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* Implement -Wmissing-kind-signaturesOleg Grenrus2021-03-251-0/+27
| | | | Fixes #19564
* More improvement to MonoLocalBinds documentationSimon Peyton Jones2021-03-231-50/+35
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* Built-in type families: CharToNat, NatToChar (#19535)Vladislav Zavialov2021-03-171-0/+2
| | | | | Co-authored-by: Daniel Rogozin <daniel.rogozin@serokell.io> Co-authored-by: Rinat Stryungis <rinat.stryungis@serokell.io>
* Document how GADT patterns are matched from left-to-right, outside-inRyan Scott2021-03-171-1/+82
| | | | | | | | | | | | | | This adds some bullet points to the GHC User's Guide section on `GADTs` to explain some subtleties in how GHC typechecks GADT patterns. In particular, this adds examples of programs being rejected for matching on GADTs in a way that does not mesh with GHC's left-to-right, outside-in order for checking patterns, which can result in programs being rejected for seemingly counterintuitive reasons. (See #12018 for examples of confusion that arose from this.) In addition, now that we have visible type application in data constructor patterns, I mention a possible workaround of using `TypeApplications` to repair programs of this sort. Resolves #12018.
* Document the interaction between ScopedTypeVariables and ↵Ryan Scott2021-03-151-0/+31
| | | | | | | | | StandaloneKindSignatures This documents a limitation of `StandaloneKindSignatures`—namely, that it does not bring type variables bound by an outermost `forall` into scope over a type-level declaration—in the GHC User's Guide. See #19498 for more discussion.
* Correct module name in `-fprof-callers` documentationMatthew Pickering2021-03-141-1/+1
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* Implement the UnliftedDatatypes extensionSebastian Graf2021-03-142-4/+113
| | | | | | | | | | | | | | | | | | GHC Proposal: 0265-unlifted-datatypes.rst Discussion: https://github.com/ghc-proposals/ghc-proposals/pull/265 Issues: https://gitlab.haskell.org/ghc/ghc/-/issues/19523 Implementation Details: Note [Implementation of UnliftedDatatypes] This patch introduces the `UnliftedDatatypes` extension. When this extension is enabled, GHC relaxes the restrictions around what result kinds are allowed in data declarations. This allows data types for which an unlifted or levity-polymorphic result kind is inferred. The most significant changes are in `GHC.Tc.TyCl`, where `Note [Implementation of UnliftedDatatypes]` describes the details of the implementation. Fixes #19523.
* Ignore breakpoint for a specified number of iterations. (#19157)Roland Senn2021-03-102-7/+34
| | | | | | | | | | | | | | | | * Implement new debugger command `:ignore` to set an `ignore count` for a specified breakpoint. * Allow new optional parameter on `:continue` command to set an `ignore count` for the current breakpoint. * In the Interpreter replace the current `Word8` BreakArray with an `Int` array. * Change semantics of values in `BreakArray` to: n < 0 : Breakpoint is disabled. n == 0 : Breakpoint is enabled. n > 0 : Breakpoint is enabled, but ignore next `n` iterations. * Rewrite `:enable`/`:disable` processing as a special case of `:ignore`. * Remove references to `BreakArray` from `ghc/UI.hs`.
* Use GHC2021 as default languageJoachim Breitner2021-03-101-4/+5
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* Introduce GHC2021 languageJoachim Breitner2021-03-103-19/+87
| | | | | | This adds support for -XGHC2021, as described in Proposal 0380 [1]. [1] https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0380-ghc2021.rst
* template-haskell: Add putDoc, getDoc, withDecDoc and friendsLuke Lau2021-03-101-0/+13
| | | | | | | | | | | | | | | | | | | | | | | This adds two new methods to the Quasi class, putDoc and getDoc. They allow Haddock documentation to be added to declarations, module headers, function arguments and class/type family instances, as well as looked up. It works by building up a map of names to attach pieces of documentation to, which are then added in the extractDocs function in GHC.HsToCore.Docs. However because these template haskell names need to be resolved to GHC names at the time they are added, putDoc cannot directly add documentation to declarations that are currently being spliced. To remedy this, withDecDoc/withDecsDoc wraps the operation with addModFinalizer, and provides a more ergonomic interface for doing so. Similarly, the funD_doc, dataD_doc etc. combinators provide a more ergonomic interface for documenting functions and their arguments simultaneously. This also changes ArgDocMap to use an IntMap rather than an Map Int, for efficiency. Part of the work towards #5467
* rts: Gradually return retained memory to the OSMatthew Pickering2021-03-102-2/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Related to #19381 #19359 #14702 After a spike in memory usage we have been conservative about returning allocated blocks to the OS in case we are still allocating a lot and would end up just reallocating them. The result of this was that up to 4 * live_bytes of blocks would be retained once they were allocated even if memory usage ended up a lot lower. For a heap of size ~1.5G, this would result in OS memory reporting 6G which is both misleading and worrying for users. In long-lived server applications this results in consistent high memory usage when the live data size is much more reasonable (for example ghcide) Therefore we have a new (2021) strategy which starts by retaining up to 4 * live_bytes of blocks before gradually returning uneeded memory back to the OS on subsequent major GCs which are NOT caused by a heap overflow. Each major GC which is NOT caused by heap overflow increases the consec_idle_gcs counter and the amount of memory which is retained is inversely proportional to this number. By default the excess memory retained is oldGenFactor (controlled by -F) / 2 ^ (consec_idle_gcs * returnDecayFactor) On a major GC caused by a heap overflow, the `consec_idle_gcs` variable is reset to 0 (as we could continue to allocate more, so retaining all the memory might make sense). Therefore setting bigger values for `-Fd` makes the rate at which memory is returned slower. Smaller values make it get returned faster. Setting `-Fd0` disables the memory return completely, which is the behaviour of older GHC versions. The default is `-Fd4` which results in the following scaling: > mapM print [(x, 1/ (2**(x / 4))) | x <- [1 :: Double ..20]] (1.0,0.8408964152537146) (2.0,0.7071067811865475) (3.0,0.5946035575013605) (4.0,0.5) (5.0,0.4204482076268573) (6.0,0.35355339059327373) (7.0,0.29730177875068026) (8.0,0.25) (9.0,0.21022410381342865) (10.0,0.17677669529663687) (11.0,0.14865088937534013) (12.0,0.125) (13.0,0.10511205190671433) (14.0,8.838834764831843e-2) (15.0,7.432544468767006e-2) (16.0,6.25e-2) (17.0,5.255602595335716e-2) (18.0,4.4194173824159216e-2) (19.0,3.716272234383503e-2) (20.0,3.125e-2) So after 13 consecutive GCs only 0.1 of the maximum memory used will be retained. Further to this decay factor, the amount of memory we attempt to retain is also influenced by the GC strategy for the oldest generation. If we are using a copying strategy then we will need at least 2 * live_bytes for copying to take place, so we always keep that much. If using compacting or nonmoving then we need a lower number, so we just retain at least `1.2 * live_bytes` for some protection. In future we might want to make this behaviour more aggressive, some relevant literature is > Ulan Degenbaev, Jochen Eisinger, Manfred Ernst, Ross McIlroy, and Hannes Payer. 2016. Idle time garbage collection scheduling. SIGPLAN Not. 51, 6 (June 2016), 570–583. DOI:https://doi.org/10.1145/2980983.2908106 which describes the "memory reducer" in the V8 javascript engine which on an idle collection immediately returns as much memory as possible.
* Document operator sections' interaction with subsumptionRyan Scott2021-03-092-0/+19
| | | | | | This resolves #19457 by making a note of breaking changes (introduced in GHC 9.2) to the way that GHC typechecks operator sections where the operator has nested `forall`s or contexts in its type signature.
* Update changelog and release notes for Data.Type.Ord changeDaniel Winograd-Cort2021-03-081-0/+24
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* eventlog: Add changelog entry for BLOCKS_SIZE and MEM_RETURNMatthew Pickering2021-03-081-0/+7
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* eventlog: Add BLOCKS_SIZE eventMatthew Pickering2021-03-081-7/+21
| | | | | | | | | | | | | The BLOCKS_SIZE event reports the size of the currently allocated blocks in bytes. It is like the HEAP_SIZE event, but reports about the blocks rather than megablocks. You can work out the current heap fragmentation by looking at the difference between HEAP_SIZE and BLOCKS_SIZE. Fixes #19357
* eventlog: Add MEM_RETURN event to give information about fragmentationMatthew Pickering2021-03-081-3/+23
| | | | | | | | | | | | | | See #19357 The event reports the * Current number of megablocks allocated * The number that the RTS thinks it needs * The number is managed to return to the OS When current > need then the difference is returned to the OS, the successful number of returned mblocks is reported by 'returned'. In a fragmented heap current > need but returned < current - need.
* Implement BoxedRep proposalwip/boxed-repBen Gamari2021-03-073-9/+19
| | | | | | | | | | | | | | | | | | | | | | | This implements the BoxedRep proposal, refactoring the `RuntimeRep` hierarchy from: ```haskell data RuntimeRep = LiftedPtrRep | UnliftedPtrRep | ... ``` to ```haskell data RuntimeRep = BoxedRep Levity | ... data Levity = Lifted | Unlifted ``` Updates binary, haddock submodules. Closes #17526. Metric Increase: T12545
* Implement record dot syntaxwip/joachim/bump-haddockShayne Fletcher2021-03-064-3/+99
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* Bring back COMPLETE sets filtered by result TyCon (#14422)Cale Gibbard2021-03-041-0/+53
| | | | | | | | | | | | | | | | | | | Commit 2a94228 dramatically simplified the implementation and improved the performance of COMPLETE sets while making them applicable in more scenarios at the same time. But it turned out that there was a change in semantics that (to me unexpectedly) broke users' expectations (see #14422): They relied on the "type signature" of a COMPLETE pragma to restrict the scrutinee types of a pattern match for which they are applicable. This patch brings back that filtering, so the semantics is the same as it was in GHC 9.0. See the updated Note [Implementation of COMPLETE pragmas]. There are a few testsuite output changes (`completesig13`, `T14422`) which assert this change. Co-authored-by: Sebastian Graf <sebastian.graf@kit.edu>
* Add a Template Haskell warning flag -Wimplicit-liftKrzysztof Gogolewski2021-03-042-0/+20
| | | | Part of #17804.
* Add release notes for -hi, -finfo-table-map and -fdistinct-constructor-tablesMatthew Pickering2021-03-031-0/+14
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* Add option to give each usage of a data constructor its own info tableMatthew Pickering2021-03-031-6/+7
| | | | | | | | | | | | | The `-fdistinct-constructor-tables` flag will generate a fresh info table for the usage of any data constructor. This is useful for debugging as now by inspecting the info table, you can determine which usage of a constructor caused that allocation rather than the old situation where the info table always mapped to the definition site of the data constructor which is useless. In conjunction with `-hi` and `-finfo-table-map` this gives a more fine grained understanding of where constructor allocations arise from in a program.
* Add -finfo-table-map which maps info tables to source positionsMatthew Pickering2021-03-033-2/+79
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This new flag embeds a lookup table from the address of an info table to information about that info table. The main interface for consulting the map is the `lookupIPE` C function > InfoProvEnt * lookupIPE(StgInfoTable *info) The `InfoProvEnt` has the following structure: > typedef struct InfoProv_{ > char * table_name; > char * closure_desc; > char * ty_desc; > char * label; > char * module; > char * srcloc; > } InfoProv; > > typedef struct InfoProvEnt_ { > StgInfoTable * info; > InfoProv prov; > struct InfoProvEnt_ *link; > } InfoProvEnt; The source positions are approximated in a similar way to the source positions for DWARF debugging information. They are only approximate but in our experience provide a good enough hint about where the problem might be. It is therefore recommended to use this flag in conjunction with `-g<n>` for more accurate locations. The lookup table is also emitted into the eventlog when it is available as it is intended to be used with the `-hi` profiling mode. Using this flag will significantly increase the size of the resulting object file but only by a factor of 2-3x in our experience.
* Profiling by info table mode (-hi)Matthew Pickering2021-03-031-0/+5
| | | | | | | | This profiling mode creates bands by the address of the info table for each closure. This provides a much more fine-grained profiling output than any of the other profiling modes. The `-hi` profiling mode does not require a profiling build.
* User's Guide: document DefaultSignatures' interaction with subsumptionRyan Scott2021-03-031-25/+118
| | | | | | | | | | As reported in #19432, the rules governing how `DefaultSignatures` are typechecked became stricter in GHC 9.0 due to simplified subsumption. However, this was far from obvious to me after reading the User's Guide section on `DefaultSignatures`. In this patch, I spruce up the documentation in that section so that it mentions these nuances. Resolves #19432.
* Add a flag to dump the FastString tableSylvain Henry2021-03-031-0/+7
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* DmdAnal: Better syntax for demand signatures (#19016)Sebastian Graf2021-03-031-30/+30
| | | | | | | | | The update of the Outputable instance resulted in a slew of documentation changes within Notes that used the old syntax. The most important doc changes are to `Note [Demand notation]` and the user's guide. Fixes #19016.
* Profiling: Allow heap profiling to be controlled dynamically.Matthew Pickering2021-03-032-1/+15
| | | | | | | | | | This patch exposes three new functions in `GHC.Profiling` which allow heap profiling to be enabled and disabled dynamically. 1. startHeapProfTimer - Starts heap profiling with the given RTS options 2. stopHeapProfTimer - Stops heap profiling 3. requestHeapCensus - Perform a heap census on the next context switch, regardless of whether the timer is enabled or not.
* Fix typo in docs [skip ci]Sebastian Graf2021-03-031-1/+1
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* Pmc: Implement `considerAccessible` (#18610)Sebastian Graf2021-03-012-5/+40
| | | | | | | | | | | | | | | | | | | | | | | | | | Consider (`T18610`): ```hs f :: Bool -> Int f x = case (x, x) of (True, True) -> 1 (False, False) -> 2 (True, False) -> 3 -- Warning: Redundant ``` The third clause will be flagged as redundant. Nevertheless, the programmer might intend to keep the clause in order to avoid bitrot. After this patch, the programmer can write ```hs g :: Bool -> Int g x = case (x, x) of (True, True) -> 1 (False, False) -> 2 (True, False) | GHC.Exts.considerAccessible -> 3 -- No warning ``` And won't be bothered any longer. See also `Note [considerAccessible]` and the updated entries in the user's guide. Fixes #18610 and #19228.
* Infer multiplicity in case expressionsKrzysztof Gogolewski2021-03-011-4/+5
| | | | This is a first step towards #18738.
* users guide: Update mathjax CDN URLBen Gamari2021-02-281-2/+2
| | | | | | Fixes #19423. [skip ci]
* Remove the -xt heap profiling optionMatthew Pickering2021-02-272-18/+4
| | | | | | | It should be left to tooling to perform the filtering to remove these specific closure types from the profile if desired. Fixes #16795
* rts: Introduce --eventlog-flush-interval flagBen Gamari2021-02-271-0/+9
| | | | | | | This introduces a flag, --eventlog-flush-interval, which can be used to set an upper bound on the amount of time for which an eventlog event will remain enqueued. This can be useful in real-time monitoring settings.
* Implement -Wambiguous-fieldsAdam Gundry2021-02-262-5/+39
| | | | | | Fixes #18966. Adds a new warning -Wambiguous-fields for uses of field selectors or record updates that will be rejected in the future, when the DuplicateRecordFields extension is simplified per https://github.com/ghc-proposals/ghc-proposals/pull/366.
* Update MonoLocalBinds documentationSimon Peyton Jones2021-02-262-11/+28
| | | | | | | | | Update the documentation to specify that MonoLocalBinds is lifted by a partial type signature. This came up in #19396. [skip ci]
* Minor fix to QualifiedDo docs about the ApplicativeDo desugaringUtku Demir2021-02-251-3/+3
| | | | | | | | | When desugaring ApplicativeDo, GHC looks up the name `fmap`, not `<$>` (see 'GHC.Builtin.Names.fmapName'). This commit fixes the misleading documentation; since exporting the name `<$>` instead of `fmap` causes a "not in scope" error when `QualifiedDo` and `ApplicativeDo` is combined. [skip ci]
* Prefer -Wmissing-signatures over -Wmissing-exported-signatures (#14794)Michiel de Bruijne2021-02-221-3/+4
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* Make openFile exception safeDavid Feuer2021-02-221-0/+3
| | | | | | | | | | | | | | | | | | | * `openFile` could sometimes leak file descriptors if it received an asynchronous exception (#19114, #19115). Fix this on POSIX. * `openFile` and more importantly `openFileBlocking` could not be interrupted effectively during the `open` system call (#17912). Fix this on POSIX. * Implement `readFile'` using `withFile` to ensure the file is closed promptly on exception. * Avoid `bracket` in `withFile`, reducing the duration of masking. Closes #19130. Addresses #17912, #19114, and #19115 on POSIX systems, but not on Windows.
* users guide: Mention that -e can be given multiple timesBen Gamari2021-02-181-2/+3
| | | | Fixes #19122.
* directory: ensure xdg compliance (Fix #6077)Gauvain 'GovanifY' Roussel-Tarbouriech2021-02-183-8/+12
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* Implement NoFieldSelectors extension (ghc-proposals 160)Adam Gundry2021-02-167-5/+149
| | | | | | | | | | | | | | | | | | | | | Fixes #5972. This adds an extension NoFieldSelectors to disable the generation of selector functions corresponding to record fields. When this extension is enabled, record field selectors are not accessible as functions, but users are still able to use them for record construction, pattern matching and updates. See Note [NoFieldSelectors] in GHC.Rename.Env for details. Defining the same field multiple times requires the DuplicateRecordFields extension to be enabled, even when NoFieldSelectors is in use. Along the way, this fixes the use of non-imported DuplicateRecordFields in GHCi with -fimplicit-import-qualified (fixes #18729). Moreover, it extends DisambiguateRecordFields to ignore non-fields when looking up fields in record updates (fixes #18999), as described by Note [DisambiguateRecordFields for updates]. Co-authored-by: Simon Hafner <hafnersimon@gmail.com> Co-authored-by: Fumiaki Kinoshita <fumiexcel@gmail.com>
* Introduce keepAlive primopBen Gamari2021-02-141-0/+17
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* Fix example code in Deriving via. songzh2021-02-131-1/+1
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* Remove deprecated -XGenerics and -XMonoPatBindsKrzysztof Gogolewski2021-02-131-3/+0
| | | | | They have no effect since 2011 (GHC 7.2/7.4), commits cb698570b2b and 49dbe60558.
* Add -Wsafe to flags not enabled by -WallFendor2021-02-101-0/+1
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* Fix example code of "Making a Haskell library that can be called from ↵Masahiro Sakai2021-02-101-2/+2
| | | | | | | foreign code" section "+RTS" in argv[0] is interpreted as a program name and does not work as an indicator of RTS options.
* Reduce inlining in deeply-nested casesSimon Peyton Jones2021-02-092-0/+136
| | | | | | | | | | | | This adds a new heuristic, controllable via two new flags to better tune inlining behaviour. The new flags are -funfolding-case-threshold and -funfolding-case-scaling which are document both in the user guide and in Note [Avoid inlining into deeply nested cases]. Co-authored-by: Andreas Klebinger <klebinger.andreas@gmx.at>
* Fix typosBrian Wignall2021-02-064-6/+6
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