CFLAGS=${save_CFLAGS}
# Detect C and LD warning flags supported by the compiler.
-AX_COMPILER_FLAGS(
- [WARN_CFLAGS], dnl CFLAGS variable name
- [WARN_LDFLAGS], dnl LDFLAGS variable name (unused for now)
- [], dnl is-release
- [], dnl Extra base CFLAGS
- [ dnl Extra "yes" CFLAGS
- dnl Disable these flags, either because we don't want them
- dnl or because we want them but are not ready to enable them
- dnl yet.
- -Wno-sign-compare dnl
- -Wno-inline dnl
- -Wno-declaration-after-statement dnl
- -Wno-switch-enum dnl
- -Wno-switch-default dnl
- -Wno-packed dnl
- -Wno-pointer-arith dnl
+
+# Detect warning flags supported by the compiler, append them to WARN_CFLAGS.
+#
+# Pass -Werror as an extra flag during the test: this is needed to make the
+# -Wunknown-warning-option diagnostic fatal with clang.
+AX_APPEND_COMPILE_FLAGS([ dnl
+ -Wall dnl
+ -Wextra dnl
+ -Wstrict-prototypes dnl
+ -Wmissing-prototypes dnl
+ -Wmissing-declarations dnl
+ -Wnull-dereference dnl
+ -Wundef dnl
+ -Wredundant-decls dnl
+ -Wshadow dnl
+ -Wjump-misses-init dnl
+ -Wtautological-constant-out-of-range-compare dnl
+ -Wnested-externs dnl
+ -Wwrite-strings dnl
+ -Wformat=2 dnl
-Wno-format-nonliteral dnl
- -Wno-double-promotion dnl
- -Wno-cast-align dnl
+ -Wstrict-aliasing dnl
+ -Wmissing-noreturn dnl
+ -Winit-self dnl
+ -Wduplicated-cond dnl
+ -Wduplicated-branches dnl
+ -Wlogical-op dnl
+ -Wno-unused-parameter dnl
+ -Wno-sign-compare dnl
dnl
dnl Some versions of SWIG (like 3.0.12) generate code that produces
dnl -Wcast-function-type warnings. This warning is present in gcc >= 8. This
dnl
dnl Ref: https://github.com/swig/swig/issues/1259
-Wno-cast-function-type dnl
- ])
-
-# CFLAGS from AX_COMPILER_FLAGS.
-AM_CFLAGS="${AM_CFLAGS} ${WARN_CFLAGS}"
+ -Wno-missing-field-initializers dnl
+ ],
+ [WARN_CFLAGS],
+ [-Werror])
+
+# When given, add -Werror to WARN_CFLAGS.
+AC_ARG_ENABLE([Werror],
+ [AS_HELP_STRING([--enable-Werror], [Treat compiler warnings as errors.])]
+)
+AS_IF([test "x$enable_Werror" = "xyes"],
+ [WARN_CFLAGS="${WARN_CFLAGS} -Werror"]
+)
-# The test used in AX_COMPILER_FLAGS, generated using AC_LANG_PROGRAM, is
+# The test used in AX_APPEND_COMPILE_FLAGS, generated using AC_LANG_PROGRAM, is
# written in such a way that it triggers a -Wold-style-definition warning. So
-# if the user has -Werror in their CFLAGS, that warning flag will end up
-# disabled, because the test program will not build.
+# this warning always ends up disabled if we put it there, because the test
+# program does not build.
#
# Enable it here unconditionally. It is supported by GCC >= 4.8 and by Clang
# (it is accepted for compatibility although it has no effect), and there is
# not reason to not want it.
-AM_CFLAGS="${AM_CFLAGS} -Wold-style-definition"
+WARN_CFLAGS="${WARN_CFLAGS} -Wold-style-definition"
-# We want this one to always be an error.
-AM_CFLAGS="${AM_CFLAGS} -Werror=implicit-function-declaration"
+# CFLAGS from AX_APPEND_COMPILE_FLAGS.
+AM_CFLAGS="${AM_CFLAGS} ${WARN_CFLAGS}"
# Done for AM_CFLAGS.
AC_SUBST(AM_CFLAGS)