Disable GCC -Wformat-truncation when suported

Pass -Wno-format-truncation when this is supported by GCC so silence
warnings like this:

  conf.c: In function ‘Read_Config’:
  conf.c:985:60: warning: ‘snprintf’ output may be truncated before
                 the last format character [-Wformat-truncation=]
    985 |                         snprintf(file, sizeof(file), "%s/%s",
        |                                                            ^
  conf.c:985:25: note: ‘snprintf’ output 2 or more bytes (assuming 257)
                 into a destination of size 256
    985 |                         snprintf(file, sizeof(file), "%s/%s",
        |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    986 |                                  Conf_IncludeDir, entry->d_name);
        |                                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The warning is correct, but this is basically why we use snprintf() in
the first place.

diff --git a/configure.ng b/configure.ng
index 195e4067beda5d12e6b0e58032c6848313ee548e..b2652c64aed63f61442a31a888f4f3e09483fd0a 100644 (file)
--- a/configure.ng
+++ b/configure.ng
@@ -125,6 +125,18 @@ main(int argc, char **argv)
        ])
 ])
 
+AC_DEFUN([GCC_W_NO_FORMAT_TRUNC],[
+       result=yes
+       AC_MSG_CHECKING([whether ${CC} accepts -Wno-format-truncation])
+       old_cflags="$CFLAGS"
+       CFLAGS="$CFLAGS -Wno-format-truncation"
+       AC_LINK_IFELSE([AC_LANG_PROGRAM([],[])],[],[result=no])
+       echo $result
+       if test "X$result" = "Xno"; then
+               CFLAGS="$old_cflags"
+       fi
+])
+
 # -- Hard coded system and compiler dependencies/features/options ... --
 
 if test "$GCC" = "yes"; then
@@ -132,6 +144,7 @@ if test "$GCC" = "yes"; then
        CFLAGS="$CFLAGS -pipe -W -Wall -Wpointer-arith -Wstrict-prototypes"
 
        GCC_STACK_PROTECT_CC
+       GCC_W_NO_FORMAT_TRUNC
 fi
 
 case "$host_os" in