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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/c456bab336bdb06ddff6812e5d767808374f86bf">c456bab3</a></strong>
<div>
<span>by Takenobu Tani</span>
<i>at 2020-08-06T18:51:14+09:00</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/2aacccb96eb01d0993d2561b0cbb5d38da52a0e8">2aacccb9</a></strong>
<div>
<span>by Vladislav Zavialov</span>
<i>at 2020-08-06T19:24:23-04:00</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/183de57982e05d601274a94a6096a7068de6cd57">183de579</a></strong>
<div>
<span>by Vladislav Zavialov</span>
<i>at 2020-08-06T19:24:23-04:00</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/b54e8a5a21c9223f67bcd6fb5327d3d556950ac9">b54e8a5a</a></strong>
<div>
<span>by Vladislav Zavialov</span>
<i>at 2020-08-06T19:24:23-04:00</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/b221579f93a13ad57e335f2038652d02c85a18b3">b221579f</a></strong>
<div>
<span>by Vladislav Zavialov</span>
<i>at 2020-08-06T19:24:23-04:00</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/e855d06e7830f1e90c85777bc4169a5d332fd2e5">e855d06e</a></strong>
<div>
<span>by Richard Eisenberg</span>
<i>at 2020-08-06T19:24:24-04:00</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/1aff3f9692f4a0c7754ca00aa0ff07ba8659b1c3">1aff3f96</a></strong>
<div>
<span>by Sylvain Henry</span>
<i>at 2020-08-06T19:24:25-04:00</i>
</div>
<pre class="commit-message" style="white-space: pre-wrap; margin: 0;">Use a type alias for Ways
</pre>
</li>
</ul>
<h4>30 changed files:</h4>
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<a href="#379343fa560df0c7451aa5a1dd4f074dd37924d0">
compiler/GHC/Core/TyCo/Ppr.hs
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<a href="#774d88050336ef660c7a219fb06c480c2fc639bc">
compiler/GHC/Driver/Session.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="#83d23a46bb6cdc8b1edc16f1fd2c8f5c53e2c9ca">
compiler/GHC/Tc/TyCl.hs
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<a href="#fb39dbd5a18747427e8ae2c57dcdde3473e65a53">
compiler/GHC/Unit/State.hs
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<a href="#85c07986c623f3180b40021d7109edd1e6a71a93">
docs/users_guide/8.12.1-notes.rst
→
docs/users_guide/9.0.1-notes.rst
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<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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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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docs/users_guide/using-warnings.rst
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testsuite/tests/ghc-api/T18522-dbg-ppr.hs
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testsuite/tests/ghc-api/all.T
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testsuite/tests/parser/should_fail/T12045d.stderr
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testsuite/tests/parser/should_fail/strictnessDataCon_B.stderr
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testsuite/tests/parser/should_fail/typeops_A.stderr
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testsuite/tests/parser/should_fail/typeops_C.stderr
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testsuite/tests/parser/should_fail/unpack_empty_type.stderr
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testsuite/tests/parser/should_fail/unpack_inside_type.stderr
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testsuite/tests/polykinds/all.T
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