| Commit message (Collapse) | Author | Age | Files | Lines |
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* FailablePattern can no longer be created since ab51bee40c82
Therefore, Opt_WarnMissingMonadFailInstances has no effect anymore.
* XWrap is no longer used, it was moved to an extension field
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* Remove outdated Note [HsForAllTy tyvar binders] and [Context quantification].
Since the wildcard refactor 1e041b7382, HsForAllTy no longer has an flag
controlling explicity. The field `hsq_implicit` is gone too.
The current situation is covered by Note [HsType binders] which is already
linked from LHsQTyVars.
* Small refactor in CoreLint, extracting common code to a function
* Remove "not so sure about WpFun" in TcEvidence, per Richard's comment
https://gitlab.haskell.org/ghc/ghc/merge_requests/852#note_223226
* Use mkIfThenElse in Foreign/Call, as it does exactly what we need.
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Before this patch, GHC relied on Ord SrcSpan to identify source elements, by
using SrcSpan as Map keys:
blackList :: Map SrcSpan () -- compiler/GHC/HsToCore/Coverage.hs
instanceMap :: Map SrcSpan Name -- compiler/GHC/HsToCore/Docs.hs
Firstly, this design is not valid in presence of UnhelpfulSpan, as it
distinguishes between UnhelpfulSpan "X" and UnhelpfulSpan "Y", but those
strings are messages for the user, unfit to serve as identifiers for source
elements.
Secondly, this design made it hard to extend SrcSpan with additional data.
Recall that the definition of SrcSpan is:
data SrcSpan =
RealSrcSpan !RealSrcSpan
| UnhelpfulSpan !FastString
Say we want to extend the RealSrcSpan constructor with additional information:
data SrcSpan =
RealSrcSpan !RealSrcSpan !AdditionalInformation
| UnhelpfulSpan !FastString
getAdditionalInformation :: SrcSpan -> AdditionalInformation
getAdditionalInformation (RealSrcSpan _ a) = a
Now, in order for Map SrcSpan to keep working correctly, we must *ignore* additional
information when comparing SrcSpan values:
instance Ord SrcSpan where
compare (RealSrcSpan r1 _) (RealSrcSpan r2 _) = compare r1 r2
...
However, this would violate an important law:
a == b therefore f a == f b
Ignoring AdditionalInformation in comparisons would mean that with
f=getAdditionalInformation, the law above does not hold.
A more robust design is to avoid Ord SrcSpan altogether, which is what this patch implements.
The mappings are changed to use RealSrcSpan instead:
blackList :: Set RealSrcSpan -- compiler/GHC/HsToCore/Coverage.hs
instanceMap :: Map RealSrcSpan Name -- compiler/GHC/HsToCore/Docs.hs
All SrcSpan comparisons are now done with explicit comparison strategies:
SrcLoc.leftmost_smallest
SrcLoc.leftmost_largest
SrcLoc.rightmost_smallest
These strategies are not subject to the law mentioned above and can easily
discard both the string stored in UnhelpfulSpan and AdditionalInformation.
Updates haddock submodule.
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The constructor HsSplicedT occurs only in the GhcTc pass.
This enforces this fact statically via TTG.
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Remove several uses of `sdocWithDynFlags`. The remaining ones are mostly
CodeGen related (e.g. depend on target platform constants) and will be
fixed separately.
Metric Decrease:
T12425
T9961
WWRec
T1969
T14683
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We now always show "forall {a}. T" for inferred variables,
previously this was controlled by -fprint-explicit-foralls.
This implements part 1 of https://github.com/ghc-proposals/ghc-proposals/pull/179.
Part of GHC ticket #16320.
Furthermore, when printing a levity restriction error, we now display
the HsWrap of the expression. This lets users see the full elaboration with
-fprint-typechecker-elaboration (see also #17670)
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There are two main payloads of this patch:
1. This introduces IsPass, which allows e.g. printing
code to ask what pass it is running in (Renamed vs
Typechecked) and thus print extension fields. See
Note [IsPass] in Hs.Extension
2. This moves the HsWrap constructor into an extension
field, where it rightly belongs. This is done for
HsExpr and HsCmd, but not for HsPat, which is left
as an exercise for the reader.
There is also some refactoring around SyntaxExprs, but this
is really just incidental.
This patch subsumes !1721 (sorry @chreekat).
Along the way, there is a bit of refactoring in GHC.Hs.Extension,
including the removal of NameOrRdrName in favor of NoGhcTc.
This meant that we had no real need for GHC.Hs.PlaceHolder, so
I got rid of it.
Updates haddock submodule.
-------------------------
Metric Decrease:
haddock.compiler
-------------------------
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```
main = do
print $ g [1..100] a
where g xs x = map (`mod` x) xs
a :: Int = 324
```
The above program previously attributed the cost of computing 324 to a cost
centre named `(...)`, with this change the cost is attributed to `a` instead.
This change only affects simple pattern bindings (decorated variables: type
signatures, parens, ~ annotations and ! annotations).
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This patch fixes #17566 by refactoring the way we decide the final
identity of the tyvars in the TyCons of a possibly-recursive nest
of type and class decls, possibly with associated types.
It's all laid out in
Note [Swizzling the tyvars before generaliseTcTyCon]
Main changes:
* We have to generalise each decl (with its associated types)
all at once: TcTyClsDecls.generaliseTyClDecl
* The main new work is done in TcTyClsDecls.swizzleTcTyConBndrs
* The mysterious TcHsSyn.zonkRecTyVarBndrs dies altogether
Other smaller things:
* A little refactoring, moving bindTyClTyVars from tcTyClDecl1
to tcDataDefn, tcSynRhs, etc. Clearer, reduces the number of
parameters
* Reduce the amount of swizzling required.
Specifically, bindExplicitTKBndrs_Q_Tv doesn't need
to clone a new Name for the TyVarTv, and not
cloning means that in the vasly common case,
swizzleTyConBndrs is a no-op
In detail:
Rename newTyVarTyVar --> cloneTyVarTyVar
Add newTyVarTyTyVar that doesn't clone
Use the non-cloning newTyVarTyVar in
bindExplicitTKBndrs_Q_Tv
Rename newFlexiKindedTyVarTyVar
--> cloneFlexiKindedTyVarTyVar
* Define new utility function and use it
HsDecls.familyDeclName ::
FamilyDecl (GhcPass p) -> IdP (GhcPass p)
Updates haddock submodule.
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incomplete-uni-patterns and incomplete-record-updates will be in -Wall at a
future date, so prepare for that by disabling those warnings on files that
trigger them.
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Richard points out in #17688 that we use `splitLHsForAllTy` and
`splitLHsSigmaTy` in places that we ought to be using the
corresponding `-Invis` variants instead, identifying two bugs
that are caused by this oversight:
* Certain TH-quoted type signatures, such as those that appear in
quoted `SPECIALISE` pragmas, silently turn visible `forall`s into
invisible `forall`s.
* When quoted, the type `forall a -> (a ~ a) => a` will turn into
`forall a -> a` due to a bug in `DsMeta.repForall` that drops
contexts that follow visible `forall`s.
These are both ultimately caused by the fact that `splitLHsForAllTy`
and `splitLHsSigmaTy` split apart visible `forall`s in addition to
invisible ones. This patch cleans things up:
* We now use `splitLHsForAllTyInvis` and `splitLHsSigmaTyInvis`
throughout the codebase. Relatedly, the `splitLHsForAllTy` and
`splitLHsSigmaTy` have been removed, as they are easy to misuse.
* `DsMeta.repForall` now only handles invisible `forall`s to reduce
the chance for confusion with visible `forall`s, which need to be
handled differently. I also renamed it from `repForall` to
`repForallT` to emphasize that its distinguishing characteristic
is the fact that it desugars down to `L.H.TH.Syntax.ForallT`.
Fixes #17688.
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Previously, `hsScopedTvs` (and its cousin `hsWcScopedTvs`) pretended
that visible dependent quantification could not possibly happen at
the term level, and cemented that assumption with an `ASSERT`:
```hs
hsScopedTvs (HsForAllTy { hst_fvf = vis_flag, ... }) =
ASSERT( vis_flag == ForallInvis )
...
```
It turns out that this assumption is wrong. You can end up tripping
this `ASSERT` if you stick it to the man and write a type for a term
that uses visible dependent quantification anyway, like in this
example:
```hs
{-# LANGUAGE ScopedTypeVariables #-}
x :: forall a -> a -> a
x = x
```
That won't typecheck, but that's not the point. Before the
typechecker has a chance to reject this, the renamer will try
to use `hsScopedTvs` to bring `a` into scope over the body of `x`,
since `a` is quantified by a `forall`. This, in turn, causes the
`ASSERT` to fail. Bummer.
Instead of walking on this dangerous ground, this patch makes GHC
adopt a more hardline stance by pattern-matching directly on
`ForallInvis` in `hsScopedTvs`:
```hs
hsScopedTvs (HsForAllTy { hst_fvf = ForallInvis, ... }) = ...
```
Now `a` will not be brought over the body of `x` at all (which is how
it should be), there's no chance of the `ASSERT` failing anymore (as
it's gone), and best of all, the behavior of `hsScopedTvs` does not
change. Everyone wins!
Fixes #17687.
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`DsMeta.rep_sig` used to skip over `FixSig` entirely, which had the
effect of causing local fixity declarations to be dropped when quoted
in Template Haskell. But there is no good reason for this state of
affairs, as the code in `DsMeta.repFixD` (which handles top-level
fixity declarations) handles local fixity declarations just fine.
This patch factors out the necessary parts of `repFixD` so that they
can be used in `rep_sig` as well.
There was one minor complication: the fixity signatures for class
methods in each `HsGroup` were stored both in `FixSig`s _and_ the
list of `LFixitySig`s for top-level fixity signatures, so I needed
to take action to prevent fixity signatures for class methods being
converted to `Dec`s twice. I tweaked `RnSource.add` to avoid putting
these fixity signatures in two places and added
`Note [Top-level fixity signatures in an HsGroup]` in `GHC.Hs.Decls`
to explain the new design.
Fixes #17608. Bumps the Haddock submodule.
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This patch implements overloaded quotation brackets which generalise the
desugaring of all quotation forms in terms of a new minimal interface.
The main change is that a quotation, for example, [e| 5 |], will now
have type `Quote m => m Exp` rather than `Q Exp`. The `Quote` typeclass
contains a single method for generating new names which is used when
desugaring binding structures.
The return type of functions from the `Lift` type class, `lift` and `liftTyped` have
been restricted to `forall m . Quote m => m Exp` rather than returning a
result in a Q monad.
More details about the feature can be read in the GHC proposal.
https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0246-overloaded-bracket.rst
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Before this patch, GHC always printed the * kind unparenthesized.
This led to two issues:
1. Sometimes GHC printed invalid or incorrect code.
For example, GHC would print: type F @* x = x
when it meant to print: type F @(*) x = x
In the former case, instead of a kind application we were getting a
type operator (@*).
2. Sometimes GHC printed kinds that were correct but hard to read.
Should Either * Int be read as Either (*) Int
or as (*) Either Int ?
This depends on whether -XStarIsType is enabled, but it would be
easier if we didn't have to check for the flag when reading the code.
We can solve both problems by assigning (*) a different precedence. Note
that Haskell98 kinds are not affected:
((* -> *) -> *) -> * does NOT become (((*) -> (*)) -> (*)) -> (*)
The parentheses are added when (*) is used in a function argument
position:
F * * * becomes F (*) (*) (*)
F A * B becomes F A (*) B
Proxy * becomes Proxy (*)
a * -> * becomes a (*) -> *
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As suggested by RyanGlScott in !2163.
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Metric Decrease:
haddock.compiler
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This is a refactoring with no user-visible changes (except for GHC API
users). Consider the HsExpr constructors that correspond to user-written
pragmas:
HsSCC representing {-# SCC ... #-}
HsCoreAnn representing {-# CORE ... #-}
HsTickPragma representing {-# GENERATED ... #-}
We can factor them out into a separate datatype, HsPragE. It makes the
code a bit tidier, especially in the parser.
Before this patch:
hpc_annot :: { Located ( (([AddAnn],SourceText),(StringLiteral,(Int,Int),(Int,Int))),
((SourceText,SourceText),(SourceText,SourceText))
) }
After this patch:
prag_hpc :: { Located ([AddAnn], HsPragE GhcPs) }
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This patch implements a part of GHC Proposal #229 that covers five
operators:
* the bang operator (!)
* the tilde operator (~)
* the at operator (@)
* the dollar operator ($)
* the double dollar operator ($$)
Based on surrounding whitespace, these operators are disambiguated into
bang patterns, lazy patterns, strictness annotations, type
applications, splices, and typed splices.
This patch doesn't cover the (-) operator or the -Woperator-whitespace
warning, which are left as future work.
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In #17270 we have the pattern-match checker emit incorrect warnings. The
reason for that behavior is ultimately an inconsistency in whether we
treat TH splices as written by the user (`FromSource :: Origin`) or as
generated code (`Generated`). This was first reported in #14838.
The current solution is to TH splices as `Generated` by default and only
treat them as `FromSource` when the user requests so
(-fenable-th-splice-warnings). There are multiple reasons for opt-in
rather than opt-out:
* It's not clear that the user that compiles a splice is the author of the code
that produces the warning. Think of the situation where she just splices in
code from a third-party library that produces incomplete pattern matches.
In this scenario, the user isn't even able to fix that warning.
* Gathering information for producing the warnings (pattern-match check
warnings in particular) is costly. There's no point in doing so if the user
is not interested in those warnings.
Fixes #17270, but not #14838, because the proper solution needs a GHC
proposal extending the TH AST syntax.
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This reverts the change in #9096.
The specialcasing done for prefix (->) is brittle and
does not support VTA, type families, type synonyms etc.
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This makes error messages a tad less noisy.
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Issue #17461 was occurring because the `Outputable` instance for
standalone kind signatures was simply calling `ppr` on the name in
the kind signature, which does not add parentheses to infix names.
The solution is simple: use `pprPrefixOcc` instead.
Fixes #17461.
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Previously an import cycle between Type and TyCoRep meant that several
functions in TyCoRep ended up SOURCE import coreView. This is quite
unfortunate as coreView is intended to be fused into a larger pattern
match and not incur an extra call.
Fix this with a bit of restructuring:
* Move the functions in `TyCoRep` which depend upon things in `Type`
into `Type`
* Fold contents of `Kind` into `Type` and turn `Kind` into a simple
wrapper re-exporting kind-ish things from `Type`
* Clean up the redundant imports that popped up as a result
Closes #17441.
Metric Decrease:
T4334
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!1906 left some loose ends in regards to Template Haskell's treatment
of unary tuples. This patch ends to tie up those loose ends:
* In addition to having `TupleT 1` produce unary tuples, `TupE [exp]`
and `TupP [pat]` also now produce unary tuples.
* I have added various special cases in GHC's pretty-printers to
ensure that explicit 1-tuples are printed using the `Unit` type.
See `testsuite/tests/th/T17380`.
* The GHC 8.10.1 release notes entry has been tidied up a little.
Fixes #16881. Fixes #17371. Fixes #17380.
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Since the Trees That Grow effort started, we had `type LPat = Pat`.
This is so that `SrcLoc`s would only be annotated in GHC's AST, which is
the reason why all GHC passes use the extension constructor `XPat` to
attach source locations. See #15495 for the design discussion behind
that.
But now suddenly there are `XPat`s everywhere!
There are several functions which dont't cope with `XPat`s by either
crashing (`hsPatType`) or simply returning incorrect results
(`collectEvVarsPat`).
This issue was raised in #17330. I also came up with a rather clean and
type-safe solution to the problem: We define
```haskell
type family XRec p (f :: * -> *) = r | r -> p f
type instance XRec (GhcPass p) f = Located (f (GhcPass p))
type instance XRec TH f = f p
type LPat p = XRec p Pat
```
This is a rather modular embedding of the old "ping-pong" style, while
we only pay for the `Located` wrapper within GHC. No ping-ponging in
a potential Template Haskell AST, for example. Yet, we miss no case
where we should've handled a `SrcLoc`: `hsPatType` and
`collectEvVarsPat` are not callable at an `LPat`.
Also, this gets rid of one indirection in `Located` variants:
Previously, we'd have to go through `XPat` and `Located` to get from
`LPat` to the wrapped `Pat`. Now it's just `Located` again.
Thus we fix #17330.
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with equality constraints
In #17304, Richard and Simon dicovered that using `-XFlexibleInstances`
for `Outputable` instances of AST data types means users can provide orphan
`Outputable` instances for passes other than `GhcPass`.
Type inference doesn't currently to suffer, and Richard gave an example
in #17304 that shows how rare a case would be where the slightly worse
type inference would matter.
So I went ahead with the refactoring, attempting to fix #17304.
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Applicative-do has a bug where it fails to use the monadic fail method
when desugaring patternmatches which can fail. See #15344.
This patch fixes that problem. It required more rewiring than I had expected.
Applicative-do happens mostly in the renamer; that's where decisions about
scheduling are made. This schedule is then carried through the typechecker and
into the desugarer which performs the actual translation. Fixing this bug
required sending information about the fail method from the renamer, through
the type checker and into the desugarer. Previously, the desugarer didn't
have enough information to actually desugar pattern matches correctly.
As a side effect, we also fix #16628, where GHC wouldn't catch missing
MonadFail instances with -XApplicativeDo.
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Previously, all constraints from all top-level groups (as
separated by top-level splices) were lumped together and solved
at the end. This could leak metavariables to TH, though, and
that's bad. This patch solves each group's constraints before
running the next group's splice.
Naturally, we now report fewer errors in some cases.
One nice benefit is that this also fixes #11680, but in a much
simpler way than the original fix for that ticket. Admittedly,
the error messages degrade just a bit from the fix from #11680
(previously, we informed users about variables that will be
brought into scope below a top-level splice, and now we just
report an out-of-scope error), but the amount of complexity
required throughout GHC to get that error was just not worth it.
This patch thus reverts much of
f93c9517a2c6e158e4a5c5bc7a3d3f88cb4ed119.
Fixes #16980
Test cases: th/T16980{,a}
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This patch also changes the way we handle empty lists, simplifying
them somewhat. See Note [Empty lists]. Previously, we had to
special-case empty lists in the type-checker. Now no more!
Finally, this patch improves some documentation around the ir_inst
field used in the type-checker.
This breaks a test case, but I really think the problem is #17251,
not really related to this patch.
Test case: typecheck/should_compile/T13680
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Implements GHC Proposal #54: .../ghc-proposals/blob/master/proposals/0054-kind-signatures.rst
With this patch, a type constructor can now be given an explicit
standalone kind signature:
{-# LANGUAGE StandaloneKindSignatures #-}
type Functor :: (Type -> Type) -> Constraint
class Functor f where
fmap :: (a -> b) -> f a -> f b
This is a replacement for CUSKs (complete user-specified
kind signatures), which are now scheduled for deprecation.
User-facing changes
-------------------
* A new extension flag has been added, -XStandaloneKindSignatures, which
implies -XNoCUSKs.
* There is a new syntactic construct, a standalone kind signature:
type <name> :: <kind>
Declarations of data types, classes, data families, type families, and
type synonyms may be accompanied by a standalone kind signature.
* A standalone kind signature enables polymorphic recursion in types,
just like a function type signature enables polymorphic recursion in
terms. This obviates the need for CUSKs.
* TemplateHaskell AST has been extended with 'KiSigD' to represent
standalone kind signatures.
* GHCi :info command now prints the kind signature of type constructors:
ghci> :info Functor
type Functor :: (Type -> Type) -> Constraint
...
Limitations
-----------
* 'forall'-bound type variables of a standalone kind signature do not
scope over the declaration body, even if the -XScopedTypeVariables is
enabled. See #16635 and #16734.
* Wildcards are not allowed in standalone kind signatures, as partial
signatures do not allow for polymorphic recursion.
* Associated types may not be given an explicit standalone kind
signature. Instead, they are assumed to have a CUSK if the parent class
has a standalone kind signature and regardless of the -XCUSKs flag.
* Standalone kind signatures do not support multiple names at the moment:
type T1, T2 :: Type -> Type -- rejected
type T1 = Maybe
type T2 = Either String
See #16754.
* Creative use of equality constraints in standalone kind signatures may
lead to GHC panics:
type C :: forall (a :: Type) -> a ~ Int => Constraint
class C a where
f :: C a => a -> Int
See #16758.
Implementation notes
--------------------
* The heart of this patch is the 'kcDeclHeader' function, which is used to
kind-check a declaration header against its standalone kind signature.
It does so in two rounds:
1. check user-written binders
2. instantiate invisible binders a la 'checkExpectedKind'
* 'kcTyClGroup' now partitions declarations into declarations with a
standalone kind signature or a CUSK (kinded_decls) and declarations
without either (kindless_decls):
* 'kinded_decls' are kind-checked with 'checkInitialKinds'
* 'kindless_decls' are kind-checked with 'getInitialKinds'
* DerivInfo has been extended with a new field:
di_scoped_tvs :: ![(Name,TyVar)]
These variables must be added to the context in case the deriving clause
references tcTyConScopedTyVars. See #16731.
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Add GHC.Hs module hierarchy replacing hsSyn.
Metric Increase:
haddock.compiler
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