Confusing parse error for missing do keyword

import Control.Monad (when)

main = do
    when (True == True) $ 
        x <- getLine
        print "y"

This piece of code is missing the do keyword before the block, yet the error message that is returned is:

poc.hs:4:11: Parse error in pattern: True == True

Yet the next variant provides a bit more helpful information

import Control.Monad (when)

main = do
    when (True == True) $ 
        print "x"
        print "y"

poc.hs:5:9:
    Couldn't match expected type `(a0 -> IO ()) -> [Char] -> m0 ()'
                with actual type `IO ()'
    The function `print' is applied to three arguments,
    but its type `[Char] -> IO ()' has only one
    In the second argument of `($)', namely `print "x" print "y"'
    In a stmt of a 'do' block:
      when (True == True) $ print "x" print "y"

Trac metadata

Trac field	Value
Version	7.6.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	low
Resolution	Unresolved
Component	Compiler (Parser)
Test case
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