December 2016 - ghc-tickets

Re: [GHC] #11445: Turn on SplitSections by default
by GHC 01 Dec '16

01 Dec '16

#11445: Turn on SplitSections by default -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: task | Status: new Priority: normal | Milestone: 8.2.1 Component: Build System | Version: 8.0.1-rc1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: 11285 Related Tickets: | Differential Rev(s): Phab:D1800 Wiki Page: | -------------------------------------+------------------------------------- Comment (by dobenour): Phyx-: Ah okay. For some reason I thought that he had. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11445#comment:10> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12796: hschooks.c #include path is incorrect
by GHC 01 Dec '16

01 Dec '16

#12796: hschooks.c #include path is incorrect -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Building GHC Unknown/Multiple | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- When replacing `rtsBool` with the C99 `bool` type I noticed (I think) that `ghc/hschooks.c` seems to be compiled with an incorrect include path. Namely, the `#include "Rts.h"` ends up including the `Rts.h` from the bootstrap compiler, not the stage1 compiler that we are compiling. I'm still not entirely certain that this is the case since it seems something like this should have blown up long ago, but it's late so I'm just leaving this here for now. Relevant command line: {{{ "/opt/exp/ghc/roots/8.0.1/bin/ghc" -optc-fno-stack-protector -optc-Wall -optc-Werror -optc-Ighc/stage1/build/ghc/autogen -optc-I'/opt/exp/ghc/ghc- linker/compiler/.' -optc-I'/opt/exp/ghc/ghc-linker/compiler/parser' -optc-I'/opt/exp/ghc/ghc-linker/compiler/utils' -optc-I'/opt/exp/ghc/ghc- linker/compiler/stage1' -optc-I'/opt/exp/ghc/roots/8.0.1/lib/ghc-8.0.1/process-1.4.2.0/include' -optc-I'/opt/exp/ghc/roots/8.0.1/lib/ghc-8.0.1/directory-1.2.6.2/include' -optc-I'/opt/exp/ghc/roots/8.0.1/lib/ghc-8.0.1/unix-2.7.2.0/include' -optc-I'/opt/exp/ghc/roots/8.0.1/lib/ghc-8.0.1/time-1.6.0.1/include' -optc-I'/opt/exp/ghc/roots/8.0.1/lib/ghc-8.0.1/bytestring-0.10.8.1/include' -optc-I'/opt/exp/ghc/roots/8.0.1/lib/ghc-8.0.1/base-4.9.0.0/include' -optc-I'/opt/exp/ghc/roots/8.0.1/lib/ghc-8.0.1/integer- gmp-1.0.0.1/include' -optc-I'/opt/exp/ghc/roots/8.0.1/lib/ghc-8.0.1/include' -optc-Werror =unused-but-set-variable -optc-Wno-error=inline -static -O0 -H64m -Wall -package-db libraries/bootstrapping.conf -hide-all-packages -i -ighc/. -ighc/stage1/build -Ighc/stage1/build -ighc/stage1/build/ghc/autogen -Ighc/stage1/build/ghc/autogen -optP-include -optPghc/stage1/build/ghc/autogen/cabal_macros.h -package-id array-0.5.1.1 -package-id base-4.9.0.0 -package-id bytestring-0.10.8.1 -package-id directory-1.2.6.2 -package-id filepath-1.4.1.0 -package-id ghc-8.1 -package-id ghc-boot-8.1 -package-id process-1.4.2.0 -package-id unix-2.7.2.0 -Wall -XHaskell2010 -O -DDEBUG -no-hs-main -no-user-package- db -rtsopts -c ghc/hschooks.c -o ghc/stage1/build/hschooks.o }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12796> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11378: Use the compiler that built ghc for dynamic code loading, for cross-compiling
by GHC 01 Dec '16

01 Dec '16

#11378: Use the compiler that built ghc for dynamic code loading, for cross- compiling -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature | Status: new request | Priority: lowest | Milestone: ⊥ Component: Template | Version: 7.11 Haskell | 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: -------------------------------------+------------------------------------- In a non cross-compiled stage 2 compiler, this coincides with what we do today, because the stage 1 implementation of GHC is the same as the stage 2 implementation. But in a cross-compiler, these are NOT the same: the cross-compiler's ghc library handles the package database in the target platform, whereas the compiler that built stage 2 (stage 1)'s ghc library handles the package database for the compiler's platform. So, the correct architecture for supporting compiler plugins is that GHC should use the package-database/interface infrastructure from the compiler which built it (stage 1) to handle loading. A few things to note: 1. There is not a backwards-compatibility problem, because we can assume that stage 1 and stage 2 are built from the same codebase. In particular, this does NOT mean that TH/plugins start working on a stage 1 compiler. You have to have bootstrapped from the same codebase. 2. Plugins (and even Template Haskell) have to be a bit more careful to take advantage of this. We cannot just assume that the package database for plugins is the same as the package database for compiling (revisiting #11244). Template Haskell is even trickier: we should NOT be allowed to use regular imports in splices; they have to go through `TH_ONLY` imports, c.f. #11377 3. Can we actually link against the old version of `ghc`? Yes we can! All we need is (1) for it to have been built with a different IPID, and (2) to use module renaming to rename the relevant modules to a different module name, so that we can import them without a conflict. Stepping back, there have been two approaches for dealing with the problem of Template Haskell/compiler plugins not reliably working: 1. Run the code in an external process run in the target code, or 2. Fix GHC to load code which is appropriately built for the bootstrap platform. While (1) offers a more uniform environment for developers, (2) is absolutely necessary in some situations when you need to load code in the same address space as GHC, e.g. as mentioned in https://mail.haskell.org/pipermail/ghc-devs/2015-November/010478.html Thus, it seems worth pursuing both. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11378> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11377: Template Haskell only imports
by GHC 01 Dec '16

01 Dec '16

#11377: Template Haskell only imports -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature | Status: new request | Priority: low | Milestone: Component: Template | Version: 7.11 Haskell | 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: -------------------------------------+------------------------------------- This is the Template Haskell equivalent of #11244. It should be possible to use the plugin package database to make a Template Haskell only import; I suggest the syntax `import {-# TH_ONLY #-} Foo`. Such imports are only allowed to be used in splices, and cannot be quoted (they are not allowed to reside in the final code generated by the splice.) The reason a user may want to use such an import is that it means that they can declare that a library is necessary when compiling splices, but not necessary when actually linking against it. There are extra benefits. If a user is compiling the package with the splices with profiling, it ordinarily requires all imports to have been compiled with profiling. This would NOT be necessary for a `TH_ONLY` import, since we're only ever going to run the imported code in the (non- profiled) compiler, and not in the (profiled) executable.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11377> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11293: Compiler plugins don't work with profiling
by GHC 01 Dec '16

01 Dec '16

#11293: Compiler plugins don't work with profiling -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Profiling | Version: 7.11 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: -------------------------------------+------------------------------------- Suppose I have a normally built compiler plugin, and I'd like to use it while building some profiled code. This doesn't work: (non-profiled) GHC searches for the profiled version of the plugin. This is wrong wrong wrong: plugin searches should be with respect to how GHC was compiled. (Test case: take the `plugins01` test and add `-prof` to it) Now that we have `-plugin-package`, it should be a simple matter to ensure that plugin lookups follow a different codepath, though I'm not sure how to figure out what GHC is built with; this should just be however TH does it. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11293> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12895: Lookup rules associated with functions/values in GHCI
by GHC 01 Dec '16

01 Dec '16

#12895: Lookup rules associated with functions/values in GHCI -------------------------------------+------------------------------------- Reporter: harpocrates | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: GHCi | 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: -------------------------------------+------------------------------------- It would be nice to have a way to look up in GHCi what rules can fire for a certain constant as the outmost symbol on the LHS. For example, something like {{{ ghci> :pragmas map {-# RULE "map" [~1] forall f xs. map f xs = build (\c n -> foldr (mapFB c f) n xs) #-} {-# RULE "map/coerce" [1] map coerce = coerce #-} }}} As the name suggests, I think we would also want to list applicable NOINLINE, INLINE, INLINABLE, CONLIKE, SPECIALIZE, etc pragmas too. This would simplify the process of debugging mis-firing rules. If this isn't too difficult, I'd love to try implementing it. I've been looking for some way of contributing to GHC. This initially came up here http://stackoverflow.com/q/38651602/3072788. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12895> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11974: `default` declaration doesn't allow higher-kinded types
by GHC 30 Nov '16

30 Nov '16

#11974: `default` declaration doesn't allow higher-kinded types -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: 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: -------------------------------------+------------------------------------- Since we now have #10971, I would expect the following to work: {{{ {-# LANGUAGE ExtendedDefaultRules #-} module Bug where default (Maybe, []) }}} But it doesn't. Sadly, the default default list contains `[]`, but the user can never set this. Fix on the way. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11974> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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