structs 0.1.6 → 0.1.7

raw patch · 4 files changed

+37/−6 lines, 4 files

Files

• .hlint.yaml +1/−1
• CHANGELOG.markdown +6/−0
• src/Data/Struct/Internal.hs +25/−1
• structs.cabal +5/−4

@@ -1,4 +1,4 @@-- arguments: [--cpp-define=HLINT, --cpp-ansi]+- arguments: [-XCPP, --cpp-define=HLINT, --cpp-ansi]  - ignore: {name: Reduce duplication} - ignore: {name: Redundant lambda}

@@ -1,3 +1,9 @@+## 0.1.7 [2023.01.22]+* Avoid a particularly dodgy use of `unsafeCoerce#` in the implementation of+  `isNil` when building with GHC 9.4 or later. This is necessary to make the+  `isNil` function behave properly on GHC 9.6, as changes to GHC's optimizer in+  9.6 make that use of `unsafeCoerce#` produce unexpected results at runtime.+ ## 0.1.6 [2021.04.30] * Make the test suite compile on recent GHCs. 

@@ -121,7 +121,31 @@ -- >>> isNil o -- False isNil :: Struct t => t s -> Bool-isNil t = isTrue# (unsafeCoerce# reallyUnsafePtrEquality# (destruct t) Null)+isNil t = isTrue# (+#if MIN_VERSION_base(4,17,0)+  -- In base-4.17.0.0 or later, reallyUnsafePtrEquality# is levity polymorphic+  -- and heterogeneous, so we can directly invoke it on @destruct t@ (of type+  -- @SmallMutableArray# s Any :: UnliftedType@)) and @Null@ (of type+  -- @Null :: Type@).+  reallyUnsafePtrEquality#+#else+  -- In earlier versions of base, reallyUnsafePtrEquality#'s type is more+  -- restrictive: both arguments must have the same type, and the type of the+  -- arguments must be lifted (i.e., of kind @Type@). To make this work, we use+  -- unsafeCoerce# to coerce both arguments to type @Any :: Type@, which allows+  -- the application of reallyUnsafePtrEquality# to typecheck.+  --+  -- Note that we are coercing from SmallMutableArray#, an unlifted type, to+  -- Any, a lifted type. This is on shaky ground, as GHC only guarantees that+  -- coercing to Any works for lifted types. GHC seemed to tolerate coercing+  -- from SmallMutableArray# to Any for many releases, but this stopped working+  -- in GHC 9.6: see https://gitlab.haskell.org/ghc/ghc/-/issues/22813. Luckily,+  -- we can avoid the issue by using a levity polymorphic version of+  -- reallyUnsafePtrEquality# directly, without any intermediate coercions to+  -- Any.+  unsafeCoerce# reallyUnsafePtrEquality#+#endif+    (destruct t) Null) {-# INLINE isNil #-}  #ifndef HLINT

@@ -1,6 +1,6 @@ name:          structs category:      Data-version:       0.1.6+version:       0.1.7 license:       BSD3 cabal-version: 1.22 license-file:  LICENSE@@ -16,8 +16,9 @@              , GHC == 8.4.4              , GHC == 8.6.5              , GHC == 8.8.4-             , GHC == 8.10.4-             , GHC == 9.0.1+             , GHC == 8.10.7+             , GHC == 9.0.2+             , GHC == 9.2.2 synopsis:      Strict GC'd imperative object-oriented programming with cheap pointers. description:   This project is an experiment with a small GC'd strict mutable imperative universe with cheap pointers inside of the GHC runtime system.@@ -35,7 +36,7 @@   build-depends:     base >= 4.9 && < 5,     deepseq,-    template-haskell >= 2.11 && < 2.19,+    template-haskell >= 2.11 && < 2.20,     th-abstraction >= 0.4 && < 0.5,     ghc-prim,     primitive