ax_compiler_flags.m4')
| -rw-r--r-- | m4/ax_compiler_flags.m4 | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/m4/ax_compiler_flags.m4 b/m4/ax_compiler_flags.m4 new file mode 100644 index 0000000..c52ae7d --- /dev/null +++ b/m4/ax_compiler_flags.m4 @@ -0,0 +1,158 @@ +# =========================================================================== +# 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-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 12 + +# _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 |