Revert "Only emit circular dependency warning for owned thread shields"

This reverts commit fa49651e05.

internal/thread.h

@@ -29,7 +29,6 @@ VALUE rb_get_coverages(void);
 int rb_get_coverage_mode(void);
 VALUE rb_default_coverage(int);
 VALUE rb_thread_shield_new(void);
-bool rb_thread_shield_owned(VALUE self);
 VALUE rb_thread_shield_wait(VALUE self);
 VALUE rb_thread_shield_release(VALUE self);
 VALUE rb_thread_shield_destroy(VALUE self);

load.c

@@ -850,8 +850,7 @@ load_lock(rb_vm_t *vm, const char *ftptr, bool warn)
         st_insert(loading_tbl, (st_data_t)ftptr, data);
         return (char *)ftptr;
     }
-
-    if (warn && rb_thread_shield_owned((VALUE)data)) {
+    if (warn) {
         VALUE warning = rb_warning_string("loading in progress, circular require considered harmful - %s", ftptr);
         rb_backtrace_each(rb_str_append, warning);
         rb_warning("%"PRIsVALUE, warning);

spec/ruby/core/kernel/shared/require.rb

@@ -237,16 +237,6 @@ describe :kernel_require, shared: true do
       }.should complain(/circular require considered harmful/, verbose: true)
       ScratchPad.recorded.should == [:loaded]
     end
-
-    ruby_bug "#17340", ''...'3.3' do
-      it "loads a file concurrently" do
-        path = File.expand_path "concurrent_require_fixture.rb", CODE_LOADING_DIR
-        ScratchPad.record(@object)
-        -> {
-          @object.require(path)
-        }.should_not complain(/circular require considered harmful/, verbose: true)
-      end
-    end
   end
 
   describe "(non-extensioned path)" do

spec/ruby/fixtures/code/concurrent_require_fixture.rb

@@ -1 +0,0 @@
-Thread.new { ScratchPad.recorded.require(__FILE__) }.join(0.1)

test/ruby/test_require.rb

@@ -562,6 +562,9 @@ 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)
+
+      assert_match(/circular require/, output)
+      assert_match(/in #{__method__}'$/o, output)
     }
   ensure
     $VERBOSE = verbose

thread.c

@@ -4920,17 +4920,6 @@ rb_thread_shield_new(void)
     return thread_shield;
 }
 
-bool
-rb_thread_shield_owned(VALUE self)
-{
-    VALUE mutex = GetThreadShieldPtr(self);
-    if (!mutex) return false;
-
-    rb_mutex_t *m = mutex_ptr(mutex);
-
-    return m->fiber == GET_EC()->fiber_ptr;
-}
-
 /*
  * Wait a thread shield.
  *