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<h3 style="margin-top: 20px; margin-bottom: 10px;">
Simon Peyton Jones pushed to branch wip/T24984 at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
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Commits:
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<strong style="font-weight: 600;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/d26482892e435f6f30ffc5616b39d09800151065">d2648289</a></strong>
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<span> by romes </span> <i> at 2024-07-30T01:38:12-04:00 </i>
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<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>TTG HsCmdArrForm: use Fixity via extension point

Also migrate Fixity from GHC.Hs to Language.Haskell.Syntax
since it no longer uses any GHC-specific data types.

Fixed arrow desugaring bug. (This was dead code before.)
Remove mkOpFormRn, it is also dead code, only used in the arrow
desugaring now removed.

Co-authored-by: Fabian Kirchner <kirchner@posteo.de>
Co-authored-by: Alan Zimmerman <alan.zimm@gmail.com>
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<strong style="font-weight: 600;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/e258ad546d96fcfffd525f9b51d237cee467ad73">e258ad54</a></strong>
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<span> by Matthew Pickering </span> <i> at 2024-07-30T01:38:48-04:00 </i>
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<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>ghcup-metadata: More metadata fixes

* Incorrect version range on the alpine bindists
* Missing underscore in "unknown_versioning"

Fixes #25119
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<strong style="font-weight: 600;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/48e9025fa252f8eb6b5fcfb321c667eeaf2bbf3c">48e9025f</a></strong>
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<span> by Simon Peyton Jones </span> <i> at 2024-07-30T11:24:27+01:00 </i>
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<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 14px; color: #333238; position: relative; font-family: var(--default-mono-font, "GitLab Mono"),"JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>Make kick-out more selective

This MR revised the crucial kick-out criteria in the constraint solver.

Ticket #24984 showed an example in which
 * We were kicking out unnecessarily
 * That gave rise to extra work, of course
 * But it /also/ led to exponentially-sized coercions due to lack
   of sharing in coercions (something we want to fix separately #20264)

This MR sharpens up the kick-out criteria; specifially in (KK2) we look
only under type family applications if (fs>=fw).

This forced me to understand the existing kick-out story, and I ended
up rewriting many of the careful Notes in GHC.Tc.Solver.InertSet.
Especially look at the new `Note [The KickOut Criteria]`

The proof of termination is not air-tight, but it is better than before,
and both Richard and I think it's correct :-).
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