Not enough inlining happens with single-method type classes

In the attached file, GHC produces code (with -O2) for foo that references a top-level definition of type Small (Either () ()), despite the fact that all bindings in the module are marked INLINE.

If I use -DOTHER_METHOD to add another method to the class, this problem goes away. It looks like a ClassOp rule is helping here.

I'm not sure if this is a bug, but it was a surprising behavior for me, so I'm reporting it. Please feel free to close this ticket if it's the correct behavior.

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
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changed weight to 5

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Attached file test.hs ($1214).

test case

I've compiled your program with -O2, and both ghc 8.0 and HEAD, and cannot see a top-level definition of type Small (Either () ()).

Can you compile with -ddump-simpl, attach the result, and point to the line number that concerns you? Thanks!

Simon

closed

You are right, it looks like I used the wrong version of the compiler. With GHC 8.0 it works fine.

I'm closing the ticket now. I'm sorry for wasting your time.

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedInvalid

added runtime perf label

added Pnormal label