* configure.ac: For --enable-compiler-warnings, don't enable
warnings that flag usage common in gnulib (such as variable-length
arrays) or which provide no value (such as switch statements
lacking a default case that would never be used). Also don't
enable some useful warnings (such as missed opportunitied to mark
a function as pure) which we don't yet have a portable way of
avoiding.
Also add a new option --enable-compiler-warnings-are-errors,
turning GCC compiler warnings into errors. This is off by
default.
---
configure.ac | 106 +++++++++++++++++++++++++++++++++++++++++++----------------
1 file changed, 77 insertions(+), 29 deletions(-)
diff --git a/configure.ac b/configure.ac
index dd2496e..8e49646 100644
--- a/configure.ac
+++ b/configure.ac
@@ -65,38 +65,86 @@ AC_SYS_LARGEFILE
gl_INIT
-dnl Enable various GCC warnings.
-gl_MANYWARN_ALL_GCC([warnings])
-# Set up the list of the pointless, undesired warnings.
-nw=
-nw="$nw -Wsystem-headers" # Don't let system headers trigger warnings
-nw="$nw -Wundef" # All compiler preprocessors support #if UNDEF
-nw="$nw -Wtraditional" # All compilers nowadays support ANSI C
-nw="$nw -Wconversion" # These warnings usually don't point to
mistakes.
-nw="$nw -Wsign-conversion" # Likewise.
-nw="$nw -Wc++-compat" # malloc returns void* and a cast would be
ugly.
-# Warnings we might enable in the future, but not yet (because they generate a
-# lot of noise).
-marginal=""
-marginal="$marginal -Wtraditional-conversion"
-marginal="$marginal -Wpadded"
-marginal="$marginal -Wformat-nonliteral"
-marginal="$marginal -Wunreachable-code"
-marginal="$marginal -Wunused-parameter"
-excluded_warnings="$nw $marginal"
-
-# Enable all GCC warnings not in this list.
-gl_MANYWARN_COMPLEMENT([warnings], [$warnings], [$excluded_warnings])
-
AC_ARG_ENABLE(compiler-warnings,
AS_HELP_STRING(--enable-compiler-warnings,Enable many compiler warnings),
[
- for w in $warnings
- do
- gl_WARN_ADD([$w])
- done
- ]
- )
+ dnl Enable various GCC warnings.
+ gl_MANYWARN_ALL_GCC([warnings])
+
+ # Set up the list of the pointless, undesired warnings.
+ findutils_nw=
+ findutils_nw="$findutils_nw -Wsystem-headers" # Don't let system
headers trigger warnings
+ findutils_nw="$findutils_nw -Wundef" # All compiler preprocessors
support #if UNDEF
+ findutils_nw="$findutils_nw -Wtraditional" # All compilers nowadays
support ANSI C
+ findutils_nw="$findutils_nw -Wconversion" # These warnings usually
don't point to mistakes.
+ findutils_nw="$findutils_nw -Wsign-conversion" # Likewise.
+ findutils_nw="$findutils_nw -Wc++-compat" # malloc returns void* and a
cast would be ugly.
+ findutils_nw="$findutils_nw -Wswitch-default" # A switch on an enum value
needs no default.
+ # gettext.h and gnulib use variable length arrays and we don't want warnings
for that.
+ findutils_gnulib_noise_warnings=
+ findutils_gnulib_noise_warnings="$findutils_gnulib_noise_warnings -Wvla"
+
+ # Warnings we might enable in the future, but not yet (because they generate
a
+ # lot of noise).
+ findutils_marginal=""
+ findutils_marginal="$findutils_marginal -Wtraditional-conversion"
+ findutils_marginal="$findutils_marginal -Wpadded"
+ findutils_marginal="$findutils_marginal -Wformat-nonliteral"
+ findutils_marginal="$findutils_marginal -Wunreachable-code"
+ findutils_marginal="$findutils_marginal -Wunused-parameter"
+ # -Wdouble-promotion generates many warnings when printing values with
fprintf.
+ findutils_marginal="$findutils_marginal -Wdouble-promotion"
+ findutils_marginal="$findutils_marginal -Woverlength-strings"
+ # Also disable some other warnings that we do in principle want, but
currently lack
+ # a way to portably avoid.
+ findutils_tmp_nowarning=
+ findutils_tmp_nowarning="$findutils_tmp_nowarning -Wsuggest-attribute=const"
+ findutils_tmp_nowarning="$findutils_tmp_nowarning -Wsuggest-attribute=pure"
+ findutils_tmp_nowarning="$findutils_tmp_nowarning -Wsuggest-attribute=format"
+ # And some other warnings that we should fix but haven't, yet.
+ findutils_tmp_nowarning="$findutils_tmp_nowarning -Wsuggest-attribute=const"
+
+ # Enable all GCC warnings not in our list of excluded warnings.
+ gl_MANYWARN_COMPLEMENT(
+ [warnings], [$warnings],
+ [$findutils_nw $findutils_marginal $findutils_tmp_nowarning
$findutils_gnulib_noise_warnings])
+ for w in $warnings
+ do
+ gl_WARN_ADD([$w])
+ done
+ # -Wextra implies -Wsign-compare, so removing -Wsign-compare from $warnings
does not
+ # actually eliminate this warning, as manywarnings will have included
-Wextra.
+ # We should actually eliminate the uses that cause this warning, but some of
them are
+ # tricky as they're comparisons between a type we choose and a type the
implementation
+ # chooses without stating whether or not it is signed (e.g. time_t).
+ WARN_CFLAGS="$WARN_CFLAGS -Wno-sign-compare"
+ ])
+
+dnl For --enable-compiler-warnings-are-errors, any GCC compiler
+dnl warning is actually an error which results in a non-zero result
+dnl from the compiler (that is, the code will fail to compile). We do
+dnl this late in the configure script so that it doesn't interfere
+dnl with the compilation tests run by other parts of the configure
+dnl script.
+AC_ARG_ENABLE(compiler-warnings-are-errors,
+ AS_HELP_STRING(--enable-compiler-warnings-are-errors,Compiler warnings are
errors),
+ [
+ AC_MSG_CHECKING([whether it is safe to use -Werror])
+ AC_PROG_CC
+ if test -n "$GCC"; then
+ CFLAGS="$CFLAGS -Werror"
+ AC_MSG_RESULT([yes])
+ # Turn off warnings that would fire for code in gnulib, which we still
want to be able
+ # to compile without error.
+ unwanted="vla"
+ AC_MSG_NOTICE([Turning off otherwise-fatal warnings in order to compile
gnulib successfully: $unwanted])
+ for w in $unwanted; do
+ WARN_CFLAGS="${WARN_CFLAGS} -Wno-${w}"
+ done
+ else
+ AC_MSG_RESULT([no, because $CC is not GCC])
+ fi
+ ])
dnl Older versions of gl/m4/nls.m4 provide AM_MKINSTALLDIRS.
dnl The current version of gnulib does not, but the version of
--
2.1.4
