Reapply "[Feature #6012] Extend source_location for end position

* This reverts commit 065c48cdf11a1c4cece84db44ed8624d294f8fd5.
* This functionality is very valuable and has already taken 14 years
  to agree on the API.
* Let's just document it's byte columns (in the next commit).
* See https://bugs.ruby-lang.org/issues/21783#note-9

NEWS.md

@@ -11,6 +11,15 @@ Note that each entry is kept to a minimum, see links for details.
 
 Note: We're only listing outstanding class updates.
 
+* Method
+
+    * `Method#source_location`, `Proc#source_location`, and
+      `UnboundMethod#source_location` now return extended location
+      information with 5 elements: `[path, start_line, start_column,
+      end_line, end_column]`. The previous 2-element format `[path,
+      line]` can still be obtained by calling `.take(2)` on the result.
+      [[Feature #6012]]
+
 * Set
 
     * A deprecated behavior, `Set#to_set`, `Range#to_set`, and
@@ -66,4 +75,5 @@ A lot of work has gone into making Ractors more stable, performant, and usable.
 
 ## JIT
 
+[Feature #6012]: https://bugs.ruby-lang.org/issues/6012
 [Feature #21390]: https://bugs.ruby-lang.org/issues/21390

proc.c

@@ -1513,14 +1513,20 @@ proc_eq(VALUE self, VALUE other)
 static VALUE
 iseq_location(const rb_iseq_t *iseq)
 {
-    VALUE loc[2];
+    VALUE loc[5];
+    int i = 0;
 
     if (!iseq) return Qnil;
     rb_iseq_check(iseq);
-    loc[0] = rb_iseq_path(iseq);
-    loc[1] = RB_INT2NUM(ISEQ_BODY(iseq)->location.first_lineno);
+    loc[i++] = rb_iseq_path(iseq);
+    const rb_code_location_t *cl = &ISEQ_BODY(iseq)->location.code_location;
+    loc[i++] = RB_INT2NUM(cl->beg_pos.lineno);
+    loc[i++] = RB_INT2NUM(cl->beg_pos.column);
+    loc[i++] = RB_INT2NUM(cl->end_pos.lineno);
+    loc[i++] = RB_INT2NUM(cl->end_pos.column);
+    RUBY_ASSERT_ALWAYS(i == numberof(loc));
 
-    return rb_ary_new4(2, loc);
+    return rb_ary_new_from_values(i, loc);
 }
 
 VALUE

spec/ruby/core/method/source_location_spec.rb

@@ -11,23 +11,23 @@ describe "Method#source_location" do
   end
 
   it "sets the first value to the path of the file in which the method was defined" do
-    file = @method.source_location.first
+    file = @method.source_location[0]
     file.should be_an_instance_of(String)
     file.should == File.realpath('fixtures/classes.rb', __dir__)
   end
 
   it "sets the last value to an Integer representing the line on which the method was defined" do
-    line = @method.source_location.last
+    line = @method.source_location[1]
     line.should be_an_instance_of(Integer)
     line.should == 5
   end
 
   it "returns the last place the method was defined" do
-    MethodSpecs::SourceLocation.method(:redefined).source_location.last.should == 13
+    MethodSpecs::SourceLocation.method(:redefined).source_location[1].should == 13
   end
 
   it "returns the location of the original method even if it was aliased" do
-    MethodSpecs::SourceLocation.new.method(:aka).source_location.last.should == 17
+    MethodSpecs::SourceLocation.new.method(:aka).source_location[1].should == 17
   end
 
   it "works for methods defined with a block" do
@@ -108,7 +108,13 @@ describe "Method#source_location" do
     c = Class.new do
       eval('def self.m; end', nil, "foo", 100)
     end
-    c.method(:m).source_location.should == ["foo", 100]
+    location = c.method(:m).source_location
+    ruby_version_is(""..."4.0") do
+      location.should == ["foo", 100]
+    end
+    ruby_version_is("4.0") do
+      location.should == ["foo", 100, 0, 100, 15]
+    end
   end
 
   describe "for a Method generated by respond_to_missing?" do

spec/ruby/core/proc/source_location_spec.rb

@@ -17,57 +17,64 @@ describe "Proc#source_location" do
   end
 
   it "sets the first value to the path of the file in which the proc was defined" do
-    file = @proc.source_location.first
+    file = @proc.source_location[0]
     file.should be_an_instance_of(String)
     file.should == File.realpath('fixtures/source_location.rb', __dir__)
 
-    file = @proc_new.source_location.first
+    file = @proc_new.source_location[0]
     file.should be_an_instance_of(String)
     file.should == File.realpath('fixtures/source_location.rb', __dir__)
 
-    file = @lambda.source_location.first
+    file = @lambda.source_location[0]
     file.should be_an_instance_of(String)
     file.should == File.realpath('fixtures/source_location.rb', __dir__)
 
-    file = @method.source_location.first
+    file = @method.source_location[0]
     file.should be_an_instance_of(String)
     file.should == File.realpath('fixtures/source_location.rb', __dir__)
   end
 
-  it "sets the last value to an Integer representing the line on which the proc was defined" do
-    line = @proc.source_location.last
+  it "sets the second value to an Integer representing the line on which the proc was defined" do
+    line = @proc.source_location[1]
     line.should be_an_instance_of(Integer)
     line.should == 4
 
-    line = @proc_new.source_location.last
+    line = @proc_new.source_location[1]
     line.should be_an_instance_of(Integer)
     line.should == 12
 
-    line = @lambda.source_location.last
+    line = @lambda.source_location[1]
     line.should be_an_instance_of(Integer)
     line.should == 8
 
-    line = @method.source_location.last
+    line = @method.source_location[1]
     line.should be_an_instance_of(Integer)
     line.should == 15
   end
 
   it "works even if the proc was created on the same line" do
-    proc { true }.source_location.should == [__FILE__, __LINE__]
-    Proc.new { true }.source_location.should == [__FILE__, __LINE__]
-    -> { true }.source_location.should == [__FILE__, __LINE__]
+    ruby_version_is(""..."4.0") do
+      proc { true }.source_location.should == [__FILE__, __LINE__]
+      Proc.new { true }.source_location.should == [__FILE__, __LINE__]
+      -> { true }.source_location.should == [__FILE__, __LINE__]
+    end
+    ruby_version_is("4.0") do
+      proc { true }.source_location.should == [__FILE__, __LINE__, 11, __LINE__, 19]
+      Proc.new { true }.source_location.should == [__FILE__, __LINE__, 15, __LINE__, 23]
+      -> { true }.source_location.should == [__FILE__, __LINE__, 8, __LINE__, 17]
+    end
   end
 
   it "returns the first line of a multi-line proc (i.e. the line containing 'proc do')" do
-    ProcSpecs::SourceLocation.my_multiline_proc.source_location.last.should == 20
-    ProcSpecs::SourceLocation.my_multiline_proc_new.source_location.last.should == 34
-    ProcSpecs::SourceLocation.my_multiline_lambda.source_location.last.should == 27
+    ProcSpecs::SourceLocation.my_multiline_proc.source_location[1].should == 20
+    ProcSpecs::SourceLocation.my_multiline_proc_new.source_location[1].should == 34
+    ProcSpecs::SourceLocation.my_multiline_lambda.source_location[1].should == 27
   end
 
   it "returns the location of the proc's body; not necessarily the proc itself" do
-    ProcSpecs::SourceLocation.my_detached_proc.source_location.last.should == 41
-    ProcSpecs::SourceLocation.my_detached_proc_new.source_location.last.should == 51
-    ProcSpecs::SourceLocation.my_detached_lambda.source_location.last.should == 46
+    ProcSpecs::SourceLocation.my_detached_proc.source_location[1].should == 41
+    ProcSpecs::SourceLocation.my_detached_proc_new.source_location[1].should == 51
+    ProcSpecs::SourceLocation.my_detached_lambda.source_location[1].should == 46
   end
 
   it "returns the same value for a proc-ified method as the method reports" do
@@ -86,6 +93,12 @@ describe "Proc#source_location" do
 
   it "works for eval with a given line" do
     proc = eval('-> {}', nil, "foo", 100)
-    proc.source_location.should == ["foo", 100]
+    location = proc.source_location
+    ruby_version_is(""..."4.0") do
+      location.should == ["foo", 100]
+    end
+    ruby_version_is("4.0") do
+      location.should == ["foo", 100, 2, 100, 5]
+    end
   end
 end

spec/ruby/core/unboundmethod/source_location_spec.rb

@@ -7,23 +7,23 @@ describe "UnboundMethod#source_location" do
   end
 
   it "sets the first value to the path of the file in which the method was defined" do
-    file = @method.source_location.first
+    file = @method.source_location[0]
     file.should be_an_instance_of(String)
     file.should == File.realpath('fixtures/classes.rb', __dir__)
   end
 
-  it "sets the last value to an Integer representing the line on which the method was defined" do
-    line = @method.source_location.last
+  it "sets the second value to an Integer representing the line on which the method was defined" do
+    line = @method.source_location[1]
     line.should be_an_instance_of(Integer)
     line.should == 5
   end
 
   it "returns the last place the method was defined" do
-    UnboundMethodSpecs::SourceLocation.method(:redefined).unbind.source_location.last.should == 13
+    UnboundMethodSpecs::SourceLocation.method(:redefined).unbind.source_location[1].should == 13
   end
 
   it "returns the location of the original method even if it was aliased" do
-    UnboundMethodSpecs::SourceLocation.instance_method(:aka).source_location.last.should == 17
+    UnboundMethodSpecs::SourceLocation.instance_method(:aka).source_location[1].should == 17
   end
 
   it "works for define_method methods" do
@@ -54,6 +54,12 @@ describe "UnboundMethod#source_location" do
     c = Class.new do
       eval('def m; end', nil, "foo", 100)
     end
-    c.instance_method(:m).source_location.should == ["foo", 100]
+    location = c.instance_method(:m).source_location
+    ruby_version_is(""..."4.0") do
+      location.should == ["foo", 100]
+    end
+    ruby_version_is("4.0") do
+      location.should == ["foo", 100, 0, 100, 10]
+    end
   end
 end

test/ruby/test_lambda.rb

@@ -276,27 +276,27 @@ class TestLambdaParameters < Test::Unit::TestCase
   end
 
   def test_do_lambda_source_location
-    exp_lineno = __LINE__ + 3
+    exp = [__LINE__ + 1, 12, __LINE__ + 5, 7]
     lmd = ->(x,
              y,
              z) do
       #
     end
-    file, lineno = lmd.source_location
+    file, *loc = lmd.source_location
     assert_match(/^#{ Regexp.quote(__FILE__) }$/, file)
-    assert_equal(exp_lineno, lineno, "must be at the beginning of the block")
+    assert_equal(exp, loc)
   end
 
   def test_brace_lambda_source_location
-    exp_lineno = __LINE__ + 3
+    exp = [__LINE__ + 1, 12, __LINE__ + 5, 5]
     lmd = ->(x,
              y,
              z) {
       #
     }
-    file, lineno = lmd.source_location
+    file, *loc = lmd.source_location
     assert_match(/^#{ Regexp.quote(__FILE__) }$/, file)
-    assert_equal(exp_lineno, lineno, "must be at the beginning of the block")
+    assert_equal(exp, loc)
   end
 
   def test_not_orphan_return

test/ruby/test_proc.rb

@@ -513,7 +513,7 @@ class TestProc < Test::Unit::TestCase
 
     file, lineno = method(:source_location_test).to_proc.binding.source_location
     assert_match(/^#{ Regexp.quote(__FILE__) }$/, file)
-    assert_equal(@@line_of_source_location_test, lineno, 'Bug #2427')
+    assert_equal(@@line_of_source_location_test[0], lineno, 'Bug #2427')
   end
 
   def test_binding_error_unless_ruby_frame
@@ -1499,15 +1499,19 @@ class TestProc < Test::Unit::TestCase
     assert_include(EnvUtil.labeled_class(name, Proc).new {}.to_s, name)
   end
 
-  @@line_of_source_location_test = __LINE__ + 1
+  @@line_of_source_location_test = [__LINE__ + 1, 2, __LINE__ + 3, 5]
   def source_location_test a=1,
     b=2
   end
 
   def test_source_location
-    file, lineno = method(:source_location_test).source_location
+    file, *loc = method(:source_location_test).source_location
     assert_match(/^#{ Regexp.quote(__FILE__) }$/, file)
-    assert_equal(@@line_of_source_location_test, lineno, 'Bug #2427')
+    assert_equal(@@line_of_source_location_test, loc, 'Bug #2427')
+
+    file, *loc = self.class.instance_method(:source_location_test).source_location
+    assert_match(/^#{ Regexp.quote(__FILE__) }$/, file)
+    assert_equal(@@line_of_source_location_test, loc, 'Bug #2427')
   end
 
   @@line_of_attr_reader_source_location_test   = __LINE__ + 3
@@ -1540,13 +1544,13 @@ class TestProc < Test::Unit::TestCase
   end
 
   def test_block_source_location
-    exp_lineno = __LINE__ + 3
-    file, lineno = block_source_location_test(1,
+    exp_loc = [__LINE__ + 3, 49, __LINE__ + 4, 49]
+    file, *loc = block_source_location_test(1,
                                               2,
                                               3) do
                                               end
     assert_match(/^#{ Regexp.quote(__FILE__) }$/, file)
-    assert_equal(exp_lineno, lineno)
+    assert_equal(exp_loc, loc)
   end
 
   def test_splat_without_respond_to