Fix calls with do-end blocks within index operators (#12824)

spec/compiler/parser/parser_spec.cr

@@ -681,6 +681,15 @@ module Crystal
     it_parses "[] of {String, ->}", ArrayLiteral.new([] of ASTNode, Generic.new(Path.global("Tuple"), ["String".path, ProcNotation.new] of ASTNode))
     it_parses "x([] of Foo, Bar.new)", Call.new(nil, "x", ArrayLiteral.new([] of ASTNode, "Foo".path), Call.new("Bar".path, "new"))
 
+    context "calls with blocks within index operator (#12818)" do
+      it_parses "foo[bar { 1 }]", Call.new("foo".call, "[]", Call.new(nil, "bar", block: Block.new(body: 1.int32)))
+      it_parses "foo.[bar { 1 }]", Call.new("foo".call, "[]", Call.new(nil, "bar", block: Block.new(body: 1.int32)))
+      it_parses "foo.[](bar { 1 })", Call.new("foo".call, "[]", Call.new(nil, "bar", block: Block.new(body: 1.int32)))
+      it_parses "foo[bar do; 1; end]", Call.new("foo".call, "[]", Call.new(nil, "bar", block: Block.new(body: 1.int32)))
+      it_parses "foo.[bar do; 1; end]", Call.new("foo".call, "[]", Call.new(nil, "bar", block: Block.new(body: 1.int32)))
+      it_parses "foo.[](bar do; 1; end)", Call.new("foo".call, "[]", Call.new(nil, "bar", block: Block.new(body: 1.int32)))
+    end
+
     it_parses "Foo(x: U)", Generic.new("Foo".path, [] of ASTNode, named_args: [NamedArgument.new("x", "U".path)])
     it_parses "Foo(x: U, y: V)", Generic.new("Foo".path, [] of ASTNode, named_args: [NamedArgument.new("x", "U".path), NamedArgument.new("y", "V".path)])
     it_parses "Foo(X: U, Y: V)", Generic.new("Foo".path, [] of ASTNode, named_args: [NamedArgument.new("X", "U".path), NamedArgument.new("Y", "V".path)])

src/compiler/crystal/syntax/parser.cr

@@ -804,14 +804,17 @@ module Crystal
 
           name_location = @token.location
           next_token_skip_space_or_newline
+
           call_args = preserve_stop_on_do do
             parse_call_args_space_consumed(
               check_plus_and_minus: false,
               allow_curly: true,
               end_token: :OP_RSQUARE,
               allow_beginless_range: true,
+              control: true,
             )
           end
+
           skip_space_or_newline
           check :OP_RSQUARE
           end_location = token_end_location