- Jun 30, 2020
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GHC is very wishy-washy about rejecting instance declarations with nested `forall`s or contexts that are surrounded by outermost parentheses. This can even lead to some strange interactions with `ScopedTypeVariables`, as demonstrated in #18240. This patch makes GHC more consistently reject instance types with nested `forall`s/contexts so as to prevent these strange interactions. On the implementation side, this patch tweaks `splitLHsInstDeclTy` and `getLHsInstDeclHead` to not look through parentheses, which can be semantically significant. I've added a `Note [No nested foralls or contexts in instance types]` in `GHC.Hs.Type` to explain why. This also introduces a `no_nested_foralls_contexts_err` function in `GHC.Rename.HsType` to catch nested `forall`s/contexts in instance types. This function is now used in `rnClsInstDecl` (for ordinary instance declarations) and `rnSrcDerivDecl` (for standalone `deriving` declarations), the latter of which fixes #18271. On the documentation side, this adds a new "Formal syntax for instance declaration types" section to the GHC User's Guide that presents a BNF-style grammar for what is and isn't allowed in instance types. Fixes #18240. Fixes #18271.
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- Jun 28, 2020
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This simple error in GHC.Core.Litn.lintJoinLams meant that Lint reported bogus errors. Fixes #18399
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`GeneralizedNewtypeDeriving` is in the unique situation where it must produce an `LHsType GhcPs` from a Core `Type`. Historically, this was done with the `typeToLHsType` function, which walked over the entire `Type` and attempted to construct an `LHsType` with the same overall structure. `typeToLHsType` is quite complicated, however, and has been the subject of numerous bugs over the years (e.g., #14579). Luckily, there is an easier way to accomplish the same thing: the `XHsType` constructor of `HsType`. `XHsType` bundles an `NHsCoreTy`, which allows embedding a Core `Type` directly into an `HsType`, avoiding the need to laboriously convert from one to another (as `typeToLHsType` did). Moreover, renaming and typechecking an `XHsType` is simple, since one doesn't need to do anything to a Core `Type`... ...well, almost. For the reasons described in `Note [Typechecking NHsCoreTys]` in `GHC.Tc.Gen.HsType`, we must apply a substitution that we build from the local `tcl_env` type environment. But that's a relatively modest price to pay. Now that `GeneralizedNewtypeDeriving` uses `NHsCoreTy`, the `typeToLHsType` function no longer has any uses in GHC, so this patch rips it out. Some additional tweaks to `hsTypeNeedsParens` were necessary to make the new `-ddump-deriv` output correctly parenthesized, but other than that, this patch is quite straightforward. This is a mostly internal refactoring, although it is likely that `GeneralizedNewtypeDeriving`-generated code will now need fewer language extensions in certain situations than it did before.
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Make sure the stack is 16 byte aligned even when reserved stack bytes are not a multiple of 16 bytes. Avoid saving r2 (TOC). On ELF v1 the function descriptor of StgReturn has the same TOC as StgRun, on ELF v2 the TOC is recomputed in the function prologue. Use the ABI provided functions to save clobbered GPRs and FPRs. Improve comments. Describe what the stack looks like and how it relates to the respective ABIs.
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- Jun 27, 2020
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The code is simpler and cleaner.
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`DynFlags.buildTag` was a field created from the set of Ways in `DynFlags.ways`. It had to be kept in sync with `DynFlags.ways` which was fragile. We want to avoid global state like this (#17957). Moreover in #14335 we also want to support loading units with different ways: target units would still use `DynFlags.ways` but plugins would use `GHC.Driver.Ways.hostFullWays`. To avoid having to deal both with build tag and with ways, we recompute the buildTag on-the-fly (should be pretty cheap) and we remove `DynFlags.buildTag` field.
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We must ensure that exceptions are not simplified. Previously we used: case raiseDivZero of _ -> 0## -- dummyValue But it was wrong because the evaluation of `raiseDivZero` was removed and the dummy value was directly returned. See new Note [ghc-bignum exceptions]. I've also removed the exception triggering primops which were fragile. We don't need them to be primops, we can have them exported by ghc-prim. I've also added a test for #18359 which triggered this patch. -
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This started as a simple fix for #18321 that organically grew into a much more sweeping refactor of how auxiliary bindings for derived instances are handled. I have rewritten `Note [Auxiliary binders]` in `GHC.Tc.Deriv.Generate` to explain all of the moving parts, but the highlights are: * Previously, the OccName of each auxiliary binding would be given a suffix containing a hash of its package name, module name, and parent data type to avoid name clashes. This was needlessly complicated, so we take the more direct approach of generating `Exact` `RdrName`s for each auxiliary binding with the same `OccName`, but using an underlying `System` `Name` with a fresh `Unique` for each binding. Unlike hashes, allocating new `Unique`s does not require any cleverness and avoid name clashes all the same... * ...speaking of which, in order to convince the renamer that multiple auxiliary bindings with the same `OccName` (but different `Unique`s) are kosher, we now use `rnLocalValBindsLHS` instead of `rnTopBindsLHS` to rename auxiliary bindings. Again, see `Note [Auxiliary binders]` for the full story. * I have removed the `DerivHsBind` constructor for `DerivStuff`—which was only used for `Data.Data`-related auxiliary bindings—and refactored `gen_Data_binds` to use `DerivAuxBind` instead. This brings the treatment of `Data.Data`-related auxiliary bindings in line with every other form of auxiliary binding. Fixes #18321.
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- Jun 26, 2020
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Matthías Páll Gissurarson authored
Co-authored-by:
Facundo Domínguez <facundo.dominguez@tweag.io> QualifiedDo is implemented using the same placeholders for operation names in the AST that were devised for RebindableSyntax. Whenever the renamer checks which names to use for do syntax, it first checks if the do block is qualified (e.g. M.do { stmts }), in which case it searches for qualified names in the module M. This allows users to write {-# LANGUAGE QualifiedDo #-} import qualified SomeModule as M f x = M.do -- desugars to: y <- M.return x -- M.return x M.>>= \y -> M.return y -- M.return y M.>> M.return y -- M.return y See Note [QualifiedDo] and the users' guide for more details. Issue #18214 Proposal: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0216-qualified-do.rst Since we change the constructors `ITdo` and `ITmdo` to carry the new module name, we need to bump the haddock submodule to account or the new shape of these constructors.
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This MR makes the UM monad in GHC.Core.Unify into a one-shot monad. See the long Note [The one-shot state monad trick]. See also #18202 and !3309, which applies this to all Reader/State-like monads in GHC for compile-time perf improvements. The pattern used here enables something similar to the state-hack, but is applicable to user-defined monads, not just `IO`. Metric Decrease 'runtime/bytes allocated' (test_env='i386-linux-deb9'): haddock.Cabal
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- Jun 25, 2020
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We're now correctly computing allocated bytes on 32-bit arch, so we get huge increases. Metric Increase: haddock.Cabal haddock.base haddock.compiler space_leak_001 -
While looking at #18348 I noticed that the treatment of HashLists are a bit more complex than necessary (which lead to some initial confusion on my part). Specifically, we allocate HashLists in chunks. Each chunk allocation makes two allocations: one for the chunk itself and one for a HashListChunk to link together the chunks for the purposes of freeing. Simplify this (and hopefully make the relationship between these clearer) but allocating the HashLists and HashListChunk in a single malloc. This will both make the implementation easier to follow and reduce C heap fragmentation. Note that even after this patch we fail to bound the size of the free HashList pool. However, this is a separate bug.
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Consider the Literal `[256] :: [Data.Word.Word8]` When the `OverloadedLists` extension is not active, then the `ol_ext` field in the `OverLitTc` record that is passed to the function `getIntegralLit` contains the type `Word8`. This is a simple type, and we can use its type constructor immediately for the `warnAboutOverflowedLiterals` function. When the `OverloadedLists` extension is active, then the `ol_ext` field contains the type family `Item [Word8]`. The function `nomaliseType` is used to convert it to the needed type `Word8`.
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These instances are taken from https://hackage.haskell.org/package/linear-1.21/docs/Linear-Instances.html They are the unique possible, so let they be in `base`.
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This updates haddock comments only. This patch focuses to update for hyperlinks in GHC API's haddock comments, because broken links especially discourage newcomers. This includes the following hierarchies: - GHC.Iface.* - GHC.Llvm.* - GHC.Rename.* - GHC.Tc.* - GHC.HsToCore.* - GHC.StgToCmm.* - GHC.CmmToAsm.* - GHC.Runtime.* - GHC.Unit.* - GHC.Utils.* - GHC.SysTools.*
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This updates haddock comments only. This patch focuses to update for hyperlinks in GHC API's haddock comments, because broken links especially discourage newcomers. This includes the following hierarchies: - GHC.Hs.* - GHC.Core.* - GHC.Stg.* - GHC.Cmm.* - GHC.Types.* - GHC.Data.* - GHC.Builtin.* - GHC.Parser.* - GHC.Driver.* - GHC top
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GHC.Hs.Extension had type GhcPs = GhcPass 'Parsed type GhcRn = GhcPass 'Renamed type GhcTc = GhcPass 'Typechecked type GhcTcId = GhcTc The last of these, GhcTcId, is a vestige of the past. This patch expunges it from GHC.
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Previously we would simply assume that makeindex was available. Now we correctly detect it in `configure` and respect this conclusion in hadrian and make.
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Previously we simply ignored the XELATEX variable when building PDF documentation.
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This patch fixes the bug and implements the feature request of #3000. 1. If `Module` is a real module name and `identifier` a name of a top-level function in `Module` then `:break Module.identifer` works also for an `identifier` that is out of scope. 2. Extend the syntax for `:break identifier` to: :break [ModQual.]topLevelIdent[.nestedIdent]...[.nestedIdent] `ModQual` is optional and is either the effective name of a module or the local alias of a qualified import statement. `topLevelIdent` is the name of a top level function in the module referenced by `ModQual`. `nestedIdent` is optional and the name of a function nested in a let or where clause inside the previously mentioned function `nestedIdent` or `topLevelIdent`. If `ModQual` is a module name, then `topLevelIdent` can be any top level identifier in this module. If `ModQual` is missing or a local alias of a qualified import, then `topLevelIdent` must be in scope. Breakpoints can be set on arbitrarily deeply nested functions, but the whole chain of nested function names must be specified. 3. To support the new functionality rewrite the code to tab complete `:break`.
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Starting with Win 8.1/Server 2012 windows no longer preallocates page tables for reserverd memory eagerly, which prevented us from using this approach in the past. We also try to allocate the heap high in the memory space. Hopefully this makes it easier to allocate things in the low 4GB of memory that need to be there. Like jump islands for the linker.
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- Jun 24, 2020
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These tweaks affect the inner loop of simplifyArgsWorker, which in turn is called from the flattener in Flatten.hs. This is a key perf bottleneck to T9872{a,b,c,d}. These two small changes have a modest but useful benefit. No change in functionality whatsoever. Relates to #18354 -
This bug, revealed by #18347, is just a missing update to sc_hole_ty in simplCast. I'd missed a code path when I made the recentchanges in commit 6d49d5be Author: Simon Peyton Jones <simonpj@microsoft.com> Date: Thu May 21 12:53:35 2020 +0100 Implement cast worker/wrapper properly The fix is very easy. Two other minor changes * Tidy up in SimpleOpt.simple_opt_expr. In fact I think this is an outright bug, introduced in the fix to #18112: we were simplifying the same coercion twice *with the same substitution*, which is just wrong. It'd be a hard bug to trigger, so I just fixed it; less code too. * Better debug printing of ApplyToVal -
Zonk residual constraints in checkForExistence to reveal user type errors. Previously when `:instances` was used with instances that have TypeError constraints the result would look something like: instance [safe] s0 => Err 'A -- Defined at ../Bug2.hs:8:10 whereas after zonking, `:instances` now sees the `TypeError` and properly eliminates the constraint from the results.
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Metric Decrease: T12150 T12234 -
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