March 2015 - ghc-tickets

[GHC] #10224: Partial type signatures generate typed hole warnings
by GHC 17 Jul '15

17 Jul '15

#10224: Partial type signatures generate typed hole warnings -------------------------------------+------------------------------------- Reporter: quchen | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.2 Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- GHCi generates typed hole warnings in type signatures even when PartialTypeSignatures is enabled: {{{ > :set -XPartialTypeSignatures > :t (==) :: Char -> _ <interactive>:1:17: Warning: Found hole ‘_’ with type: Char -> Bool In an expression type signature: Char -> _ In the expression: (==) :: Char -> _ (==) :: Char -> _ :: Char -> Char -> Bool > :set -XNoPartialTypeSignatures > :t (==) :: Char -> _ <interactive>:1:17: Found hole ‘_’ with type: Char -> Bool To use the inferred type, enable PartialTypeSignatures In an expression type signature: Char -> _ In the expression: (==) :: Char -> _ }}} Similarly, GHC 7.10.1, when given the following source, {{{ {-# LANGUAGE PartialTypeSignatures #-} f = (==) :: Char -> _ main = return () }}} mentions that it "found a hole". -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10224> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9243: Recompilation avoidance works imperfectly with -fno-code/-fwrite-interface
by GHC 17 Jul '15

17 Jul '15

#9243: Recompilation avoidance works imperfectly with -fno-code/-fwrite-interface -------------------------+------------------------------------------------- Reporter: | Owner: ezyang | Status: new Type: bug | Milestone: Priority: | Version: 7.9 normal | Operating System: Unknown/Multiple Component: | Type of failure: Compile-time performance bug Compiler | Test Case: Keywords: | Blocking: Architecture: | Unknown/Multiple | Difficulty: | Unknown | Blocked By: | Related Tickets: | -------------------------+------------------------------------------------- With the latest `-fwrite-interface` enhancements, a build directory can contain interface files independently of object files. In cases like this, we would like to have recompilation avoidance avoid typechecking files whose interface files are up-to-date. However, this does not currently work: we always re-typecheck: {{{ t-edyang@cam-05-unx:/5playpen/t-edyang/sandbox/q$ /5playpen/t-edyang/ghc- backpack/inplace/bin/ghc-stage2 --make A.hs -fno-code -fwrite-interface [1 of 1] Compiling A ( A.hs, nothing ) t-edyang@cam-05-unx:/5playpen/t-edyang/sandbox/q$ /5playpen/t-edyang/ghc- backpack/inplace/bin/ghc-stage2 --make A.hs -fno-code -fwrite-interface [1 of 1] Compiling A ( A.hs, nothing ) }}} The reason for this is that recompilation avoidance logic in `compileOne` (in `DriverPipeline.hs`) seems to rely exclusively on "linkables" in order to figure out if source has been modified or not. We never generate an object file with `-fwrite-interface`, so the compiler always concludes that we need to retypecheck. However, recompilation avoidance for hs-boot does work. The reason for this is because we create a dummy o-boot linkable. We can't use this strategy for `-fno-code`, because the dummy object file would imply that we actually compiled the file (which we didn't). The upshot is that to fix this problem, it looks like we might have to rejigger all of the logic in `compileOne`, which why I gave up on this for now. Related to https://github.com/haskell/cabal/issues/1179 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9243> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9618: Undocument ImpredicativeTypes
by GHC 16 Jul '15

16 Jul '15

#9618: Undocument ImpredicativeTypes -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Documentation | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Easy (less than 1 | Type of failure: hour) | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- I understand that Simon Peyton Jones intends to make `ImpredicativeTypes` work some day, but it doesn't work now. I think the thing to do for now is to remove it from the user manual. It can be put back in later if it's ever fixed. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9618> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10009: type inference regression when faking injective type families
by GHC 13 Jul '15

13 Jul '15

#10009: type inference regression when faking injective type families -------------------------------------+------------------------------------- Reporter: aavogt | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1-rc1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- ghc-7.10.0.20141222 does not accept the program unless I uncomment the type signature (a :: a). ghc-7.8 accepts it as-is. {{{#!hs {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeFamilies #-} class (UnF (F a) ~ a, Show a) => C a where type F a f :: F a -> a type family UnF a g :: forall a. C a => a -> String g _ = show a where a = f (undefined :: F a) -- :: a }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10009> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8709: `make 1` does not work (well)
by GHC 10 Jul '15

10 Jul '15

#8709: `make 1` does not work (well) ------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Say I do a `sync-all pull` and then fix a bunch of merge errors. The changes mean that I need to recompile the stage-1 compiler. So, I dutifully `make distclean` and start rebuilding. I then find a bunch of compiler errors in my edited code. Now, I'd like to start the fix error/recompile loop. BUT, when I do `make 1` in the `compiler/` directory, I get errors: {{{ rae:13:49:29 ~/Documents/ghc/compiler> make 1 make -C .. stage=1 all_ghc_stage1 compiler_dist_NO_BUILD_DEPS=YES compiler_dist-boot_NO_BUILD_DEPS=YES compiler_dist- install_NO_BUILD_DEPS=YES NO_GENERATED_MAKEFILE_RULES=YES OMIT_PHASE_0=YES OMIT_PHASE_1=YES compiler_stage1_NO_BUILD_DEPS=YES compiler_stage2_NO_BUILD_DEPS=YES compiler_stage3_NO_BUILD_DEPS=YES ghc_stage1_NO_BUILD_DEPS=YES ghc_stage2_NO_BUILD_DEPS=YES ghc_stage3_NO_BUILD_DEPS=YES ONLY_DEPS_FOR="compiler_stage1 ghc_stage1" ===--- building final phase make -r --no-print-directory -f ghc.mk phase=final all_ghc_stage1 libraries/old-time/ghc.mk:5: libraries/old-time/dist-install/package- data.mk: No such file or directory libraries/haskell98/ghc.mk:5: libraries/haskell98/dist-install/package- data.mk: No such file or directory libraries/haskell2010/ghc.mk:5: libraries/haskell2010/dist-install /package-data.mk: No such file or directory libraries/random/ghc.mk:5: libraries/random/dist-install/package-data.mk: No such file or directory libraries/primitive/ghc.mk:5: libraries/primitive/dist-install/package- data.mk: No such file or directory libraries/vector/ghc.mk:5: libraries/vector/dist-install/package-data.mk: No such file or directory libraries/dph/dph-base/ghc.mk:5: libraries/dph/dph-base/dist-install /package-data.mk: No such file or directory libraries/dph/dph-prim-interface/ghc.mk:5: libraries/dph/dph-prim- interface/dist-install/package-data.mk: No such file or directory libraries/dph/dph-prim-seq/ghc.mk:5: libraries/dph/dph-prim-seq/dist- install/package-data.mk: No such file or directory libraries/dph/dph-prim-par/ghc.mk:5: libraries/dph/dph-prim-par/dist- install/package-data.mk: No such file or directory libraries/dph/dph-lifted-base/ghc.mk:5: libraries/dph/dph-lifted-base /dist-install/package-data.mk: No such file or directory libraries/dph/dph-lifted-boxed/ghc.mk:5: libraries/dph/dph-lifted-boxed /dist-install/package-data.mk: No such file or directory libraries/dph/dph-lifted-copy/ghc.mk:5: libraries/dph/dph-lifted-copy /dist-install/package-data.mk: No such file or directory libraries/dph/dph-lifted-vseg/ghc.mk:5: libraries/dph/dph-lifted-vseg /dist-install/package-data.mk: No such file or directory libraries/ghc-prim/ghc.mk:4: libraries/ghc-prim/dist-install/package- data.mk: No such file or directory libraries/integer-gmp/ghc.mk:4: libraries/integer-gmp/dist-install /package-data.mk: No such file or directory libraries/base/ghc.mk:4: libraries/base/dist-install/package-data.mk: No such file or directory libraries/filepath/ghc.mk:4: libraries/filepath/dist-install/package- data.mk: No such file or directory libraries/array/ghc.mk:4: libraries/array/dist-install/package-data.mk: No such file or directory libraries/deepseq/ghc.mk:4: libraries/deepseq/dist-install/package- data.mk: No such file or directory libraries/bytestring/ghc.mk:4: libraries/bytestring/dist-install/package- data.mk: No such file or directory libraries/containers/ghc.mk:4: libraries/containers/dist-install/package- data.mk: No such file or directory libraries/old-locale/ghc.mk:4: libraries/old-locale/dist-install/package- data.mk: No such file or directory libraries/time/ghc.mk:4: libraries/time/dist-install/package-data.mk: No such file or directory libraries/unix/ghc.mk:4: libraries/unix/dist-install/package-data.mk: No such file or directory libraries/directory/ghc.mk:4: libraries/directory/dist-install/package- data.mk: No such file or directory libraries/process/ghc.mk:4: libraries/process/dist-install/package- data.mk: No such file or directory libraries/hpc/ghc.mk:4: libraries/hpc/dist-install/package-data.mk: No such file or directory libraries/pretty/ghc.mk:4: libraries/pretty/dist-install/package-data.mk: No such file or directory libraries/template-haskell/ghc.mk:4: libraries/template-haskell/dist- install/package-data.mk: No such file or directory libraries/Cabal/Cabal/ghc.mk:4: libraries/Cabal/Cabal/dist-install /package-data.mk: No such file or directory libraries/binary/ghc.mk:4: libraries/binary/dist-install/package-data.mk: No such file or directory libraries/bin-package-db/ghc.mk:4: libraries/bin-package-db/dist-install /package-data.mk: No such file or directory libraries/hoopl/ghc.mk:4: libraries/hoopl/dist-install/package-data.mk: No such file or directory libraries/transformers/ghc.mk:4: libraries/transformers/dist-install /package-data.mk: No such file or directory libraries/xhtml/ghc.mk:4: libraries/xhtml/dist-install/package-data.mk: No such file or directory libraries/terminfo/ghc.mk:4: libraries/terminfo/dist-install/package- data.mk: No such file or directory libraries/haskeline/ghc.mk:4: libraries/haskeline/dist-install/package- data.mk: No such file or directory libraries/integer-gmp/gmp/ghc.mk:49: libraries/integer-gmp/gmp/config.mk: No such file or directory utils/hsc2hs/ghc.mk:16: utils/hsc2hs/dist-install/package-data.mk: No such file or directory utils/ghc-pkg/ghc.mk:66: utils/ghc-pkg/dist-install/package-data.mk: No such file or directory utils/dll-split/ghc.mk:18: utils/dll-split/dist-install/package-data.mk: No such file or directory utils/ghc-pwd/ghc.mk:8: utils/ghc-pwd/dist-install/package-data.mk: No such file or directory utils/ghc-cabal/ghc.mk:67: utils/ghc-cabal/dist-install/package-data.mk: No such file or directory utils/hpc/ghc.mk:18: utils/hpc/dist-install/package-data.mk: No such file or directory utils/runghc/ghc.mk:28: utils/runghc/dist-install/package-data.mk: No such file or directory utils/mkUserGuidePart/ghc.mk:18: utils/mkUserGuidePart/dist/package- data.mk: No such file or directory utils/compare_sizes/ghc.mk:8: utils/compare_sizes/dist-install/package- data.mk: No such file or directory make[2]: *** No rule to make target `libraries/integer-gmp/gmp/config.mk'. Stop. make[1]: *** [all_ghc_stage1] Error 2 make: *** [1] Error 2 }}} Using `make stage=1` works fine, but computing the dependencies each time is annoying. In past experience, I've seen that, once the stage-1 compiler builds to completion at least once, `make 1` works just fine -- it just fails after a `clean`. I don't recall having this problem with `make 2`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8709> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9665: Add "since" information to LANGUAGE extensions in GHC user guide
by GHC 07 Jul '15

07 Jul '15

#9665: Add "since" information to LANGUAGE extensions in GHC user guide -------------------------------------+------------------------------------- Reporter: andreas.abel | Owner: Type: task | Status: new Priority: high | Milestone: Component: Documentation | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- If one wants to support older versions of GHC, it is hard to find out whether one can use a certain LANGUAGE extension. One has to go to older versions of the GHC manual to find out whether the corresponding documentation was already there, or browse release notes. Requests: 1. Document for new LANGUAGE extensions that they are available since version 7.10. For example, by adding "(Since GHC 7.10)" to the heading of the new feature. 2. Do this also for the previous LANGUAGE extensions, by adding e.g., "(Since GHC 7.6)" etc. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9665> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10023: Relax Monad constraint in traceM and traceShowM to Applicative
by GHC 07 Jul '15

07 Jul '15

#10023: Relax Monad constraint in traceM and traceShowM to Applicative -------------------------------------+------------------------------------- Reporter: | Owner: RyanGlScott | Status: new Type: feature | Milestone: request | Version: 7.10.1-rc1 Priority: normal | Operating System: Unknown/Multiple Component: | Type of failure: Other libraries/base | Blocked By: Keywords: | Related Tickets: Architecture: | Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Now that {{{Applicative}}} is a superclass of {{{Monad}}} in GHC 7.10, the current type signatures of {{{traceM}}} and {{{traceShowM}}} from {{{Debug.Trace}}} are too constricted: {{{#!hs traceM :: Monad m => String -> m () traceM string = trace string $ return () traceShowM :: (Show a, Monad m) => a -> m () traceShowM = traceM . show }}} These can be equivalently defined with {{{Applicative}}}: {{{#!hs traceM :: Applicative m => String -> m () traceM string = trace string $ pure () traceShowM :: (Show a, Applicative m) => a -> m () traceShowM = traceM . show }}} However, the {{{M}}} suffixes probably won't make sense after changing the type signatures, so it might be wise to create new {{{traceA}}} and {{{traceShowA}}} functions and deprecate {{{traceM}}} and {{{traceShowM}}}. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10023> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9863: Provide PowerPC 64 bit native code generator
by GHC 07 Jul '15

07 Jul '15

#9863: Provide PowerPC 64 bit native code generator -------------------------------------+------------------------------------- Reporter: trommler | Owner: trommler Type: feature request | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Linux Architecture: powerpc64 | Type of failure: Difficulty: Project (more | None/Unknown than a week) | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- I have started work on a native code generator for PowerPC 64 bit by extending the 32 bit code generator. The code is hosted on github: [https://github.com/trommler/ghc/tree/native] So far I plan to support the old ELF v1.9 ABI on big endian. I might look into little endian and ELF 2.0 later. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9863> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10205: On Windows ghc-pkg always reports cache out of date
by GHC 07 Jul '15

07 Jul '15

#10205: On Windows ghc-pkg always reports cache out of date -------------------------------------+------------------------------------- Reporter: hgolden | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: ghc-pkg | Version: 7.10.1 Keywords: | Operating System: Windows Architecture: x86 | Type of failure: Incorrect result Test Case: | at runtime Blocking: | Blocked By: Differential Revisions: | Related Tickets: -------------------------------------+------------------------------------- When I ran {{{ghc-pkg list}}} on Windows, it reported that the global and user caches were out of date. As instructed, I recached both caches. Despite this, I continued to get the same error message. It appears that the timestamp on the package.conf.d directory is always a few milliseconds later than the timestamp of the package cache, even after recaching, as shown by the log excerpt below. Original error: {{{ C:\Users\hgolden\AppData\Roaming>ghc-pkg check WARNING: cache is out of date: C:\Users\hgolden\AppData\Roaming\ghc\i386-mingw32-7.10.1\package.conf.d\package.cache ghc will see an old view of this package db. Use 'ghc-pkg recache' to fix. WARNING: cache is out of date: C:/Program Files/MinGHC-7.10.1/ghc-7.10.1\lib\package.conf.d\package.cache ghc will see an old view of this package db. Use 'ghc-pkg recache' to fix. [snip...] }}} Checking timestamps: {{{ C:\Users\hgolden\AppData\Roaming>ghc-pkg -v2 list Timestamp 2015-03-27 21:18:29.5247984 UTC for C:\Users\hgolden\AppData\Roaming\ghc\i386-mingw32-7.10.1\package.conf.d\pa ckage.cache Timestamp 2015-03-27 21:18:29.5277984 UTC for C:\Users\hgolden\AppData\Roaming\ghc\i386-mingw32-7.10.1\package.conf.d (N EWER than cache) WARNING: cache is out of date: C:\Users\hgolden\AppData\Roaming\ghc\i386-mingw32-7.10.1\package.conf.d\package.cache ghc will see an old view of this package db. Use 'ghc-pkg recache' to fix. [snip...] Timestamp 2015-03-27 21:15:48.6285984 UTC for C:/Program Files/MinGHC-7.10.1/ghc-7.10.1\lib\package.conf.d\package.cache Timestamp 2015-03-27 21:15:48.6835984 UTC for C:/Program Files/MinGHC-7.10.1/ghc-7.10.1\lib\package.conf.d (NEWER than c ache) WARNING: cache is out of date: C:/Program Files/MinGHC-7.10.1/ghc-7.10.1\lib\package.conf.d\package.cache ghc will see an old view of this package db. Use 'ghc-pkg recache' to fix. [snip...] }}} Recaching as instructed: {{{ C:\Users\hgolden\AppData\Roaming>ghc-pkg -v2 recache --user [snip...] modifying: Just "C:\\Users\\hgolden\\AppData\\Roaming\\ghc\\i386-mingw32-7.10.1\\package.conf.d" flag db stack: ["C:\\Users\\hgolden\\AppData\\Roaming\\ghc\\i386-mingw32-7.10.1\\package.conf.d"] writing cache C:\Users\hgolden\AppData\Roaming\ghc\i386-mingw32-7.10.1\package.conf.d\package.cache C:\Users\hgolden\AppData\Roaming>ghc-pkg -v2 recache --global [snip...] modifying: Just "C:/Program Files/MinGHC-7.10.1/ghc-7.10.1\\lib\\package.conf.d" flag db stack: ["C:/Program Files/MinGHC-7.10.1/ghc-7.10.1\\lib\\package.conf.d"] writing cache C:/Program Files/MinGHC-7.10.1/ghc-7.10.1\lib\package.conf.d\package.cache }}} Looking at timestamps after recaching: {{{ C:\Users\hgolden\AppData\Roaming>ghc-pkg -v2 list Timestamp 2015-03-27 21:21:50.3341984 UTC for C:\Users\hgolden\AppData\Roaming\ghc\i386-mingw32-7.10.1\package.conf.d\pa ckage.cache Timestamp 2015-03-27 21:21:50.3371984 UTC for C:\Users\hgolden\AppData\Roaming\ghc\i386-mingw32-7.10.1\package.conf.d (N EWER than cache) WARNING: cache is out of date: C:\Users\hgolden\AppData\Roaming\ghc\i386-mingw32-7.10.1\package.conf.d\package.cache ghc will see an old view of this package db. Use 'ghc-pkg recache' to fix. [snip...] Timestamp 2015-03-27 21:23:05.4329984 UTC for C:/Program Files/MinGHC-7.10.1/ghc-7.10.1\lib\package.conf.d\package.cache Timestamp 2015-03-27 21:23:05.4359984 UTC for C:/Program Files/MinGHC-7.10.1/ghc-7.10.1\lib\package.conf.d (NEWER than c ache) WARNING: cache is out of date: C:/Program Files/MinGHC-7.10.1/ghc-7.10.1\lib\package.conf.d\package.cache ghc will see an old view of this package db. Use 'ghc-pkg recache' to fix. C:\Users\hgolden\AppData\Roaming> }}} Timestamps have changed, but each directory's timestamp is still a few milliseconds after each cache file's timestamp. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10205> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9839: RTS options parser silently accepts invalid flags
by GHC 05 Jul '15

05 Jul '15

#9839: RTS options parser silently accepts invalid flags -------------------------------------+------------------------------------- Reporter: adamgundry | Owner: simonmar Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Incorrect Blocked By: | result at runtime Related Tickets: #4243 | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- RTS options that do not take arguments (such as `-T`) silently ignore anything that comes afterwards. For example, `+RTS -T,-s` or `+RTS -T-s` turns on collection of GC statistics (`-T`) but does not print out a summary (`-s`). Instead, this should produce an error message. Otherwise, users may mistakenly think that options have been applied. (This has just bitten us in a production system.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9839> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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