The previous fix where the Grammar comment style was changed to remove the newlines was incorrect, because if you have foo=1#comment bar=2 after the Grammar comment ignoring, it would transform into foo=1bar=2 which will clearly fail to parse, so the new line has to stay. But we would still have the following case which would fail: foo=a \ # comment b Apparently qmake things that's the equivalent of foo=a b but the grammar parses it as foo=a \ \n (newline) b Thus the parsing fails because there's a newline and then some weird 'b' token which the grammar does not expect. The best fix I found is to preprocess the source, to remove completely commented out lines. So: foo=a \ # comment b gets transformed into foo=a \ b Change-Id: I2487a0dbf94a6ad4d917d0a0ce05247341e9b7da Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>