The dot-shorthands feature is not working in some operator expressions.

[mmcdon20]

It fails when using the shorthand in the left-hand side of a binary operator:

int a = 1 + .parse('1'); // works
int b = .parse('1') + 1; // Error: No type was provided to find the dot shorthand 'parse'.

It fails when using some unary operators:

bool a = !.parse('true'); // works
int b = -.parse('1'); // Error: No type was provided to find the dot shorthand 'parse'.
int c = ~.parse('1'); // Error: No type was provided to find the dot shorthand 'parse'.

[FMorschel]

FYI @kallentu

[mraleph]

I think it is working as intended. In an expression like a + 1, -a and ~a a can be anything, so you don't have any information to resolve .parse. In the expressions like !a and 1 + a a is actually constrained.

[mmcdon20]

@mraleph the type of the variable is used as lookup context when doing a dot-shorthand.

The following works for example:

int a = .parse('-1').abs();

But it obviously would not work for:

var a = .parse('-1').abs();

[mraleph]

The spec mentions these cases specifically. Search NOT ALLOWED, ALL .id ARE ERRORS! in the specification.

https://github.com/dart-lang/language/blob/main/working/3616%20-%20enum%20value%20shorthand/proposal-simple-lrhn.md

[mmcdon20]

Alright it does mention this case as an error.

I guess the question then is how come operators can't get a context type for the left hand side?

[RohitSaily]

Had to think about this for a while because it seemed nonintuitive, but the decision seems to make sense. Consider we do something odd

class MyInt
{	final int mine;
	MyInt(this.mine);
	int operator +(int i)
	{	return mine+i;
	}
	// ...
}

Suppose MyInt also has parse. Then we can't be sure what is being referenced in the dot-shorthand in int b = .parse('1') + 1;. It could be that of int or MyInt