[Diagnostics] Improve diagnostic when using == instead of = for defau…

[vguerra]

…lt function argument.

Resolves SR-11006.

[theblixguy]

cc @rintaro

[jrose-apple]

Is it possible for the compiler to check this earlier and recover by parsing the expression normally?

[vguerra]

The check could indeed be taken before l.272 for instance, but just to be sure I understand: in this case "recover" means that the token for '==' should be consumed so that the code can continue parsing the default value and so on?

[jrose-apple]

Yeah, I was thinking you'd essentially have the compiler just pretend that the user wrote =.

[vguerra]

Got it. Will try this.

[rintaro]

I think this check and recovery should be performed later, like l.385.

[vguerra]

but somehow I need to avoid the parsing logic to get into any of this branches, so a check would be needed before.

[rintaro]

It should work as expected if you consume == as if it's = and parse the default value after ==.

[vguerra]

pushed d82dd84 so check is now performed later as @rintaro suggested and compiler is recovering :).

[vguerra]

I wonder if consumption of either '=' or '==' should be taken out of here and be performed on caller site?

[jrose-apple]

consumeToken also allows not passing a token kind at all, but I still think you might be right. It's weird to consume something when you don't know what it is.

[rintaro]

I'm OK with:

assert(Tok.is(tok::equal) ||
       (Tok.isBinaryOperator() && Tok.getText() == "=="));
consumeToken();

inside parseDefaultArgument(). Like

swift/lib/Parse/ParseDecl.cpp

Lines 6632 to 6634 in 26c4ccc

	Parser::parseDeclInit(ParseDeclOptions Flags, DeclAttributes &Attributes) {
	assert(Tok.is(tok::kw_init));
	SourceLoc ConstructorLoc = consumeToken();

[vguerra]

thanks for the feedback .. addressed in 2cfe8ad

[rintaro]

@swift-ci Please smoke test

[rintaro]

@swift-ci Please smoke test Linux platform

[rintaro]

Thank you Victor!

[vguerra]

thank you both for the guidance.