Parse error in multiline subscription expression

[Scony]

Godot version:
master @ d11d7df

OS/device including version:
Linux

Issue description:
Godot raises parse error on the code below:

class X:
	func foo(p):
		var x = p[
			1
		]

Godot Engine v3.2.rc.custom_build.d11d7dfe3 - https://godotengine.org
 
SCRIPT ERROR: GDScript::reload: Parse Error: Error parsing expression, misplaced: '\n'
   At: res://tests/potential-godot-bugs/multiline-subscription-expression.gd:4.
ERROR: reload: Method/Function Failed, returning: ERR_PARSE_ERROR
   At: modules/gdscript/gdscript.cpp:576.

[bojidar-bg]

Adding parenthesis++ and parenthesis-- around this line should resolve the issue:

godot/modules/gdscript/gdscript_parser.cpp

Lines 1251 to 1253 in 1c6d1fc

	Node *subexpr = _parse_expression(op, p_static, p_allow_assign, p_parsing_constant);
	if (!subexpr) {

Note that the following code would continue erroring, but it should be resolved with #35415:

var x = (z
    [p])

[RandomShaper]

I don't think that should be changed. The language is just designed after Python in that regard: to require parentheses for allowing line breaks in expressions).

(See #208 (comment) for context.)

[lakshay-angrish]

@RandomShaper
Shouldn't the newline after [ be ignored by the following code?

godot/modules/gdscript/gdscript_parser.cpp

Lines 946 to 988 in a61f5a7

	} else if (tokenizer->get_token() == GDScriptTokenizer::TK_BRACKET_OPEN) {
	// array
	tokenizer->advance();
	ArrayNode *arr = alloc_node<ArrayNode>();
	bool expecting_comma = false;
	while (true) {
	if (tokenizer->get_token() == GDScriptTokenizer::TK_EOF) {
	_set_error("Unterminated array");
	return NULL;
	} else if (tokenizer->get_token() == GDScriptTokenizer::TK_BRACKET_CLOSE) {
	tokenizer->advance();
	break;
	} else if (tokenizer->get_token() == GDScriptTokenizer::TK_NEWLINE) {
	tokenizer->advance(); //ignore newline
	} else if (tokenizer->get_token() == GDScriptTokenizer::TK_COMMA) {
	if (!expecting_comma) {
	_set_error("expression or ']' expected");
	return NULL;
	}
	expecting_comma = false;
	tokenizer->advance(); //ignore newline
	} else {
	//parse expression
	if (expecting_comma) {
	_set_error("',' or ']' expected");
	return NULL;
	}
	Node *n = _parse_expression(arr, p_static, p_allow_assign, p_parsing_constant);
	if (!n)
	return NULL;
	arr->elements.push_back(n);
	expecting_comma = true;
	}
	}
	expr = arr;

[RandomShaper]

I think that's for the context when an array is declared, to allow one item per line:

var a = [
    1,
    2,
    3,
]

What is happening in the example code is indexing, which is parsed here:

godot/modules/gdscript/gdscript_parser.cpp

Line 1245 in a61f5a7

} else if (tokenizer->get_token() == GDScriptTokenizer::TK_BRACKET_OPEN) {

[bojidar-bg]

I don't think that should be changed. The language is just designed after Python in that regard: to require parentheses for allowing line breaks in expressions).

[ and ] are technically parenthesis.
I mean, the following two are identical:

p[(x + y)]
p[x + y]

So it makes sense that the following two are:

p[(
  x + y
)]

p[
  x + y
]

[RandomShaper]

I wasn't too convinced about your point since I thought the rule was intended for actual parentheses, rather than expression "enclosing".

I was wrong.

Moreover, regardless any other consideration, since Python allows it and the intent is that GDScript imitates its syntax, it should be allowed.

[vignesh-j-shetty]

This issue doesn't seem to be there in master branch.

[akien-mga]

There was a proposed fix in #35597 which couldn't be reviewed/merged before the author deleted their fork. Could likely be salvaged as it seems to be a valid fix, the same was done for preload() in #52521 as advised by @vnen.

Edit: I'll do it.

[dalexeev]

Fixed by #54227.