Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: 70b58c8f by Vladislav Zavialov at 2026-08-05T14:56:27-04:00 Test cases for #18725 Starting with GHC 9.4 (the first release to include 268efcc9a4), the program in this ticket no longer panics. A standalone kind signature breaks the recursive loop, so the type constructor can be used in a kind within its own group. T18725a checks that this is accepted with the signature present, while T18725b confirms it is still rejected without it. - - - - - 5 changed files: - + testsuite/tests/saks/should_compile/T18725a.hs - testsuite/tests/saks/should_compile/all.T - + testsuite/tests/saks/should_fail/T18725b.hs - + testsuite/tests/saks/should_fail/T18725b.stderr - testsuite/tests/saks/should_fail/all.T Changes: ===================================== testsuite/tests/saks/should_compile/T18725a.hs ===================================== @@ -0,0 +1,10 @@ +{-# LANGUAGE ExplicitForAll, KindSignatures, StandaloneKindSignatures, + DataKinds, GADTs #-} + +module T18725a where + +import Data.Kind (Type) + +type U :: Type +data U where P :: forall u. E u -> U +data E (u :: U) ===================================== testsuite/tests/saks/should_compile/all.T ===================================== @@ -35,6 +35,7 @@ test('T16726', normal, compile, ['']) test('T16731', normal, compile, ['']) test('T16721', normal, ghci_script, ['T16721.script']) test('T16756a', normal, compile, ['']) +test('T18725a', normal, compile, ['']) test('saks027', req_th, compile, ['-v0 -ddump-splices -dsuppress-uniques']) test('saks028', req_th, compile, ['']) ===================================== testsuite/tests/saks/should_fail/T18725b.hs ===================================== @@ -0,0 +1,8 @@ +{-# LANGUAGE ExplicitForAll, KindSignatures, StandaloneKindSignatures, + DataKinds, GADTs #-} + +module T18725b where + +-- type U :: Type -- Rejected without the sig +data U where P :: forall u. E u -> U +data E (u :: U) ===================================== testsuite/tests/saks/should_fail/T18725b.stderr ===================================== @@ -0,0 +1,6 @@ +T18725b.hs:8:14: error: [GHC-85413] + • Type constructor ‘U’ cannot be used here + (it is defined and used in the same recursive group) + • In the kind ‘U’ + In the data type declaration for ‘E’ + ===================================== testsuite/tests/saks/should_fail/all.T ===================================== @@ -38,3 +38,5 @@ test('T18863d', normal, compile_fail, ['']) test('T20916', normal, compile_fail, ['']) test('saks018-fail', normal, compile_fail, ['']) test('saks021-fail', normal, compile_fail, ['']) +test('T18725b', normal, compile_fail, ['']) + View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/70b58c8f5a8ffa937bb3435610b038d3... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/70b58c8f5a8ffa937bb3435610b038d3... You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help