Long format string causes bogus error in editor FS0001

[asik]

If you remove one character from the string, the bogus error message disappears.

let a username password = 
    sprintf """aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa%s%s""" username password

Error FS0001 This expression was expected to have type
''a -> 'b -> 'c'
but here has type
'string'

Expected behavior:

should not have this error in the editor.

Visual Studio 15.7.2
Visual F# Tools 10.1 for F# 4.1 - 15.7.0.0.

Possibly related (?) Seems to be a different limit. Coloring re-appears only after several more characters are deleted from the string.
#4268

[cartermp]

Looks like this is the same cause as #4268; i.e., compiler ranges are too small to support this. Closing as a duplicate, and this further motivates the PR #4476 which makes them considerably longer.