Parser: Fix restrict grammar for name and supertype in type def (#12622)

spec/compiler/parser/parser_spec.cr

@@ -253,6 +253,17 @@ module Crystal
       assert_syntax_error "foo { |(#{kw})| }", "cannot use '#{kw}' as a block parameter name", 1, 9
     end
 
+    describe "literals in class definitions" do
+      # #11209
+      %w("a" 'a' [1] {1} {|a|a} ->{} ->(x : Bar){} :Bar :bar %x() %w() %()).each do |invalid|
+        assert_syntax_error "class Foo#{invalid}; end"
+        assert_syntax_error "class Foo#{invalid} < Baz; end"
+        assert_syntax_error "class Foo#{invalid} < self; end"
+        assert_syntax_error "class Foo < Baz#{invalid}; end"
+        assert_syntax_error "class Foo < self#{invalid}; end"
+      end
+    end
+
     it_parses "def self.foo\n1\nend", Def.new("foo", body: 1.int32, receiver: "self".var)
     it_parses "def self.foo()\n1\nend", Def.new("foo", body: 1.int32, receiver: "self".var)
     it_parses "def self.foo=\n1\nend", Def.new("foo=", body: 1.int32, receiver: "self".var)

src/compiler/crystal/syntax/parser.cr

@@ -1637,6 +1637,10 @@ module Crystal
       name = parse_path
       skip_space
 
+      unexpected_token unless @token.type.op_lt? ||     # Inheritance
+                              @token.type.op_lparen? || # Generic Arguments
+                              is_statement_end?
+
       type_vars, splat_index = parse_type_vars
 
       superclass = nil
@@ -1649,6 +1653,8 @@ module Crystal
         else
           superclass = parse_generic
         end
+
+        unexpected_token unless @token.type.space? || is_statement_end?
       end
       skip_statement_end
 
@@ -1668,6 +1674,10 @@ module Crystal
       class_def
     end
 
+    def is_statement_end?
+      @token.type.newline? || @token.type.op_semicolon? || @token.keyword?(:end)
+    end
+
     def parse_type_vars
       type_vars = nil
       splat_index = nil