Add specs for the it variable in blocks

Author: herwinw

language/block_spec.rb

@@ -1049,6 +1049,12 @@ def all_kwrest(arg1, arg2, *rest, post1, post2, kw1: 1, kw2: 2, okw1:, okw2:, **
  }.should complain(/warning: `it` calls without arguments will refer to the first block param in Ruby 3.4; use it\(\) or self.it/)
  end
 
+ it "emits a deprecation warning if numbered parameters are used" do
+ -> {
+ eval "proc { it; _1 }"
+ }.should complain(/warning: `it` calls without arguments will refer to the first block param in Ruby 3.4; use it\(\) or self.it/)
+ end
+
  it "does not emit a deprecation warning when a block has parameters" do
  -> { eval "proc { |a, b| it }" }.should_not complain
  -> { eval "proc { |*rest| it }" }.should_not complain
@@ -1058,21 +1064,75 @@ def all_kwrest(arg1, arg2, *rest, post1, post2, kw1: 1, kw2: 2, okw1:, okw2:, **
  -> { eval "proc { |**| it }" }.should_not complain
  -> { eval "proc { |&block| it }" }.should_not complain
  -> { eval "proc { |&| it }" }.should_not complain
+ -> { eval "proc { || it }" }.should_not complain
  end
 
  it "does not emit a deprecation warning when `it` calls with arguments" do
  -> { eval "proc { it(42) }" }.should_not complain
+ -> { eval "proc { it 42 }" }.should_not complain
+ end
+
+ it "does not emit a deprecation warning when `it` calls with a block" do
+ -> { eval "proc { it {} }" }.should_not complain
+ end
+
+ it "does not emit a deprecation warning when a local variable inside the block named `it` exists" do
+ -> { eval "proc { it = 42; it }" }.should_not complain
  end
 
  it "does not emit a deprecation warning when `it` calls with explicit empty arguments list" do
  -> { eval "proc { it() }" }.should_not complain
  end
+
+ it "calls the method `it` if defined" do
+ o = Object.new
+ def o.it
+ 21
+ end
+ suppress_warning do
+ o.instance_eval("proc { it * 2 }").call(1).should == 42
+ end
+ end
+ end
+
+ ruby_version_is "3.4" do
+ it "does not emit a deprecation warning" do
+ -> {
+ eval "proc { it }"
+ }.should_not complain
+ end
+
+ it "acts as the first argument if no local variables exist" do
+ eval("proc { it * 2 }").call(5).should == 10
+ end
+
+ it "can be reassigned to act as a local variable" do
+ eval("proc { tmp = it; it = tmp * 2; it }").call(21).should == 42
+ end
+
+ it "can be used in nested calls" do
+ eval("proc { it.map { it * 2 } }").call([1, 2, 3]).should == [2, 4, 6]
+ end
+
+ it "cannot be mixed with numbered parameters" do
+ -> {
+ eval "proc { it + _1 }"
+ }.should raise_error(SyntaxError, /numbered parameters are not allowed when 'it' is already used|'it' is already used in/)
+
+ -> {
+ eval "proc { _1 + it }"
+ }.should raise_error(SyntaxError, /numbered parameter is already used in|`it` is not allowed when a numbered parameter is already used/)
+ end
  end
 end
 
-describe "if `it` is defined outside of a block" do
- it "treats `it` as a captured variable" do
+describe "if `it` is defined as a variable" do
+ it "treats `it` as a captured variable if defined outside of a block" do
  it = 5
  proc { it }.call(0).should == 5
  end
+
+ it "treats `it` as a local variable if defined inside of a block" do
+ proc { it = 5; it }.call(0).should == 5
+ end
 end