for var = expr1 to expr2 do expr3 done

[kevmal]

Seems identifiers between var and = simply get ignored. For example the following compiles/runs:

for i bleh bleh this runs fine = 1 to 20 do 
    printfn "%d" i

[cartermp]

Even more fun:

let foo x = x

for i foo 12 = 1 to 20 do 
    printfn "%d" i

Prints 1-12 in FSI on a new line, just as your repro.

Definitely feels like a bug 😄

[dsyme]

How odd. Anyway fix is at #6621

[cartermp]

Re-opening as this is not resolved in VS

[cartermp]

Confirmed as fixed in 16.2.