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Re: [GHC] #5654: Profiling semantics bug
by GHC 29 Mar '17

29 Mar '17

#5654: Profiling semantics bug -------------------------------------+------------------------------------- Reporter: simonmar | Owner: (none) Type: bug | Status: closed Priority: low | Milestone: 8.2.1 Component: Profiling | Version: 7.2.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | profiling/should_run/scc004 Blocked By: | Blocking: Related Tickets: #10007 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: merge => closed Comment: Reverted reverting commits on `ghc-8.2` and merged fix to #13433. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5654#comment:24> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13433: Segmentation faults in profiled way
by GHC 29 Mar '17

29 Mar '17

#13433: Segmentation faults in profiled way -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.2.1 Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- It seems that profiling has regressed sometime between GHC 8.0 and 8.2. A few times since September I have noticed that profiled programs (in particular, GHC itself built with profiling enabled) seem to segmentation fault. This most recent case was produced by building commit 6ebfbdfb64cb8bb5c2ddaf2ad3ad350755c5eb2b with the following in `build.mk`, {{{ BuildFlavour = prof define add_mods_flag = $(foreach mod,$(2),$(eval $(basename $(mod))_HC_OPTS += $(1))) endef $(call add_mods_flag,-fprof-auto,$(wildcard compiler/typecheck/*.hs)) STRIP_CMD = : }}} and using the resulting stage2 compiler to bootstrap the same commit. Eventually the build will fail with a segmentation fault. Unfortunately it seems the crash isn't entirely reproducible. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13433> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13491: UNIQUE_BITS is not crosscompiler-friendly
by GHC 29 Mar '17

29 Mar '17

#13491: UNIQUE_BITS is not crosscompiler-friendly -------------------------------------+------------------------------------- Reporter: slyfox | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Things break when I try to build crosscompiler from 32-bit system to 64-bit system. For example i386-linux -> powerpc64-linux: {{{ $ ./configure --target=powerpc64-unknown-linux-gnu --with-system-libffi --with-libffi-includes=/usr/lib/libffi-3.2.1/include/ $ make "inplace/bin/ghc-stage1" -static -H32m -O -optc-I/usr/lib/libffi-3.2.1/include -Wall -Iincludes -Iincludes/dist -Iincludes/dist-derivedconstants/header -Iincludes/dist- ghcconstants/header -Irts -Irts/dist/build -DCOMPILING_RTS -this-unit-id rts -dcmm-lint -i -irts -irts/dist/build -Irts/dist/build -irts/dist/build/./autogen -Irts/dist/build/./autogen -O2 -Wno ncanonical-monad-instances -c rts/StgStartup.cmm -o rts/dist/build/StgStartup.o /tmp/ghc19687_0/ghc_4.s: Assembler messages: /tmp/ghc19687_0/ghc_4.s:11:0: error: Error: unknown pseudo-op: `.l' | 11 | .L�4: | ^ }}} The problem here comes from definition of `UNIQUE_BITS`: {{{#!hs # cat compiler/Unique.h #include "../includes/MachDeps.h" #define UNIQUE_BITS (WORD_SIZE_IN_BITS - 8) }}} Here `WORD_SIZE_IN_BITS` is a target platform size (64) while `stage1` is still running on host platform (32). As a result uniques truncate down to zero: {{{#!hs compiler/basicTypes/Unique.hs: tag = ord c `shiftL` UNIQUE_BITS compiler/basicTypes/Unique.hs: tag = chr (u `shiftR` UNIQUE_BITS) }}} As we operate on host '''Int'''s we could use the following: {{{#!hs #define UNIQUE_BITS sizeof(HsInt) * 8 -- C code #define UNIQUE_BITS (finiteBitSize (undefined :: Int) * 8) -- Haskell code }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13491> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8501: Improve error message when using rec/mdo keyword without RecursiveDo extention.
by GHC 29 Mar '17

29 Mar '17

#8501: Improve error message when using rec/mdo keyword without RecursiveDo extention. -------------------------------------+------------------------------------- Reporter: shelarcy | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Parser) | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #3968 | -------------------------------------+------------------------------------- GHC shows unhelpful error message when using rec keyword and/or mdo keyword without RecursiveDo extention. {{{ module NoRecursiveDo where foo = do rec str <- return "foo" putStrLn str }}} {{{ $ ghc -c NoRecursiveDo.hs NoRecursiveDo1.hs:4:5: Parse error in pattern: rec }}} {{{ module NoRecursiveDo2 where bar = mdo str <- return "bar" putStrLn str }}} {{{ $ ghc -c NoRecursiveDo2.hs NoRecursiveDo2.hs:4:9: parse error on input `<-' }}} {{{ module NoRecursiveDo3 where baz = mdo putStrLn "baz" }}} {{{ $ ghc -c NoRecursiveDo3.hs NoRecursiveDo3.hs:3:7: Not in scope: `mdo' Perhaps you meant `mod' (imported from Prelude) }}} I think that GHC should suggest to use RecursiveDo extention when using mdo/rec keyword. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8501> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13454: Operators not allowed as fields in Record Pattern Synonyms
by GHC 29 Mar '17

29 Mar '17

#13454: Operators not allowed as fields in Record Pattern Synonyms -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple PatternSynonyms | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I want to write the following record pattern synonym {{{#!hs pattern MkOp :: Op -> Exp -> Exp -> Exp pattern MkOp {(·), a, b} <- (splitOp -> Just ((·), a, b)) where MkOp (·) a b = a · b }}} given this code {{{#!hs data Exp = Val Int | Add Exp Exp | Mul Exp Exp deriving Show type Op = Exp -> Exp -> Exp splitOp :: Exp -> Maybe (Op, Exp, Exp) splitOp (Add a b) = Just (Add, a, b) splitOp (Mul a b) = Just (Mul, a, b) splitOp _ = Nothing }}} It works fine if `(·)` is replaced by `operator`. Fields of regular data types works just fine: {{{#!hs data F a = F { (·) :: a -> a -> a, x :: a, y :: a } f F{(·), x, y} = x·y g F{..} = x·y }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13454> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13490: Ambiguous types with constraints on new variables
by GHC 29 Mar '17

29 Mar '17

#13490: Ambiguous types with constraints on new variables -------------------------------------+------------------------------------- Reporter: crockeea | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The following code fails to compile: {{{ {-# LANGUAGE FlexibleContexts, TypeFamilies #-} import Data.Typeable type family Foo a data C a foo :: (Typeable (C z), z ~ Foo zp) => C zp foo = undefined }}} with the error {{{ • Could not deduce (Typeable z) from the context: (Typeable (C z), z ~ Foo zp) bound by the type signature for: foo :: (Typeable (C z), z ~ Foo zp) => C zp at Bug.hs:(9,8)-(10,9) • In the ambiguity check for ‘foo’ To defer the ambiguity check to use sites, enable AllowAmbiguousTypes In the type signature: foo :: (Typeable (C z), z ~ Foo zp) => C zp }}} It's quite unclear why GHC feels thta it needs `Typeable z`. The code compiles if I change the `Typeable` constraint to `Typeable (C (Foo zp))`, which should be identical to what I wrote. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13490> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13496: Add Generic instance to GHC.Stack.SrcLoc
by GHC 29 Mar '17

29 Mar '17

#13496: Add Generic instance to GHC.Stack.SrcLoc -------------------------------------+------------------------------------- Reporter: Fuuzetsu | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: | Version: 8.0.1 libraries/base | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Useful for deriving orphan instances. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13496> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5288: Less noisy version of -fwarn-name-shadowing
by GHC 29 Mar '17

29 Mar '17

#5288: Less noisy version of -fwarn-name-shadowing -------------------------------------+------------------------------------- Reporter: batterseapower | Owner: (none) Type: feature request | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.0.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by mpickering): I think there still needs to be a proper specification and then of course an implementation. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5288#comment:17> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5288: Less noisy version of -fwarn-name-shadowing
by GHC 29 Mar '17

29 Mar '17

#5288: Less noisy version of -fwarn-name-shadowing -------------------------------------+------------------------------------- Reporter: batterseapower | Owner: (none) Type: feature request | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.0.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by ntc2): * cc: nathan.collins@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5288#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5288: Less noisy version of -fwarn-name-shadowing
by GHC 29 Mar '17

29 Mar '17

#5288: Less noisy version of -fwarn-name-shadowing -------------------------------------+------------------------------------- Reporter: batterseapower | Owner: (none) Type: feature request | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.0.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by ntc2): +1 (and is there a better way to say "I like this idea" than adding a "+1" comment like this?) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5288#comment:15> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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