Hannes Siebenhandl pushed to branch wip/fendor/backtraces-decoders at Glasgow Haskell Compiler / GHC Commits: 7324479a by fendor at 2025-07-18T15:56:55+02:00 Expose `StackTrace` and `StackSnapshot` from `Backtraces` Instead of decoding the stack traces when collecting the `Backtraces`, defer this decoding until actually showing the `Backtraces`. This allows users to customise how `Backtraces` are displayed by using a custom implementation of `displayExceptionWithInfo`, overwriting the default implementation for `Backtraces` (`displayBacktraces`). - - - - - 5 changed files: - libraries/ghc-internal/src/GHC/Internal/Exception/Backtrace.hs - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs - testsuite/tests/interface-stability/base-exports.stdout-mingw32 - testsuite/tests/interface-stability/base-exports.stdout-ws-32 Changes: ===================================== libraries/ghc-internal/src/GHC/Internal/Exception/Backtrace.hs ===================================== @@ -11,9 +11,9 @@ import GHC.Internal.IORef import GHC.Internal.IO.Unsafe (unsafePerformIO) import GHC.Internal.Exception.Context import GHC.Internal.Ptr +import GHC.Internal.Data.Maybe (fromMaybe) import GHC.Internal.Stack.Types as GHC.Stack (CallStack) import qualified GHC.Internal.Stack as HCS -import qualified GHC.Internal.ExecutionStack as ExecStack import qualified GHC.Internal.ExecutionStack.Internal as ExecStack import qualified GHC.Internal.Stack.CloneStack as CloneStack import qualified GHC.Internal.Stack.CCS as CCS @@ -91,8 +91,8 @@ data Backtraces = Backtraces { btrCostCentre :: Maybe (Ptr CCS.CostCentreStack), btrHasCallStack :: Maybe HCS.CallStack, - btrExecutionStack :: Maybe [ExecStack.Location], - btrIpe :: Maybe [CloneStack.StackEntry] + btrExecutionStack :: Maybe ExecStack.StackTrace, + btrIpe :: Maybe CloneStack.StackSnapshot } -- | Render a set of backtraces to a human-readable string. @@ -109,8 +109,10 @@ displayBacktraces bts = concat -- The unsafePerformIO here is safe as we don't currently unload cost-centres. displayCc = unlines . map (indent 2) . unsafePerformIO . CCS.ccsToStrings - displayExec = unlines . map (indent 2 . flip ExecStack.showLocation "") - displayIpe = unlines . map (indent 2 . CloneStack.prettyStackEntry) + displayExec = unlines . map (indent 2 . flip ExecStack.showLocation "") . fromMaybe [] . ExecStack.stackFrames + -- The unsafePerformIO here is safe as 'StackSnapshot' makes sure neither the stack frames nor + -- references closures can be garbage collected. + displayIpe = unlines . map (indent 2 . CloneStack.prettyStackEntry) . unsafePerformIO . CloneStack.decode displayHsc = unlines . map (indent 2 . prettyCallSite) . HCS.getCallStack where prettyCallSite (f, loc) = f ++ ", called at " ++ HCS.prettySrcLoc loc @@ -140,12 +142,11 @@ collectBacktraces' enabled = HCS.withFrozenCallStack $ do Just `fmap` CCS.getCurrentCCS () exec <- collect ExecutionBacktrace $ do - ExecStack.getStackTrace + ExecStack.collectStackTrace ipe <- collect IPEBacktrace $ do stack <- CloneStack.cloneMyStack - stackEntries <- CloneStack.decode stack - return (Just stackEntries) + return (Just stack) hcs <- collect HasCallStackBacktrace $ do return (Just ?callStack) ===================================== testsuite/tests/interface-stability/base-exports.stdout ===================================== @@ -323,7 +323,7 @@ module Control.Exception.Backtrace where type BacktraceMechanism :: * data BacktraceMechanism = CostCentreBacktrace | HasCallStackBacktrace | ExecutionBacktrace | IPEBacktrace type Backtraces :: * - data Backtraces = Backtraces {btrCostCentre :: GHC.Internal.Maybe.Maybe (GHC.Internal.Ptr.Ptr GHC.Internal.Stack.CCS.CostCentreStack), btrHasCallStack :: GHC.Internal.Maybe.Maybe GHC.Internal.Stack.Types.CallStack, btrExecutionStack :: GHC.Internal.Maybe.Maybe [GHC.Internal.ExecutionStack.Internal.Location], btrIpe :: GHC.Internal.Maybe.Maybe [GHC.Internal.Stack.CloneStack.StackEntry]} + data Backtraces = Backtraces {btrCostCentre :: GHC.Internal.Maybe.Maybe (GHC.Internal.Ptr.Ptr GHC.Internal.Stack.CCS.CostCentreStack), btrHasCallStack :: GHC.Internal.Maybe.Maybe GHC.Internal.Stack.Types.CallStack, btrExecutionStack :: GHC.Internal.Maybe.Maybe GHC.Internal.ExecutionStack.Internal.StackTrace, btrIpe :: GHC.Internal.Maybe.Maybe GHC.Internal.Stack.CloneStack.StackSnapshot} collectBacktraces :: (?callStack::GHC.Internal.Stack.Types.CallStack) => GHC.Internal.Types.IO Backtraces displayBacktraces :: Backtraces -> GHC.Internal.Base.String getBacktraceMechanismState :: BacktraceMechanism -> GHC.Internal.Types.IO GHC.Internal.Types.Bool ===================================== testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs ===================================== @@ -323,7 +323,7 @@ module Control.Exception.Backtrace where type BacktraceMechanism :: * data BacktraceMechanism = CostCentreBacktrace | HasCallStackBacktrace | ExecutionBacktrace | IPEBacktrace type Backtraces :: * - data Backtraces = Backtraces {btrCostCentre :: GHC.Internal.Maybe.Maybe (GHC.Internal.Ptr.Ptr GHC.Internal.Stack.CCS.CostCentreStack), btrHasCallStack :: GHC.Internal.Maybe.Maybe GHC.Internal.Stack.Types.CallStack, btrExecutionStack :: GHC.Internal.Maybe.Maybe [GHC.Internal.ExecutionStack.Internal.Location], btrIpe :: GHC.Internal.Maybe.Maybe [GHC.Internal.Stack.CloneStack.StackEntry]} + data Backtraces = Backtraces {btrCostCentre :: GHC.Internal.Maybe.Maybe (GHC.Internal.Ptr.Ptr GHC.Internal.Stack.CCS.CostCentreStack), btrHasCallStack :: GHC.Internal.Maybe.Maybe GHC.Internal.Stack.Types.CallStack, btrExecutionStack :: GHC.Internal.Maybe.Maybe GHC.Internal.ExecutionStack.Internal.StackTrace, btrIpe :: GHC.Internal.Maybe.Maybe GHC.Internal.Stack.CloneStack.StackSnapshot} collectBacktraces :: (?callStack::GHC.Internal.Stack.Types.CallStack) => GHC.Internal.Types.IO Backtraces displayBacktraces :: Backtraces -> GHC.Internal.Base.String getBacktraceMechanismState :: BacktraceMechanism -> GHC.Internal.Types.IO GHC.Internal.Types.Bool ===================================== testsuite/tests/interface-stability/base-exports.stdout-mingw32 ===================================== @@ -323,7 +323,7 @@ module Control.Exception.Backtrace where type BacktraceMechanism :: * data BacktraceMechanism = CostCentreBacktrace | HasCallStackBacktrace | ExecutionBacktrace | IPEBacktrace type Backtraces :: * - data Backtraces = Backtraces {btrCostCentre :: GHC.Internal.Maybe.Maybe (GHC.Internal.Ptr.Ptr GHC.Internal.Stack.CCS.CostCentreStack), btrHasCallStack :: GHC.Internal.Maybe.Maybe GHC.Internal.Stack.Types.CallStack, btrExecutionStack :: GHC.Internal.Maybe.Maybe [GHC.Internal.ExecutionStack.Internal.Location], btrIpe :: GHC.Internal.Maybe.Maybe [GHC.Internal.Stack.CloneStack.StackEntry]} + data Backtraces = Backtraces {btrCostCentre :: GHC.Internal.Maybe.Maybe (GHC.Internal.Ptr.Ptr GHC.Internal.Stack.CCS.CostCentreStack), btrHasCallStack :: GHC.Internal.Maybe.Maybe GHC.Internal.Stack.Types.CallStack, btrExecutionStack :: GHC.Internal.Maybe.Maybe GHC.Internal.ExecutionStack.Internal.StackTrace, btrIpe :: GHC.Internal.Maybe.Maybe GHC.Internal.Stack.CloneStack.StackSnapshot} collectBacktraces :: (?callStack::GHC.Internal.Stack.Types.CallStack) => GHC.Internal.Types.IO Backtraces displayBacktraces :: Backtraces -> GHC.Internal.Base.String getBacktraceMechanismState :: BacktraceMechanism -> GHC.Internal.Types.IO GHC.Internal.Types.Bool ===================================== testsuite/tests/interface-stability/base-exports.stdout-ws-32 ===================================== @@ -323,7 +323,7 @@ module Control.Exception.Backtrace where type BacktraceMechanism :: * data BacktraceMechanism = CostCentreBacktrace | HasCallStackBacktrace | ExecutionBacktrace | IPEBacktrace type Backtraces :: * - data Backtraces = Backtraces {btrCostCentre :: GHC.Internal.Maybe.Maybe (GHC.Internal.Ptr.Ptr GHC.Internal.Stack.CCS.CostCentreStack), btrHasCallStack :: GHC.Internal.Maybe.Maybe GHC.Internal.Stack.Types.CallStack, btrExecutionStack :: GHC.Internal.Maybe.Maybe [GHC.Internal.ExecutionStack.Internal.Location], btrIpe :: GHC.Internal.Maybe.Maybe [GHC.Internal.Stack.CloneStack.StackEntry]} + data Backtraces = Backtraces {btrCostCentre :: GHC.Internal.Maybe.Maybe (GHC.Internal.Ptr.Ptr GHC.Internal.Stack.CCS.CostCentreStack), btrHasCallStack :: GHC.Internal.Maybe.Maybe GHC.Internal.Stack.Types.CallStack, btrExecutionStack :: GHC.Internal.Maybe.Maybe GHC.Internal.ExecutionStack.Internal.StackTrace, btrIpe :: GHC.Internal.Maybe.Maybe GHC.Internal.Stack.CloneStack.StackSnapshot} collectBacktraces :: (?callStack::GHC.Internal.Stack.Types.CallStack) => GHC.Internal.Types.IO Backtraces displayBacktraces :: Backtraces -> GHC.Internal.Base.String getBacktraceMechanismState :: BacktraceMechanism -> GHC.Internal.Types.IO GHC.Internal.Types.Bool View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/7324479a0f7ddba03d6c73f7c8db669c... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/7324479a0f7ddba03d6c73f7c8db669c... 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