[Git][ghc/ghc][wip/T21909] 7 commits: Take more care with unlifted bindings in the specialiser

Wed Mar 1 18:03:15 UTC 2023

Apoorv Ingle pushed to branch wip/T21909 at Glasgow Haskell Compiler / GHC

Commits:
7192ef91 by Simon Peyton Jones at 2023-02-28T18:54:59-05:00
Take more care with unlifted bindings in the specialiser

As #22998 showed, we were floating an unlifted binding to top
level, which breaks a Core invariant.

The fix is easy, albeit a little bit conservative.  See
Note [Care with unlifted bindings] in GHC.Core.Opt.Specialise

- - - - -
bb500e2a by Simon Peyton Jones at 2023-02-28T18:55:35-05:00
Account for TYPE vs CONSTRAINT in mkSelCo

As #23018 showed, in mkRuntimeRepCo we need to account for coercions
between TYPE and COERCION.

See Note [mkRuntimeRepCo] in GHC.Core.Coercion.

- - - - -
79ffa170 by Ben Gamari at 2023-03-01T04:17:20-05:00
hadrian: Add dependency from lib/settings to mk/config.mk

In 81975ef375de07a0ea5a69596b2077d7f5959182 we attempted to fix #20253
by adding logic to the bindist Makefile to regenerate the `settings`
file from information gleaned by the bindist `configure` script.
However, this fix had no effect as `lib/settings` is shipped in the
binary distribution (to allow in-place use of the binary distribution).
As `lib/settings` already existed and its rule declared no dependencies,
`make` would fail to use the added rule to regenerate it.

Fix this by explicitly declaring a dependency from `lib/settings` on
`mk/config.mk`.

Fixes #22982.

- - - - -
a2a1a1c0 by Sebastian Graf at 2023-03-01T04:17:56-05:00
Revert the main payload of "Make `drop` and `dropWhile` fuse (#18964)"

This reverts the bits affecting fusion of `drop` and `dropWhile` of commit
0f7588b5df1fc7a58d8202761bf1501447e48914 and keeps just the small refactoring
unifying `flipSeqTake` and `flipSeqScanl'` into `flipSeq`.

It also adds a new test for #23021 (which was the reason for reverting) as
well as adds a clarifying comment to T18964.

Fixes #23021, unfixes #18964.

Metric Increase:
    T18964
Metric Decrease:
    T18964

- - - - -
cf118e2f by Simon Peyton Jones at 2023-03-01T04:18:33-05:00
Refine the test for naughty record selectors

The test for naughtiness in record selectors is surprisingly subtle.
See the revised Note [Naughty record selectors] in GHC.Tc.TyCl.Utils.

Fixes #23038.

- - - - -
86f240ca by romes at 2023-03-01T04:19:10-05:00
fix: Consider strictness annotation in rep_bind

Fixes #23036

- - - - -
f89fefc5 by Apoorv Ingle at 2023-03-01T12:03:01-06:00
Constraint simplification loop now depends on `ExpansionFuel`
instead of a boolean flag for `CDictCan.cc_pend_sc`.
Pending givens get a fuel of 3 while Wanted and quantified constraints get a fuel of 1.
This helps pending given constraints to keep up with pending wanted constraints in case of
`UndecidableSuperClasses` and superclass expansions while simplifying the infered type.

Adds 3 dynamic flags for controlling the fuels for each type of constraints
`-fgivens-expansion-fuel` for givens `-fwanteds-expansion-fuel` for wanteds and `-fqcs-expansion-fuel` for quantified constraints

Fixes #21909
Added Tests T21909, T21909b
Added Note [SimplifyInfer and UndecidableSuperClasses]

- - - - -

30 changed files:

- compiler/GHC/Core.hs
- compiler/GHC/Core/Coercion.hs
- compiler/GHC/Core/Coercion/Opt.hs
- compiler/GHC/Core/Opt/Specialise.hs
- compiler/GHC/Core/Type.hs
- compiler/GHC/Driver/Session.hs
- compiler/GHC/HsToCore/Quote.hs
- compiler/GHC/Settings/Constants.hs
- compiler/GHC/Tc/Solver.hs
- compiler/GHC/Tc/Solver/Canonical.hs
- compiler/GHC/Tc/Solver/Monad.hs
- compiler/GHC/Tc/TyCl/Utils.hs
- compiler/GHC/Tc/Types/Constraint.hs
- docs/users_guide/expected-undocumented-flags.txt
- hadrian/bindist/Makefile
- libraries/base/GHC/List.hs
- + testsuite/tests/patsyn/should_compile/T23038.hs
- + testsuite/tests/patsyn/should_compile/T23038.stderr
- testsuite/tests/patsyn/should_compile/all.T
- testsuite/tests/perf/should_run/T18964.hs
- + testsuite/tests/perf/should_run/T23021.hs
- + testsuite/tests/perf/should_run/T23021.stdout
- testsuite/tests/perf/should_run/all.T
- + testsuite/tests/simplCore/should_run/T22998.hs
- + testsuite/tests/simplCore/should_run/T22998.stdout
- testsuite/tests/simplCore/should_run/all.T
- + testsuite/tests/th/T23036.hs
- + testsuite/tests/th/T23036.stderr
- testsuite/tests/th/all.T
- + testsuite/tests/typecheck/should_compile/T21909.hs

The diff was not included because it is too large.

View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/42dac9ef24ff1f7486ddae3c6429b2ca7c2802ae...f89fefc53ff33f9d478889552bbdbc2bd6fb5b3a

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/42dac9ef24ff1f7486ddae3c6429b2ca7c2802ae...f89fefc53ff33f9d478889552bbdbc2bd6fb5b3a
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