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| author | Ben Gamari <ben@smart-cactus.org> | 2022-02-22 21:29:18 -0500 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2022-02-23 13:40:34 -0500 |
| commit | 8bbdba450980c2b0054e19ae737eeaa3cfdb452d (patch) | |
| tree | f8f8b2a58b0b0bd8c9055f164ce0f25e0ff41810 | |
| parent | dd0ac6e5fdc8e4d2cdc52267bfa829ff27ec4bd7 (diff) | |
| download | haskell-8bbdba450980c2b0054e19ae737eeaa3cfdb452d.tar.gz | |
simplCore: Correctly extend in-scope set in rule matching
Note [Matching lets] in GHC.Core.Rules claims the following:
> We use GHC.Core.Subst.substBind to freshen the binding, using an
> in-scope set that is the original in-scope variables plus the
> rs_bndrs (currently floated let-bindings).
However, previously the implementation didn't actually do extend the
in-scope set with rs_bndrs. This appears to be a regression which was
introduced by 4ff4d434e9a90623afce00b43e2a5a1ccbdb4c05. Reintroduce
`rs_bndrs` into the in-scope set, ensuring that let-binders cannot
shadow one another due to rule rewrites.
Fixes #21122.
(cherry picked from commit 0f7dc6701cfb6be59deb8601da8da000fe70263f)
| -rw-r--r-- | compiler/GHC/Core/Rules.hs | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/compiler/GHC/Core/Rules.hs b/compiler/GHC/Core/Rules.hs index ccfbbe6a78..96f9bece4c 100644 --- a/compiler/GHC/Core/Rules.hs +++ b/compiler/GHC/Core/Rules.hs @@ -955,7 +955,7 @@ match renv subst e1 (Let bind e2) mco | otherwise = Nothing where - (flt_subst', bind') = substBind (rv_fltR renv) bind + (flt_subst', bind') = substBind (rv_fltR renv `extendInScopeList` rs_bndrs subst) bind new_bndrs = bindersOf bind' ------------------------ Lambdas --------------------- |