diff options
| -rw-r--r-- | m4/compiler_warnings.m4 | 80 |
1 files changed, 64 insertions, 16 deletions
diff --git a/m4/compiler_warnings.m4 b/m4/compiler_warnings.m4 index 97897e44..21e5c88c 100644 --- a/m4/compiler_warnings.m4 +++ b/m4/compiler_warnings.m4 @@ -1,3 +1,24 @@ +dnl Check whether a particular compiler flag works with code provided, +dnl disable it in CFLAGS if the check fails. +AC_DEFUN([NM_COMPILER_WARNING], [ + CFLAGS_SAVED="$CFLAGS" + CFLAGS="$CFLAGS -Werror -W$1" + AC_MSG_CHECKING(whether -W$1 works) + + AC_COMPILE_IFELSE([AC_LANG_SOURCE([[]])], [ + AC_COMPILE_IFELSE([AC_LANG_SOURCE([[$2]])], [ + AC_MSG_RESULT(yes) + CFLAGS="$CFLAGS_SAVED -W$1" + ],[ + AC_MSG_RESULT(no) + CFLAGS="$CFLAGS_SAVED -Wno-$1" + ]) + ],[ + AC_MSG_RESULT(not supported) + CFLAGS="$CFLAGS_SAVED" + ]) +]) + AC_DEFUN([NM_COMPILER_WARNINGS], [AC_ARG_ENABLE(more-warnings, AS_HELP_STRING([--enable-more-warnings], [Possible values: no/yes/error]), @@ -5,22 +26,26 @@ AC_DEFUN([NM_COMPILER_WARNINGS], 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="$CFLAGS" - CFLAGS_MORE_WARNINGS="-Wall -std=gnu89" + CFLAGS="$CFLAGS -Qunused-arguments" + AC_COMPILE_IFELSE([AC_LANG_SOURCE([])], [], CFLAGS="$CFLAGS_SAVED") + unset CFLAGS_SAVED dnl clang only warns about unknown warnings, unless dnl called with "-Werror=unknown-warning-option" dnl Test if the compiler supports that, and if it does dnl attach it to the CFLAGS. - CFLAGS_EXTRA="-Werror=unknown-warning-option" - CFLAGS="$CFLAGS_MORE_WARNINGS $CFLAGS_EXTRA $CFLAGS_SAVED" - AC_TRY_COMPILE([], [], - has_option=yes, - has_option=no,) - if test $has_option = no; then - CFLAGS_EXTRA= + NM_COMPILER_WARNING([unknown-warning-option], []) + + CFLAGS_SAVED="$CFLAGS" + CFLAGS_MORE_WARNINGS="-Wall -std=gnu89" + + if test "x$set_more_warnings" = xerror; then + CFLAGS_MORE_WARNINGS="$CFLAGS_MORE_WARNINGS -Werror" fi - unset has_option for option in -Wshadow -Wmissing-declarations -Wmissing-prototypes \ -Wdeclaration-after-statement -Wformat-security \ @@ -31,8 +56,8 @@ if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then -Wpointer-arith -Winit-self \ -Wmissing-include-dirs -Waggregate-return; do dnl GCC 4.4 does not warn when checking for -Wno-* flags (https://gcc.gnu.org/wiki/FAQ#wnowarning) - CFLAGS="$CFLAGS_MORE_WARNINGS $CFLAGS_EXTRA $(printf '%s' "$option" | sed 's/^-Wno-/-W/') $CFLAGS_SAVED" - AC_MSG_CHECKING([whether gcc understands $option]) + CFLAGS="$CFLAGS_MORE_WARNINGS $(printf '%s' "$option" | sed 's/^-Wno-/-W/') $CFLAGS_SAVED" + AC_MSG_CHECKING([whether compiler understands $option]) AC_TRY_COMPILE([], [], has_option=yes, has_option=no,) @@ -43,12 +68,35 @@ if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then unset has_option done unset option - unset CFLAGS_EXTRA - if test "x$set_more_warnings" = xerror; then - CFLAGS_MORE_WARNINGS="$CFLAGS_MORE_WARNINGS -Werror" - fi - CFLAGS="$CFLAGS_MORE_WARNINGS $CFLAGS_SAVED" + + CFLAGS="$CFLAGS_SAVED" unset CFLAGS_SAVED + + dnl Disable warnings triggered by known compiler problems + + dnl https://bugzilla.gnome.org/show_bug.cgi?id=745821 + NM_COMPILER_WARNING([unknown-attributes], [#include <glib.h>]) + + dnl https://llvm.org/bugs/show_bug.cgi?id=21614 + NM_COMPILER_WARNING([array-bounds], + [#include <string.h>] + [void f () { strcmp ("something", "0"); }] + ) + + dnl https://llvm.org/bugs/show_bug.cgi?id=22949 + NM_COMPILER_WARNING([parentheses-equality], + [#include <sys/wait.h>] + [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; }] + ) + + CFLAGS="$CFLAGS_MORE_WARNINGS $CFLAGS" else AC_MSG_RESULT(no) fi |