Supported category option in Warning#warn

error.c

@@ -238,7 +238,7 @@ rb_warning_s_aset(VALUE mod, VALUE category, VALUE flag)
  *
  * Writes warning message +msg+ to $stderr. This method is called by
  * Ruby for all emitted warnings. A +category+ may be included with
- * the warning, but is ignored by default.
+ * the warning.
  *
  * See the documentation of the Warning module for how to customize this.
  */
@@ -248,13 +248,17 @@ rb_warning_s_warn(int argc, VALUE *argv, VALUE mod)
 {
     VALUE str;
     VALUE opt;
-    VALUE category;
+    VALUE category = Qnil;
 
     rb_scan_args(argc, argv, "1:", &str, &opt);
     if (!NIL_P(opt)) rb_get_kwargs(opt, &id_category, 0, 1, &category);
 
     Check_Type(str, T_STRING);
     rb_must_asciicompat(str);
+    if (!NIL_P(category)) {
+        rb_warning_category_t cat = rb_warning_category_from_name(category);
+        if (!rb_warning_category_enabled_p(cat)) return Qnil;
+    }
     rb_write_error_str(str);
     return Qnil;
 }
@@ -301,7 +305,8 @@ rb_warning_warn(VALUE mod, VALUE str)
 
 
 static int
-rb_warning_warn_arity(void) {
+rb_warning_warn_arity(void)
+{
     return rb_method_entry_arity(rb_method_entry(rb_singleton_class(rb_mWarning), id_warn));
 }
 

test/ruby/test_exception.rb

@@ -918,6 +918,7 @@ def test_message_of_name_error
   def capture_warning_warn(category: false)
     verbose = $VERBOSE
     deprecated = Warning[:deprecated]
+    experimental = Warning[:experimental]
     warning = []
 
     ::Warning.class_eval do
@@ -937,12 +938,14 @@ def capture_warning_warn(category: false)
 
     $VERBOSE = true
     Warning[:deprecated] = true
+    Warning[:experimental] = true
     yield
 
     return warning
   ensure
     $VERBOSE = verbose
     Warning[:deprecated] = deprecated
+    Warning[:experimental] = experimental
 
     ::Warning.class_eval do
       remove_method :warn
@@ -1057,6 +1060,46 @@ def test_warning_category
     assert_include([true, false], Warning[:experimental])
   end
 
+  def test_warning_category_deprecated
+    warning = EnvUtil.verbose_warning do
+      deprecated = Warning[:deprecated]
+      Warning[:deprecated] = true
+      Warning.warn "deprecated feature", category: :deprecated
+    ensure
+      Warning[:deprecated] = deprecated
+    end
+    assert_equal "deprecated feature", warning
+
+    warning = EnvUtil.verbose_warning do
+      deprecated = Warning[:deprecated]
+      Warning[:deprecated] = false
+      Warning.warn "deprecated feature", category: :deprecated
+    ensure
+      Warning[:deprecated] = deprecated
+    end
+    assert_empty warning
+  end
+
+  def test_warning_category_experimental
+    warning = EnvUtil.verbose_warning do
+      experimental = Warning[:experimental]
+      Warning[:experimental] = true
+      Warning.warn "experimental feature", category: :experimental
+    ensure
+      Warning[:experimental] = experimental
+    end
+    assert_equal "experimental feature", warning
+
+    warning = EnvUtil.verbose_warning do
+      experimental = Warning[:experimental]
+      Warning[:experimental] = false
+      Warning.warn "experimental feature", category: :experimental
+    ensure
+      Warning[:experimental] = experimental
+    end
+    assert_empty warning
+  end
+
   def test_undefined_backtrace
     assert_separately([], "#{<<-"begin;"}\n#{<<-"end;"}")
     begin;