July 2018 - ghc-tickets

[GHC] #14770: Allow static pointer expressions to have static pointer free variables
by GHC 14 Sep '18

14 Sep '18

#14770: Allow static pointer expressions to have static pointer free variables -------------------------------------+------------------------------------- Reporter: TheKing01 | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple StaticPointers | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Static pointer expressions can not have free variables. For example: {{{#!hs addPointers :: StaticPtr Int -> StaticPtr Int -> StaticPtr Int addPointers x y = static (deRefStaticPtr x + deRefStaticPtr y) }}} would be invalid, since `x` and `y` are free variables. My proposal would be to make this code sample valid. In particular, my proposal is to allow free variables in `static` expressions if the free variables of the type `StaticPtr a` for some type `a`. Let's say that `m` `n` are Static pointers to integers. The serialized form would of `addPointers m n` would be: A pointer to the code `deRefStaticPtr x + deRefStaticPtr y` The serialized form of `m`, associated with `x`. The serialized form of `n`, associated with `y`. When this is sent over the wire and dereferenced, the other machine would Find `m` and `n`'s pointers Find the code `deRefStaticPtr x + deRefStaticPtr y` Evaluate `deRefStaticPtr x + deRefStaticPtr y`, substituting `m`'s value for `x`, and `n`'s value for y. The reason this feature would be useful is would let the user modify and combine static pointers. You might ask "why not let the user create a GADT to do that (like in https://hackage.haskell.org/package/distributed-static-0.3.8/docs/Control- Distributed-Static.html#t:Static)?" The reason is that then it won't fuse (with recreating every fusion rule for that GADT). For example, if `m` is `static 7` and `n` is `static 3`, then `addPointers m n` can fuse to `static 11`. This is more important then it seems. For example, say you have `composePointers :: StaticPtr (a -> b) -> StaticPtr (b -> c) -> StaticPtr (a -> c)`, and you compose a bunch of pointers. With the GADTS, every `composePointers` would be its own node, but with GHC support, it would probably fuse. In general, dealing with a GADT requires a lot of "glue code" that can be eliminated with GHC support. I'm not sure if this proposal makes a performance difference (it probably makes it more efficient), but it would make code more elegant, cutting out all the glue code. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14770> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14313: “Result signatures are no longer supported in pattern matches” lost
by GHC 14 Sep '18

14 Sep '18

#14313: “Result signatures are no longer supported in pattern matches” lost -------------------------------------+------------------------------------- Reporter: nomeata | Owner: (none) Type: task | Status: new Priority: low | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #2310 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This commit (b98ff25f4c8cb4bf18b784c848fabaaa6e4b11b8) from two years ago broke the error message (at least according to when `T2310.stderr` was modified): {{{ T2310.hs:5:22: Illegal result type signature ‘a’ Result signatures are no longer supported in pattern matches In a lambda abstraction: \ x :: a -> (x :: a) }}} that was displayed previously. Either we do want that error message (then this is a bug) or we don’t care about this error message any more, then probably we can remove the `m_type` field of `Match` in `HsExpr`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14313> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14229: Contraditions in users_guide/using-warnings.html
by GHC 14 Sep '18

14 Sep '18

#14229: Contraditions in users_guide/using-warnings.html -------------------------------------+------------------------------------- Reporter: | Owner: (none) MikolajKonarski | Type: bug | Status: new Priority: low | Milestone: Component: Documentation | Version: 8.2.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Documentation Unknown/Multiple | bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Lists are not updated in https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/using- warnings.html E.g., it says "The warnings that are not enabled by -Wall are ...-Wredundant-constraints", but then it says "This option is on by default". Also "-Worphans" is on none of the list of enabled or not enabled flags and also there is no mention in its description if its enabled by default or not. I guess there may be more. Also, it may be worth mentioning that obsolete warnings or warnings subsumed by others are not on any of the list, or whatever the actual rule is. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14229> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14711: Machine readable output of coverage
by GHC 14 Sep '18

14 Sep '18

#14711: Machine readable output of coverage -------------------------------------+------------------------------------- Reporter: Koterpillar | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Code Coverage | Version: 8.2.2 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: -------------------------------------+------------------------------------- When integrating with a CI system, it might be useful to fail the build, alert or take other actions based on coverage percentage. To do that, hpc needs to output a summary coverage report in a machine readable format. For example, the current output: {{{ 38% expressions used (1779/4624) 57% boolean coverage (16/28) 56% guards (9/16), 6 always True, 1 always False 58% 'if' conditions (7/12), 2 always False, 3 unevaluated 100% qualifiers (0/0) 7% alternatives used (103/1410) 75% local declarations used (102/136) 40% top-level declarations used (185/457) }}} can be represented as: {{{ { expressions: { total: 4624, used: 1779, percentage: 0.38 }, boolean: { total: 28, used: 16, percentage: 0.57 }, <...> } }}} This output can be then parsed to decide whether to fail the build, produce a coverage graph over time, etc. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14711> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14099: Document fundeps
by GHC 14 Sep '18

14 Sep '18

#14099: Document fundeps -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Component: Documentation | Version: 8.2.1 Keywords: newcomers | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Currently the documentation for functional dependencies in the GHC user's guide is quite poor. Fix this. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14099> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11143: Feature request: Add index/read/write primops with byte offset for ByteArray#
by GHC 14 Sep '18

14 Sep '18

#11143: Feature request: Add index/read/write primops with byte offset for ByteArray# -------------------------------------+------------------------------------- Reporter: vagarenko | Owner: Type: feature | Status: new request | Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 7.10.2 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: -------------------------------------+------------------------------------- Currently, primops for indexing `ByteArray#` and reading/writing `MutableByteArray#` have the following form: {{{#!hs indexTYPEArray# :: ByteArray# -> Int# -> TYPE# readTYPEArray# :: MutableByteArray# s -> Int# -> State# s -> (#State# s, TYPE##) writeTYPEArray# :: MutableByteArray# s -> Int# -> TYPE# -> State# s -> State# s }}} where second argument of type `Int#` is an offset measured in terms of the size of `TYPE#`. This is inconvinient if I want to store values of different types inside `ByteArray#`: I have to read values of type `Int8` and then glue them together with some bitwise operations. I suggest adding number of primops, similar to existing ones, which would accept offset in bytes from the start of the `ByteArray#`: {{{#!hs -- | Read 8-bit integer; offset in bytes. indexByteInt8Array# :: ByteArray# -> Int# -> Int# -- | Read 16-bit integer; offset in bytes. indexByteInt16Array# :: ByteArray# -> Int# -> Int# -- | Read 32-bit integer; offset in bytes. indexByteInt32Array# :: ByteArray# -> Int# -> Int# -- | Read 8-bit integer; offset in bytes. readInt8Array# :: MutableByteArray# s -> Int# -> State# s -> (#State# s, Int##) -- | Read 16-bit integer; offset in bytes. readInt16Array# :: MutableByteArray# s -> Int# -> State# s -> (#State# s, Int##) -- | Read 32-bit integer; offset in bytes. readInt32Array# :: MutableByteArray# s -> Int# -> State# s -> (#State# s, Int##) }}} and so on... -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11143> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10700: include/stg/Prim.h isn't C++ compatible
by GHC 14 Sep '18

14 Sep '18

#10700: include/stg/Prim.h isn't C++ compatible -------------------------------------+------------------------------------- Reporter: Fabian | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build | Version: 7.10.1 System | Keywords: FFI | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- StgWord hs_cmpxchg8(volatile StgWord8 *x, StgWord old, StgWord new); and a few other declarations in Prim.h causes problems as they use ''new'' as a variable name. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10700> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10833: Use injective type families when dealing with givens
by GHC 14 Sep '18

14 Sep '18

#10833: Use injective type families when dealing with givens -------------------------------------+------------------------------------- Reporter: jstolarek | Owner: jstolarek Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #6018 Differential Revisions: | -------------------------------------+------------------------------------- Consider this code: {{{#!hs type family Id a = r | r -> a id :: (Id a ~ Id b) => a -> b id x = x }}} GHC currently rejects it because it does not use type family injectivity information when dealing with the given constraints. Implementing this requires changing Core. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10833> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14902: GHC HEAD cannot be booted GHC 8.4.1
by GHC 13 Sep '18

13 Sep '18

#14902: GHC HEAD cannot be booted GHC 8.4.1 -------------------------------------+------------------------------------- Reporter: osa1 | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 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: -------------------------------------+------------------------------------- I get this when I try to boot GHC HEAD with GHC 8.4.1 (using official binaries): {{{ $ make ===--- building phase 0 make --no-print-directory -f ghc.mk phase=0 phase_0_builds utils/genprimopcode/ghc.mk:19: utils/genprimopcode/dist/package-data.mk: No such file or directory utils/deriveConstants/ghc.mk:19: utils/deriveConstants/dist/package- data.mk: No such file or directory utils/genapply/ghc.mk:23: utils/genapply/dist/package-data.mk: No such file or directory libraries/hpc/ghc.mk:3: libraries/hpc/dist-boot/package-data.mk: No such file or directory libraries/binary/ghc.mk:3: libraries/binary/dist-boot/package-data.mk: No such file or directory libraries/text/ghc.mk:3: libraries/text/dist-boot/package-data.mk: No such file or directory libraries/transformers/ghc.mk:3: libraries/transformers/dist-boot/package- data.mk: No such file or directory libraries/mtl/ghc.mk:3: libraries/mtl/dist-boot/package-data.mk: No such file or directory libraries/parsec/ghc.mk:3: libraries/parsec/dist-boot/package-data.mk: No such file or directory libraries/Cabal/Cabal/ghc.mk:3: libraries/Cabal/Cabal/dist-boot/package- data.mk: No such file or directory libraries/ghc-boot-th/ghc.mk:3: libraries/ghc-boot-th/dist-boot/package- data.mk: No such file or directory libraries/ghc-boot/ghc.mk:3: libraries/ghc-boot/dist-boot/package-data.mk: No such file or directory libraries/template-haskell/ghc.mk:3: libraries/template-haskell/dist-boot /package-data.mk: No such file or directory libraries/terminfo/ghc.mk:3: libraries/terminfo/dist-boot/package-data.mk: No such file or directory libraries/ghci/ghc.mk:3: libraries/ghci/dist-boot/package-data.mk: No such file or directory compiler/ghc.mk:446: compiler/stage1/package-data.mk: No such file or directory utils/hsc2hs/ghc.mk:21: utils/hsc2hs/dist/package-data.mk: No such file or directory utils/ghc-pkg/ghc.mk:70: utils/ghc-pkg/dist/package-data.mk: No such file or directory ghc/ghc.mk:111: ghc/stage1/package-data.mk: No such file or directory "inplace/bin/ghc-cabal" configure libraries/binary dist-boot --with- ghc="/home/omer/ghc_bins/ghc-8.4.1-bin/bin/ghc" --with-ghc- pkg="/home/omer/ghc_bins/ghc-8.4.1-bin/bin/ghc-pkg" --package- db=/home/omer/haskell/ghc/libraries/bootstrapping.conf --disable-library- for-ghci --enable-library-vanilla --enable-library-for-ghci --disable- library-profiling --disable-shared --configure-option=CFLAGS="-Wall -fno- stack-protector -Werror=unused-but-set-variable -Wno-error=inline" --configure- option=LDFLAGS=" " --configure-option=CPPFLAGS=" " --gcc-options="-Wall -fno-stack-protector -Werror=unused-but-set-variable -Wno-error=inline " --constraint "binary == 0.8.5.1" --constraint "text == 1.2.3.0" --constraint "transformers == 0.5.5.0" --constraint "mtl == 2.2.2" --constraint "parsec == 3.1.13.0" --constraint "Cabal == 2.2.0.0" --constraint "hpc == 0.6.0.3" --constraint "ghc-boot-th == 8.5" --constraint "ghc-boot == 8.5" --constraint "template-haskell == 2.13.0.0" --constraint "ghci == 8.5" --constraint "terminfo == 0.4.1.1" --with-gcc="gcc" --with-ld="ld.gold" --with-ar="ar" --with- alex="/home/omer/.local/bin/alex" --with- happy="/home/omer/.local/bin/happy" Warning: binary.cabal:19:24: unexpected unknown build-type: 'Simple' Simple ghc-cabal: dieVerbatim: user error (ghc-cabal: Failed parsing "./binary.cabal". ) libraries/binary/ghc.mk:3: recipe for target 'libraries/binary/dist-boot /package-data.mk' failed make[1]: *** [libraries/binary/dist-boot/package-data.mk] Error 1 Makefile:122: recipe for target 'all' failed make: *** [all] Error 2 }}} Switching to 8.2.1 works fine. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14902> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12420: Users guide link for hsc2hs has bitrotten
by GHC 13 Sep '18

13 Sep '18

#12420: Users guide link for hsc2hs has bitrotten -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: task | Status: new Priority: normal | Milestone: Component: hsc2hs | 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: -------------------------------------+------------------------------------- https://hackage.haskell.org/package/hsc2hs links to http://www.haskell.org/ghc/docs/latest/html/users_guide/hsc2hs.html which is dead. I think https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/utils.html #writing-haskell-interfaces-to-c-code-hsc2hs is what is desired. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12420> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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