November 2014 - ghc-tickets

[GHC] #9011: panic - interactiveUI:setBuffering2
by GHC 06 Nov '14

06 Nov '14

#9011: panic - interactiveUI:setBuffering2 ----------------------------------+------------------------------- Reporter: irneb | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.6.3 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: GHCi crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+------------------------------- I've looked through some other tickets and tried installing libffi5, though in my distro (Kubuntu 13.10 x86-64) only libffi6 is available. Even after installing that I get the following: {{{ $ ghci GHCi, version 7.6.3: http://www.haskell.org/ghc/ :? for help ghc: panic! (the 'impossible' happened) (GHC version 7.6.3 for x86_64-unknown-linux): interactiveUI:setBuffering2 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9011> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7531: after manualy installing array-0.4.0.1
by GHC 06 Nov '14

06 Nov '14

#7531: after manualy installing array-0.4.0.1 -----------------------------------------+--------------------------- Reporter: guest | Owner: igloo Type: bug | Status: closed Priority: normal | Milestone: 7.8.1 Component: Package system | Version: 7.6.1 Resolution: worksforme | Keywords: Operating System: Windows | Architecture: x86 Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: #7692 Differential Revisions: | -----------------------------------------+--------------------------- Changes (by thomie): * related: => #7692 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7531#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7692: ghci -ignore-package base lets the impossible happen
by GHC 06 Nov '14

06 Nov '14

#7692: ghci -ignore-package base lets the impossible happen -------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.6.2 Resolution: wontfix | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: | Blocked By: None/Unknown | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by thomie): This has been fixed somewhere along the way: {{{ $ ghci -ignore-package base GHCi, version 7.8.3: http://www.haskell.org/ghc/ :? for help Top level: Failed to load interface for ‘Prelude’ Use -v to see a list of the files searched for. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7692#comment:2> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9771: Excessive memory usage compiling T3064
by GHC 06 Nov '14

06 Nov '14

#9771: Excessive memory usage compiling T3064 -------------------------------------+------------------------------------- Reporter: hvr | Owner: simonpj Type: bug | Status: new Priority: highest | Milestone: 7.10.1 Component: Compiler | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Compile- Blocked By: | time performance bug Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- With 64dc4d1085a7db375f6532362bf7e23fac3a25eb the testsuite suffers from T3064 allocating an excessive amount of memory (several GiBs) and finally getting killed due to timeout and/or out-of-memory. {{{ =====> T3064(normal) 3054 of 4150 [0, 0, 0] cd ./perf/compiler && '/home/hvr/ghc/inplace/bin/ghc-stage2' -fforce- recomp -dno-debug-output -no-user-package-db -rtsopts -fno-warn-tabs -fno- ghci-history -c T3064.hs +RTS -V0 -tT3064.comp.stats --machine-readable -RTS >T3064.comp.stderr 2>&1 Compile failed (status 35072) errors were: Killed Failed to find field: peak_megabytes_allocated *** framework failure for T3064(normal) do_test exception Traceback (most recent call last): File "/home/hvr/ghc/testsuite/driver/testlib.py", line 793, in do_test result = func(*[name,way] + args) File "/home/hvr/ghc/testsuite/driver/testlib.py", line 995, in compile return do_compile( name, way, 0, '', [], extra_hc_opts ) File "/home/hvr/ghc/testsuite/driver/testlib.py", line 1024, in do_compile result = simple_build( name, way, extra_hc_opts, should_fail, top_mod, 0, 1, force, override_flags ) File "/home/hvr/ghc/testsuite/driver/testlib.py", line 1262, in simple_build statsResult = checkStats(name, way, stats_file, opts.compiler_stats_range_fields) File "/home/hvr/ghc/testsuite/driver/testlib.py", line 1136, in checkStats val = int(m.group(1)) AttributeError: 'NoneType' object has no attribute 'group' OVERALL SUMMARY for test run started at Wed Nov 5 08:29:10 2014 CET 0:04:14 spent to go through 4150 total tests, which gave rise to 16187 test cases, of which 16186 were skipped 0 had missing libraries 0 expected passes 0 expected failures 1 caused framework failures 0 unexpected passes 0 unexpected failures 0 unexpected stat failures make[1]: Leaving directory '/home/hvr/ghc/testsuite/tests' real 4m13.317s user 3m49.476s sys 0m5.831s }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9771> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3064: Very long compile times with type functions
by GHC 06 Nov '14

06 Nov '14

#3064: Very long compile times with type functions -------------------------------------------------+------------------------- Reporter: simonpj | Owner: Type: bug | Status: Priority: low | closed Component: Compiler (Type checker) | Milestone: 7.6.1 Resolution: fixed | Version: Operating System: Unknown/Multiple | 6.10.1 Type of failure: Compile-time performance bug | Keywords: Test Case: perf/compiler/T3064 | Architecture: Blocking: | Unknown/Multiple | Difficulty: | Unknown | Blocked By: | Related Tickets: -------------------------------------------------+------------------------- Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"096b7e664351d102cc9e15f3aa226a976af5dae2/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="096b7e664351d102cc9e15f3aa226a976af5dae2" Switch off lazy flattening (fix Trac #3064) See Note [Lazy flattening] in TcFlatten. Lazy flattening was an apparently good idea which actually made the type inference engine go a LOTS slower in T3064. So I switched it off again. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3064#comment:17> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9774: Type error messages containing calls to assert could be prettier.
by GHC 06 Nov '14

06 Nov '14

#9774: Type error messages containing calls to assert could be prettier. -------------------------------------+------------------------------------- Reporter: josef | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- The following piece of code contains a type error. It also contains a call to `assert`. {{{#!hs import Control.Exception.Assert main = putStrLn (assert True 'a') }}} GHC 7.8.3 reports the type error as follows: {{{ Err.hs:3:30: Couldn't match type ‘Char’ with ‘[Char]’ Expected type: String Actual type: Char In the third argument of ‘GHC.IO.Exception.assertError’, namely ‘'a'’ In the first argument of ‘putStrLn’, namely ‘(GHC.IO.Exception.assertError "Err.hs:3:18-23"## True 'a')’ In the expression: putStrLn (GHC.IO.Exception.assertError "Err.hs:3:18-23"## True 'a') }}} The calls to `assert` has already been desugared, which is not necessarily very readable. I think it would be better if GHC just printed the call to `assert` as it appeared in the source. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9774> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9358: Improve flag description in the user guide
by GHC 06 Nov '14

06 Nov '14

#9358: Improve flag description in the user guide -------------------------------------+------------------------------------- Reporter: jstolarek | Owner: Type: bug | Status: new Priority: low | Milestone: 7.10.1 Component: Documentation | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Easy (less than 1 | Type of failure: hour) | Documentation bug Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Sections 4.20 (Flag reference) and 4.10.2 (-f*: platform-independent flags) of the User Guide could use some updating: - `-floopification` is mentioned in 4.20 but not in 4.10.2 (which, sadly, is my fault), - Section 4.10.2 says: "These flags turn on and off individual optimisations. They are normally set via the -O options (...) The flags below are off by default, except where noted below." Does the last sentence mean they are on by default for `-O` or that they are enabled even with `-O0` (which is the default optimisation level)? - What is the default value of `-fmax-simplifier-iterations`? - 4.20 mentions `-fmax-simplifier-iterations`, `-fmax-relevant-bindings` and `-fmax-worker-args` but only the first one is described in 4.10.2 I suspect there are more inconsistencies. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9358> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7192: Bug in -fregs-graph with -fnew-codegen
by GHC 06 Nov '14

06 Nov '14

#7192: Bug in -fregs-graph with -fnew-codegen -------------------------------------+------------------------------------- Reporter: simonmar | Owner: benl Type: bug | Status: closed Priority: highest | Milestone: 7.8.1 Component: Compiler | Version: 7.7 Resolution: fixed | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: | Blocked By: None/Unknown | Related Tickets: Test Case: | Blocking: 4258 | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by jstolarek): Replying to [comment:17 simonmar]: > The comment is wrong, I'll fix it. Please don't. I'll fix it. I'm just working on that code in DynFlags. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7192#comment:18> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7192: Bug in -fregs-graph with -fnew-codegen
by GHC 06 Nov '14

06 Nov '14

#7192: Bug in -fregs-graph with -fnew-codegen -------------------------------------+------------------------------------- Reporter: simonmar | Owner: benl Type: bug | Status: closed Priority: highest | Milestone: 7.8.1 Component: Compiler | Version: 7.7 Resolution: fixed | Keywords: Operating System: | Architecture: Unknown/Multiple Unknown/Multiple | Difficulty: Unknown Type of failure: | Blocked By: None/Unknown | Related Tickets: Test Case: | Blocking: 4258 | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by simonmar): @jstolarek we don't want to turn it on by default due to #7679. The comment is wrong, I'll fix it. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7192#comment:17> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9741: Interpreter stack checks are not quite right
by GHC 06 Nov '14

06 Nov '14

#9741: Interpreter stack checks are not quite right -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- In my experimental branch, I'm getting this failure on `tests/ghci/should_run/ghcirun002`: {{{ <interactive>: internal error: ASSERTION FAILED: file rts/Interpreter.c, line 778 (GHC version 7.9.20141029 for x86_64_unknown_linux) }}} The ASSERTION failure means that I must have `-DDEBUG` in my RTS; I have no idea why. My `validate.mk` looks like this: {{{ GhcStage1HcOpts += -ticky -DDEBUG GhcStage2HcOpts += -ticky GhcLibHcOpts += -Wwarn -ticky SplitObjs = YES }}} That is mysterious but not the main point. Somehow we are getting a stack overflow in the interpreter. So I added this line to `Interpreter` on line 772: {{{ debugBelch ( "Interpreter Sp=%p SpLim=%p headroom = %ld\n\n", Sp, SpLim, Sp-SpLim ) ; }}} Sure enough, when running test `ghcirun002` on HEAD, I get this output {{{ Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0238 SpLim=0x7f42649d00c0 headroom = 47 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0228 SpLim=0x7f42649d00c0 headroom = 45 Interpreter Sp=0x7f42649d0210 SpLim=0x7f42649d00c0 headroom = 42 Interpreter Sp=0x7f4264b40230 SpLim=0x7f4264b400c0 headroom = 46 Interpreter Sp=0x7f42649e1230 SpLim=0x7f42649e10c0 headroom = 46 Interpreter Sp=0x7f42649d9230 SpLim=0x7f42649d90c0 headroom = 46 Interpreter Sp=0x7f4264182230 SpLim=0x7f42641820c0 headroom = 46 Interpreter Sp=0x7f426417a230 SpLim=0x7f426417a0c0 headroom = 46 Interpreter Sp=0x7f4264172230 SpLim=0x7f42641720c0 headroom = 46 Interpreter Sp=0x7f426416a230 SpLim=0x7f426416a0c0 headroom = 46 Interpreter Sp=0x7f4264162230 SpLim=0x7f42641620c0 headroom = 46 Interpreter Sp=0x7f426415a230 SpLim=0x7f426415a0c0 headroom = 46 Interpreter Sp=0x7f4264152230 SpLim=0x7f42641520c0 headroom = 46 Interpreter Sp=0x7f426414a230 SpLim=0x7f426414a0c0 headroom = 46 Interpreter Sp=0x7f4264142230 SpLim=0x7f42641420c0 headroom = 46 Interpreter Sp=0x7f426413a230 SpLim=0x7f426413a0c0 headroom = 46 Interpreter Sp=0x7f4264132230 SpLim=0x7f42641320c0 headroom = 46 Interpreter Sp=0x7f42649d0238 SpLim=0x7f42649d00c0 headroom = 47 Interpreter Sp=0x7f4264a1e238 SpLim=0x7f4264a1e0c0 headroom = 47 Interpreter Sp=0x7f4264a16238 SpLim=0x7f4264a160c0 headroom = 47 Interpreter Sp=0x7f4264a0e238 SpLim=0x7f4264a0e0c0 headroom = 47 Interpreter Sp=0x7f4264a06238 SpLim=0x7f4264a060c0 headroom = 47 Interpreter Sp=0x7f4257ff8238 SpLim=0x7f4257ff80c0 headroom = 47 Interpreter Sp=0x7f4257ff0238 SpLim=0x7f4257ff00c0 headroom = 47 Interpreter Sp=0x7f4257fe8238 SpLim=0x7f4257fe80c0 headroom = 47 Interpreter Sp=0x7f4257fe0238 SpLim=0x7f4257fe00c0 headroom = 47 Interpreter Sp=0x7f4257fd8238 SpLim=0x7f4257fd80c0 headroom = 47 Interpreter Sp=0x7f4257fd0238 SpLim=0x7f4257fd00c0 headroom = 47 Interpreter Sp=0x7f4257fc8238 SpLim=0x7f4257fc80c0 headroom = 47 Interpreter Sp=0x7f4257fc0238 SpLim=0x7f4257fc00c0 headroom = 47 Interpreter Sp=0x7f4257fb8238 SpLim=0x7f4257fb80c0 headroom = 47 Interpreter Sp=0x7f4257fb0238 SpLim=0x7f4257fb00c0 headroom = 47 Interpreter Sp=0x7f42641f8238 SpLim=0x7f42641f80c0 headroom = 47 Interpreter Sp=0x7f42641f0238 SpLim=0x7f42641f00c0 headroom = 47 Interpreter Sp=0x7f42644f8238 SpLim=0x7f42644f80c0 headroom = 47 Interpreter Sp=0x7f42644ef238 SpLim=0x7f42644ef0c0 headroom = 47 Interpreter Sp=0x7f42644e7238 SpLim=0x7f42644e70c0 headroom = 47 Interpreter Sp=0x7f42644de238 SpLim=0x7f42644de0c0 headroom = 47 Interpreter Sp=0x7f42644d6238 SpLim=0x7f42644d60c0 headroom = 47 Interpreter Sp=0x7f42644ce238 SpLim=0x7f42644ce0c0 headroom = 47 Interpreter Sp=0x7f42644c5238 SpLim=0x7f42644c50c0 headroom = 47 Interpreter Sp=0x7f42644bd238 SpLim=0x7f42644bd0c0 headroom = 47 Interpreter Sp=0x7f42644b4238 SpLim=0x7f42644b40c0 headroom = 47 Interpreter Sp=0x7f42644ac238 SpLim=0x7f42644ac0c0 headroom = 47 Interpreter Sp=0x7f42644a4238 SpLim=0x7f42644a40c0 headroom = 47 Interpreter Sp=0x7f426449b238 SpLim=0x7f426449b0c0 headroom = 47 Interpreter Sp=0x7f4264493238 SpLim=0x7f42644930c0 headroom = 47 Interpreter Sp=0x7f426448a238 SpLim=0x7f426448a0c0 headroom = 47 Interpreter Sp=0x7f4264482238 SpLim=0x7f42644820c0 headroom = 47 Interpreter Sp=0x7f426447a238 SpLim=0x7f426447a0c0 headroom = 47 Interpreter Sp=0x7f426454e238 SpLim=0x7f426454e0c0 headroom = 47 Interpreter Sp=0x7f42641e8238 SpLim=0x7f42641e80c0 headroom = 47 Interpreter Sp=0x7f426417c238 SpLim=0x7f426417c0c0 headroom = 47 Interpreter Sp=0x7f4264174238 SpLim=0x7f42641740c0 headroom = 47 Interpreter Sp=0x7f426416c238 SpLim=0x7f426416c0c0 headroom = 47 Interpreter Sp=0x7f4264164238 SpLim=0x7f42641640c0 headroom = 47 Interpreter Sp=0x7f426415c238 SpLim=0x7f426415c0c0 headroom = 47 Interpreter Sp=0x7f4264154238 SpLim=0x7f42641540c0 headroom = 47 Interpreter Sp=0x7f426414c238 SpLim=0x7f426414c0c0 headroom = 47 Interpreter Sp=0x7f42643e0238 SpLim=0x7f42643e00c0 headroom = 47 Interpreter Sp=0x7f42643d8238 SpLim=0x7f42643d80c0 headroom = 47 Interpreter Sp=0x7f42643d0238 SpLim=0x7f42643d00c0 headroom = 47 Interpreter Sp=0x7f42643c8238 SpLim=0x7f42643c80c0 headroom = 47 Interpreter Sp=0x7f42643c0238 SpLim=0x7f42643c00c0 headroom = 47 Interpreter Sp=0x7f42643b8238 SpLim=0x7f42643b80c0 headroom = 47 Interpreter Sp=0x7f42643e0238 SpLim=0x7f42643e00c0 headroom = 47 Interpreter Sp=0x7f4264154138 SpLim=0x7f42641540c0 headroom = 15 Interpreter Sp=0x7f42641541d0 SpLim=0x7f42641540c0 headroom = 34 Interpreter Sp=0x7f426415c230 SpLim=0x7f426415c0c0 headroom = 46 Interpreter Sp=0x7f4264164130 SpLim=0x7f42641640c0 headroom = 14 Interpreter Sp=0x7f42641641c8 SpLim=0x7f42641640c0 headroom = 33 Interpreter Sp=0x7f426447a0e0 SpLim=0x7f426447a0c0 headroom = 4 Interpreter Sp=0x7f426447a178 SpLim=0x7f426447a0c0 headroom = 23 Interpreter Sp=0x7f426447a210 SpLim=0x7f426447a0c0 headroom = 42 Interpreter Sp=0x7f4264482138 SpLim=0x7f42644820c0 headroom = 15 Interpreter Sp=0x7f42644821d0 SpLim=0x7f42644820c0 headroom = 34 Interpreter Sp=0x7f426448a228 SpLim=0x7f426448a0c0 headroom = 45 Interpreter Sp=0x7f4264493238 SpLim=0x7f42644930c0 headroom = 47 Interpreter Sp=0x7f426449b130 SpLim=0x7f426449b0c0 headroom = 14 Interpreter Sp=0x7f426449b1c8 SpLim=0x7f426449b0c0 headroom = 33 Interpreter Sp=0x7f42644ac0d0 SpLim=0x7f42644ac0c0 headroom = 2 Interpreter Sp=0x7f42644ac168 SpLim=0x7f42644ac0c0 headroom = 21 Interpreter Sp=0x7f42644ac200 SpLim=0x7f42644ac0c0 headroom = 40 Interpreter Sp=0x7f42644b4230 SpLim=0x7f42644b40c0 headroom = 46 Interpreter Sp=0x7f42644bd108 SpLim=0x7f42644bd0c0 headroom = 9 Interpreter Sp=0x7f42644bd1a0 SpLim=0x7f42644bd0c0 headroom = 28 Interpreter Sp=0x7f42644bd238 SpLim=0x7f42644bd0c0 headroom = 47 Interpreter Sp=0x7f42644ce140 SpLim=0x7f42644ce0c0 headroom = 16 Interpreter Sp=0x7f42644ce1d8 SpLim=0x7f42644ce0c0 headroom = 35 Interpreter Sp=0x7f42644d6218 SpLim=0x7f42644d60c0 headroom = 43 Interpreter Sp=0x7f42644de0e0 SpLim=0x7f42644de0c0 headroom = 4 Interpreter Sp=0x7f42644de178 SpLim=0x7f42644de0c0 headroom = 23 Interpreter Sp=0x7f42644de210 SpLim=0x7f42644de0c0 headroom = 42 Interpreter Sp=0x7f42644e70c0 SpLim=0x7f42644e70c0 headroom = 0 Interpreter Sp=0x7f42644e7158 SpLim=0x7f42644e70c0 headroom = 19 Interpreter Sp=0x7f42644e71f0 SpLim=0x7f42644e70c0 headroom = 38 Interpreter Sp=0x7f42644ef230 SpLim=0x7f42644ef0c0 headroom = 46 Interpreter Sp=0x7f42644f8190 SpLim=0x7f42644f80c0 headroom = 26 Interpreter Sp=0x7f42644f8228 SpLim=0x7f42644f80c0 headroom = 45 Interpreter Sp=0x7f42641f00d8 SpLim=0x7f42641f00c0 headroom = 3 Interpreter Sp=0x7f42641f0170 SpLim=0x7f42641f00c0 headroom = 22 Interpreter Sp=0x7f42641f0208 SpLim=0x7f42641f00c0 headroom = 41 Interpreter Sp=0x7f4257fb8210 SpLim=0x7f4257fb80c0 headroom = 42 Interpreter Sp=0x7f4257fb80f0 SpLim=0x7f4257fb80c0 headroom = 6 Interpreter Sp=0x7f4257fb8188 SpLim=0x7f4257fb80c0 headroom = 25 Interpreter Sp=0x7f4257fb8220 SpLim=0x7f4257fb80c0 headroom = 44 Interpreter Sp=0x7f4257fc00d0 SpLim=0x7f4257fc00c0 headroom = 2 Interpreter Sp=0x7f4257fc0168 SpLim=0x7f4257fc00c0 headroom = 21 Interpreter Sp=0x7f4257fc0200 SpLim=0x7f4257fc00c0 headroom = 40 Interpreter Sp=0x7f4257fc80b0 SpLim=0x7f4257fc80c0 headroom = -2 <---- NB Interpreter Sp=0x7f4257fc8148 SpLim=0x7f4257fc80c0 headroom = 17 Interpreter Sp=0x7f4257fc81e0 SpLim=0x7f4257fc80c0 headroom = 36 Interpreter Sp=0x7f4257fd0228 SpLim=0x7f4257fd00c0 headroom = 45 Interpreter Sp=0x7f4257fe0228 SpLim=0x7f4257fe00c0 headroom = 45 Interpreter Sp=0x7f4257fe8140 SpLim=0x7f4257fe80c0 headroom = 16 Interpreter Sp=0x7f4257fe81d8 SpLim=0x7f4257fe80c0 headroom = 35 Interpreter Sp=0x7f4257ff0120 SpLim=0x7f4257ff00c0 headroom = 12 Interpreter Sp=0x7f4257ff01b8 SpLim=0x7f4257ff00c0 headroom = 31 Interpreter Sp=0x7f4257ff8100 SpLim=0x7f4257ff80c0 headroom = 8 Interpreter Sp=0x7f4257ff8198 SpLim=0x7f4257ff80c0 headroom = 27 Interpreter Sp=0x7f4257ff8230 SpLim=0x7f4257ff80c0 headroom = 46 Interpreter Sp=0x7f4264a060e0 SpLim=0x7f4264a060c0 headroom = 4 Interpreter Sp=0x7f4264a06178 SpLim=0x7f4264a060c0 headroom = 23 Interpreter Sp=0x7f4264a06210 SpLim=0x7f4264a060c0 headroom = 42 Interpreter Sp=0x7f4264a0e0c0 SpLim=0x7f4264a0e0c0 headroom = 0 Interpreter Sp=0x7f4264a0e158 SpLim=0x7f4264a0e0c0 headroom = 19 Interpreter Sp=0x7f4264a0e1f0 SpLim=0x7f4264a0e0c0 headroom = 38 Interpreter Sp=0x7f4264a16138 SpLim=0x7f4264a160c0 headroom = 15 Interpreter Sp=0x7f4264a161d0 SpLim=0x7f4264a160c0 headroom = 34 Interpreter Sp=0x7f4264a1e118 SpLim=0x7f4264a1e0c0 headroom = 11 }}} So yes, we get into a situation in which we have negative headroom. Presumably if the ASSERT is off, we simply don't notice. But it's clearly wrong. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9741> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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