extconf.rb in d_heap-0.4.0

- old
+ new

@@ -1,11 +1,16 @@
 # frozen_string_literal: true
 
 require "mkmf"
 
-# if /darwin/ =~ RUBY_PLATFORM
-#   $CFLAGS << " -D__D_HEAP_DEBUG"
-# end
+# For testing in CI (because I don't otherwise have easy access to Mac OS):
+# $CFLAGS << " -D__D_HEAP_DEBUG" if /darwin/ =~ RUBY_PLATFORM
 
 have_func "rb_gc_mark_movable" # since ruby-2.7
 
+check_sizeof("long")
+check_sizeof("unsigned long long")
+check_sizeof("long double")
+have_macro("LDBL_MANT_DIG", "float.h")
+
+CONFIG["warnflags"] << " -Werror"
 create_makefile("d_heap/d_heap")