Weverything ignores some OPTIONS_GHC flags

When I enable -Weverything, some OPTIONS_GHC pragmas are respected, while others are ignored. For example, with -Weverything, this file

main = print "hello"

foo :: (Num a, Show a) => a -> IO ()
foo = print . show

generates warnings about:

1. missing an export list
2. top-level binding [main] with no type sig
3. redundant constraint [Num a]

If I add {-# OPTIONS_GHC -fno-warn-missing-signatures -fno-warn-missing-export-lists -fno-warn-redundant-constraints #-} to the top of the file and recompile, I expect all warnings to go away. But GHC still reports that main has no signature.

Note that this problem doesn't occur with -Wall. With -Wall, the code snippet warns about the missing signature on main, but when I add the OPTIONS_GHC, the warning goes away. Thus this problem appears to be unique to Weverything.

changed weight to 5

added Tbug Trac import labels

changed title from OPTIONS_GHC Ignored to Weverything ignores some OPTIONS_GHC flags

Similarly, adding {-# OPTIONS_GHC -w #-} (turn off all warnings) still results in warnings about missing top-level bindings, but hides other errors.

changed the description

closed

Upon further review, I do not think there is a bug here. The problem appears to be that when using -Wall, a -Wmissing-signature warning is issued, thus adding the pragma makes the warning go away. But with the same pragma and -Weverything, a -Wmissing-exported-signature is issued, which the pragma doesn't affect. I just missed that the warning changed.

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedInvalid

added error messages label

added Pnormal label