AC_DEFUN([_NM_COMPILER_FLAG], [ CFLAGS_SAVED="$CFLAGS" CFLAGS="$CFLAGS $GLIB_CFLAGS -Werror $1" AC_MSG_CHECKING([whether $1 works as expected]) AC_COMPILE_IFELSE([AC_LANG_SOURCE([[]])], [ AC_COMPILE_IFELSE([AC_LANG_SOURCE([[$2]])], [ AC_MSG_RESULT(yes) CFLAGS="$CFLAGS_SAVED" $3 ],[ AC_MSG_RESULT(no) CFLAGS="$CFLAGS_SAVED" $4 ]) ],[ AC_MSG_RESULT(not supported) CFLAGS="$CFLAGS_SAVED" ]) ]) dnl Check whether a particular compiler flag is supported, dnl add it to CFLAGS if it is AC_DEFUN([NM_COMPILER_FLAG], [ _NM_COMPILER_FLAG([$1], [], [ CFLAGS="$CFLAGS $1" $2 ], [$3]) ]) dnl Check whether a particular warning is not emitted with code provided, dnl disable it in CFLAGS if the check fails. AC_DEFUN([NM_COMPILER_WARNING], [ _NM_COMPILER_FLAG([-W$1], [$2], [CFLAGS="$CFLAGS -W$1"], [CFLAGS="$CFLAGS -Wno-$1"]) ]) AC_DEFUN([NM_COMPILER_WARNINGS], [AC_ARG_ENABLE(more-warnings, AS_HELP_STRING([--enable-more-warnings], [Possible values: no/yes/error]), set_more_warnings="$enableval",set_more_warnings=$1) AC_MSG_CHECKING(for more warnings) if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then AC_MSG_RESULT(yes) dnl This is enabled in clang by default, makes little sense, dnl and causes the build to abort with -Werror. CFLAGS_SAVED="$CFLAGS" CFLAGS="$CFLAGS -Qunused-arguments" AC_COMPILE_IFELSE([AC_LANG_SOURCE([])], [], CFLAGS="$CFLAGS_SAVED") unset CFLAGS_SAVED dnl clang only warns about unknown warnings, unless dnl called with "-Werror=unknown-warning-option" dnl Test if the compiler supports that, and if it does dnl attach it to the CFLAGS. NM_COMPILER_WARNING([unknown-warning-option], []) CFLAGS_MORE_WARNINGS="-Wall -std=gnu99" if test "x$set_more_warnings" = xerror; then CFLAGS_MORE_WARNINGS="$CFLAGS_MORE_WARNINGS -Werror" fi for option in \ -Wextra \ -Wdeclaration-after-statement \ -Wfloat-equal \ -Wformat-nonliteral \ -Wformat-security \ -Wimplicit-fallthrough \ -Wimplicit-function-declaration \ -Winit-self \ -Wlogical-op \ -Wmissing-declarations \ -Wmissing-include-dirs \ -Wmissing-prototypes \ -Wpointer-arith \ -Wshadow \ -Wshift-negative-value \ -Wstrict-prototypes \ -Wundef \ -Wno-duplicate-decl-specifier \ -Wno-format-truncation \ -Wno-format-y2k \ -Wno-missing-field-initializers \ -Wno-pragmas \ -Wno-sign-compare \ -Wno-unused-but-set-variable \ -Wno-unused-parameter \ ; do dnl GCC 4.4 does not warn when checking for -Wno-* flags (https://gcc.gnu.org/wiki/FAQ#wnowarning) _NM_COMPILER_FLAG([$(printf '%s' "$option" | sed 's/^-Wno-/-W/')], [], [CFLAGS_MORE_WARNINGS="$CFLAGS_MORE_WARNINGS $option"], []) done unset option dnl Disable warnings triggered by known compiler problems dnl https://bugzilla.gnome.org/show_bug.cgi?id=745821 NM_COMPILER_WARNING([unknown-attributes], [#include ]) dnl https://bugzilla.gnome.org/show_bug.cgi?id=744473 NM_COMPILER_WARNING([typedef-redefinition], [#include ]) dnl https://llvm.org/bugs/show_bug.cgi?id=21614 NM_COMPILER_WARNING([array-bounds], [#include ] [void f () { strcmp ("something", "0"); }] ) dnl https://llvm.org/bugs/show_bug.cgi?id=22949 NM_COMPILER_WARNING([parentheses-equality], [#include ] [void f () { if (WIFCONTINUED(0)) return; }] ) dnl systemd-dhcp's log_internal macro and our handle_warn are sometimes dnl used in void context,u sometimes in int. Makes clang unhappy. NM_COMPILER_WARNING([unused-value], [#define yolo ({ (666 + 666); })] [int f () { int i = yolo; yolo; return i; }] ) dnl clang 3.9 would like to see "{ { 0 } }" here, but that does not dnl look too wise. NM_COMPILER_WARNING([missing-braces], [union { int a[1]; int b[2]; } c = { 0 }] ) CFLAGS="$CFLAGS_MORE_WARNINGS $CFLAGS" else AC_MSG_RESULT(no) fi ]) AC_DEFUN([NM_LTO], [AC_ARG_ENABLE(lto, AS_HELP_STRING([--enable-lto], [Enable Link Time Optimization for smaller size (default: no)])) if (test "${enable_lto}" = "yes"); then CC_CHECK_FLAG_APPEND([lto_flags], [CFLAGS], [-flto]) if (test -n "${lto_flags}"); then CFLAGS="-flto $CFLAGS" else AC_MSG_ERROR([Link Time Optimization -flto is not supported.]) fi else enable_lto='no' fi ]) AC_DEFUN([NM_LD_GC], [AC_ARG_ENABLE(ld-gc, AS_HELP_STRING([--enable-ld-gc], [Enable garbage collection of unused symbols on linking (default: auto)])) if (test "${enable_ld_gc}" != "no"); then CC_CHECK_FLAG_APPEND([ld_gc_flags], [CFLAGS], [-fdata-sections -ffunction-sections -Wl,--gc-sections]) if (test -n "${ld_gc_flags}"); then enable_ld_gc="yes" CFLAGS="$ld_gc_flags $CFLAGS" else if (test "${enable_ld_gc}" = "yes"); then AC_MSG_ERROR([Unused symbol eviction requested but not supported.]) else enable_ld_gc="no" fi fi fi ])