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<h3>
Marge Bot pushed to branch wip/marge_bot_batch_merge_job
at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
</h3>
<h4>
Commits:
</h4>
<ul>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/686e06c59c3aa6b66895e8a501c7afb019b09e36">686e06c5</a></strong>
<div>
<span>by Vladislav Zavialov</span>
<i>at 2020-08-06T13:34:05-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Grammar for types and data/newtype constructors
Before this patch, we parsed types into a reversed sequence
of operators and operands. For example, (F x y + G a b * X)
would be parsed as [X, *, b, a, G, +, y, x, F],
using a simple grammar:
tyapps
: tyapp
| tyapps tyapp
tyapp
: atype
| PREFIX_AT atype
| tyop
| unpackedness
Then we used a hand-written state machine to assemble this
either into a type, using 'mergeOps',
or into a constructor, using 'mergeDataCon'.
This is due to a syntactic ambiguity:
data T1 a = MkT1 a
data T2 a = Ord a => MkT2 a
In T1, what follows after the = sign is a data/newtype constructor
declaration. However, in T2, what follows is a type (of kind
Constraint). We don't know which of the two we are parsing until we
encounter =>, and we cannot check for => without unlimited lookahead.
This poses a few issues when it comes to e.g. infix operators:
data I1 = Int :+ Bool :+ Char -- bad
data I2 = Int :+ Bool :+ Char => MkI2 -- fine
By this issue alone we are forced into parsing into an intermediate
representation and doing a separate validation pass.
However, should that intermediate representation be as low-level as a
flat sequence of operators and operands?
Before GHC Proposal #229, the answer was Yes, due to some particularly
nasty corner cases:
data T = ! A :+ ! B -- used to be fine, hard to parse
data T = ! A :+ ! B => MkT -- bad
However, now the answer is No, as this corner case is gone:
data T = ! A :+ ! B -- bad
data T = ! A :+ ! B => MkT -- bad
This means we can write a proper grammar for types, overloading it in
the DisambECP style, see Note [Ambiguous syntactic categories].
With this patch, we introduce a new class, DisambTD. Just like
DisambECP is used to disambiguate between expressions, commands, and patterns,
DisambTD is used to disambiguate between types and data/newtype constructors.
This way, we get a proper, declarative grammar for constructors and
types:
infixtype
: ftype
| ftype tyop infixtype
| unpackedness infixtype
ftype
: atype
| tyop
| ftype tyarg
| ftype PREFIX_AT tyarg
tyarg
: atype
| unpackedness atype
And having a grammar for types means we are a step closer to using a
single grammar for types and expressions.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/6770e199645b0753d2edfddc68c199861a1be980">6770e199</a></strong>
<div>
<span>by Vladislav Zavialov</span>
<i>at 2020-08-06T13:34:05-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Clean up the story around runPV/runECP_P/runECP_PV
This patch started as a small documentation change, an attempt to make
Note [Parser-Validator] and Note [Ambiguous syntactic categories]
more clear and up-to-date.
But it turned out that runECP_P/runECP_PV are weakly motivated,
and it's easier to remove them than to find a good rationale/explanation
for their existence.
As the result, there's a bit of refactoring in addition to
a documentation update.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/826d07db0e0f31fe2b2d2e0661be7f0cb3cde3c7">826d07db</a></strong>
<div>
<span>by Vladislav Zavialov</span>
<i>at 2020-08-06T13:34:06-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Fix debug_ppr_ty ForAllTy (#18522)
Before this change, GHC would
pretty-print forall k. forall a -> ()
as forall @k a. ()
which isn't even valid Haskell.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/0ddb43848b9fc24f5404915f57dc504546e68292">0ddb4384</a></strong>
<div>
<span>by Vladislav Zavialov</span>
<i>at 2020-08-06T13:34:06-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Fix visible forall in ppr_ty (#18522)
Before this patch, this type:
T :: forall k -> (k ~ k) => forall j -> k -> j -> Type
was printed incorrectly as:
T :: forall k j -> (k ~ k) => k -> j -> Type
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/d2a432258fa00e22ca386ef30d0a77ff5b277db8">d2a43225</a></strong>
<div>
<span>by Richard Eisenberg</span>
<i>at 2020-08-06T13:34:06-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Fail eagerly on a lev-poly datacon arg
Close #18534.
See commentary in the patch.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/63348155404c64334fa864454132630f9d2a4d7f">63348155</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-08-06T13:34:08-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Use a type alias for Ways
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/9570c21295a2b4a1d1e40939869124f0b9b9bf91">9570c212</a></strong>
<div>
<span>by Takenobu Tani</span>
<i>at 2020-08-06T19:46:46-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">users-guide: Rename 8.12 to 9.0
GHC 8.12.1 has been renamed to GHC 9.0.1.
See also:
https://mail.haskell.org/pipermail/ghc-devs/2020-July/019083.html
[skip ci]
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/786ca39553c0e7f9a9399dc93b48cb779164adfa">786ca395</a></strong>
<div>
<span>by Cale Gibbard</span>
<i>at 2020-08-07T02:24:39-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">A fix to an error message in monad comprehensions, and a move of dsHandleMonadicFailure
as suggested by comments on !2330.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/758cb7a23d16b82a2003af09739dfb7fe84d231a">758cb7a2</a></strong>
<div>
<span>by Cale Gibbard</span>
<i>at 2020-08-07T02:24:39-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Add some tests for fail messages in do-expressions and monad-comprehensions.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/1e242fd82077b7f059796ca12b7b5ba6b8138f83">1e242fd8</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-08-07T02:24:39-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">cmm: Clean up Notes a bit
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/c3ce0089016bc2d53cded02c1a1d8fb03400bd8b">c3ce0089</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-08-07T02:24:39-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">CmmLint: Check foreign call argument register invariant
As mentioned in Note [Register parameter passing] the arguments of
foreign calls cannot refer to caller-saved registers.
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/8e48ae7b259f0fe3499528bcc3c13ee8b03c18e1">8e48ae7b</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-08-07T02:24:39-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">nativeGen: One approach to fix #18527
Previously the code generator could produce corrupt C call sequences due
to register overlap between MachOp lowerings and the platform's calling
convention. We fix this using a hack described in Note [Evaluate C-call
arguments before placing in destination registers].
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/2891a91de559d9dc81a1746ee0355b8b2aef9dfa">2891a91d</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-08-07T02:24:39-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">testsuite: Add test for #18527
</pre>
</li>
<li>
<strong><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/2edc326efadb1d9cb9e412ecbee47cc9bf3d9b31">2edc326e</a></strong>
<div>
<span>by Ben Gamari</span>
<i>at 2020-08-07T02:24:39-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">testsuite: Fix prog001
Previously it failed as the `ghc` package was not visible.
</pre>
</li>
</ul>
<h4>30 changed files:</h4>
<ul>
<li class="file-stats">
<a href="#cf82b82d6e47b3c81686a3340668a31ce028e2a1">
compiler/GHC/Cmm/Lint.hs
</a>
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<li class="file-stats">
<a href="#c898e00d01234ab22d3b485be68db3645f52f220">
compiler/GHC/Cmm/MachOp.hs
</a>
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<li class="file-stats">
<a href="#90378e83c3a00a78bc0b3c01da111e0a787de451">
compiler/GHC/Cmm/Node.hs
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<a href="#b1390f6749e1a2dddcae35f88d55623ea6269f56">
compiler/GHC/Cmm/Sink.hs
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<li class="file-stats">
<a href="#2bae5947e9412f6deebf4db7dcb89d780913130f">
compiler/GHC/CmmToAsm/X86/CodeGen.hs
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<li class="file-stats">
<a href="#379343fa560df0c7451aa5a1dd4f074dd37924d0">
compiler/GHC/Core/TyCo/Ppr.hs
</a>
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<li class="file-stats">
<a href="#774d88050336ef660c7a219fb06c480c2fc639bc">
compiler/GHC/Driver/Session.hs
</a>
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<a href="#6bdd5abc649727f2a802bc96ce5c276de19d3726">
compiler/GHC/HsToCore/Expr.hs
</a>
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<li class="file-stats">
<a href="#0f81db91b67c3e47ac75aa942ac3aa080f676036">
compiler/GHC/HsToCore/Expr.hs-boot
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<a href="#912bb8ed70a132c8eb2e037f8c9ecb045d2c229c">
compiler/GHC/HsToCore/ListComp.hs
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<a href="#94864be2e2eb1959a038d5d903a6c784e5cfb32a">
compiler/GHC/HsToCore/Utils.hs
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<a href="#f2b2b84d138b362920ab9f144f58bf16254aab64">
compiler/GHC/Iface/Type.hs
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<a href="#bf951467d4a9aa443cb109cb4c84a2891945649b">
compiler/GHC/Parser.y
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<a href="#446cb12ca6cefaf1c6eb79b7db643632744263c7">
compiler/GHC/Parser/PostProcess.hs
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<a href="#c27cdc950c486cfe9eb3b7c0373e9dfbe084c6c4">
compiler/GHC/Platform/Profile.hs
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<a href="#86ace7226fc7af9ab86c9de74cea778459a0f84f">
compiler/GHC/Platform/Ways.hs
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<a href="#e18aab7fcc134a71d91f9d26e33b5110a3917e44">
compiler/GHC/StgToCmm/Foreign.hs
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<li class="file-stats">
<a href="#13bc6c694b9a1fa78aeab1e992926d759374ecb2">
compiler/GHC/StgToCmm/Utils.hs
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<a href="#83d23a46bb6cdc8b1edc16f1fd2c8f5c53e2c9ca">
compiler/GHC/Tc/TyCl.hs
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<a href="#fb39dbd5a18747427e8ae2c57dcdde3473e65a53">
compiler/GHC/Unit/State.hs
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<li class="file-stats">
<a href="#85c07986c623f3180b40021d7109edd1e6a71a93">
docs/users_guide/8.12.1-notes.rst
→
docs/users_guide/9.0.1-notes.rst
</a>
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<li class="file-stats">
<a href="#67a7e440f848e5233e24f587c2e02fde258d232a">
docs/users_guide/exts/lambda_case.rst
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<a href="#f86c1b4986fc1a29572fa45c0cb2eb181d605273">
docs/users_guide/exts/lexical_negation.rst
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<a href="#228f7530ac2289de7848ad95774f7aa4673c4431">
docs/users_guide/exts/linear_types.rst
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<a href="#afc5c9567f619749d27f89c5904b2eb41814069c">
docs/users_guide/exts/negative_literals.rst
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<a href="#1c247d41be445a4c69a7b78b184d59d807c6183e">
docs/users_guide/exts/qualified_do.rst
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<a href="#96a304b83d0bf4600831c1a4fbfe7fd74edeee69">
docs/users_guide/release-notes.rst
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<a href="#e16ae6db99f98868d3603a0c7df0bb6a793a330d">
docs/users_guide/using-warnings.rst
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<a href="#4434985a7a188ba62b31af1c0a14b5ddedb221e6">
includes/stg/MachRegs.h
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<a href="#090bc0f4cd0ee7544ed8f4cc022124c133b89a1a">
<span class="new-file">
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testsuite/tests/codeGen/should_run/T18527.hs
</span>
</a>
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