Hi, I think the function you are looking for is reportUnusedNames in GHC.Rename.Names [1], which calls findUses [2]. You may find the Note [Tracking unused binding and imports] in GHC.Tc.Types [3] helpful. Roughly, GHC's renamer traverses the syntax tree to resolve names and along the way collects sets of defined/used names in tcg_dus. There are also a set of names used by the typechecker in tcg_keep. After typechecking, findUses takes the transitive closure of the set of uses and reportUnusedNames then issues unused-top-binds warnings for all names defined in the current module that are not in the set. Hope this helps, Adam [1] https://gitlab.haskell.org/ghc/ghc/-/blob/e1fb56b24e2fe45a6f628f651bfc12b2b9... [2] https://gitlab.haskell.org/ghc/ghc/-/blob/e1fb56b24e2fe45a6f628f651bfc12b2b9... [3] https://gitlab.haskell.org/ghc/ghc/-/blob/e1fb56b24e2fe45a6f628f651bfc12b2b9... On 14/03/2023 17:13, Razetime wrote:
This message is related to a feature in the futhark compiler https://github.com/diku-dk/futhark/issues/550, which is a language with a similar module system.
I am trying to create a tool to detect unused top-level functions in Futhark, and I have been looking in the ghc codebase to find out how it does so. So far I have found these areas:
1. warning flag https://gitlab.haskell.org/ghc/ghc/-/blob/master/compiler/GHC/Driver/Flags.h... 2. WarnUnusedTopBinds https://gitlab.haskell.org/ghc/ghc/-/blob/master/compiler/GHC/Rename/Utils.h...
The project is a bit too big for my machine to take, so HLS is not helping me with finding where the computation of unused bindings (specifically functions) is done. I would like some help with finding where ghc does this computation, and maybe some help with the naming conventions of the code.
Thanks in advance.
-- Adam Gundry, Haskell Consultant Well-Typed LLP, https://www.well-typed.com/ Registered in England & Wales, OC335890 27 Old Gloucester Street, London WC1N 3AX, England