load.c: display backtrace to $stderr

* load.c (load_lock): display backtrace to $stderr at circular
  require.
* vm_backtrace.c (rb_backtrace_print_to): new function to print
  backtrace to the given output.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43204 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 10 insertions, 7 deletions

diff --git a/test/ruby/test_require.rb b/test/ruby/test_require.rb
index 34c5fde96f..ad08bf85de 100644
--- a/test/ruby/test_require.rb
+++ b/test/ruby/test_require.rb
@@ -399,6 +399,7 @@ class TestRequire < Test::Unit::TestCase
   def test_race_exception
     bug5754 = '[ruby-core:41618]'
     path = nil
+    stderr = $stderr
     Tempfile.create(%w"bug5754 .rb") {|tmp|
       path = tmp.path
       tmp.print %{\
@@ -416,12 +417,11 @@ class TestRequire < Test::Unit::TestCase
       }
       tmp.close
 
-      # "circular require" warnings to $stderr, but backtraces to stderr
-      # in C-level.  And redirecting stderr to a pipe seems to change
-      # some blocking timings and causes a deadlock, so run in a
-      # separated process for the time being.
-      assert_separately(["-w", "-", path, bug5754], <<-'end;', ignore_stderr: true)
-      path, bug5754 = *ARGV
+      class << (output = "")
+        alias write concat
+      end
+      $stderr = output
+
       start = false
 
       scratch = []
@@ -454,9 +454,12 @@ class TestRequire < Test::Unit::TestCase
 
       assert_equal(true, (t1_res ^ t2_res), bug5754 + " t1:#{t1_res} t2:#{t2_res}")
       assert_equal([:pre, :post], scratch, bug5754)
-      end;
+
+      assert_match(/circular require/, output)
+      assert_match(/in #{__method__}'$/o, output)
     }
   ensure
+    $stderr = stderr
     $".delete(path)
   end