#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: #8101 | Differential Revisions: -------------------------------------+------------------------------------- Changes (by thomie): * related: => #8101 * milestone: => 7.12.1 Comment: This has been addressed before in #8101. The fix there doesn't seem to work, and is missing a test. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: #8101 | Differential Revisions: -------------------------------------+------------------------------------- Comment (by Reid Barton ): In [changeset:"aa230540f5868263740fd7d2f31505a39e2fcb4e/ghc" aa230540/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="aa230540f5868263740fd7d2f31505a39e2fcb4e" Add test for #10600 (exhaustiveness check with --make and -fno-code) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Incorrect | Test Case: warning at compile-time | driver/T8101b Blocked By: | Blocking: Related Tickets: #8101 | Differential Revisions: -------------------------------------+------------------------------------- Comment (by ntc2): This causes Emacs Flycheck to not warn for non-exhaustive patterns, because it runs GHC with `-fno-code`: https://github.com/flycheck/flycheck/issues/722. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Incorrect | Test Case: warning at compile-time | driver/T8101b Blocked By: | Blocking: Related Tickets: #8101 | Differential Revisions: -------------------------------------+------------------------------------- Changes (by thomie): * keywords: => newcomer -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: ezyang Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Incorrect | Test Case: warning at compile-time | driver/T8101b Blocked By: | Blocking: Related Tickets: #8101 | Differential Revisions: -------------------------------------+------------------------------------- Comment (by ezyang): So... I implemented this. But then I got a lint error! {{{ "/home/hs01/ezyang/ghc-validate/inplace/bin/haddock" --verbosity=0 --odir="libraries/ghc-prim/dist-install/doc/html/ghc-prim" --no-tmp-comp- dir --dump-interface=libraries/ghc-prim/dist-install/doc/html/ghc-prim /ghc-prim.haddock --html --hoogle --title="ghc-prim-0.4.0.0: GHC primitives" --prologue="libraries/ghc-prim/dist-install/haddock- prologue.txt" --optghc=-hisuf --optghc=dyn_hi --optghc=-osuf --optghc=dyn_o --optghc=-hcsuf --optghc=dyn_hc --optghc=-fPIC --optghc=-dynamic --optghc=-O0 --optghc=-H64m --optghc=-Werror --optghc =-this-package-key --optghc=8TmvWUcS1U1IKHT0levwg3 --optghc=-hide-all- packages --optghc=-i --optghc=-ilibraries/ghc-prim/. --optghc=-ilibraries /ghc-prim/dist-install/build --optghc=-ilibraries/ghc-prim/dist- install/build/autogen --optghc=-Ilibraries/ghc-prim/dist-install/build --optghc=-Ilibraries/ghc-prim/dist-install/build/autogen --optghc=-Ilibraries/ghc-prim/. --optghc=-optP-include --optghc=-optPlibraries/ghc-prim/dist-install/build/autogen/cabal_macros.h --optghc=-package-id --optghc=builtin_rts --optghc=-this-package-key --optghc=ghc-prim --optghc=-XHaskell2010 --optghc=-O --optghc=-dcore-lint --optghc=-no-user-package-db --optghc=-rtsopts --optghc=-fno-warn- trustworthy-safe --optghc=-fno-warn-deprecated-flags --optghc=-fno-warn- tabs --optghc=-odir --optghc=libraries/ghc-prim/dist-install/build --optghc=-hidir --optghc=libraries/ghc-prim/dist-install/build --optghc=-stubdir --optghc=libraries/ghc-prim/dist-install/build --source- module=src/%{MODULE/./-}.html --source- entity=src/%{MODULE/./-}.html#%{NAME} libraries/ghc- prim/./GHC/CString.hs libraries/ghc-prim/./GHC/Classes.hs libraries/ghc- prim/./GHC/Debug.hs libraries/ghc-prim/./GHC/IntWord64.hs libraries/ghc- prim/./GHC/Magic.hs libraries/ghc-prim/dist- install/build/GHC/PrimopWrappers.hs libraries/ghc-prim/./GHC/Tuple.hs libraries/ghc-prim/./GHC/Types.hs libraries/ghc-prim/dist- install/build/autogen/GHC/Prim.hs +RTS -t"libraries/ghc-prim/dist- install/haddock.t" --machine-readable *** Core Lint errors : in result of Desugar (after optimization) *** <wired into compiler>: warning: [RHS of proxy# :: forall a_a3EW. Proxy# a_a3EW] The type of this binder is primitive: proxy# Binder's type: forall a_a3EW. Proxy# a_a3EW }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: ezyang Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: driver/T8101b Blocked By: | Blocking: Related Tickets: #8101 | Differential Rev(s): Phab:D1278 -------------------------------------+------------------------------------- Changes (by thoughtpolice): * differential: => Phab:D1278 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: ezyang Type: bug | Status: patch Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: driver/T8101b Blocked By: | Blocking: Related Tickets: #8101 | Differential Rev(s): Phab:D1278 -------------------------------------+------------------------------------- Comment (by bgamari): We discussed this during the weekly meeting; no one was terribly excited about any of the alternatives, * Fix `GHC.Prim` to pass Core Lint (perhaps not even possible) * Add a special case to skip desugaring for `GHC.Prim` * Add a special case to skip Core Linting `GHC.Prim` * Disable Core Linting when not generating code * Add a command line option to specifically disable desugaring (which could be used by Haddock) The point also came up that we should really try to avoid desugaring when invoked by Haddock as this is otherwise wasted effort. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:14 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: ezyang Type: bug | Status: patch Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: driver/T8101b Blocked By: | Blocking: Related Tickets: #8101 | Differential Rev(s): Phab:D1278 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * milestone: 8.0.1 => 8.2.1 Comment: This won't happen for 8.0. Punting. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:16 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: driver/T8101b Blocked By: | Blocking: Related Tickets: #8101 | Differential Rev(s): Phab:D1278 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * owner: ezyang => * status: patch => new * milestone: 8.2.1 => 8.4.1 Comment: It looks unlikely that this will happen for 8.2. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:18 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: ezyang Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: driver/T8101b Blocked By: | Blocking: Related Tickets: #8101 | Differential Rev(s): Phab:D1278 Wiki Page: | -------------------------------------+------------------------------------- Comment (by duog): I have had a look at this issue and I think the situation must have changed somewhat since the last time a fix was attempted. Several errors can be thrown during desugaring now, including at least - Top-level bindings for unlifted types aren't allowed: - Top-level strict pattern bindings aren't allowed: which I assume must not have previously been the case? If I add an unconditional desugaring in HscMain.finishTypecheckOnly then haddock errors on Ghc.Prim with "Top-level bindings for unlifted types aren't allowed:" This means that currently these desugaring errors are not thrown for modules compiled with -fno-code. I have pushed D3533 which includes a test for this. Let's add a special case to skip desugaring of Ghc.Prim? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:20 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: ezyang Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: driver/T8101b Blocked By: | Blocking: Related Tickets: #8101 | Differential Rev(s): Phab:D1278 Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari):

* Top-level bindings for unlifted types aren't allowed: * Top-level strict pattern bindings aren't allowed:

While these were never really "allowed", Richard Eisenberg did tighten the checks to ensure that they are caught between 8.0 and 8.2.

Let's always desugar with -fno-code, except for Ghc.Prim?

Sounds like a reasonable first approximation to me. Let me know if you get stuck. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:22 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

Is there a conceptual problem of moving the pattern match checker to the end of typechecking? There is the additional fiddlyness to make sure all

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: ezyang Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: driver/T8101b Blocked By: | Blocking: Related Tickets: #8101 | Differential Rev(s): Phab:D1278 Wiki Page: | -------------------------------------+------------------------------------- Comment (by duog): Replying to [comment:23 mpickering]: pattern occurrences are checked but this seems preferable than making `-fno-code` slower for everyone. I'm not qualified to answer that, but it's a bigger problem than just pattern match checking(Maybe we should change the ticket name?). The whole point of -fno-code is to check code for errors and warnings, and many errors and warnings are currently thrown by the desugarer. I would expect that correctness is the most important concern, and that a slower, more correct -fno-code is preferable. I also expect that desugaring is in general a much less expensive operation than typechecking. Please correct me if I'm wrong! Below I give a rough enumeration of the warnings and errors that the desugarer can currently throw, and some ideas about how to proceed. The warnings listed in D1278 (comment 12, 20 months ago) as throwable by the desugarer are: * Opt_WarnIncompletePatterns (-W) * Opt_WarnIncompleteUniPatterns * Opt_WarnIncompletePatternsRecUpd * Opt_WarnIdentities * Opt_WarnOverflowedLiterals (def) * Opt_WarnEmptyEnumerations (def) * Opt_WarnInlineRuleShadowing (def) * Opt_WarnOverlappingPatterns (def) * Opt_WarnUnusedDoBind (-Wall) * Opt_WarnWrongDoBind (def) I haven't verified that this list is up to date. I have noted in brackets default warnings (def), -W warnings and -Wall warnings. The errors throwable by desugaring are a bit hard to find. Grepping and chasing errDs, I can see at least: * "A levity-polymorphic type is not allowed here:" : DsMonad.dsNoLevPoly * "Malformed constructor signature" : updateGadtResult called by DsMeta.repC * "Top level bindings for unlifted types" : DsBinds.dsTopLevelBinds * "Top level strict pattern bindings" : DsBinds.dsTopLevelBinds * "You can't mix polymorphic and unlifted bindings:" : DsExpr.ds_val_bind * "Recursive bindings for unlifted types aren't allowed:" : DsExpr.ds_val_bind * "Cannot use primitive with levity-polymorphic arguments:" : DsExpr.levPolyPrimopErr * "A lazy (~) pattern cannot bind variables of unlifted type." : Match.tidy1 Perhaps there is a list of extensions, where if none were enabled then some or all of these errors could be excluded? Say * TypeInType * MagicHash * UnboxedTuples * UnboxedSums * GADTs * BangPatterns One would have to think carefully and understand this better than I do. Then the first, easiest, solution is to unconditionally desugar with -fno- code. This has no maintenance burden and is easy to verify for correctness. D3542 implements this. Then next improvement could be reducing the work done by the desugarer in -fno-code, I intend to look at this. Finally one could implement a predicate to determine whether desugaring could produce warnings and errors, for example by checking enabled warnings and extensions, and desugar only when necessary. One could potentially move warnings/errors from desugaring to typechecking to facilitate this. This seems like a bit of a maintenance nightmare, but maybe it's not even so difficult to get them all out? Or at least everything except the TypeInType stuff. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:24 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code -------------------------------------+------------------------------------- Reporter: akio | Owner: ezyang Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: driver/T8101b Blocked By: | Blocking: Related Tickets: #8101 | Differential Rev(s): Phab:D1278 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ben Gamari ): In [changeset:"c9eb4385aad248118650725b7b699bb97ee21c0d/ghc" c9eb4385/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="c9eb4385aad248118650725b7b699bb97ee21c0d" Desugar modules compiled with -fno-code Previously modules with hscTarget == HscNothing were not desugared. This patch changes behavior so that all modules HsSrcFile Modules except GHC.Prim are desugared. Modules with hscTarget == HscNothing are not simplified. Warnings and errors produced by the desugarer will now be produced when compiling with -fno-code. HscMain.finishTypecheckingOnly is removed, HscMain.hscIncrementalCompile is simplified a bit, and HscMain.finish takes in the removed logic. I think this is easier to follow. Updates haddock submodule. Tests T8101, T8101b, T10600 are no longer expect_broken. Reviewers: ezyang, austin, bgamari Subscribers: rwbarton, thomie GHC Trac Issues: #10600 Differential Revision: https://phabricator.haskell.org/D3542 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10600#comment:26 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler