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Diffstat (limited to 'compiler/GHC/Core.hs')
| -rw-r--r-- | compiler/GHC/Core.hs | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/compiler/GHC/Core.hs b/compiler/GHC/Core.hs index c5d0a86d14..7b3f4cfd05 100644 --- a/compiler/GHC/Core.hs +++ b/compiler/GHC/Core.hs @@ -1246,6 +1246,17 @@ setRuleIdName nm ru = ru { ru_fn = nm } ************************************************************************ The @Unfolding@ type is declared here to avoid numerous loops + +Note [Never put `OtherCon` unfoldings on lambda binders] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Based on #21496 we never attach unfoldings of any kind to lambda binders. +It's just too easy for the call site to change and invalidate the unfolding. +E.g. the caller of the lambda drops a seq (e.g. because the lambda is strict in it's binder) +which in turn makes the OtherCon[] unfolding a lie. +So unfoldings on lambda binders can never really be trusted when on lambda binders if there +is the chance of the call site to change. So it's easiest to just never attach any +to lambda binders to begin with, as well as stripping them off if we e.g. float out +and expression while abstracting over some arguments. -} -- | Records the /unfolding/ of an identifier, which is approximately the form the |