Syntax errors involving compound literals

[sb...@google.com]

Hello group,

Why are the following snippets errors?

https://play.golang.org/p/mgEYMNNw9h

type S struct {
 i int
}

 if S{i: 0} == S{} {
 }

syntax error: unexpected == at end of statement

 switch S{i: 0} == S{} {
 }

syntax error: unexpected i, expecting case or default or }

It works without error if you surround each literal with ( ), or the entire comparison expression with ( ).

The following also works without error:

 _ = S{i: 0} == S{}

Does the language spec state those are errors, or is this a bug in the parser?

Thanks!

[Ian Lance Taylor]

Search for "parsing ambiguity" in
https://golang.org/ref/spec#Composite_literals .

Ian

[sb...@google.com]

Why hadn't I found that? Thanks for the pointer!

I guess this has to do with the fact that the parser doesn't care whether S is a type name or not.