Set most compiler flags as late as possible in configure.

Some flags, e.g. -Wfatal-errors, will cause tests in configure to behave incorrectly so we have not been able to add them to --enable-test.

Add the compiler flags as late as possible so configure checks are not affected. This will allow us to add flags that we need for testing without having to explicitly pass them to make.

src/build/configure.ac

@@ -40,39 +40,6 @@ AC_LINK_IFELSE(
     [AC_LANG_PROGRAM([], [[int x; static int y[__builtin_types_compatible_p(__typeof__(x), int)];]])],
     [AC_DEFINE(HAVE_BUILTIN_TYPES_COMPATIBLE_P)])
 
-# Set warnings and optimizations based on build type (i.e. production or test)
-# ----------------------------------------------------------------------------------------------------------------------------------
-AC_SUBST(CFLAGS, "${CFLAGS} -Wall -Wextra -Wno-missing-field-initializers -Wno-implicit-fallthrough")
-
-# -Wno-clobbered is not supported on all compilers
-AX_CHECK_COMPILE_FLAG([-Wno-clobbered], [AC_SUBST(CFLAGS, "${CFLAGS} -Wno-clobbered")], [], [-Werror])
-
-AC_ARG_ENABLE(
-    test, [AS_HELP_STRING([--enable-test], [enable internal test code and assertions for debugging])])
-
-if test "$enable_test" != yes
-then
-    AC_DEFINE(NDEBUG)
-
-    # Enable optimizations if not testing and they have not been disabled
-    AC_ARG_ENABLE(optimize, [AS_HELP_STRING([--disable-optimize], [disable compiler optimizations])])
-
-    if test "$enable_optimize" != no
-    then
-        AC_SUBST(CFLAGS, "${CFLAGS} -O2")
-        AC_SUBST(CFLAGS_PAGE_CHECKSUM, "-funroll-loops -ftree-vectorize")
-    fi
-else
-    # Check for optional warnings (note that these must be checked before the additional warnings below are added)
-    AX_CHECK_COMPILE_FLAG([-Wformat-signedness], [AC_SUBST(CFLAGS, "${CFLAGS} -Wformat-signedness")], [], [-Werror])
-    AX_CHECK_COMPILE_FLAG([-Wduplicated-branches], [AC_SUBST(CFLAGS, "${CFLAGS} -Wduplicated-branches")], [], [-Werror])
-    AX_CHECK_COMPILE_FLAG([-Wduplicated-cond], [AC_SUBST(CFLAGS, "${CFLAGS} -Wduplicated-cond")], [], [-Werror])
-
-    # Add additional warnings
-    AC_SUBST(CFLAGS, "${CFLAGS} -Wwrite-strings -Wconversion -Wformat=2 -Wformat-nonliteral -Wstrict-prototypes -Wpointer-arith")
-    AC_SUBST(CFLAGS, "${CFLAGS} -Wvla")
-fi
-
 # Include the build directory
 # ----------------------------------------------------------------------------------------------------------------------------------
 AC_SUBST(CPPFLAGS, "${CPPFLAGS} -I.")
@@ -163,6 +130,39 @@ AC_ARG_WITH(
     [AC_DEFINE_UNQUOTED([CFGOPTDEF_CONFIG_PATH], ["${withval}"])],
     [AC_DEFINE_UNQUOTED([CFGOPTDEF_CONFIG_PATH], ["/etc/" PROJECT_BIN])])
 
+# Set warnings and optimizations based on build type (i.e. production or test)
+# ----------------------------------------------------------------------------------------------------------------------------------
+AC_SUBST(CFLAGS, "${CFLAGS} -Wall -Wextra -Wno-missing-field-initializers -Wno-implicit-fallthrough")
+
+# -Wno-clobbered is not supported on all compilers
+AX_CHECK_COMPILE_FLAG([-Wno-clobbered], [AC_SUBST(CFLAGS, "${CFLAGS} -Wno-clobbered")], [], [-Werror])
+
+AC_ARG_ENABLE(
+    test, [AS_HELP_STRING([--enable-test], [enable internal test code and assertions for debugging])])
+
+if test "$enable_test" != yes
+then
+    AC_DEFINE(NDEBUG)
+
+    # Enable optimizations if not testing and they have not been disabled
+    AC_ARG_ENABLE(optimize, [AS_HELP_STRING([--disable-optimize], [disable compiler optimizations])])
+
+    if test "$enable_optimize" != no
+    then
+        AC_SUBST(CFLAGS, "${CFLAGS} -O2")
+        AC_SUBST(CFLAGS_PAGE_CHECKSUM, "-funroll-loops -ftree-vectorize")
+    fi
+else
+    # Check for optional warnings (note that these must be checked before the additional warnings below are added)
+    AX_CHECK_COMPILE_FLAG([-Wformat-signedness], [AC_SUBST(CFLAGS, "${CFLAGS} -Wformat-signedness")], [], [-Werror])
+    AX_CHECK_COMPILE_FLAG([-Wduplicated-branches], [AC_SUBST(CFLAGS, "${CFLAGS} -Wduplicated-branches")], [], [-Werror])
+    AX_CHECK_COMPILE_FLAG([-Wduplicated-cond], [AC_SUBST(CFLAGS, "${CFLAGS} -Wduplicated-cond")], [], [-Werror])
+
+    # Add additional warnings
+    AC_SUBST(CFLAGS, "${CFLAGS} -Wwrite-strings -Wconversion -Wformat=2 -Wformat-nonliteral -Wstrict-prototypes -Wpointer-arith")
+    AC_SUBST(CFLAGS, "${CFLAGS} -Wvla")
+fi
+
 # Write output
 # ----------------------------------------------------------------------------------------------------------------------------------
 AC_CONFIG_HEADERS([build.auto.h])