extconf.rb in kcar-0.7.0

- old
+ new
@@ -3,12 +3,37 @@
 
 dir_config("kcar")
 
 have_macro("SIZEOF_OFF_T", "ruby.h") or check_sizeof("off_t", "sys/types.h")
 have_macro("SIZEOF_LONG", "ruby.h") or check_sizeof("long", "sys/types.h")
-have_func("rb_str_set_len", "ruby.h")
-have_func("rb_str_modify", "ruby.h")
 
-# -fPIC is needed for Rubinius, MRI already uses it regardless
-with_cflags($CFLAGS + " -fPIC ") do
-  create_makefile("kcar_ext")
+message('checking if String#-@ (str_uminus) dedupes... ')
+begin
+  a = -(%w(t e s t).join)
+  b = -(%w(t e s t).join)
+  if a.equal?(b)
+    $CPPFLAGS += " -DSTR_UMINUS_DEDUPE=1 "
+    message("yes\n")
+  else
+    $CPPFLAGS += " -DSTR_UMINUS_DEDUPE=0 "
+    message("no, needs Ruby 2.5+\n")
+  end
+rescue NoMethodError
+  $CPPFLAGS += " -DSTR_UMINUS_DEDUPE=0 "
+  message("no, String#-@ not available\n")
 end
+
+message('checking if Hash#[]= (rb_hash_aset) dedupes... ')
+h = {}
+x = {}
+r = rand.to_s
+h[%W(#{r}).join('')] = :foo
+x[%W(#{r}).join('')] = :foo
+if x.keys[0].equal?(h.keys[0])
+  $CPPFLAGS += ' -DHASH_ASET_DEDUPE=1 '
+  message("yes\n")
+else
+  $CPPFLAGS += ' -DHASH_ASET_DEDUPE=0 '
+  message("no, needs Ruby 2.6+\n")
+end
+
+create_makefile("kcar_ext")