[Git][ghc/ghc][wip/backports-9.8] users-guide: Amend discussion of incoherent specialisation

[Ben Gamari (@bgamari)]

Ben Gamari pushed to branch wip/backports-9.8 at Glasgow Haskell Compiler / GHC


Commits:
f7b3fcb3 by Ben Gamari at 2023-09-27T14:25:14-04:00
users-guide: Amend discussion of incoherent specialisation

Closing #23988.

- - - - -


1 changed file:

- docs/users_guide/9.8.1-notes.rst


Changes:

=====================================
docs/users_guide/9.8.1-notes.rst
=====================================
@@ -100,9 +100,12 @@ Compiler
   This is convenient for TH code generation, as you can now uniformly use record wildcards
   regardless of number of fields.
 
-- Incoherent instance applications are no longer specialised. The previous implementation of
-  specialisation resulted in nondeterministic instance resolution in certain cases, breaking
-  the specification described in the documentation of the :pragma:`INCOHERENT` pragma. See :ghc-ticket:`22448` for further details.
+- Specialisation of incoherent instance applications can now be disabled with
+  :ghc-flag:`-fno-specialise-incoherents`. This is necessary as the current
+  specialisation implementation can result in in nondeterministic instance
+  resolution in certain cases, breaking the specification described in the
+  documentation of the :pragma:`INCOHERENT` pragma. See :ghc-ticket:`22448` for
+  further details.
 
 - Fix a bug in TemplateHaskell evaluation causing excessive calls to ``setNumCapabilities`` when :ghc-flag:`-j[⟨n⟩]` is greater than :rts-flag:`-N`.
   See :ghc-ticket:`23049`.



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/f7b3fcb3da218d00bd0afe468edc43b4951f5c3f

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/f7b3fcb3da218d00bd0afe468edc43b4951f5c3f
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