mkmf.rb: avoid interference

* lib/mkmf.rb (try_cppflags, try_cflags, try_ldflags): get rid of
  interference by modifying global variables in have_devel? method.
  [ruby-core:67962] [Bug #10821]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49482 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 21 insertions, 0 deletions

diff --git a/test/mkmf/test_flags.rb b/test/mkmf/test_flags.rb
index 3bb278071a..4e0d5f66a2 100644
--- a/test/mkmf/test_flags.rb
+++ b/test/mkmf/test_flags.rb
@@ -31,5 +31,26 @@ class TestMkmf
       $warnflags = warnflags
       $extmk = val
     end
+
+    def test_try_ldflag_invalid_opt
+      assert_separately([], <<-'end;') #do
+        assert(!try_ldflags("----------"))
+        assert(have_devel?, TestMkmf::MKMFLOG)
+      end;
+    end
+
+    def test_try_cflag_invalid_opt
+      assert_separately([], <<-'end;') #do
+        assert(!try_cflags("----------"))
+        assert(have_devel?, TestMkmf::MKMFLOG)
+      end;
+    end
+
+    def test_try_cppflag_invalid_opt
+      assert_separately([], <<-'end;') #do
+        assert(!try_cppflags("----------"))
+        assert(have_devel?, TestMkmf::MKMFLOG)
+      end;
+    end
   end
 end