[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 4 commits: Add heqT, a kind-heterogeneous variant of heq

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC


Commits:
b3e98a92 by Oleg Grenrus at 2022-12-11T12:26:17-05:00
Add heqT, a kind-heterogeneous variant of heq

CLC proposal https://github.com/haskell/core-libraries-committee/issues/99

- - - - -
bfd7c1e6 by Bodigrim at 2022-12-11T12:26:55-05:00
Document that Bifunctor instances for tuples are lawful only up to laziness

- - - - -
c1871200 by Bryan Richter at 2022-12-12T11:32:29-05:00
Mark T21336a fragile

- - - - -
26edef7b by Matthew Pickering at 2022-12-12T11:32:30-05:00
Add test for #21476

This issues seems to have been fixed since the ticket was made, so let's
add a test and move on.

Fixes #21476

- - - - -


6 changed files:

- libraries/base/Data/Bifunctor.hs
- libraries/base/Data/Typeable.hs
- libraries/base/changelog.md
- libraries/base/tests/IO/T21336/all.T
- + testsuite/tests/simplCore/should_compile/T21476.hs
- testsuite/tests/simplCore/should_compile/all.T


Changes:

=====================================
libraries/base/Data/Bifunctor.hs
=====================================
@@ -120,8 +120,17 @@ class (forall a. Functor (p a)) => Bifunctor p where
     second = bimap id
 
 
-
--- | @since 4.8.0.0
+-- | Class laws for tuples hold only up to laziness. Both
+-- 'first' 'id' and 'second' 'id' are lazier than 'id' (and 'fmap' 'id'):
+--
+-- >>> first id (undefined :: (Int, Word)) `seq` ()
+-- ()
+-- >>> second id (undefined :: (Int, Word)) `seq` ()
+-- ()
+-- >>> id (undefined :: (Int, Word)) `seq` ()
+-- *** Exception: Prelude.undefined
+--
+-- @since 4.8.0.0
 instance Bifunctor (,) where
     bimap f g ~(a, b) = (f a, g b)
 


=====================================
libraries/base/Data/Typeable.hs
=====================================
@@ -4,6 +4,7 @@
 {-# LANGUAGE PolyKinds #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE Trustworthy #-}
+{-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE TypeOperators #-}
 
 -----------------------------------------------------------------------------
@@ -56,6 +57,7 @@ module Data.Typeable
       -- * Type-safe cast
     , cast
     , eqT
+    , heqT
     , gcast                -- a generalisation of cast
 
       -- * Generalized casts for higher-order kinds
@@ -135,8 +137,14 @@ cast x
 -- @since 4.7.0.0
 eqT :: forall a b. (Typeable a, Typeable b) => Maybe (a :~: b)
 eqT
-  | Just HRefl <- ta `I.eqTypeRep` tb = Just Refl
-  | otherwise                         = Nothing
+  | Just HRefl <- heqT @a @b = Just Refl
+  | otherwise                = Nothing
+
+-- | Extract a witness of heterogeneous equality of two types
+--
+-- @since 4.18.0.0
+heqT :: forall a b. (Typeable a, Typeable b) => Maybe (a :~~: b)
+heqT = ta `I.eqTypeRep` tb
   where
     ta = I.typeRep :: I.TypeRep a
     tb = I.typeRep :: I.TypeRep b


=====================================
libraries/base/changelog.md
=====================================
@@ -57,6 +57,7 @@
     of individually allocated pointers as well as freeing each one of them when
     freeing a `Pool`. (#14762) (#18338)
   * `Type.Reflection.Unsafe` is now marked as unsafe.
+  * Add `Data.Typeable.heqT`, a kind-heterogeneous version of `Data.Typeable.eqT`.
 
 ## 4.17.0.0 *August 2022*
 


=====================================
libraries/base/tests/IO/T21336/all.T
=====================================
@@ -1,6 +1,9 @@
 # N.B. /dev/full exists on Darwin but cannot be opened, failing with -EPERM
 test('T21336a',
-     [unless(opsys('linux') or opsys('freebsd'), skip), js_broken(22261)],
+     [ unless(opsys('linux') or opsys('freebsd'), skip)
+     , js_broken(22261)
+     , fragile(22022)
+     ],
      compile_and_run, [''])
 test('T21336b',
      [unless(opsys('linux') or opsys('freebsd'), skip), js_broken(22352)],


=====================================
testsuite/tests/simplCore/should_compile/T21476.hs
=====================================
@@ -0,0 +1,4 @@
+{-# LANGUAGE MagicHash #-}
+module T21476 where
+import GHC.Exts
+f = keepAlive#


=====================================
testsuite/tests/simplCore/should_compile/all.T
=====================================
@@ -456,3 +456,4 @@ test('T22317', [grep_errmsg(r'ANSWER = YES') ], compile, ['-O -dinline-check m -
 
 test('T22494', [grep_errmsg(r'case') ], compile, ['-O -ddump-simpl -dsuppress-uniques'])
 test('T22491', normal, compile, ['-O2'])
+test('T21476', normal, compile, [''])



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/2eedf815a9c58484dc1a27be7f508551953d7594...26edef7bde915be5481b1b42a1cbd1414538e57c

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/2eedf815a9c58484dc1a27be7f508551953d7594...26edef7bde915be5481b1b42a1cbd1414538e57c
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