[Git][ghc/ghc][wip/T18240] 8 commits: Implement the proposed -XQualifiedDo extension
Ryan Scott
gitlab at gitlab.haskell.org
Sat Jun 27 18:56:33 UTC 2020
Ryan Scott pushed to branch wip/T18240 at Glasgow Haskell Compiler / GHC
Commits:
9ee58f8d by Matthias Pall Gissurarson at 2020-06-26T17:12:45+00:00
Implement the proposed -XQualifiedDo extension
Co-authored-by: Facundo Domínguez <facundo.dominguez at 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.
- - - - -
ce987865 by Ryan Scott at 2020-06-27T11:55:21-04:00
Revamp the treatment of auxiliary bindings for derived instances
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.
- - - - -
a403eb91 by Sylvain Henry at 2020-06-27T11:55:59-04:00
ghc-bignum: fix division by zero (#18359)
- - - - -
1b3d13b6 by Sylvain Henry at 2020-06-27T11:55:59-04:00
Fix ghc-bignum exceptions
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.
- - - - -
a74ec37c by Simon Peyton Jones at 2020-06-27T11:56:34-04:00
Better loop detection in findTypeShape
Andreas pointed out, in !3466, that my fix for #18304 was not
quite right. This patch fixes it properly, by having just one
RecTcChecker rather than (implicitly) two nested ones, in
findTypeShape.
- - - - -
a04020b8 by Sylvain Henry at 2020-06-27T11:57:11-04:00
DynFlags: don't store buildTag
`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.
- - - - -
0e83efa2 by Krzysztof Gogolewski at 2020-06-27T11:57:49-04:00
Don't generalize when typechecking a tuple section
The code is simpler and cleaner.
- - - - -
00418ed8 by Ryan Scott at 2020-06-27T14:56:18-04:00
Reject nested foralls/contexts in instance types more consistently
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.
- - - - -
30 changed files:
- compiler/GHC/Builtin/Names.hs
- compiler/GHC/Builtin/Names/TH.hs
- compiler/GHC/Builtin/Types/Prim.hs
- compiler/GHC/Builtin/primops.txt.pp
- compiler/GHC/Core/FamInstEnv.hs
- compiler/GHC/Core/Make.hs
- compiler/GHC/Core/Opt/WorkWrap/Utils.hs
- compiler/GHC/Driver/Finder.hs
- compiler/GHC/Driver/MakeFile.hs
- compiler/GHC/Driver/Session.hs
- compiler/GHC/Driver/Ways.hs
- compiler/GHC/Hs/Expr.hs
- compiler/GHC/Hs/Instances.hs
- compiler/GHC/Hs/Type.hs
- compiler/GHC/HsToCore/Arrows.hs
- compiler/GHC/HsToCore/Coverage.hs
- compiler/GHC/HsToCore/Expr.hs
- compiler/GHC/HsToCore/ListComp.hs
- compiler/GHC/HsToCore/Match.hs
- compiler/GHC/HsToCore/PmCheck/Oracle.hs
- compiler/GHC/HsToCore/Quote.hs
- compiler/GHC/HsToCore/Usage.hs
- compiler/GHC/Iface/Binary.hs
- compiler/GHC/Iface/Env.hs
- compiler/GHC/Iface/Ext/Ast.hs
- compiler/GHC/Iface/Make.hs
- compiler/GHC/Parser.y
- compiler/GHC/Parser/Lexer.x
- compiler/GHC/Parser/PostProcess.hs
- compiler/GHC/Rename/Env.hs
The diff was not included because it is too large.
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/bd9e357fc7a795c2adc93dc0662872dcde0b71d6...00418ed8459639a3843231c8b916c5fa88fdd8d2
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/bd9e357fc7a795c2adc93dc0662872dcde0b71d6...00418ed8459639a3843231c8b916c5fa88fdd8d2
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