Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC

Commits:

5 changed files:

Changes:

  • changelog.d/T27455
    1 
    +section: base
    2 
    +issues: #27455
    3 
    +mrs: !16274
    4 
    +synopsis:
    5 
    +  Don't drop `ExceptionContext` in `SomeException(toException)`
    6 
    +description:
    7 
    +  Previously the implementation of ``Exception(toException)`` given to `SomeException` would inappropriately drop the carried `ExceptionContext`. Now ``toException = id``, faithfully implementing the semantics proposed in :ref:`CLC Proposal #200 <https://github.com/haskell/core-libraries-committee/issues/200>`.
    8 
    +

  • libraries/base/changelog.md
    ... ... @@ -38,6 +38,7 @@
    38 38 
       * Show `ExceptionContext` in `displayExceptionAnnotation` implementation of `WhileHandling` ([GHC #27456](https://gitlab.haskell.org/ghc/ghc/-/issues/27456))
    39 39 
       * Hide implementation details when throwing exceptions in throw and throwSTM. ([CLC proposal #387](https://github.com/haskell/core-libraries-committee/issues/387))
    40 40 
       * Change `hIsReadable` and `hIsWritable` such that they always throw a respective exception when encountering a closed or semi-closed handle, not just in the case of a file handle. ([CLC proposal #371](github.com/haskell/core-libraries-committee/issues/371))
    41 
    +  * The implementation of `toException` in `SomeException`'s `Exception` instance no longer drops exception context, in keeping with the behavior originally proposed in [CLC Proposal #200](https://github.com/haskell/core-libraries-committee/issues/200).
    41 42 
       * Annotate `onException` continuation with `WhileHandling`. ([CLC Proposal #397](https://github.com/haskell/core-libraries-committee/issues/397))
    42 43 
       * Improve error message for `Data.Char.chr`. ([CLC Proposal #384](https://github.com/haskell/core-libraries-committee/issues/384))
    43 44

  • libraries/ghc-internal/src/GHC/Internal/Exception/Type.hs
    ... ... @@ -55,7 +55,7 @@ import GHC.Internal.Data.Maybe
    55 55 
     import GHC.Internal.Data.Typeable (Typeable, TypeRep, cast)
    56 56 
     import qualified GHC.Internal.Data.Typeable as Typeable
    57 57 
        -- loop: GHC.Internal.Data.Typeable -> GHC.Internal.Err -> GHC.Internal.Exception
    58 
    -import GHC.Internal.Base (String, Void, fmap, return, ($), (.), (++))
    58 
    +import GHC.Internal.Base (String, Void, fmap, return, ($), (.), (++), id)
    59 59 
     import GHC.Internal.Show
    60 60 
     import GHC.Internal.Types (Bool(..))
    61 61 
     import GHC.Internal.Exception.Context
    ... ... @@ -208,7 +208,16 @@ Caught MismatchedParentheses
    208 208
    209 209 
     -}
    210 210 
     class (Typeable e, Show e) => Exception e where
    211 
    -    -- | @toException@ should produce a 'SomeException' with no attached 'ExceptionContext'.
    211 
    +    -- | 'toException' converts an exception into the existential 'SomeException'
    212 
    +    -- wrapper type.
    213 
    +    --
    214 
    +    -- In doing so, 'toException' should not /add/ an 'ExceptionContext'.
    215 
    +    --
    216 
    +    --   - In most cases, the exception does not store its own 'ExceptionContext'.
    217 
    +    --     The default implementation of 'toException' (which does not store any
    218 
    +    --     'ExceptionContext') is suitable for these cases.
    219 
    +    --   - In the rare case that the exception itself stores an 'ExceptionContext',
    220 
    +    --     this context should be preserved by 'toException'.
    212 221 
         toException   :: e -> SomeException
    213 222 
         fromException :: SomeException -> Maybe e
    214 223
    ... ... @@ -231,13 +240,11 @@ class (Typeable e, Show e) => Exception e where
    231 240 
     -- | @since base-4.8.0.0
    232 241 
     instance Exception Void
    233 242
    234 
    --- | This drops any attached 'ExceptionContext'.
    243 
    +-- | NB: this instance preserves the attached 'ExceptionContext'.
    235 244 
     --
    236 245 
     -- @since base-3.0
    237 246 
     instance Exception SomeException where
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    -    toException (SomeException e) =
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    -        let ?exceptionContext = emptyExceptionContext
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    -        in SomeException e
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    +    toException = id
    241 248 
         fromException = Just
    242 249 
         backtraceDesired (SomeException e) = backtraceDesired e
    243 250 
         displayException (SomeException e) = displayException e

  • testsuite/tests/ghc-e/should_fail/T18441fail7.stderr
    ... ... @@ -5,8 +5,12 @@ IO error: "Abcde" does not exist
    5 5 
     While handling ghc-10.1-inplace:GHC.Utils.Panic.GhcException:
    6 6 
       |
    7 7 
       | IO error:  "Abcde" does not exist
    8 
    +  |
    9 
    +  | HasCallStack backtrace:
    10 
    +  |   throw, called at compiler/GHC/Utils/Panic.hs:180:21 in ghc-10.1-inplace:GHC.Utils.Panic
    11 
    +  |   throwGhcException, called at ghc/GHCi/UI.hs:2851:21 in ghc-bin-10.1.20260801-inplace:GHCi.UI
    8 12
    9 13 
     HasCallStack backtrace:
    10 
    -  throwIO, called at compiler\GHC\Utils\Error.hs:499:19 in ghc-10.1-inplace:GHC.Utils.Error
    14 
    +  throwIO, called at compiler/GHC/Utils/Error.hs:513:19 in ghc-10.1-inplace:GHC.Utils.Error
    11 15
    12 16 
     1

  • testsuite/tests/ghc-e/should_run/ghc-e005.stderr
    ... ... @@ -4,3 +4,8 @@ foo
    4 4
    5 5 
     HasCallStack backtrace:
    6 6 
       error, called at ghc-e005.hs:12:10 in main:Main
    7 
    +
    8 
    +
    9 
    +HasCallStack backtrace:
    10 
    +  throwIO, called at ghc\GHCi\UI.hs:1655:31 in ghc-bin-10.1.20260629-inplace:GHCi.UI
    11 
    +

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