* configure.in (warnflags): add -Werror=implicit-function-declaration

if available.
* lib/mkmf.rb (init_mkmf): ignore warnings in mkmf tests.
* test/mkmf/base.rb (setup, teardown): restore config values.
* test/mkmf/test_flags.rb: split from test_find_executable.rb.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@30550 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/mkmf/test_flags.rb

@@ -0,0 +1,35 @@
+require_relative 'base'
+
+class TestMkmf
+  class TestFlags < TestMkmf
+    def test_valid_warnflags
+      val = $extmk
+      warnflags = $warnflags
+      makefile = mkmf do
+        $extmk = false
+        self.class::CONFIG['warnflags'] = %w"-Wextra
+        -Wno-unused-parameter -Wno-parentheses -Wno-long-long
+        -Wno-missing-field-initializers -Werror=pointer-arith
+        -Werror=write-strings -Werror=declaration-after-statement
+        -Werror=shorten-64-to-32
+        -Werror-implicit-function-declaration
+        ".join(' ')
+        self.class::CONFIG['GCC'] = 'yes'
+        init_mkmf(self.class::CONFIG)
+        configuration '.'
+      end
+      generated_flags = makefile.grep(/warnflags/).first[/^warnflags = (.*)$/, 1].split
+
+      assert_equal %w"
+      -Wextra -Wno-unused-parameter -Wno-parentheses
+      -Wno-long-long -Wno-missing-field-initializers -Wpointer-arith
+      -Wwrite-strings -Wdeclaration-after-statement
+      -Wshorten-64-to-32 -Wimplicit-function-declaration
+      ", generated_flags
+
+    ensure
+      $warnflags = warnflags
+      $extmk = val
+    end
+  end
+end