Rodrigo Mesquita pushed to branch wip/romes/step-out at Glasgow Haskell Compiler / GHC

Commits:

20 changed files:

Changes:

  • compiler/GHC/Driver/Config.hs
    ... ... @@ -3,6 +3,7 @@ module GHC.Driver.Config
    3 3 
        ( initOptCoercionOpts
    4 4 
        , initSimpleOpts
    5 5 
        , initEvalOpts
    6 
    +   , EvalStep(..)
    6 7 
        )
    7 8 
     where
    8 9
    ... ... @@ -28,13 +29,28 @@ initSimpleOpts dflags = SimpleOpts
    28 29 
        , so_inline  = True
    29 30 
        }
    30 31
    32 
    +-- | Instruct the interpreter evaluation to break...
    33 
    +data EvalStep
    34 
    +  -- | ... at every breakpoint tick
    35 
    +  = EvalStepSingle
    36 
    +  -- | ... after every return stmt
    37 
    +  | EvalStepOut
    38 
    +  -- | ... only on explicit breakpoints
    39 
    +  | EvalStepNone
    40 
    +
    31 41 
     -- | Extract GHCi options from DynFlags and step
    32 
    -initEvalOpts :: DynFlags -> Bool -> EvalOpts
    42 
    +initEvalOpts :: DynFlags -> EvalStep -> EvalOpts
    33 43 
     initEvalOpts dflags step =
    34 44 
       EvalOpts
    35 45 
         { useSandboxThread = gopt Opt_GhciSandbox dflags
    36 
    -    , singleStep       = step
    46 
    +    , singleStep       = singleStep
    47 
    +    , stepOut          = stepOut
    37 48 
         , breakOnException = gopt Opt_BreakOnException dflags
    38 49 
         , breakOnError     = gopt Opt_BreakOnError dflags
    39 50 
         }
    51 
    +  where
    52 
    +    (singleStep, stepOut) = case step of
    53 
    +      EvalStepSingle -> (True,  False)
    54 
    +      EvalStepOut    -> (False, True)
    55 
    +      EvalStepNone   -> (False, False)
    40 56

  • compiler/GHC/Runtime/Eval.hs
    ... ... @@ -343,7 +343,12 @@ handleRunStatus step expr bindings final_ids status history0 = do
    343 343 
           setSession hsc_env2
    344 344 
           return (ExecBreak names Nothing)
    345 345
    346 
    -    -- Just case: we stopped at a breakpoint
    346 
    +    -- EvalBreak (Just ...) case: the interpreter stopped at a breakpoint
    347 
    +    --
    348 
    +    -- The interpreter yields on a breakpoint if:
    349 
    +    --  - the breakpoint was explicitly enabled (in @BreakArray@)
    350 
    +    --  - or @singleStep = True@ in EvalOpts
    351 
    +    --  - or @stepOut = True@ in EvalOpts
    347 352 
         EvalBreak apStack_ref (Just eval_break) resume_ctxt ccs -> do
    348 353 
           let ibi = evalBreakpointToId eval_break
    349 354 
           tick_brks <- liftIO $ readModBreaks hsc_env (ibi_tick_mod ibi)
    ... ... @@ -351,13 +356,14 @@ handleRunStatus step expr bindings final_ids status history0 = do
    351 356 
             span      = modBreaks_locs tick_brks ! ibi_tick_index ibi
    352 357 
             decl      = intercalate "." $ modBreaks_decls tick_brks ! ibi_tick_index ibi
    353 358
    359 
    +      -- Was the breakpoint explicitly enabled?
    354 360 
           b <- liftIO $ breakpointStatus interp (modBreaks_flags tick_brks) (ibi_tick_index ibi)
    355 361
    356 362 
           apStack_fhv <- liftIO $ mkFinalizedHValue interp apStack_ref
    357 363 
           resume_ctxt_fhv   <- liftIO $ mkFinalizedHValue interp resume_ctxt
    358 364
    359 
    -      -- This breakpoint is explicitly enabled; we want to stop
    360 
    -      -- instead of just logging it.
    365 
    +      -- This breakpoint is enabled or we mean to break here;
    366 
    +      -- we want to stop instead of just logging it.
    361 367 
           if b || breakHere step span then do
    362 368 
             -- This function only returns control to ghci with 'ExecBreak' when it is really meant to break.
    363 369 
             -- Specifically, for :steplocal or :stepmodule, don't return control
    ... ... @@ -1247,7 +1253,7 @@ compileParsedExprRemote expr@(L loc _) = withSession $ \hsc_env -> do
    1247 1253 
             _ -> panic "compileParsedExprRemote"
    1248 1254
    1249 1255 
       updateFixityEnv fix_env
    1250 
    -  let eval_opts = initEvalOpts dflags False
    1256 
    +  let eval_opts = initEvalOpts dflags EvalStepNone
    1251 1257 
       status <- liftIO $ evalStmt interp eval_opts (EvalThis hvals_io)
    1252 1258 
       case status of
    1253 1259 
         EvalComplete _ (EvalSuccess [hval]) -> return hval

  • compiler/GHC/Runtime/Eval/Types.hs
    ... ... @@ -17,6 +17,7 @@ import GHC.Prelude
    17 17
    18 18 
     import GHCi.RemoteTypes
    19 19 
     import GHCi.Message (EvalExpr, ResumeContext)
    20 
    +import GHC.Driver.Config (EvalStep(..))
    20 21 
     import GHC.Types.Id
    21 22 
     import GHC.Types.Name
    22 23 
     import GHC.Types.TyThing
    ... ... @@ -46,6 +47,9 @@ data SingleStep
    46 47 
        -- | :step [expr]
    47 48 
        | SingleStep
    48 49
    50 
    +   -- | :stepout [expr]
    51 
    +   | StepOut
    52 
    +
    49 53 
        -- | :steplocal [expr]
    50 54 
        | LocalStep
    51 55 
           { breakAt :: SrcSpan }
    ... ... @@ -55,10 +59,12 @@ data SingleStep
    55 59 
           { breakAt :: SrcSpan }
    56 60
    57 61 
     -- | Whether this 'SingleStep' mode requires instructing the interpreter to
    58 
    --- step at every breakpoint.
    59 
    -enableGhcStepMode :: SingleStep -> Bool
    60 
    -enableGhcStepMode RunToCompletion = False
    61 
    -enableGhcStepMode _ = True
    62 
    +-- step at every breakpoint or after every return (see @'EvalStep'@).
    63 
    +enableGhcStepMode :: SingleStep -> EvalStep
    64 
    +enableGhcStepMode RunToCompletion = EvalStepNone
    65 
    +enableGhcStepMode StepOut         = EvalStepOut
    66 
    +-- for the remaining step modes we need to stop at every single breakpoint.
    67 
    +enableGhcStepMode _               = EvalStepSingle
    62 68
    63 69 
     -- | Given a 'SingleStep' mode and the SrcSpan of a breakpoint we hit, return
    64 70 
     -- @True@ if based on the step-mode alone we should stop at this breakpoint.
    ... ... @@ -70,6 +76,7 @@ breakHere :: SingleStep -> SrcSpan -> Bool
    70 76 
     breakHere step break_span = case step of
    71 77 
       RunToCompletion -> False
    72 78 
       RunAndLogSteps  -> False
    79 
    +  StepOut         -> True -- hmm. this function may not be a good abstraction?
    73 80 
       SingleStep      -> True
    74 81 
       LocalStep  span -> break_span `isSubspanOf` span
    75 82 
       ModuleStep span -> srcSpanFileName_maybe span == srcSpanFileName_maybe break_span

  • docs/users_guide/ghci.rst
    ... ... @@ -2980,6 +2980,35 @@ commonly used commands.
    2980 2980 
         hit by an error (:ghc-flag:`-fbreak-on-error`) or an
    2981 2981 
         exception (:ghc-flag:`-fbreak-on-exception`).
    2982 2982
    2983 
    +.. ghci-cmd:: :stepout
    2984 
    +
    2985 
    +    Stop at the first breakpoint immediately after returning from the current
    2986 
    +    function scope.
    2987 
    +
    2988 
    +    Known limitations: because a function tail-call does not push a stack
    2989 
    +    frame, if step-out is used inside of a function that was tail-called,
    2990 
    +    execution will not be returned to its caller, but rather its caller's
    2991 
    +    first non-tail caller. On the other hand, it means the debugger
    2992 
    +    follows the more realistic execution of the program.
    2993 
    +    In the following example:
    2994 
    +
    2995 
    +    .. code-block:: none
    2996 
    +
    2997 
    +    f = do
    2998 
    +       a
    2999 
    +       b <--- (1) set breakpoint then step in here
    3000 
    +       c
    3001 
    +    b = do
    3002 
    +       ...
    3003 
    +       d <--- (2) step-into this tail call
    3004 
    +    d = do
    3005 
    +       ...
    3006 
    +       something <--- (3) step-out here
    3007 
    +       ...
    3008 
    +
    3009 
    +    Stepping-out will stop execution at the `c` invokation in `f`, rather than
    3010 
    +    stopping at `b`.
    3011 
    +
    2983 3012 
     .. ghci-cmd:: :stepmodule
    2984 3013
    2985 3014 
         Enable only breakpoints in the current module and resume evaluation

  • ghc/GHCi/UI.hs
    ... ... @@ -247,6 +247,7 @@ ghciCommands = map mkCmd [
    247 247 
       ("sprint",    keepGoing sprintCmd,            completeExpression),
    248 248 
       ("step",      keepGoing stepCmd,              completeIdentifier),
    249 249 
       ("steplocal", keepGoing stepLocalCmd,         completeIdentifier),
    250 
    +  ("stepout",   keepGoing stepOutCmd,           completeIdentifier),
    250 251 
       ("stepmodule",keepGoing stepModuleCmd,        completeIdentifier),
    251 252 
       ("type",      keepGoingMulti' typeOfExpr,          completeExpression),
    252 253 
       ("trace",     keepGoing traceCmd,             completeExpression),
    ... ... @@ -407,6 +408,7 @@ defFullHelpText =
    407 408 
       "   :step                       single-step after stopping at a breakpoint\n"++
    408 409 
       "   :step <expr>                single-step into <expr>\n"++
    409 410 
       "   :steplocal                  single-step within the current top-level binding\n"++
    411 
    +  "   :stepout                    stop at the first breakpoint after returning from the current scope\n"++
    410 412 
       "   :stepmodule                 single-step restricted to the current module\n"++
    411 413 
       "   :trace                      trace after stopping at a breakpoint\n"++
    412 414 
       "   :trace <expr>               evaluate <expr> with tracing on (see :history)\n"++
    ... ... @@ -3793,6 +3795,12 @@ stepCmd arg = withSandboxOnly ":step" $ step arg
    3793 3795 
       step []         = doContinue GHC.SingleStep
    3794 3796 
       step expression = runStmt expression GHC.SingleStep >> return ()
    3795 3797
    3798 
    +stepOutCmd :: GhciMonad m => String -> m ()
    3799 
    +stepOutCmd arg = withSandboxOnly ":stepout" $ step arg
    3800 
    +  where
    3801 
    +  step []         = doContinue GHC.StepOut
    3802 
    +  step expression = stepCmd expression
    3803 
    +
    3796 3804 
     stepLocalCmd :: GhciMonad m => String -> m ()
    3797 3805 
     stepLocalCmd arg = withSandboxOnly ":steplocal" $ step arg
    3798 3806 
       where

  • libraries/ghci/GHCi/Message.hs
    ... ... @@ -374,6 +374,7 @@ putTHMessage m = case m of
    374 374 
     data EvalOpts = EvalOpts
    375 375 
       { useSandboxThread :: Bool
    376 376 
       , singleStep :: Bool
    377 
    +  , stepOut :: Bool
    377 378 
       , breakOnException :: Bool
    378 379 
       , breakOnError :: Bool
    379 380 
       }

  • libraries/ghci/GHCi/Run.hs
    ... ... @@ -210,6 +210,7 @@ evalOptsSeq :: EvalOpts
    210 210 
     evalOptsSeq = EvalOpts
    211 211 
                   { useSandboxThread = True
    212 212 
                   , singleStep = False
    213 
    +              , stepOut    = False
    213 214 
                   , breakOnException = False
    214 215 
                   , breakOnError = False
    215 216 
                   }
    ... ... @@ -333,6 +334,7 @@ withBreakAction opts breakMVar statusMVar act
    333 334 
          poke breakPointIOAction stablePtr
    334 335 
          when (breakOnException opts) $ poke exceptionFlag 1
    335 336 
          when (singleStep opts) $ setStepFlag
    337 
    +     when (stepOut opts) $ poke stepOutFlag 1
    336 338 
          return stablePtr
    337 339 
             -- Breaking on exceptions is not enabled by default, since it
    338 340 
             -- might be a bit surprising.  The exception flag is turned off
    ... ... @@ -363,6 +365,7 @@ withBreakAction opts breakMVar statusMVar act
    363 365 
        resetBreakAction stablePtr = do
    364 366 
          poke breakPointIOAction noBreakStablePtr
    365 367 
          poke exceptionFlag 0
    368 
    +     poke stepOutFlag 0
    366 369 
          resetStepFlag
    367 370 
          freeStablePtr stablePtr
    368 371
    ... ... @@ -398,6 +401,7 @@ abandonStmt hvref = do
    398 401
    399 402 
     foreign import ccall "&rts_stop_next_breakpoint" stepFlag      :: Ptr CInt
    400 403 
     foreign import ccall "&rts_stop_on_exception"    exceptionFlag :: Ptr CInt
    404 
    +foreign import ccall "&rts_stop_after_return"    stepOutFlag   :: Ptr CInt
    401 405
    402 406 
     setStepFlag :: IO ()
    403 407 
     setStepFlag = poke stepFlag 1

  • rts/Interpreter.c
    ... ... @@ -194,6 +194,24 @@ See also Note [Width of parameters] for some more motivation.
    194 194 
     #define WITHIN_CHUNK_BOUNDS(n, s)  \
    195 195 
       (RTS_LIKELY((StgWord*)(Sp_plusW(n)) < ((s)->stack + (s)->stack_size - sizeofW(StgUnderflowFrame))))
    196 196
    197 
    +// Note [Debugger Step-out]
    198 
    +// ~~~~~~~~~~~~~~~~~~~~~~~~
    199 
    +// When the global debugger step-out flag is set (`rts_stop_after_return`),
    200 
    +// the interpreter must yield execution right after the first RETURN.
    201 
    +//
    202 
    +// When stepping-out, we simply enable `rts_stop_next_breakpoint` when we hit a
    203 
    +// return instruction (in `do_return_pointer` and `do_return_nonpointer`).
    204 
    +// The step-out flag is cleared and must be re-enabled explicitly to step-out again.
    205 
    +//
    206 
    +// A limitation of this approach is that stepping-out of a function that was
    207 
    +// tail-called will skip its caller since no stack frame is pushed for a tail
    208 
    +// call (i.e. a tail call returns directly to its caller's first non-tail caller).
    209 
    +#define CHECK_BRK_AFTER_RET()               \
    210 
    +    if (rts_stop_after_return)              \
    211 
    +    {                                       \
    212 
    +      rts_stop_next_breakpoint = true;      \
    213 
    +      rts_stop_after_return = false;        \
    214 
    +    }                                       \
    197 215
    198 216 
     /* Note [PUSH_L underflow]
    199 217 
        ~~~~~~~~~~~~~~~~~~~~~~~
    ... ... @@ -245,6 +263,7 @@ allocate_NONUPD (Capability *cap, int n_words)
    245 263
    246 264 
     int rts_stop_next_breakpoint = 0;
    247 265 
     int rts_stop_on_exception = 0;
    266 
    +int rts_stop_after_return = 0;
    248 267
    249 268 
     #if defined(INTERP_STATS)
    250 269
    ... ... @@ -734,6 +753,8 @@ do_return_pointer:
    734 753
    735 754 
         IF_DEBUG(sanity,checkStackChunk(Sp, cap->r.rCurrentTSO->stackobj->stack+cap->r.rCurrentTSO->stackobj->stack_size));
    736 755
    756 
    +    CHECK_BRK_AFTER_RET();
    757 
    +
    737 758 
         switch (get_itbl((StgClosure *)Sp)->type) {
    738 759
    739 760 
         case RET_SMALL: {
    ... ... @@ -883,6 +904,8 @@ do_return_nonpointer:
    883 904 
             // get the offset of the header of the next stack frame
    884 905 
             offset = stack_frame_sizeW((StgClosure *)Sp);
    885 906
    907 
    +        CHECK_BRK_AFTER_RET();
    908 
    +
    886 909 
             switch (get_itbl((StgClosure*)(Sp_plusW(offset)))->type) {
    887 910
    888 911 
             case RET_BCO:

  • rts/RtsSymbols.c
    ... ... @@ -908,6 +908,7 @@ extern char **environ;
    908 908 
           SymI_NeedsDataProto(rts_breakpoint_io_action)                     \
    909 909 
           SymI_NeedsDataProto(rts_stop_next_breakpoint)                     \
    910 910 
           SymI_NeedsDataProto(rts_stop_on_exception)                        \
    911 
    +      SymI_NeedsDataProto(rts_stop_after_return)                        \
    911 912 
           SymI_HasProto(stopTimer)                                          \
    912 913 
           SymI_HasProto(n_capabilities)                                     \
    913 914 
           SymI_HasProto(max_n_capabilities)                                 \

  • rts/include/stg/MiscClosures.h
    ... ... @@ -619,6 +619,7 @@ RTS_FUN_DECL(stg_castFloatToWord32zh);
    619 619 
     // Interpreter.c
    620 620 
     extern StgWord rts_stop_next_breakpoint[];
    621 621 
     extern StgWord rts_stop_on_exception[];
    622 
    +extern StgWord rts_stop_after_return[];
    622 623 
     extern StgWord rts_breakpoint_io_action[];
    623 624
    624 625 
     // Schedule.c

  • testsuite/tests/ghci.debugger/scripts/T26042a.hs
    1 
    +module Main where
    2 
    +
    3 
    +main :: IO ()
    4 
    +main = do
    5 
    +  a <- foo
    6 
    +  print a
    7 
    +
    8 
    +foo :: IO Int
    9 
    +foo = do
    10 
    +  let x = 3
    11 
    +      y = 4
    12 
    +  b <- bar (x + y)
    13 
    +  return b
    14 
    +
    15 
    +bar :: Int -> IO Int
    16 
    +bar z = return (z * 2)
    17 
    +

  • testsuite/tests/ghci.debugger/scripts/T26042a.script
    1 
    +:load T26042a.hs
    2 
    +-- simple use of stepout
    3 
    +:break bar
    4 
    +main
    5 
    +:list
    6 
    +:stepout
    7 
    +:list
    8 
    +:stepout
    9 
    +:list
    10 
    +-- from here on we're going to evaluate the thunks for `a` in `print a`
    11 
    +:stepout
    12 
    +:list
    13 
    +:stepout
    14 
    +:list
    15 
    +:stepout
    16 
    +:list
    17 
    +:stepout
    18 
    +:list
    19 
    +-- finish execution
    20 
    +:stepout

  • testsuite/tests/ghci.debugger/scripts/T26042a.stdout
    1 
    +Breakpoint 0 activated at T26042a.hs:16:9-22
    2 
    +Stopped in Main.bar, T26042a.hs:16:9-22
    3 
    +_result :: IO Int = _
    4 
    +z :: Int = _
    5 
    +15  bar :: Int -> IO Int
    6 
    +16  bar z = return (z * 2)
    7 
    +            ^^^^^^^^^^^^^^
    8 
    +17
    9 
    +Stopped in Main.foo, T26042a.hs:13:3-10
    10 
    +_result :: IO Int = _
    11 
    +b :: Int = _
    12 
    +12    b <- bar (x + y)
    13 
    +13    return b
    14 
    +      ^^^^^^^^
    15 
    +14
    16 
    +Stopped in Main.main, T26042a.hs:6:3-9
    17 
    +_result :: IO () = _
    18 
    +a :: Int = _
    19 
    +5    a <- foo
    20 
    +6    print a
    21 
    +     ^^^^^^^
    22 
    +7
    23 
    +Stopped in Main.bar, T26042a.hs:16:17-21
    24 
    +_result :: Int = _
    25 
    +z :: Int = _
    26 
    +15  bar :: Int -> IO Int
    27 
    +16  bar z = return (z * 2)
    28 
    +                    ^^^^^
    29 
    +17
    30 
    +Stopped in Main.foo, T26042a.hs:12:13-17
    31 
    +_result :: Int = _
    32 
    +x :: Int = _
    33 
    +y :: Int = _
    34 
    +11        y = 4
    35 
    +12    b <- bar (x + y)
    36 
    +                ^^^^^
    37 
    +13    return b
    38 
    +Stopped in Main.foo.x, T26042a.hs:10:11
    39 
    +_result :: Int = _
    40 
    +9  foo = do
    41 
    +10    let x = 3
    42 
    +              ^
    43 
    +11        y = 4
    44 
    +Stopped in Main.foo.y, T26042a.hs:11:11
    45 
    +_result :: Int = _
    46 
    +10    let x = 3
    47 
    +11        y = 4
    48 
    +              ^
    49 
    +12    b <- bar (x + y)
    50 
    +14

  • testsuite/tests/ghci.debugger/scripts/T26042b.hs
    1 
    +module Main where
    2 
    +
    3 
    +main :: IO ()
    4 
    +main = do
    5 
    +  a <- foo False undefined
    6 
    +  print a
    7 
    +
    8 
    +foo :: Bool -> Int -> IO Int
    9 
    +foo True  i = return i
    10 
    +foo False _ = do
    11 
    +  let x = 3
    12 
    +      y = 4
    13 
    +  n <- bar (x + y)
    14 
    +  return n
    15 
    +
    16 
    +bar :: Int -> IO Int
    17 
    +bar z = do
    18 
    +  let t = z * 2
    19 
    +  y <- foo True t
    20 
    +  return y
    21 
    +
    22 
    +

  • testsuite/tests/ghci.debugger/scripts/T26042b.script
    1 
    +:load T26042b.hs
    2 
    +-- break on the True branch of foo
    3 
    +:break 9
    4 
    +main
    5 
    +:list
    6 
    +-- stepout of foo True to caller (ie bar)
    7 
    +:stepout
    8 
    +:list
    9 
    +-- stepout of bar (to branch of foo False, where bar was called)
    10 
    +:stepout
    11 
    +:list
    12 
    +-- stepout to right after the call to foo False in main
    13 
    +:stepout
    14 
    +:list
    15 
    +-- done
    16 
    +:continue

  • testsuite/tests/ghci.debugger/scripts/T26042b.stdout
    1 
    +Breakpoint 0 activated at T26042b.hs:9:15-22
    2 
    +Stopped in Main.foo, T26042b.hs:9:15-22
    3 
    +_result :: IO Int = _
    4 
    +i :: Int = _
    5 
    +8  foo :: Bool -> Int -> IO Int
    6 
    +9  foo True  i = return i
    7 
    +                 ^^^^^^^^
    8 
    +10  foo False _ = do
    9 
    +Stopped in Main.bar, T26042b.hs:20:3-10
    10 
    +_result :: IO Int = _
    11 
    +y :: Int = _
    12 
    +19    y <- foo True t
    13 
    +20    return y
    14 
    +      ^^^^^^^^
    15 
    +21
    16 
    +Stopped in Main.foo, T26042b.hs:14:3-10
    17 
    +_result :: IO Int = _
    18 
    +n :: Int = _
    19 
    +13    n <- bar (x + y)
    20 
    +14    return n
    21 
    +      ^^^^^^^^
    22 
    +15
    23 
    +Stopped in Main.main, T26042b.hs:6:3-9
    24 
    +_result :: IO () = _
    25 
    +a :: Int = _
    26 
    +5    a <- foo False undefined
    27 
    +6    print a
    28 
    +     ^^^^^^^
    29 
    +7
    30 
    +14

  • testsuite/tests/ghci.debugger/scripts/T26042c.hs
    1 
    +module Main where
    2 
    +
    3 
    +main :: IO ()
    4 
    +main = do
    5 
    +  a <- foo False undefined
    6 
    +  print a
    7 
    +
    8 
    +foo :: Bool -> Int -> IO Int
    9 
    +foo True  i = return i
    10 
    +foo False _ = do
    11 
    +  let x = 3
    12 
    +      y = 4
    13 
    +  bar (x + y)
    14 
    +
    15 
    +bar :: Int -> IO Int
    16 
    +bar z = do
    17 
    +  let t = z * 2
    18 
    +  foo True t
    19 
    +

  • testsuite/tests/ghci.debugger/scripts/T26042c.script
    1 
    +:load T26042c.hs
    2 
    +-- similar to T26042b, but uses tail calls
    3 
    +-- recall: for step-out, we skip the caller of tail calls
    4 
    +-- (because we don't push a stack frame for tail calls, so
    5 
    +-- there's no RET instruction to stop after)
    6 
    +
    7 
    +-- break on foo True branch
    8 
    +:break 9
    9 
    +main
    10 
    +:list
    11 
    +-- step out of foo True and observe that we have skipped its call in bar,
    12 
    +-- and the call of bar in foo False.
    13 
    +-- we go straight to `main`.
    14 
    +:stepout
    15 
    +:list
    16 
    +-- stepping out from here will jump into the thunk because it's where we'll
    17 
    +-- go after returning.
    18 
    +:stepout
    19 
    +:list
    20 
    +-- and so on
    21 
    +:stepout
    22 
    +:list
    23 
    +-- finish
    24 
    +:continue

  • testsuite/tests/ghci.debugger/scripts/T26042c.stdout
    1 
    +Breakpoint 0 activated at T26042c.hs:9:15-22
    2 
    +Stopped in Main.foo, T26042c.hs:9:15-22
    3 
    +_result :: IO Int = _
    4 
    +i :: Int = _
    5 
    +8  foo :: Bool -> Int -> IO Int
    6 
    +9  foo True  i = return i
    7 
    +                 ^^^^^^^^
    8 
    +10  foo False _ = do
    9 
    +Stopped in Main.main, T26042c.hs:6:3-9
    10 
    +_result :: IO () = _
    11 
    +a :: Int = _
    12 
    +5    a <- foo False undefined
    13 
    +6    print a
    14 
    +     ^^^^^^^
    15 
    +7
    16 
    +Stopped in Main.bar.t, T26042c.hs:17:11-15
    17 
    +_result :: Int = _
    18 
    +z :: Int = _
    19 
    +16  bar z = do
    20 
    +17    let t = z * 2
    21 
    +              ^^^^^
    22 
    +18    foo True t
    23 
    +Stopped in Main.foo, T26042c.hs:13:8-12
    24 
    +_result :: Int = _
    25 
    +x :: Int = _
    26 
    +y :: Int = _
    27 
    +12        y = 4
    28 
    +13    bar (x + y)
    29 
    +           ^^^^^
    30 
    +14
    31 
    +14

  • testsuite/tests/ghci.debugger/scripts/all.T
    ... ... @@ -144,3 +144,6 @@ test('T24306', normal, ghci_script, ['T24306.script'])
    144 144 
     test('T24712', normal, ghci_script, ['T24712.script'])
    145 145 
     test('T25109', normal, ghci_script, ['T25109.script'])
    146 146 
     test('T25932', extra_files(['T25932.hs']), ghci_script, ['T25932.script'])
    147 
    +test('T26042a', extra_files(['T26042a.hs']), ghci_script, ['T26042a.script'])
    148 
    +test('T26042b', extra_files(['T26042b.hs']), ghci_script, ['T26042b.script'])
    149 
    +test('T26042c', extra_files(['T26042c.hs']), ghci_script, ['T26042c.script'])

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