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<h3 style="margin-top: 20px; margin-bottom: 10px;">
Simon Peyton Jones pushed to branch wip/T23070-unify at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
</h3>
<h4 style="margin-top: 10px; margin-bottom: 10px;">
Commits:
</h4>
<ul>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/6e2eb275a1b6d3d1dae9c2864f001bea69d20c2a">6e2eb275</a></strong>
<div>
<span> by doyougnu </span> <i> at 2023-04-01T18:27:56-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>JS: Linker: use saturated JExpr
Follow on to MR!10142 in pursuit of #22736
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/3da693466fd3e6a609a1a77361c50ed1b141858d">3da69346</a></strong>
<div>
<span> by sheaf </span> <i> at 2023-04-01T18:28:37-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Improve haddocks of template-haskell Con datatype
This adds a bit more information, in particular about the lists of
constructors in the GadtC and RecGadtC cases.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/3b7bbb39f28c926f8cfd30744253a418854bee31">3b7bbb39</a></strong>
<div>
<span> by sheaf </span> <i> at 2023-04-01T18:28:37-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>TH: revert changes to GadtC & RecGadtC
Commit 3f374399 included a breaking-change to the template-haskell
library when it made the GadtC and RecGadtC constructors take non-empty
lists of names. As this has the potential to break many users' packages,
we decided to revert these changes for now.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/f60f6110c1d08cb1885dce1984d5051de03dce8e">f60f6110</a></strong>
<div>
<span> by Bodigrim </span> <i> at 2023-04-02T18:59:30-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Rework documentation for data Char
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/43ebd5dcdb7ff65b6afccbdee22d2c27f9df6b1c">43ebd5dc</a></strong>
<div>
<span> by Bodigrim </span> <i> at 2023-04-02T19:00:09-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>cmm: implement parsing of MO_AtomicRMW from hand-written CMM files
Fixes #23206
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/ab9cd52d4fac34a2b37ce07bc9e9e2943c92d181">ab9cd52d</a></strong>
<div>
<span> by Sylvain Henry </span> <i> at 2023-04-03T08:15:21-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>ghc-heap: remove wrong Addr# coercion (#23181)
Conversion from Addr# to I# isn't correct with the JS backend.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/2b2afff3ac8de85e7a035b71ab3890b8eed760c9">2b2afff3</a></strong>
<div>
<span> by Matthew Pickering </span> <i> at 2023-04-03T08:15:58-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>hadrian: Update bootstrap plans for 9.2.6, 9.2.7, 9.4.4, 9.4.5, 9.6.1
Also fixes the ./generate_bootstrap_plans script which was recently
broken
We can hopefully drop the 9.2 plans soon but they still work so kept
them around for now.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/c2605e25bb166245310a13386e7f77915e9c2c3f">c2605e25</a></strong>
<div>
<span> by Matthew Pickering </span> <i> at 2023-04-03T08:15:58-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>ci: Add job to test 9.6 bootstrapping
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/53e4d513a55df3c13424e7b649ce85b8113fa4c2">53e4d513</a></strong>
<div>
<span> by Krzysztof Gogolewski </span> <i> at 2023-04-03T08:16:35-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>hadrian: Improve option parsing
Several options in Hadrian had their argument marked as optional
(`OptArg`), but if the argument wasn't there they were just giving an
error. It's more idiomatic to mark the argument as required instead;
the code uses less Maybes, the parser can enforce that the argument
is present, --help gives better output.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/a8e36892689bd6b8fb472844f79aeeddeda92e0a">a8e36892</a></strong>
<div>
<span> by Sylvain Henry </span> <i> at 2023-04-03T08:17:16-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>JS: fix issues with FD api support
- Add missing implementations for fcntl_read/write/lock
- Fix fdGetMode
These were found while implementing TH in !9779. These functions must be
used somehow by the external interpreter code.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/8b092910ac18a2b5dc97a29ced9fc469c663a03b">8b092910</a></strong>
<div>
<span> by Haskell-mouse </span> <i> at 2023-04-03T19:31:26-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Convert diagnostics in GHC.Rename.HsType to proper TcRnMessage
I've turned all occurrences of TcRnUnknownMessage in GHC.Rename.HsType
module into a proper TcRnMessage.
Instead, these TcRnMessage messages were introduced:
TcRnDataKindsError
TcRnUnusedQuantifiedTypeVar
TcRnIllegalKindSignature
TcRnUnexpectedPatSigType
TcRnSectionPrecedenceError
TcRnPrecedenceParsingError
TcRnIllegalKind
TcRnNegativeNumTypeLiteral
TcRnUnexpectedKindVar
TcRnBindMultipleVariables
TcRnBindVarAlreadyInScope
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/220a7a48cabdcfd2ef7bf5dbe3fd6df99e8d3c5b">220a7a48</a></strong>
<div>
<span> by Krzysztof Gogolewski </span> <i> at 2023-04-03T19:32:02-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Fixes around unsafeCoerce#
1. `unsafeCoerce#` was documented in `GHC.Prim`. But since the overhaul
in 74ad75e87317, `unsafeCoerce#` is no longer defined there.
I've combined the documentation in `GHC.Prim` with the `Unsafe.Coerce` module.
2. The documentation of `unsafeCoerce#` stated that you should not
cast a function to an algebraic type, even if you later cast it back
before applying it. But ghci was doing that type of cast, as can be seen
with 'ghci -ddump-ds' and typing 'x = not'. I've changed it to use Any
following the documentation.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/9095e297fbb46781fd182210609ce2a3f6c59b7a">9095e297</a></strong>
<div>
<span> by Matthew Craven </span> <i> at 2023-04-04T01:04:10-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Add a few more memcpy-ish primops
* copyMutableByteArrayNonOverlapping#
* copyAddrToAddr#
* copyAddrToAddrNonOverlapping#
* setAddrRange#
The implementations of copyBytes, moveBytes, and fillBytes
in base:Foreign.Marshal.Utils now use these new primops,
which can cause us to work a bit harder generating code for them,
resulting in the metric increase in T21839c observed by CI on
some architectures. But in exchange, we get better code!
Metric Increase:
T21839c
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/f7da530c80c0117d5684bb52481e4a40d7e724cc">f7da530c</a></strong>
<div>
<span> by Matthew Craven </span> <i> at 2023-04-04T01:04:10-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>StgToCmm: Upgrade -fcheck-prim-bounds behavior
Fixes #21054. Additionally, we can now check for range overlap
when generating Cmm for primops that use memcpy internally.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/cd00e321d5d7aaee3999b283a2a2f0d77f7b3e8e">cd00e321</a></strong>
<div>
<span> by sheaf </span> <i> at 2023-04-04T01:04:50-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Relax assertion in varToRecFieldOcc
When using Template Haskell, it is possible to re-parent a field OccName
belonging to one data constructor to another data constructor. The
lsp-types package did this in order to "extend" a data constructor
with additional fields.
This ran into an assertion in 'varToRecFieldOcc'. This assertion
can simply be relaxed, as the resulting splices are perfectly sound.
Fixes #23220
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/eed0d9307b3f48b6a2e45dbb246610cf4ab73896">eed0d930</a></strong>
<div>
<span> by Sylvain Henry </span> <i> at 2023-04-04T11:09:15-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>GHCi.RemoteTypes: fix doc and avoid unsafeCoerce (#23201)
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/071139c30ab95e6a292bec8ae0dcb6bf2be6308d">071139c3</a></strong>
<div>
<span> by Ryan Scott </span> <i> at 2023-04-04T11:09:51-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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 INLINE pragmas for pattern synonyms work with TH
Previously, the code for converting `INLINE <name>` pragmas from TH splices
used `vNameN`, which assumed that `<name>` must live in the variable namespace.
Pattern synonyms, on the other hand, live in the constructor namespace. I've
fixed the issue by switching to `vcNameN` instead, which works for both the
variable and constructor namespaces.
Fixes #23203.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/7c16f3be6e1ac92f87d752f12ad6c6e7b7fd6207">7c16f3be</a></strong>
<div>
<span> by Krzysztof Gogolewski </span> <i> at 2023-04-04T17:13:00-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Fix unification with oversaturated type families
unify_ty was incorrectly saying that F x y ~ T x are surely apart,
where F x y is an oversaturated type family and T x is a tyconapp.
As a result, the simplifier dropped a live case alternative (#23134).
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/c165f079a13232a44689c55a61c70e2c9aea5464">c165f079</a></strong>
<div>
<span> by sheaf </span> <i> at 2023-04-04T17:13:40-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Add testcase for #23192
This issue around solving of constraints arising from superclass
expansion using other constraints also borned from superclass expansion
was the topic of commit aed1974e. That commit made sure we don't emit
a "redundant constraint" warning in a situation in which removing the
constraint would cause errors.
Fixes #23192
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/d1bb16ed3e18a4f41fcfe31f0bf57dbaf589d6c5">d1bb16ed</a></strong>
<div>
<span> by Ben Gamari </span> <i> at 2023-04-06T03:40:45-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>nonmoving: Disable slop-zeroing
As noted in #23170, the nonmoving GC can race with a mutator zeroing the
slop of an updated thunk (in much the same way that two mutators would
race). Consequently, we must disable slop-zeroing when the nonmoving GC
is in use.
Closes #23170
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/04b80850c535fa8c11f435711577296a99499105">04b80850</a></strong>
<div>
<span> by Brandon Chinn </span> <i> at 2023-04-06T03:41:21-04:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Fix reverse flag for -Wunsupported-llvm-version</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/90eb4d8534a04d68686db5a8fda2dff76afb405b">90eb4d85</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-04-06T10:47:36+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Major refactor in the handling of equality constraints
This MR substantially refactors the way in which the constraint
solver deals with equality constraints. The big thing is:
* Intead of a pipeline in which we /first/ canonicalise and /then/
interact (the latter including performing unification) the two steps
are more closely integreated into one. That avoids the current
rather indirect communication between the two steps.
The proximate cause for this refactoring is fixing #22194, which involve
solving [W] alpha[2] ~ Maybe (F beta[4])
by doing this:
alpha[2] := Maybe delta[2]
[W] delta[2] ~ F beta[4]
That is, we don't promote beta[4]! This is very like introducing a cycle
breaker, and was very awkward to do before, but now it is all nice.
See GHC.Tc.Utils.Unify Note [Promotion and level-checking] and
Note [Family applications in canonical constraints].
The big change is this:
* Several canonicalisation checks (occurs-check, cycle-breaking,
checking for concreteness) are combined into one new function:
GHC.Tc.Utils.Unify.checkTyEqRhs
This function is controlled by `TyEqFlags`, which says what to do
for foralls, type families etc.
* `canEqCanLHSFinish` now sees if unification is possible, and if so,
actually does it: see `canEqCanLHSFinish_try_unification`.
There are loads of smaller changes:
* The on-the-fly unifier `GHC.Tc.Utils.Unify.unifyType` has a
cheap-and-cheerful version of `checkTyEqRhs`, called
`simpleUnifyCheck`. If `simpleUnifyCheck` succeeds, it can unify,
otherwise it defers by emitting a constraint. This is simpler than
before.
* I simplified the swapping code in `GHC.Tc.Solver.Equality.canEqCanLHS`.
Especially the nasty stuff involving `swap_for_occurs` and
`canEqTyVarFunEq`. Much nicer now. See
Note [Orienting TyVarLHS/TyFamLHS]
Note [Orienting TyFamLHS/TyFamLHS]
* Added `cteSkolemOccurs`, `cteConcrete`, and `cteCoercionHole` to the
problems that can be discovered by `checkTyEqRhs`.
* I fixed #23199 `pickQuantifiablePreds`, which actually allows GHC to
to accept both cases in #22194 rather than rejecting both.
Yet smaller:
* Added a `synIsConcrete` flag to `SynonymTyCon` (alongside `synIsFamFree`)
to reduce the need for synonym expansion when checking concreteness.
Use it in `isConcreteType`.
* Renamed `isConcrete` to `isConcreteType`
* Defined `GHC.Core.TyCo.FVs.isInjectiveInType` as a more efficient
way to find if a particular type variable is used injectively than
finding all the injective variables. It is called in
`GHC.Tc.Utils.Unify.definitely_poly`, which in turn is used quite a
lot.
* Moved `rewriterView` to `GHC.Core.Type`, so we can use it from the
constraint solver.
Fixes #22194, #23199
Compile times decrease by an average of 0.1%; but there is a 7.4%
drop in compiler allocation on T15703.
Metric Decrease:
T15703
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/a96b14fd3ffb6b73fc1846232fbfb9b69a437bd7">a96b14fd</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-04-06T10:47:36+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Add some documentation about redundant constraints
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/65fd65ab7aa85eee6dfb1dda52830fbe9565e50d">65fd65ab</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-04-07T22:28:57+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Improve partial signatures
This MR fixes #23223. The changes are in two places:
* GHC.Tc.Bind.checkMonomorphismRestriction
See the new `Note [When the MR applies]`
We now no longer stupidly attempt to apply the MR when the user
specifies a context, e.g. f :: Eq a => _ -> _
* GHC.Tc.Solver.decideQuantification
See rewritten `Note [Constraints in partial type signatures]`
Fixing this bug apparently breaks three tests:
* partial-sigs/should_compile/T11192
* partial-sigs/should_fail/Defaulting1MROff
* partial-sigs/should_fail/T11122
However they are all symptoms of #23232, so I'm marking them as
expect_broken(23232).
I feel happy about this MR. Nice.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/7d6284dacc3bf215bfe55006e830583b0d163074">7d6284da</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-04-07T22:29:24+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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 approximateWC a bit cleverer
This MR fixes #23224: making approximateWC more clever
See the long `Note [ApproximateWC]` in GHC.Tc.Solver
All this is delicate and ad-hoc -- but it /has/ to be: we are
talking about inferring a type for a binding in the presence of
GADTs, type families and whatnot: known difficult territory.
We just try as hard as we can.
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/04bb9568dd2d5ee64d9eb4e6ea5dc33266ee5dee">04bb9568</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-04-07T22:34:11+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>First steps killing unifyWanted
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/7e58559666eb0ba7fc71a389cd169c334449c72e">7e585596</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-04-07T22:34:11+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Fix a boo boo
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/cc990ff83fd2614b7f56d9dc7de5760c3a391064">cc990ff8</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-04-07T22:34:11+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Fix another error: missing kick-out
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/b691a4dc2b541c85957f44ec10e03b9c42e6c535">b691a4dc</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-04-07T22:34:11+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Maybe working now
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/697a57108fd33caf0fbff1de7700e09fdae9d768">697a5710</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-04-07T22:34:11+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Wibbles
</pre>
</li>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/9db42e84401798e8eedf43a2287e9aa74ac8f209">9db42e84</a></strong>
<div>
<span> by Simon Peyton Jones </span> <i> at 2023-04-07T23:04:53+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "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;'>Stop loop
</pre>
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