159 lines
7.8 KiB
Plaintext
159 lines
7.8 KiB
Plaintext
# ===========================================================================
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# http://www.gnu.org/software/autoconf-archive/ax_compiler_flags.html
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# ===========================================================================
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#
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# SYNOPSIS
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#
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# 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])
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#
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# DESCRIPTION
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#
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# Check for the presence of an --enable-compile-warnings option to
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# configure, defaulting to "error" in normal operation, or "yes" if
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# IS-RELEASE is equal to "yes". Return the value in the variable
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# $ax_enable_compile_warnings.
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#
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# Depending on the value of --enable-compile-warnings, different compiler
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# warnings are checked to see if they work with the current compiler and,
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# if so, are appended to CFLAGS-VARIABLE and LDFLAGS-VARIABLE. This
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# allows a consistent set of baseline compiler warnings to be used across
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# a code base, irrespective of any warnings enabled locally by individual
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# developers. By standardising the warnings used by all developers of a
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# project, the project can commit to a zero-warnings policy, using -Werror
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# to prevent compilation if new warnings are introduced. This makes
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# catching bugs which are flagged by warnings a lot easier.
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#
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# By providing a consistent --enable-compile-warnings argument across all
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# projects using this macro, continuous integration systems can easily be
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# configured the same for all projects. Automated systems or build
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# systems aimed at beginners may want to pass the --disable-Werror
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# argument to unconditionally prevent warnings being fatal.
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#
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# --enable-compile-warnings can take the values:
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#
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# * no: Base compiler warnings only; not even -Wall.
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# * yes: The above, plus a broad range of useful warnings.
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# * error: The above, plus -Werror so that all warnings are fatal.
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# Use --disable-Werror to override this and disable fatal
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# warnings.
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#
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# The set of base and enabled flags can be augmented using the
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# EXTRA-*-CFLAGS and EXTRA-*-LDFLAGS variables, which are tested and
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# appended to the output variable if --enable-compile-warnings is not
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# "no". Flags should not be disabled using these arguments, as the entire
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# point of AX_COMPILER_FLAGS is to enforce a consistent set of useful
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# compiler warnings on code, using warnings which have been chosen for low
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# false positive rates. If a compiler emits false positives for a
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# warning, a #pragma should be used in the code to disable the warning
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# locally. See:
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#
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# https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/Diagnostic-Pragmas.html#Diagnostic-Pragmas
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#
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# The EXTRA-* variables should only be used to supply extra warning flags,
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# and not general purpose compiler flags, as they are controlled by
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# configure options such as --disable-Werror.
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#
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# IS-RELEASE can be used to disable -Werror when making a release, which
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# is useful for those hairy moments when you just want to get the release
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# done as quickly as possible. Set it to "yes" to disable -Werror. By
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# default, it uses the value of $ax_is_release, so if you are using the
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# AX_IS_RELEASE macro, there is no need to pass this parameter. For
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# example:
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#
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# AX_IS_RELEASE([git-directory])
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# AX_COMPILER_FLAGS()
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#
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# CFLAGS-VARIABLE defaults to WARN_CFLAGS, and LDFLAGS-VARIABLE defaults
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# to WARN_LDFLAGS. Both variables are AC_SUBST-ed by this macro, but must
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# be manually added to the CFLAGS and LDFLAGS variables for each target in
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# the code base.
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#
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# If C++ language support is enabled with AC_PROG_CXX, which must occur
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# before this macro in configure.ac, warning flags for the C++ compiler
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# are AC_SUBST-ed as WARN_CXXFLAGS, and must be manually added to the
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# CXXFLAGS variables for each target in the code base. EXTRA-*-CFLAGS can
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# be used to augment the base and enabled flags.
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#
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# Warning flags for g-ir-scanner (from GObject Introspection) are
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# AC_SUBST-ed as WARN_SCANNERFLAGS. This variable must be manually added
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# to the SCANNERFLAGS variable for each GIR target in the code base. If
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# extra g-ir-scanner flags need to be enabled, the AX_COMPILER_FLAGS_GIR
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# macro must be invoked manually.
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#
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# AX_COMPILER_FLAGS may add support for other tools in future, in addition
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# to the compiler and linker. No extra EXTRA-* variables will be added
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# for those tools, and all extra support will still use the single
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# --enable-compile-warnings configure option. For finer grained control
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# over the flags for individual tools, use AX_COMPILER_FLAGS_CFLAGS,
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# AX_COMPILER_FLAGS_LDFLAGS and AX_COMPILER_FLAGS_* for new tools.
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#
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# The UNUSED variables date from a previous version of this macro, and are
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# automatically appended to the preceding non-UNUSED variable. They should
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# be left empty in new uses of the macro.
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#
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# LICENSE
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#
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# Copyright (c) 2014, 2015 Philip Withnall <philip@tecnocode.co.uk>
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# Copyright (c) 2015 David King <amigadave@amigadave.com>
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#
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# Copying and distribution of this file, with or without modification, are
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# permitted in any medium without royalty provided the copyright notice
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# and this notice are preserved. This file is offered as-is, without any
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# warranty.
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#serial 13
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# _AX_COMPILER_FLAGS_LANG([LANGNAME])
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m4_defun([_AX_COMPILER_FLAGS_LANG],
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[m4_ifdef([_AX_COMPILER_FLAGS_LANG_]$1[_enabled], [],
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[m4_define([_AX_COMPILER_FLAGS_LANG_]$1[_enabled], [])dnl
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AX_REQUIRE_DEFINED([AX_COMPILER_FLAGS_]$1[FLAGS])])dnl
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])
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AC_DEFUN([AX_COMPILER_FLAGS],[
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# C support is enabled by default.
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_AX_COMPILER_FLAGS_LANG([C])
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# Only enable C++ support if AC_PROG_CXX is called. The redefinition of
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# AC_PROG_CXX is so that a fatal error is emitted if this macro is called
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# before AC_PROG_CXX, which would otherwise cause no C++ warnings to be
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# checked.
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AC_PROVIDE_IFELSE([AC_PROG_CXX],
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[_AX_COMPILER_FLAGS_LANG([CXX])],
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[m4_define([AC_PROG_CXX], defn([AC_PROG_CXX])[_AX_COMPILER_FLAGS_LANG([CXX])])])
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AX_REQUIRE_DEFINED([AX_COMPILER_FLAGS_LDFLAGS])
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# Default value for IS-RELEASE is $ax_is_release
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ax_compiler_flags_is_release=m4_tolower(m4_normalize(ifelse([$3],,
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[$ax_is_release],
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[$3])))
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AC_ARG_ENABLE([compile-warnings],
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AS_HELP_STRING([--enable-compile-warnings=@<:@no/yes/error@:>@],
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[Enable compiler warnings and errors]),,
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[AS_IF([test "$ax_compiler_flags_is_release" = "yes"],
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[enable_compile_warnings="yes"],
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[enable_compile_warnings="error"])])
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AC_ARG_ENABLE([Werror],
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AS_HELP_STRING([--disable-Werror],
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[Unconditionally make all compiler warnings non-fatal]),,
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[enable_Werror=maybe])
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# Return the user's chosen warning level
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AS_IF([test "$enable_Werror" = "no" -a \
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"$enable_compile_warnings" = "error"],[
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enable_compile_warnings="yes"
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])
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ax_enable_compile_warnings=$enable_compile_warnings
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AX_COMPILER_FLAGS_CFLAGS([$1],[$ax_compiler_flags_is_release],
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[$4],[$5 $6 $7 $8])
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m4_ifdef([_AX_COMPILER_FLAGS_LANG_CXX_enabled],
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[AX_COMPILER_FLAGS_CXXFLAGS([WARN_CXXFLAGS],
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[$ax_compiler_flags_is_release],
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[$4],[$5 $6 $7 $8])])
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AX_COMPILER_FLAGS_LDFLAGS([$2],[$ax_compiler_flags_is_release],
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[$9],[$10 $11 $12 $13])
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AX_COMPILER_FLAGS_GIR([WARN_SCANNERFLAGS],[$ax_compiler_flags_is_release])
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])dnl AX_COMPILER_FLAGS
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