Fix mismatch between unsafeDupablePerformIO and note

ghc/libraries/base/GHC/IO/Unsafe.hs contains the following note:

-- Note [unsafeDupablePerformIO is NOINLINE]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- Why do we NOINLINE unsafeDupablePerformIO?  See the comment with
-- GHC.ST.runST.  Essentially the issue is that the IO computation
-- inside unsafePerformIO must be atomic: it must either all run, or
-- not at all.  If we let the compiler see the application of the IO
-- to realWorld#, it might float out part of the IO.

However, unsafeDupablePerformIO does not actually have a NOINLINE pragma. So either the note is out of date and should be removed/modified, or someone messed up the code.

Trac metadata

Trac field	Value
Version	8.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Core Libraries
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	ekmett
Operating system
Architecture

changed milestone to %8.2.1

changed weight to 5

added Tbug Trac import core libraries labels

Oops, I deleted the reference to the note in https://phabricator.haskell.org/D1103, but failed to remove the note itself. Same story with the note [unsafeDupablePerformIO has a lazy RHS].

The lack of NOINLINE is okay because runRW# is NOINLINE. I'm not sure what the story about strictness was though.

mentioned in commit 18312086

closed

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed

added Pnormal label