Unexpected FS3571 shorthand lambda atomic error

[cmeeren]

let call (f: string -> int) x = f x

let x = call _.Length ""

Expected behavior

Compiles.

Actual behavior

0>Program.fs(10,1): Error FS0010 : Incomplete structured construct at or before this point in expression
0>Program.fs(10,14): Error FS3571 : _. shorthand syntax for lambda functions can only be used with atomic expressions. That means expressions with no whitespace unless enclosed in parentheses.

Known workarounds

Enclose shorthand lambda in parentheses:

let x = call (_.Length) ""

[brianrourkeboll]

I think this was fixed by #16240. That error number no longer exists in main.

[psfinaki]

@cmeeren can you please check this case on the latest VS or FCS?

[cmeeren]

Still happens with VS 17.8.3.

[vzarytovskii]

It won't go into 17.8.*, only in 17.9. Also not sure if 17.9 preview with the fix was released. It was inserted November 21st: #16320

[psfinaki]

Doesn't reproduce in 17.9.0 Preview 2.0. Should be good.