Ben Gamari pushed to branch wip/T27455 at Glasgow Haskell Compiler / GHC Commits: 48f61255 by Ben Gamari at 2026-06-29T10:47:27-04:00 base: Don't drop exception context in SomeException(toException) For reasons that are lost to time, the implementation of [CLC #200] that was merged inappropriately dropped `ExceptionContext` in the `toException` implementation given to `SomeException`. Fix this infelicity. [CLC #200]: https://github.com/haskell/core-libraries-committee/issues/200 - - - - - 3 changed files: - + changelog.d/T27455 - libraries/base/changelog.md - libraries/ghc-internal/src/GHC/Internal/Exception/Type.hs Changes: ===================================== changelog.d/T27455 ===================================== @@ -0,0 +1,8 @@ +section: base +issues: #27455 +mrs: +synopsis: + Don't drop `ExceptionContext` in `SomeException(toException)` +description: + 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>`. + ===================================== libraries/base/changelog.md ===================================== @@ -33,6 +33,7 @@ * Evaluate backtraces for "error" exceptions at the moment they are thrown. ([CLC proposal #383](https://github.com/haskell/core-libraries-committee/issues/383)) * Hide implementation details when throwing exceptions in throw and throwSTM. ([CLC proposal #387](https://github.com/haskell/core-libraries-committee/issues/387)) * 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)) + * 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). * Annotate `onException` continuation with `WhileHandling`. ([CLC Proposal #397](https://github.com/haskell/core-libraries-committee/issues/397)) * Improve error message for `Data.Char.chr`. ([CLC Proposal #384](https://github.com/haskell/core-libraries-committee/issues/384)) ===================================== libraries/ghc-internal/src/GHC/Internal/Exception/Type.hs ===================================== @@ -235,9 +235,7 @@ instance Exception Void -- -- @since base-3.0 instance Exception SomeException where - toException (SomeException e) = - let ?exceptionContext = emptyExceptionContext - in SomeException e + toException = id fromException = Just backtraceDesired (SomeException e) = backtraceDesired e displayException (SomeException e) = displayException e View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/48f61255b9c19b7bb7d9da7b66bdffaa... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/48f61255b9c19b7bb7d9da7b66bdffaa... You're receiving this email because of your account on gitlab.haskell.org.