| Commit message (Collapse) | Author | Age | Files | Lines |
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Fixes #11270
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This fixes the fact that we were not reporting orphan family instances
at all. The fix here is easy, but touches a bit of code. I refactored
the code to be much more similar to the way that class instances are done:
- Add a fi_orphan field to FamInst, like the is_orphan field in ClsInst
- Make newFamInst initialise this field, just like newClsInst
- And make newFamInst report a warning for an orphan, just like newClsInst
- I moved newFamInst from GHC.Tc.Instance.Family to GHC.Tc.Utils.Instantiate,
just like newClsInst.
- I added mkLocalFamInst to FamInstEnv, just like mkLocalClsInst in InstEnv
- TcRnOrphanInstance and SuggestFixOrphanInstance are now parametrised
over class instances vs type/data family instances.
Fixes #19773
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This patch completely re-engineers how we deal with loopy superclass
dictionaries in instance declarations. It fixes #20666 and #19690
The highlights are
* Recognise that the loopy-superclass business should use precisely
the Paterson conditions. This is much much nicer. See
Note [Recursive superclasses] in GHC.Tc.TyCl.Instance
* With that in mind, define "Paterson-smaller" in
Note [Paterson conditions] in GHC.Tc.Validity, and the new
data type `PatersonSize` in GHC.Tc.Utils.TcType, along with
functions to compute and compare PatsonSizes
* Use the new PatersonSize stuff when solving superclass constraints
See Note [Solving superclass constraints] in GHC.Tc.TyCl.Instance
* In GHC.Tc.Solver.Monad.lookupInInerts, add a missing call to
prohibitedSuperClassSolve. This was the original cause of #20666.
* Treat (TypeError "stuff") as having PatersonSize zero. See
Note [Paterson size for type family applications] in GHC.Tc.Utils.TcType.
* Treat the head of a Wanted quantified constraint in the same way
as the superclass of an instance decl; this is what fixes #19690.
See GHC.Tc.Solver.Canonical Note [Solving a Wanted forall-constraint]
(Thanks to Matthew Craven for this insight.)
This entailed refactoring the GivenSc constructor of CtOrigin a bit,
to say whether it comes from an instance decl or quantified constraint.
* Some refactoring way in which redundant constraints are reported; we
don't want to complain about the extra, apparently-redundant
constraints that we must add to an instance decl because of the
loopy-superclass thing. I moved some work from GHC.Tc.Errors to
GHC.Tc.Solver.
* Add a new section to the user manual to describe the loopy
superclass issue and what rules it follows.
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This big patch addresses the rats-nest of issues that have plagued
us for years, about the relationship between Type and Constraint.
See #11715/#21623.
The main payload of the patch is:
* To introduce CONSTRAINT :: RuntimeRep -> Type
* To make TYPE and CONSTRAINT distinct throughout the compiler
Two overview Notes in GHC.Builtin.Types.Prim
* Note [TYPE and CONSTRAINT]
* Note [Type and Constraint are not apart]
This is the main complication.
The specifics
* New primitive types (GHC.Builtin.Types.Prim)
- CONSTRAINT
- ctArrowTyCon (=>)
- tcArrowTyCon (-=>)
- ccArrowTyCon (==>)
- funTyCon FUN -- Not new
See Note [Function type constructors and FunTy]
and Note [TYPE and CONSTRAINT]
* GHC.Builtin.Types:
- New type Constraint = CONSTRAINT LiftedRep
- I also stopped nonEmptyTyCon being built-in; it only needs to be wired-in
* Exploit the fact that Type and Constraint are distinct throughout GHC
- Get rid of tcView in favour of coreView.
- Many tcXX functions become XX functions.
e.g. tcGetCastedTyVar --> getCastedTyVar
* Kill off Note [ForAllTy and typechecker equality], in (old)
GHC.Tc.Solver.Canonical. It said that typechecker-equality should ignore
the specified/inferred distinction when comparein two ForAllTys. But
that wsa only weakly supported and (worse) implies that we need a separate
typechecker equality, different from core equality. No no no.
* GHC.Core.TyCon: kill off FunTyCon in data TyCon. There was no need for it,
and anyway now we have four of them!
* GHC.Core.TyCo.Rep: add two FunTyFlags to FunCo
See Note [FunCo] in that module.
* GHC.Core.Type. Lots and lots of changes driven by adding CONSTRAINT.
The key new function is sORTKind_maybe; most other changes are built
on top of that.
See also `funTyConAppTy_maybe` and `tyConAppFun_maybe`.
* Fix a longstanding bug in GHC.Core.Type.typeKind, and Core Lint, in
kinding ForAllTys. See new tules (FORALL1) and (FORALL2) in GHC.Core.Type.
(The bug was that before (forall (cv::t1 ~# t2). blah), where
blah::TYPE IntRep, would get kind (TYPE IntRep), but it should be
(TYPE LiftedRep). See Note [Kinding rules for types] in GHC.Core.Type.
* GHC.Core.TyCo.Compare is a new module in which we do eqType and cmpType.
Of course, no tcEqType any more.
* GHC.Core.TyCo.FVs. I moved some free-var-like function into this module:
tyConsOfType, visVarsOfType, and occCheckExpand. Refactoring only.
* GHC.Builtin.Types. Compiletely re-engineer boxingDataCon_maybe to
have one for each /RuntimeRep/, rather than one for each /Type/.
This dramatically widens the range of types we can auto-box.
See Note [Boxing constructors] in GHC.Builtin.Types
The boxing types themselves are declared in library ghc-prim:GHC.Types.
GHC.Core.Make. Re-engineer the treatment of "big" tuples (mkBigCoreVarTup
etc) GHC.Core.Make, so that it auto-boxes unboxed values and (crucially)
types of kind Constraint. That allows the desugaring for arrows to work;
it gathers up free variables (including dictionaries) into tuples.
See Note [Big tuples] in GHC.Core.Make.
There is still work to do here: #22336. But things are better than
before.
* GHC.Core.Make. We need two absent-error Ids, aBSENT_ERROR_ID for types of
kind Type, and aBSENT_CONSTRAINT_ERROR_ID for vaues of kind Constraint.
Ditto noInlineId vs noInlieConstraintId in GHC.Types.Id.Make;
see Note [inlineId magic].
* GHC.Core.TyCo.Rep. Completely refactor the NthCo coercion. It is now called
SelCo, and its fields are much more descriptive than the single Int we used to
have. A great improvement. See Note [SelCo] in GHC.Core.TyCo.Rep.
* GHC.Core.RoughMap.roughMatchTyConName. Collapse TYPE and CONSTRAINT to
a single TyCon, so that the rough-map does not distinguish them.
* GHC.Core.DataCon
- Mainly just improve documentation
* Some significant renamings:
GHC.Core.Multiplicity: Many --> ManyTy (easier to grep for)
One --> OneTy
GHC.Core.TyCo.Rep TyCoBinder --> GHC.Core.Var.PiTyBinder
GHC.Core.Var TyCoVarBinder --> ForAllTyBinder
AnonArgFlag --> FunTyFlag
ArgFlag --> ForAllTyFlag
GHC.Core.TyCon TyConTyCoBinder --> TyConPiTyBinder
Many functions are renamed in consequence
e.g. isinvisibleArgFlag becomes isInvisibleForAllTyFlag, etc
* I refactored FunTyFlag (was AnonArgFlag) into a simple, flat data type
data FunTyFlag
= FTF_T_T -- (->) Type -> Type
| FTF_T_C -- (-=>) Type -> Constraint
| FTF_C_T -- (=>) Constraint -> Type
| FTF_C_C -- (==>) Constraint -> Constraint
* GHC.Tc.Errors.Ppr. Some significant refactoring in the TypeEqMisMatch case
of pprMismatchMsg.
* I made the tyConUnique field of TyCon strict, because I
saw code with lots of silly eval's. That revealed that
GHC.Settings.Constants.mAX_SUM_SIZE can only be 63, because
we pack the sum tag into a 6-bit field. (Lurking bug squashed.)
Fixes
* #21530
Updates haddock submodule slightly.
Performance changes
~~~~~~~~~~~~~~~~~~~
I was worried that compile times would get worse, but after
some careful profiling we are down to a geometric mean 0.1%
increase in allocation (in perf/compiler). That seems fine.
There is a big runtime improvement in T10359
Metric Decrease:
LargeRecord
MultiLayerModulesTH_OneShot
T13386
T13719
Metric Increase:
T8095
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* Rename pprCLabel to pprCLabelStyle, and use the name pprCLabel
for a function using CStyle (analogous to pprAsmLabel)
* Move LabelStyle to the CLabel module, it no longer needs to be in Outputable.
* Move calls to 'text' right next to literals, to make sure the text/str
rule is triggered.
* Remove FastString/String roundtrip in Tc.Deriv.Generate
* Introduce showSDocForUser', which abstracts over a pattern in
GHCi.UI
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Lets us avoid some use of `head` and `tail`, and some panics.
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Previously, derived instances of `Functor` (as well as the related classes
`Foldable`, `Traversable`, and `Generic1`) would determine which constraints to
infer by checking for fields that contain the last type variable. The problem
was that this last type variable was taken from `tyConTyVars`. For GADTs, the
type variables in each data constructor are _not_ the same type variables as
in `tyConTyVars`, leading to #22167.
This fixes the issue by instead checking for the last type variable using
`dataConUnivTyVars`. (This is very similar in spirit to the fix for #21185,
which also replaced an errant use of `tyConTyVars` with type variables from
each data constructor.)
Fixes #22167.
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• Delete some dead code, largely under `GHC.Utils`.
• Clean up a few definitions in `GHC.Utils.(Misc, Monad)`.
• Clean up `GHC.Types.SrcLoc`.
• Derive stock `Functor, Foldable, Traversable` for more types.
• Derive more instances for newtypes.
Bump haddock submodule.
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This fixes various typos and spelling mistakes
in the compiler.
Fixes #21891
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For the code
{-# LANGUAGE OverloadedRecordUpdate #-}
operatorUpdate f = f{(+) = 1}
There are no exact print annotations for the parens around the +
symbol, nor does normal ppr print them.
This MR fixes that.
Closes #21805
Updates haddock submodule
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This patch removes the TCvSubst data type and instead uses Subst as
the environment for both term and type level substitution. This
change is partially motivated by the existential type proposal,
which will introduce types that contain expressions and therefore
forces us to carry around an "IdSubstEnv" even when substituting for
types. It also reduces the amount of code because "Subst" and
"TCvSubst" share a lot of common operations. There isn't any
noticeable impact on performance (geo. mean for ghc/alloc is around
0.0% but we have -94 loc and one less data type to worry abount).
Currently, the "TCvSubst" data type for substitution on types is
identical to the "Subst" data type except the former doesn't store
"IdSubstEnv". Using "Subst" for type-level substitution means there
will be a redundant field stored in the data type. However, in cases
where the substitution starts from the expression, using "Subst" for
type-level substitution saves us from having to project "Subst" into a
"TCvSubst". This probably explains why the allocation is mostly even
despite the redundant field.
The patch deletes "TCvSubst" and moves "Subst" and its relevant
functions from "GHC.Core.Subst" into "GHC.Core.TyCo.Subst".
Substitution on expressions is still defined in "GHC.Core.Subst" so we
don't have to expose the definition of "Expr" in the hs-boot file that
"GHC.Core.TyCo.Subst" must import to refer to "IdSubstEnv" (whose
codomain is "CoreExpr"). Most functions named fooTCvSubst are renamed
into fooSubst with a few exceptions (e.g. "isEmptyTCvSubst" is a
distinct function from "isEmptySubst"; the former ignores the
emptiness of "IdSubstEnv"). These exceptions mainly exist for
performance reasons and will go away when "Expr" and "Type" are
mutually recursively defined (we won't be able to take those
shortcuts if we can't make the assumption that expressions don't
appear in types).
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There was an assert error, as Gergo pointed out in #21896.
I fixed this by adding an InScopeSet argument to tcUnifyTyWithTFs.
And also to GHC.Core.Unify.niFixTCvSubst.
I also took the opportunity to get a couple more InScopeSets right,
and to change some substTyUnchecked into substTy.
This MR touches a lot of other files, but only because I also took the
opportunity to introduce mkInScopeSetList, and use it.
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ModuleName used to live in GHC.Unit.Module.Name. In this commit, the
definition of ModuleName and its associated functions are moved to
Language.Haskell.Syntax.Module.Name according to the current plan
towards making the AST GHC-independent.
The instances for ModuleName for Outputable, Uniquable and Binary were
moved to the module in which the class is defined because these instances
depend on GHC.
The instance of Eq for ModuleName is slightly changed to no longer
depend on unique explicitly and instead uses FastString's instance of
Eq.
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One more step towards the new design of EPA.
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This commit redefines the structure of Splices in the AST.
We get rid of `HsSplice` which used to represent typed and untyped
splices, quasi quotes, and the result of splicing either an expression,
a type or a pattern.
Instead we have `HsUntypedSplice` which models an untyped splice or a
quasi quoter, which works in practice just like untyped splices.
The `HsExpr` constructor `HsSpliceE` which used to be constructed with
an `HsSplice` is split into `HsTypedSplice` and `HsUntypedSplice`. The
former is directly constructed with an `HsExpr` and the latter now takes
an `HsUntypedSplice`.
Both `HsType` and `Pat` constructors `HsSpliceTy` and `SplicePat` now
take an `HsUntypedSplice` instead of a `HsSplice` (remember only
/untyped splices/ can be spliced as types or patterns).
The result of splicing an expression, type, or pattern is now
comfortably stored in the extension fields `XSpliceTy`, `XSplicePat`,
`XUntypedSplice` as, respectively, `HsUntypedSpliceResult (HsType
GhcRn)`, `HsUntypedSpliceResult (Pat GhcRn)`, and `HsUntypedSpliceResult
(HsExpr GhcRn)`
Overall the TTG extension points are now better used to
make invalid states unrepresentable and model the progression between
stages better.
See Note [Lifecycle of an untyped splice, and PendingRnSplice]
and Note [Lifecycle of an typed splice, and PendingTcSplice] for more
details.
Updates haddock submodule
Fixes #21263
-------------------------
Metric Decrease:
hard_hole_fits
-------------------------
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This patch adds a PromotionFlag field to HsOpTy, which is used
in pretty-printing and when determining whether to emit warnings
with -fwarn-unticked-promoted-constructors.
This allows us to correctly report tick-related warnings for things
like:
type A = Int : '[]
type B = [Int, Bool]
Updates haddock submodule
Fixes #19984
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- Remove unused functions exprToCoercion_maybe, applyTypeToArg,
typeMonoPrimRep_maybe, runtimeRepMonoPrimRep_maybe.
- Replace orValid with a simpler check
- Use splitAtList in applyTysX
- Remove calls to extra_clean in the testsuite; it does not do anything.
Metric Decrease:
T18223
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As explained in `Note [Gathering and simplifying constraints for DeriveAnyClass]`
in `GHC.Tc.Deriv.Infer`, `DeriveAnyClass` infers instance contexts by emitting
implication constraints. Previously, these implication constraints were
constructed by hand. This is a terribly trick thing to get right, as it
involves a delicate interplay of skolemisation, metavariable instantiation, and
`TcLevel` bumping. Despite much effort, we discovered in #20719 that the
implementation was subtly incorrect, leading to valid programs being rejected.
While we could scrutinize the code that manually constructs implication
constraints and repair it, there is a better, less error-prone way to do
things. After all, the heart of `DeriveAnyClass` is generating code which
fills in each class method with defaults, e.g., `foo = $gdm_foo`. Typechecking
this sort of code is tantamount to calling `tcSubTypeSigma`, as we much ensure
that the type of `$gdm_foo` is a subtype of (i.e., more polymorphic than) the
type of `foo`. As an added bonus, `tcSubTypeSigma` is a battle-tested function
that handles skolemisation, metvariable instantiation, `TcLevel` bumping, and
all other means of tricky bookkeeping correctly.
With this insight, the solution to the problems uncovered in #20719 is simple:
use `tcSubTypeSigma` to check if `$gdm_foo`'s type is a subtype of `foo`'s
type. As a side effect, `tcSubTypeSigma` will emit exactly the implication
constraint that we were attempting to construct by hand previously. Moreover,
it does so correctly, fixing #20719 as a consequence.
This patch implements the solution thusly:
* The `PredSpec` data type (previously named `PredOrigin`) is now split into
`SimplePredSpec`, which directly stores a `PredType`, and `SubTypePredSpec`,
which stores the actual and expected types in a subtype check.
`SubTypePredSpec` is only used for `DeriveAnyClass`; all other deriving
strategies use `SimplePredSpec`.
* Because `tcSubTypeSigma` manages the finer details of type variable
instantiation and constraint solving under the hood, there is no longer any
need to delicately split apart the method type signatures in
`inferConstraintsAnyclass`. This greatly simplifies the implementation of
`inferConstraintsAnyclass` and obviates the need to store skolems,
metavariables, or given constraints in a `ThetaSpec` (previously named
`ThetaOrigin`). As a bonus, this means that `ThetaSpec` now simply becomes a
synonym for a list of `PredSpec`s, which is conceptually much simpler than it
was before.
* In `simplifyDeriv`, each `SubTypePredSpec` results in a call to
`tcSubTypeSigma`. This is only performed for its side effect of emitting
an implication constraint, which is fed to the rest of the constraint solving
machinery in `simplifyDeriv`. I have updated
`Note [Gathering and simplifying constraints for DeriveAnyClass]` to explain
this in more detail.
To make the changes in `simplifyDeriv` more manageable, I also performed some
auxiliary refactoring:
* Previously, every iteration of `simplifyDeriv` was skolemising the type
variables at the start, simplifying, and then performing a reverse
substitution at the end to un-skolemise the type variables. This is not
necessary, however, since we can just as well skolemise once at the
beginning of the `deriving` pipeline and zonk the `TcTyVar`s after
`simplifyDeriv` is finished. This patch does just that, having been made
possible by prior work in !7613. I have updated `Note [Overlap and deriving]`
in `GHC.Tc.Deriv.Infer` to explain this, and I have also left comments on
the relevant data structures (e.g., `DerivEnv` and `DerivSpec`) to explain
when things might be `TcTyVar`s or `TyVar`s.
* All of the aforementioned cleanup allowed me to remove an ad hoc
deriving-related in `checkImplicationInvariants`, as all of the skolems in
a `tcSubTypeSigma`–produced implication constraint should now be `TcTyVar`
at the time the implication is created.
* Since `simplifyDeriv` now needs a `SkolemInfo` and `UserTypeCtxt`, I have
added `ds_skol_info` and `ds_user_ctxt` fields to `DerivSpec` to store these.
Similarly, I have also added a `denv_skol_info` field to `DerivEnv`, which
ultimately gets used to initialize the `ds_skol_info` in a `DerivSpec`.
Fixes #20719.
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This patch improves code generation for derived Eq instances.
The idea is to use 'dataToTag' to evaluate both arguments.
This allows to 'short-circuit' when tags do not match.
Unfortunately, inner evals are still present when we branch
on tags. This is due to the way 'dataToTag#' primop
evaluates its argument in the code generator. #21207 was
created to explore further optimizations.
Metric Decrease:
LargeRecord
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When desugaring a bracket we want to desugar /renamed/ rather than
/typechecked/ code; So in (HsExpr GhcTc) tree, we must
have a (HsExpr GhcRn) for the quotation itself.
This commit reworks the TTG refactor on typed and untyped brackets by
storing the /renamed/ code in the bracket field extension rather than in
the constructor extension in `HsQuote` (previously called
`HsUntypedBracket`)
See Note [The life cycle of a TH quotation] and https://gitlab.haskell.org/ghc/ghc/-/merge_requests/4782
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Split HsBracket into HsTypedBracket and HsUntypedBracket.
Unfortunately, we still cannot get rid of
instance XXTypedBracket GhcTc = HsTypedBracket GhcRn
despite no longer requiring it for typechecking, but rather because the
TH desugarer works on GhcRn rather than GhcTc (See GHC.HsToCore.Quote)
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As #20837 pointed out, `isLiftedType_maybe` returned `Just False` in
many situations where it should return `Nothing`, because it didn't
take into account type families or type variables.
In this patch, we fix this issue. We rename `isLiftedType_maybe` to
`typeLevity_maybe`, which now returns a `Levity` instead of a boolean.
We now return `Nothing` for types with kinds of the form
`TYPE (F a1 ... an)` for a type family `F`, as well as
`TYPE (BoxedRep l)` where `l` is a type variable.
This fix caused several other problems, as other parts of the compiler
were relying on `isLiftedType_maybe` returning a `Just` value, and were
now panicking after the above fix. There were two main situations in
which panics occurred:
1. Issues involving the let/app invariant. To uphold that invariant,
we need to know whether something is lifted or not. If we get an
answer of `Nothing` from `isLiftedType_maybe`, then we don't know
what to do. As this invariant isn't particularly invariant, we
can change the affected functions to not panic, e.g. by behaving
the same in the `Just False` case and in the `Nothing` case
(meaning: no observable change in behaviour compared to before).
2. Typechecking of data (/newtype) constructor patterns. Some programs
involving patterns with unknown representations were accepted, such
as T20363. Now that we are stricter, this caused further issues,
culminating in Core Lint errors. However, the behaviour was
incorrect the whole time; the incorrectness only being revealed by
this change, not triggered by it.
This patch fixes this by overhauling where the representation
polymorphism involving pattern matching are done. Instead of doing
it in `tcMatches`, we instead ensure that the `matchExpected`
functions such as `matchExpectedFunTys`, `matchActualFunTySigma`,
`matchActualFunTysRho` allow return argument pattern types which
have a fixed RuntimeRep (as defined in Note [Fixed RuntimeRep]).
This ensures that the pattern matching code only ever handles types
with a known runtime representation. One exception was that
patterns with an unknown representation type could sneak in via
`tcConPat`, which points to a missing representation-polymorphism
check, which this patch now adds.
This means that we now reject the program in #20363, at least until
we implement PHASE 2 of FixedRuntimeRep (allowing type families in
RuntimeRep positions). The aforementioned refactoring, in which
checks have been moved to `matchExpected` functions, is a first
step in implementing PHASE 2 for patterns.
Fixes #20837
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Previously, there was an awful hack in `genInst` (now called `genInstBinds`
after this patch) where we had to return a continutation rather than directly
returning the bindings for a derived instance. This was done for staging
purposes, as we had to first infer the instance contexts for derived instances
and then feed these contexts into the continuations to ensure the generated
instance bindings had accurate instance contexts.
`Note [Staging of tcDeriving]` in `GHC.Tc.Deriving` described this confusing
state of affairs.
The root cause of this confusing design was the fact that `genInst` was trying
to generate instance bindings and associated type family instances for derived
instances simultaneously. This really isn't possible, however: as
`Note [Staging of tcDeriving]` explains, one needs to have access to the
associated type family instances before one can properly infer the instance
contexts for derived instances. The use of continuation-returning style was an
attempt to circumvent this dependency, but it did so in an awkward way.
This patch detangles this awkwardness by splitting up `genInst` into two
functions: `genFamInsts` (for associated type family instances) and
`genInstBinds` (for instance bindings). Now, the `tcDeriving` function calls
`genFamInsts` and brings all the family instances into scope before calling
`genInstBinds`. This removes the need for the awkward continuation-returning
style seen in the previous version of `genInst`, making the code easier to
understand.
There are some knock-on changes as well:
1. `hasStockDeriving` now needs to return two separate functions: one that
describes how to generate family instances for a stock-derived instance,
and another that describes how to generate the instance bindings. I factored
out this pattern into a new `StockGenFns` data type.
2. While documenting `StockGenFns`, I realized that there was some
inconsistency regarding which `StockGenFns` functions needed which
arguments. In particular, the function in `GHC.Tc.Deriv.Generics` which
generates `Rep(1)` instances did not take a `SrcSpan` like other `gen_*`
functions did, and it included an extra `[Type]` argument that was entirely
redundant. As a consequence, I refactored the code in
`GHC.Tc.Deriv.Generics` to more closely resemble other `gen_*` functions.
A happy result of all this is that all `StockGenFns` functions now take
exactly the same arguments, which makes everything more uniform.
This is purely a refactoring that should not have any effect on user-observable
behavior. The new design paves the way for an eventual fix for #20719.
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When deriving a `Generic1` instance, we need to know what the last type
variable of a data type is. Previously, there were two mechanisms to determine
this information:
* `GenericKind_`, where `Gen1_` stored the last type variable of a data type
constructor (i.e., the `tyConTyVars`).
* `GenericKind_DC`, where `Gen1_DC` stored the last universally quantified
type variable in a data constructor (i.e., the `dataConUnivTyVars`).
These had different use cases, as `GenericKind_` was used for generating
`Rep(1)` instances, while `GenericKind_DC` was used for generating `from(1)`
and `to(1)` implementations. This was already a bit confusing, but things went
from confusing to outright wrong after !6976. This is because after !6976,
the `deriving` machinery stopped using `tyConTyVars` in favor of
`dataConUnivTyVars`. Well, everywhere with the sole exception of
`GenericKind_`, which still continued to use `tyConTyVars`. This lead to
disaster when deriving a `Generic1` instance for a GADT family instance, as
the `tyConTyVars` do not match the `dataConUnivTyVars`. (See #21185.)
The fix is to stop using `GenericKind_` and replace it with `GenericKind_DC`.
For the most part, this proves relatively straightforward. Some highlights:
* The `forgetArgVar` function was deleted entirely, as it no longer proved
necessary after `GenericKind_`'s demise.
* The substitution that maps from the last type variable to `Any` (see
`Note [Generating a correctly typed Rep instance]`) had to be moved from
`tc_mkRepTy` to `tc_mkRepFamInsts`, as `tc_mkRepTy` no longer has access to
the last type variable.
Fixes #21185.
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It turns out this job hasn't been running for quite a while (perhaps
ever) so there are quite a few failures when running the linter locally.
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Co-authored by: Sam Derbyshire
Previously, GHC had three flavours of constraint:
Wanted, Given, and Derived. This removes Derived constraints.
Though serving a number of purposes, the most important role
of Derived constraints was to enable better error messages.
This job has been taken over by the new RewriterSets, as explained
in Note [Wanteds rewrite wanteds] in GHC.Tc.Types.Constraint.
Other knock-on effects:
- Various new Notes as I learned about under-described bits of GHC
- A reshuffling around the AST for implicit-parameter bindings,
with better integration with TTG.
- Various improvements around fundeps. These were caused by the
fact that, previously, fundep constraints were all Derived,
and Derived constraints would get dropped. Thus, an unsolved
Derived didn't stop compilation. Without Derived, this is no
longer possible, and so we have to be considerably more careful
around fundeps.
- A nice little refactoring in GHC.Tc.Errors to center the work
on a new datatype called ErrorItem. Constraints are converted
into ErrorItems at the start of processing, and this allows for
a little preprocessing before the main classification.
- This commit also cleans up the behavior in generalisation around
functional dependencies. Now, if a variable is determined by
functional dependencies, it will not be quantified. This change
is user facing, but it should trim down GHC's strange behavior
around fundeps.
- Previously, reportWanteds did quite a bit of work, even on an empty
WantedConstraints. This commit adds a fast path.
- Now, GHC will unconditionally re-simplify constraints during
quantification. See Note [Unconditionally resimplify constraints when
quantifying], in GHC.Tc.Solver.
Close #18398.
Close #18406.
Solve the fundep-related non-confluence in #18851.
Close #19131.
Close #19137.
Close #20922.
Close #20668.
Close #19665.
-------------------------
Metric Decrease:
LargeRecord
T9872b
T9872b_defer
T9872d
TcPlugin_RewritePerf
-------------------------
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The main purpose of this patch is to attach a SkolemInfo directly to
each SkolemTv. This fixes the large number of bugs which have
accumulated over the years where we failed to report errors due to
having "no skolem info" for particular type variables. Now the origin of
each type varible is stored on the type variable we can always report
accurately where it cames from.
Fixes #20969 #20732 #20680 #19482 #20232 #19752 #10946
#19760 #20063 #13499 #14040
The main changes of this patch are:
* SkolemTv now contains a SkolemInfo field which tells us how the
SkolemTv was created. Used when reporting errors.
* Enforce invariants relating the SkolemInfoAnon and level of an implication (ic_info, ic_tclvl)
to the SkolemInfo and level of the type variables in ic_skols.
* All ic_skols are TcTyVars -- Check is currently disabled
* All ic_skols are SkolemTv
* The tv_lvl of the ic_skols agrees with the ic_tclvl
* The ic_info agrees with the SkolInfo of the implication.
These invariants are checked by a debug compiler by
checkImplicationInvariants.
* Completely refactor kcCheckDeclHeader_sig which kept
doing my head in. Plus, it wasn't right because it wasn't skolemising
the binders as it decomposed the kind signature.
The new story is described in Note [kcCheckDeclHeader_sig]. The code
is considerably shorter than before (roughly 240 lines turns into 150
lines).
It still has the same awkward complexity around computing arity as
before, but that is a language design issue.
See Note [Arity inference in kcCheckDeclHeader_sig]
* I added new type synonyms MonoTcTyCon and PolyTcTyCon, and used
them to be clear which TcTyCons have "finished" kinds etc, and
which are monomorphic. See Note [TcTyCon, MonoTcTyCon, and PolyTcTyCon]
* I renamed etaExpandAlgTyCon to splitTyConKind, becuase that's a
better name, and it is very useful in kcCheckDeclHeader_sig, where
eta-expansion isn't an issue.
* Kill off the nasty `ClassScopedTvEnv` entirely.
Co-authored-by: Simon Peyton Jones <simon.peytonjones@gmail.com>
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Previously, `DeriveGeneric` would look up the fixity of a data constructor
using `getFixityEnv`, but this is subtly incorrect for data constructors
defined in external modules. This sort of situation can happen with
`StandaloneDeriving`, as noticed in #20994. In fact, the same bug has occurred
in the past in #9830, and while that bug was fixed for `deriving Read` and
`deriving Show`, the fix was never extended to `DeriveGeneric` due to an
oversight. This patch corrects that oversight.
Fixes #20994.
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Use primOpId instead of mkPrimOpId in a few places to benefit from
Id caching.
I had to mess a little bit with the module hierarchy to fix cycles and
to avoid adding too many new dependencies to count-deps tests.
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It isn't much more complicated to be more precise when deriving Lift so
we now generate
```
data Foo = Foo Int Bool
instance Lift Foo where
lift (Foo a b) = [| Foo $(lift a) $(lift b) |]
liftTyped (Foo a b) = [|| Foo $$(lift a) $$(lift b) |]
```
This fixes #20688 which complained about using implicit lifting in the
derived code.
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Previously, the `deriving` machinery was very loosey-goosey about how it used
the types of data constructor fields when generating code. It would usually
just consult `dataConOrigArgTys`, which returns the _uninstantiated_ field
types of each data constructor. Usually, you can get away with this, but
issues #20375 and #20387 revealed circumstances where this approach fails.
Instead, when generated code for a stock-derived instance
`C (T arg_1 ... arg_n)`, one must take care to instantiate the field types of
each data constructor with `arg_1 ... arg_n`. The particulars of how this is
accomplished is described in the new
`Note [Instantiating field types in stock deriving]` in
`GHC.Tc.Deriv.Generate`. Some highlights:
* `DerivInstTys` now has a new `dit_dc_inst_arg_env :: DataConEnv [Type]`
field that caches the instantiated field types of each data constructor.
Whenever we need to consult the field types somewhere in `GHC.Tc.Deriv.*`
we avoid using `dataConOrigArgTys` and instead look it up in
`dit_dc_inst_arg_env`.
* Because `DerivInstTys` now stores the instantiated field types of each
constructor, some of the details of the `GHC.Tc.Deriv.Generics.mkBindsRep`
function were able to be simplified. In particular, we no longer need to
apply a substitution to instantiate the field types in a `Rep(1)` instance,
as that is already done for us by `DerivInstTys`. We still need a
substitution to implement the "wrinkle" section of
`Note [Generating a correctly typed Rep instance]`, but the code is
nevertheless much simpler than before.
* The `tyConInstArgTys` function has been removed in favor of the new
`GHC.Core.DataCon.dataConInstUnivs` function, which is really the proper tool
for the job. `dataConInstUnivs` is much like `tyConInstArgTys` except that it
takes a data constructor, not a type constructor, as an argument, and it adds
extra universal type variables from that data constructor at the end of the
returned list if need be. `dataConInstUnivs` takes care to instantiate the
kinds of the universal type variables at the end, thereby avoiding a bug in
`tyConInstArgTys` discovered in
https://gitlab.haskell.org/ghc/ghc/-/issues/20387#note_377037.
Fixes #20375. Fixes #20387.
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Various functions in GHC.Tc.Deriv.* were passing around `TyCon`s and
`[Type]`s that ultimately come from the same `DerivInstTys`. This patch
moves the definition of `DerivInstTys` to `GHC.Tc.Deriv.Generate` so that
all of these `TyCon` and `[Type]` arguments can be consolidated into a
single `DerivInstTys`. Not only does this make the code easier to read
(in my opinion), this will also be important in a subsequent commit where we
need to add another field to `DerivInstTys` that will also be used from
`GHC.Tc.Deriv.Generate` and friends.
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`Note [The stupid context]` in `GHC.Core.DataCon` talks about stupid contexts
from `DatatypeContexts`, but prior to this commit, it was rather outdated.
This commit spruces it up and references it from places where it is relevant.
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Previously, derived instances that use `deriving` clauses would infer
`DatatypeContexts` by using `tyConStupidTheta`. But this sometimes causes
redundant constraints to be included in the derived instance contexts, as the
constraints that appear in the `tyConStupidTheta` may not actually appear in
the types of the data constructors (i.e., the `dataConStupidTheta`s). For
instance, in `data Show a => T a = MkT deriving Eq`, the type of `MkT` does
not require `Show`, so the derived `Eq` instance should not require `Show`
either. This patch makes it so with some small tweaks to
`inferConstraintsStock`.
Fixes #20501.
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(#20496)
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This (big) commit finishes porting the GHC.Tc.Deriv module to support
the new diagnostic infrastructure (#18516) by getting rid of the legacy
calls to `TcRnUnknownMessage`. This work ended up being quite pervasive
and touched not only the Tc.Deriv module but also the Tc.Deriv.Utils and
Tc.Deriv.Generics module, which needed to be adapted to use the new
infrastructure. This also required generalising `Validity`.
More specifically, this is a breakdown of the work done:
* Add and use the TcRnUselessTypeable data constructor
* Add and use TcRnDerivingDefaults data constructor
* Add and use the TcRnNonUnaryTypeclassConstraint data constructor
* Add and use TcRnPartialTypeSignatures
* Add T13324_compile2 test to test another part of the
TcRnPartialTypeSignatures diagnostic
* Add and use TcRnCannotDeriveInstance data constructor, which introduces a
new data constructor to TcRnMessage called TcRnCannotDeriveInstance, which
is further sub-divided to carry a `DeriveInstanceErrReason` which explains
the reason why we couldn't derive a typeclass instance.
* Add DerivErrSafeHaskellGenericInst data constructor to DeriveInstanceErrReason
* Add DerivErrDerivingViaWrongKind and DerivErrNoEtaReduce
* Introduce the SuggestExtensionInOrderTo Hint, which adds (and use) a new
constructor to the hint type `LanguageExtensionHint` called `SuggestExtensionInOrderTo`,
which can be used to give a bit more "firm" recommendations when it's
obvious what the required extension is, like in the case for the
`DerivingStrategies`, which automatically follows from having enabled
both `DeriveAnyClass` and `GeneralizedNewtypeDeriving`.
* Wildcard-free pattern matching in mk_eqn_stock, which removes `_` in
favour of pattern matching explicitly on `CanDeriveAnyClass` and
`NonDerivableClass`, because that determine whether or not we can
suggest to the user `DeriveAnyClass` or not.
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This commit makes the `Validity` type polymorphic:
```
data Validity' a
= IsValid -- ^ Everything is fine
| NotValid a -- ^ A problem, and some indication of why
-- | Monomorphic version of @Validity'@ specialised for 'SDoc's.
type Validity = Validity' SDoc
```
The type has been (provisionally) renamed to Validity' to not break
existing code, as the monomorphic `Validity` type is quite pervasive
in a lot of signatures in GHC.
Why having a polymorphic Validity? Because it carries the evidence of
"what went wrong", but the old type carried an `SDoc`, which clashed
with the new GHC diagnostic infrastructure (#18516). Having it
polymorphic it means we can carry an arbitrary, richer diagnostic type,
and this is very important for things like the
`checkOriginativeSideConditions` function, which needs to report the
actual diagnostic error back to `GHC.Tc.Deriv`.
It also generalises Validity-related functions to be polymorphic in @a@.
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This fixes a long standard bug where the module prefix was omitted
from the data type name supplied by Data.Typeable instances.
Instead of reusing the Outputable instance for TyCon, we now take
matters into our own hands and explicitly print the module followed by
the type constructor name.
Fixes #20371
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This prepares us to actually use them when the native size is 64 bits
too.
I more than saitisfied my curiosity finding they were gated since
47774449c9d66b768a70851fe82c5222c1f60689.
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Word64#/Int64# are only used on 32-bit architectures. Before this patch,
operations on these types were directly using the FFI. Now we use real
primops that are then lowered into ccalls.
The advantage of doing this is that we can now perform constant folding on
Word64#/Int64# (#19024).
Most of this work was done by John Ericson in !3658. However this patch
doesn't go as far as e.g. changing Word64 to always be using Word64#.
Noticeable performance improvements
T9203(normal) run/alloc 89870808.0 66662456.0 -25.8% GOOD
haddock.Cabal(normal) run/alloc 14215777340.8 12780374172.0 -10.1% GOOD
haddock.base(normal) run/alloc 15420020877.6 13643834480.0 -11.5% GOOD
Metric Decrease:
T9203
haddock.Cabal
haddock.base
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fixes #19756, updates haddock submodule
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Replace uses of WARN macro with calls to:
warnPprTrace :: Bool -> SDoc -> a -> a
Remove the now unused HsVersions.h
Bump haddock submodule
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There is no reason to use CPP. __LINE__ and __FILE__ macros are now
better replaced with GHC's CallStack. As a bonus, assert error messages
now contain more information (function name, column).
Here is the mapping table (HasCallStack omitted):
* ASSERT: assert :: Bool -> a -> a
* MASSERT: massert :: Bool -> m ()
* ASSERTM: assertM :: m Bool -> m ()
* ASSERT2: assertPpr :: Bool -> SDoc -> a -> a
* MASSERT2: massertPpr :: Bool -> SDoc -> m ()
* ASSERTM2: assertPprM :: m Bool -> SDoc -> m ()
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Metric Increase:
T10370
parsing001
Updates haddock submodule
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The first change makes the array ones use the proper fixed-size types,
which also means that just like before, they can be used without
explicit conversions with the boxed sized types. (Before, it was Int# /
Word# on both sides, now it is fixed sized on both sides).
For the second change, don't use "extend" or "narrow" in some of the
user-facing primops names for conversions.
- Names like `narrowInt32#` are misleading when `Int` is 32-bits.
- Names like `extendInt64#` are flat-out wrong when `Int is
32-bits.
- `narrow{Int,Word}<N>#` however map a type to itself, and so don't
suffer from this problem. They are left as-is.
These changes are batched together because Alex happend to use the array
ops. We can only use released versions of Alex at this time, sadly, and
I don't want to have to have a release thatwon't work for the final GHC
9.2. So by combining these we get all the changes for Alex done at once.
Bump hackage state in a few places, and also make that workflow slightly
easier for the future.
Bump minimum Alex version
Bump Cabal, array, bytestring, containers, text, and binary submodules
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