In module declaration treat M = { as if it were M : {

[cristianoc]

A common mistake is to write this in an interface file:

module M = { let x: int }

where the correct syntax is:

module M : { let x: int }

This PR parses the former as if it were the latter. So it compiles and will reformat to the latter.
An alternative is to give an error message with a suggestion to change the code.

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commit: 7ee821a

[cristianoc]

@mediremi thoughts?

[cknitt]

Ran into this quite a few times myself.

Just a thought, couldn't we do it the other way around?
I.e. use = in both .res and .resi, and reformat : to =?

Or is there any reason to use : here other than that's what OCaml does?

[mediremi]

This is great, thanks @cristianoc!

[cristianoc]

Ran into this quite a few times myself.

Just a thought, couldn't we do it the other way around? I.e. use = in both .res and .resi, and reformat : to =?

Or is there any reason to use : here other than that's what OCaml does?

It's by analogy to let x = 3 vs let x : int in implementation/interface files. The former takes an expression, the latter takes a type. so : ... is the pattern one expects for types.
In the case of modules, = is for module values, and : is for module types.

[cknitt]

👍 Could you add a CHANGELOG entry?