Make narrowing conversions an error

E.g. on ARM64 with unsigned chars, this is a real error, and causes the build to fail: https://buildd.debian.org/status/fetch.php?pkg=boxbackup&arch=arm64&ver=0.11.1~r2837-4&stamp=1485057548&raw=0
boxbackup · Jul 23, 2017 · ab43e24 · ab43e24
1 parent 9324200
commit ab43e24
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/infrastructure/m4/boxbackup_tests.m4 b/infrastructure/m4/boxbackup_tests.m4
@@ -19,6 +19,8 @@ AX_CHECK_COMPILE_FLAG(-Werror=non-virtual-dtor,
 	[cxxflags_strict="$cxxflags_strict -Werror=non-virtual-dtor"])
 AX_CHECK_COMPILE_FLAG(-Werror=delete-non-virtual-dtor,
 	[cxxflags_strict="$cxxflags_strict -Werror=delete-non-virtual-dtor"])
+AX_CHECK_COMPILE_FLAG(-Werror=narrowing,
+	[cxxflags_strict="$cxxflags_strict -Werror=narrowing"])
 AC_SUBST([CXXFLAGS_STRICT], [$cxxflags_strict])
 
 if test "x$GXX" = "xyes"; then