| Commit message (Collapse) | Author | Age | Files | Lines |
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With this change, `Backend` becomes an abstract type
(there are no more exposed value constructors).
Decisions that were formerly made by asking "is the
current back end equal to (or different from) this named value
constructor?" are now made by interrogating the back end about
its properties, which are functions exported by `GHC.Driver.Backend`.
There is a description of how to migrate code using `Backend` in the
user guide.
Clients using the GHC API can find a backdoor to access the Backend
datatype in GHC.Driver.Backend.Internal.
Bumps haddock submodule.
Fixes #20927
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As #20941 describes, this patch implements a couple of small
fixes to the Simplifier. They make a difference principally
with -O0, so few people will notice. But with -O0 they can
reduce the number of Simplifer iterations.
* In occurrence analysis we avoid making x = (a,b) into a loop breaker
because we want to be able to inline x, or (more likely) do
case-elimination. But HEAD does not treat
x = let y = blah in (a,b)
in the same way. We should though, because we are going to float
that y=blah out of the x-binding. A one-line fix in OccurAnal.
* The crucial function exprIsConApp_maybe uses getUnfoldingInRuleMatch
(rightly) but the latter was deeply strange. In HEAD, if
rule-rewriting was off (-O0) we only looked inside stable
unfoldings. Very stupid. The patch simplifies.
* I also noticed that in simplStableUnfolding we were failing to
delete the DFun binders from the usage. So I added that.
Practically zero perf change across the board, except that we get more
compiler allocation in T3064 (which is compiled with -O0). There's a
good reason: we get better code. But there are lots of other small
compiler allocation decreases:
Metrics: compile_time/bytes allocated
---------------------
Baseline
Test Metric value New value Change
-----------------------------------------------------------------
PmSeriesG(normal) ghc/alloc 44,260,817 44,184,920 -0.2%
PmSeriesS(normal) ghc/alloc 52,967,392 52,891,632 -0.1%
PmSeriesT(normal) ghc/alloc 75,498,220 75,421,968 -0.1%
PmSeriesV(normal) ghc/alloc 52,341,849 52,265,768 -0.1%
T10421(normal) ghc/alloc 109,702,291 109,626,024 -0.1%
T10421a(normal) ghc/alloc 76,888,308 76,809,896 -0.1%
T10858(normal) ghc/alloc 125,149,038 125,073,648 -0.1%
T11276(normal) ghc/alloc 94,159,364 94,081,640 -0.1%
T11303b(normal) ghc/alloc 40,230,059 40,154,368 -0.2%
T11822(normal) ghc/alloc 107,424,540 107,346,088 -0.1%
T12150(optasm) ghc/alloc 76,486,339 76,426,152 -0.1%
T12234(optasm) ghc/alloc 55,585,046 55,507,352 -0.1%
T12425(optasm) ghc/alloc 88,343,288 88,265,312 -0.1%
T13035(normal) ghc/alloc 98,919,768 98,845,600 -0.1%
T13253-spj(normal) ghc/alloc 121,002,153 120,851,040 -0.1%
T16190(normal) ghc/alloc 290,313,131 290,074,152 -0.1%
T16875(normal) ghc/alloc 34,756,121 34,681,440 -0.2%
T17836b(normal) ghc/alloc 45,198,100 45,120,288 -0.2%
T17977(normal) ghc/alloc 39,479,952 39,404,112 -0.2%
T17977b(normal) ghc/alloc 37,213,035 37,137,728 -0.2%
T18140(normal) ghc/alloc 79,430,588 79,350,680 -0.1%
T18282(normal) ghc/alloc 128,303,182 128,225,384 -0.1%
T18304(normal) ghc/alloc 84,904,713 84,831,952 -0.1%
T18923(normal) ghc/alloc 66,817,241 66,731,984 -0.1%
T20049(normal) ghc/alloc 86,188,024 86,107,920 -0.1%
T5837(normal) ghc/alloc 35,540,598 35,464,568 -0.2%
T6048(optasm) ghc/alloc 99,812,171 99,736,032 -0.1%
T9198(normal) ghc/alloc 46,380,270 46,304,984 -0.2%
geo. mean -0.0%
Metric Increase:
T3064
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* Remove wrong comment about panic in `break003.script`.
* Improve test `break008`.
* Add test `break028` to `all.T`
* Fix wrong comments in `print019.script`, `print026.script` and `result001.script`.
* Remove wrong comments from `print024.script` and `print031.script`.
* Replace old module name with current name in `print035.script`.
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(Fixes #10616 and #10617)
Co-authored-by: Roland Senn <rsx@bluewin.ch>
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Issue #18045 got fixed by !6971.
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In addition to providing stack traces, the scary HasCallStack will
hopefully make people think whether they want to use these functions,
i.e. act as a documentation hint that something weird might happen.
A single metric increased, which doesn't visibly
use any method with `HasCallStack`.
-------------------------
Metric Decrease:
T9630
Metric Decrease:
T19695
T9630
-------------------------
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When processing the heap, use also `APClosures` to create additional type
constraints. This adds more equations and therefore improves the unification
process to infer the correct type of values at breakpoints.
(Fix the `incr` part of #19559)
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Previously we would traverse the STG AST twice looking for free variables.
* Once in `annTopBindingsDeps` which considers top level and imported ids free.
Its output is used to put bindings in dependency order. The pass happens
in STG pipeline.
* Once in `annTopBindingsFreeVars` which only considers non-top level ids free.
Its output is used by the code generator to compute offsets into closures.
This happens in Cmm (CodeGen) pipeline.
Now these two traversal operations are merged into one - `FVs.depSortWithAnnotStgPgm`.
The pass happens right at the end of STG pipeline. Some type signatures had to be
updated due to slight shifts of StgPass boundaries (for example, top-level CodeGen
handler now directly works with CodeGen flavoured Stg AST instead of Vanilla).
Due to changed order of bindings, a few debugger type reconstruction bugs
have resurfaced again (see tests break018, break021) - work item #18004 tracks this
investigation.
authors: simonpj, nineonine
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When instances overlap, we now include additional information
about why we weren't able to select an instance: perhaps
one instance overlapped another but was not strictly more specific,
so we aren't able to directly choose it.
Fixes #20542
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Users of `undefined` don’t want to see
```
files.hs: Prelude.undefined:
CallStack (from HasCallStack):
error, called at libraries/base/GHC/Err.hs:79:14 in base:GHC.Err
undefined, called at file.hs:151:19 in main:Main
```
but want to see
```
files.hs: Prelude.undefined:
CallStack (from HasCallStack):
undefined, called at file.hs:151:19 in main:Main
```
so let’s make that so.
The function for that is `withFrozenCallStack`, but that is not usable
here (module dependencies, and also not representation-polymorphic). And
even if it were, it could confuse GHC’s strictness analyzer, leading to
big regressions in some perf tests (T10421 in particular).
So after shuffling modules and definitions around, I eventually noticed
that the easiest way is to just not call `error` here.
Fixes #19886
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There were two problems around `mkDictErr`:
1. An outdated call to `flattenTys` meant that we missed out on some
instances. As we no longer flatten type-family applications,
the logic is obsolete and can be removed.
2. We reported "out of scope" errors in a poly-kinded situation
because `BoxedRep` and `Lifted` were considered out of scope.
We fix this by using `pretendNameIsInScope`.
fixes #20465
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The test case `print036` was marked `broken` by #9046. Issue #9046 is a duplicate of #12449.
However the test case `T12449` contains several test that are similar to those in `print036`.
Hence test case `print036` is redundant and can be deleted.
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This patch comprises of four different but closely related ideas. The
net result is fixing a large number of open issues with the driver
whilst making it simpler to understand.
1. Use the hash of the source file to determine whether the source file
has changed or not. This makes the recompilation checking more robust to
modern build systems which are liable to copy files around changing
their modification times.
2. Remove the concept of a "stable module", a stable module was one
where the object file was older than the source file, and all transitive
dependencies were also stable. Now we don't rely on the modification
time of the source file, the notion of stability is moot.
3. Fix TH/plugin recompilation after the removal of stable modules. The
TH recompilation check used to rely on stable modules. Now there is a
uniform and simple way, we directly track the linkables which were
loaded into the interpreter whilst compiling a module. This is an
over-approximation but more robust wrt package dependencies changing.
4. Fix recompilation checking for dynamic object files. Now we actually
check if the dynamic object file exists when compiling with -dynamic-too
Fixes #19774 #19771 #19758 #17434 #11556 #9121 #8211 #16495 #7277 #16093
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* For primops from `GHC.Prim` lookup the HValues in `GHC.PrimopWrappers`.
* Add short error messages if a user tries to use a *Non-Id* value or a
`pseudoop` in a `:print`, `:sprint` or `force`command.
* Add additional test cases for `Magic Ids`.
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In the GHCi debugger use the function `pprSigmaType` to print out
Suspension Terms. The function `pprSigmaType` respect the flag
`-f(no-)print-explicit-foralls` and so it fixes #19355.
Switch back output of existing tests to default mode (no explicit foralls).
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In function `compiler/GHC/Runtime/Heap/Inspect.hs:quantifyType` replace
`tcSplitForAllInvisTyVars` by `tcSplitNestedSigmaTys`. This will properly split
off the nested foralls in examples like `:print fmap`.
Do not remove the `forall`s from the `snd` part of the tuple returned
by `quantifyType`. It's not necessary and the reason for the bug in #12449.
Some code simplifications at the calling sites of `quantifyTypes`.
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This vastly reduces memory usage when compiling with `--make` mode, from
about 900M when compiling Cabal to about 300M.
As a matter of uniformity, it also ensures that reading from an
interface performs the same as using the in-memory cache. We can also
delete all the horrible knot-tying in updateIdInfos.
Goes some way to fixing #13586
Accept new output of tests fixing some bugs along the way
-------------------------
Metric Decrease:
T12545
-------------------------
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* 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`.
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Ticket #19364 helpfully points out that we do not currently take
advantage of pushing the result type of an application into the
arguments. This makes error messages notably less good.
The fix is rather easy: move the result-type unification step earlier.
It's even a bit more efficient; in the the checking case we now
do one less zonk.
See Note [Unify with expected type before typechecking arguments]
in GHC.Tc.Gen.App
This change generally improves error messages, but it made one worse:
typecheck/should_fail/T16204c. That led me to the realisation that
a good error can be replaced by a less-good one, which provoked
me to change GHC.Tc.Solver.Interact.inertsCanDischarge. It's
explained in the new Note [Combining equalities]
One other refactoring: I discovered that KindEqOrigin didn't need a
Maybe in its type -- a nice simplification.
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When implementing Quick Look I'd failed to remember that overloaded
labels, like #foo, should be treated as a "head", so that they can be
instantiated with Visible Type Application. This caused #19154.
A very similar ticket covers overloaded literals: #19167.
This patch fixes both problems, but (annoyingly, albeit temporarily)
in two different ways.
Overloaded labels
I dealt with overloaded labels by buying fully into the
Rebindable Syntax approach described in GHC.Hs.Expr
Note [Rebindable syntax and HsExpansion].
There is a good overview in GHC.Rename.Expr
Note [Handling overloaded and rebindable constructs].
That module contains much of the payload for this patch.
Specifically:
* Overloaded labels are expanded in the renamer, fixing #19154.
See Note [Overloaded labels] in GHC.Rename.Expr.
* Left and right sections used to have special code paths in the
typechecker and desugarer. Now we just expand them in the
renamer. This is harder than it sounds. See GHC.Rename.Expr
Note [Left and right sections].
* Infix operator applications are expanded in the typechecker,
specifically in GHC.Tc.Gen.App.splitHsApps. See
Note [Desugar OpApp in the typechecker] in that module
* ExplicitLists are expanded in the renamer, when (and only when)
OverloadedLists is on.
* HsIf is expanded in the renamer when (and only when) RebindableSyntax
is on. Reason: the coverage checker treats HsIf specially. Maybe
we could instead expand it unconditionally, and fix up the coverage
checker, but I did not attempt that.
Overloaded literals
Overloaded literals, like numbers (3, 4.2) and strings with
OverloadedStrings, were not working correctly with explicit type
applications (see #19167). Ideally I'd also expand them in the
renamer, like the stuff above, but I drew back on that because they
can occur in HsPat as well, and I did not want to to do the HsExpanded
thing for patterns.
But they *can* now be the "head" of an application in the typechecker,
and hence something like ("foo" @T) works now. See
GHC.Tc.Gen.Head.tcInferOverLit. It's also done a bit more elegantly,
rather than by constructing a new HsExpr and re-invoking the
typechecker. There is some refactoring around tcShortCutLit.
Ultimately there is more to do here, following the Rebindable Syntax
story.
There are a lot of knock-on effects:
* HsOverLabel and ExplicitList no longer need funny (Maybe SyntaxExpr)
fields to support rebindable syntax -- good!
* HsOverLabel, OpApp, SectionL, SectionR all become impossible in the
output of the typecheker, GhcTc; so we set their extension fields to
Void. See GHC.Hs.Expr Note [Constructor cannot occur]
* Template Haskell quotes for HsExpanded is a bit tricky. See
Note [Quotation and rebindable syntax] in GHC.HsToCore.Quote.
* In GHC.HsToCore.Match.viewLExprEq, which groups equal HsExprs for the
purpose of pattern-match overlap checking, I found that dictionary
evidence for the same type could have two different names. Easily
fixed by comparing types not names.
* I did quite a bit of annoying fiddling around in GHC.Tc.Gen.Head and
GHC.Tc.Gen.App to get error message locations and contexts right,
esp in splitHsApps, and the HsExprArg type. Tiresome and not very
illuminating. But at least the tricky, higher order, Rebuilder
function is gone.
* Some refactoring in GHC.Tc.Utils.Monad around contexts and locations
for rebindable syntax.
* Incidentally fixes #19346, because we now print renamed, rather than
typechecked, syntax in error mesages about applications.
The commit removes the vestigial module GHC.Builtin.RebindableNames,
and thus triggers a 2.4% metric decrease for test MultiLayerModules
(#19293).
Metric Decrease:
MultiLayerModules
T12545
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The `Applicative` instance is the most important one (for
array/vector/sequence indexing purposes), but it deserves
all the usual ones.
T12545 does silly 1% wibbles both ways, it seems, maybe depending
on architecture.
Metric Increase:
T12545
Metric Decrease:
T12545
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This patch delivers on #17656, by entirel killing off the complex
floatEqualities mechanism. Previously, floatEqualities would float an
equality out of an implication, so that it could be solved at an outer
level. But now we simply do unification in-place, without floating the
constraint, relying on level numbers to determine untouchability.
There are a number of important new Notes:
* GHC.Tc.Utils.Unify Note [Unification preconditions]
describes the preconditions for unification, including both
skolem-escape and touchability.
* GHC.Tc.Solver.Interact Note [Solve by unification]
describes what we do when we do unify
* GHC.Tc.Solver.Monad Note [The Unification Level Flag]
describes how we control solver iteration under this new scheme
* GHC.Tc.Solver.Monad Note [Tracking Given equalities]
describes how we track when we have Given equalities
* GHC.Tc.Types.Constraint Note [HasGivenEqs]
is a new explanation of the ic_given_eqs field of an implication
A big raft of subtle Notes in Solver, concerning floatEqualities,
disappears.
Main code changes:
* GHC.Tc.Solver.floatEqualities disappears entirely
* GHC.Tc.Solver.Monad: new fields in InertCans, inert_given_eq_lvl
and inert_given_eq, updated by updateGivenEqs
See Note [Tracking Given equalities].
* In exchange for updateGivenEqa, GHC.Tc.Solver.Monad.getHasGivenEqs
is much simpler and more efficient
* I found I could kill of metaTyVarUpdateOK entirely
One test case T14683 showed a 5.1% decrease in compile-time
allocation; and T5631 was down 2.2%. Other changes were small.
Metric Decrease:
T14683
T5631
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This patch does two things:
* It refactors GHC.Tc.Errors a bit. In debugging Quick Look I was
forced to look in detail at error messages, and ended up doing a bit
of refactoring, esp in mkTyVarEqErr'. It's still quite a mess, but
a bit better, I think.
* It makes a significant improvement to the kind checking of type and
class declarations. Specifically, we now ensure that if kind
checking fails with an unsolved constraint, all the skolems are in
scope. That wasn't the case before, which led to some obscure error
messages; and occasional failures with "no skolem info" (eg #16245).
Both of these, and the main Quick Look patch itself, affect a /lot/ of
error messages, as you can see from the number of files changed. I've
checked them all; I think they are as good or better than before.
Smaller things
* I documented the various instances of VarBndr better.
See Note [The VarBndr tyep and its uses] in GHC.Types.Var
* Renamed GHC.Tc.Solver.simpl_top to simplifyTopWanteds
* A bit of refactoring in bindExplicitTKTele, to avoid the
footwork with Either. Simpler now.
* Move promoteTyVar from GHC.Tc.Solver to GHC.Tc.Utils.TcMType
Fixes #16245 (comment 211369), memorialised as
typecheck/polykinds/T16245a
Also fixes the three bugs in #18640
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On big-endian platforms executing
import GHC.Exts
data Foo = Foo Float# deriving Show
foo = Foo 42.0#
foo
:print foo
results in an arithmetic overflow exception which is caused by function
index where moveBytes equals
word_size - (r + item_size_b) * 8
Here we have a mixture of units. Both, word_size and item_size_b have
unit bytes whereas r has unit bits. On 64-bit platforms moveBytes
equals then
8 - (0 + 4) * 8
which results in a negative and therefore invalid second parameter for a
shiftL operation.
In order to make things more clear the expression
(word .&. (mask `shiftL` moveBytes)) `shiftR` moveBytes
is equivalent to
(word `shiftR` moveBytes) .&. mask
On big-endian platforms the shift must be a left shift instead of a
right shift. For symmetry reasons not a mask is used but two shifts in
order to zero out bits. Thus the fixed version equals
case endian of
BigEndian -> (word `shiftL` moveBits) `shiftR` zeroOutBits `shiftL` zeroOutBits
LittleEndian -> (word `shiftR` moveBits) `shiftL` zeroOutBits `shiftR` zeroOutBits
Fixes #16548 and #14455
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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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* support detection of slow ghc-bignum backend (to replace the detection
of integer-simple use). There are still some test cases that the
native backend doesn't handle efficiently enough.
* remove tests for GMP only functions that have been removed from
ghc-bignum
* fix test results showing dependent packages (e.g. integer-gmp) or
showing suggested instances
* fix test using Integer/Natural API or showing internal names
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This is the first step towards implementation of the linear types proposal
(https://github.com/ghc-proposals/ghc-proposals/pull/111).
It features
* A language extension -XLinearTypes
* Syntax for linear functions in the surface language
* Linearity checking in Core Lint, enabled with -dlinear-core-lint
* Core-to-core passes are mostly compatible with linearity
* Fields in a data type can be linear or unrestricted; linear fields
have multiplicity-polymorphic constructors.
If -XLinearTypes is disabled, the GADT syntax defaults to linear fields
The following items are not yet supported:
* a # m -> b syntax (only prefix FUN is supported for now)
* Full multiplicity inference (multiplicities are really only checked)
* Decent linearity error messages
* Linear let, where, and case expressions in the surface language
(each of these currently introduce the unrestricted variant)
* Multiplicity-parametric fields
* Syntax for annotating lambda-bound or let-bound with a multiplicity
* Syntax for non-linear/multiple-field-multiplicity records
* Linear projections for records with a single linear field
* Linear pattern synonyms
* Multiplicity coercions (test LinearPolyType)
A high-level description can be found at
https://ghc.haskell.org/trac/ghc/wiki/LinearTypes/Implementation
Following the link above you will find a description of the changes made to Core.
This commit has been authored by
* Richard Eisenberg
* Krzysztof Gogolewski
* Matthew Pickering
* Arnaud Spiwack
With contributions from:
* Mark Barbone
* Alexander Vershilov
Updates haddock submodule.
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This patch simplifies GHC to use simple subsumption.
Ticket #17775
Implements GHC proposal #287
https://github.com/ghc-proposals/ghc-proposals/blob/master/
proposals/0287-simplify-subsumption.rst
All the motivation is described there; I will not repeat it here.
The implementation payload:
* tcSubType and friends become noticably simpler, because it no
longer uses eta-expansion when checking subsumption.
* No deeplyInstantiate or deeplySkolemise
That in turn means that some tests fail, by design; they can all
be fixed by eta expansion. There is a list of such changes below.
Implementing the patch led me into a variety of sticky corners, so
the patch includes several othe changes, some quite significant:
* I made String wired-in, so that
"foo" :: String rather than
"foo" :: [Char]
This improves error messages, and fixes #15679
* The pattern match checker relies on knowing about in-scope equality
constraints, andd adds them to the desugarer's environment using
addTyCsDs. But the co_fn in a FunBind was missed, and for some reason
simple-subsumption ends up with dictionaries there. So I added a
call to addTyCsDs. This is really part of #18049.
* I moved the ic_telescope field out of Implication and into
ForAllSkol instead. This is a nice win; just expresses the code
much better.
* There was a bug in GHC.Tc.TyCl.Instance.tcDataFamInstHeader.
We called checkDataKindSig inside tc_kind_sig, /before/
solveEqualities and zonking. Obviously wrong, easily fixed.
* solveLocalEqualitiesX: there was a whole mess in here, around
failing fast enough. I discovered a bad latent bug where we
could successfully kind-check a type signature, and use it,
but have unsolved constraints that could fill in coercion
holes in that signature -- aargh.
It's all explained in Note [Failure in local type signatures]
in GHC.Tc.Solver. Much better now.
* I fixed a serious bug in anonymous type holes. IN
f :: Int -> (forall a. a -> _) -> Int
that "_" should be a unification variable at the /outer/
level; it cannot be instantiated to 'a'. This was plain
wrong. New fields mode_lvl and mode_holes in TcTyMode,
and auxiliary data type GHC.Tc.Gen.HsType.HoleMode.
This fixes #16292, but makes no progress towards the more
ambitious #16082
* I got sucked into an enormous refactoring of the reporting of
equality errors in GHC.Tc.Errors, especially in
mkEqErr1
mkTyVarEqErr
misMatchMsg
misMatchMsgOrCND
In particular, the very tricky mkExpectedActualMsg function
is gone.
It took me a full day. But the result is far easier to understand.
(Still not easy!) This led to various minor improvements in error
output, and an enormous number of test-case error wibbles.
One particular point: for occurs-check errors I now just say
Can't match 'a' against '[a]'
rather than using the intimidating language of "occurs check".
* Pretty-printing AbsBinds
Tests review
* Eta expansions
T11305: one eta expansion
T12082: one eta expansion (undefined)
T13585a: one eta expansion
T3102: one eta expansion
T3692: two eta expansions (tricky)
T2239: two eta expansions
T16473: one eta
determ004: two eta expansions (undefined)
annfail06: two eta (undefined)
T17923: four eta expansions (a strange program indeed!)
tcrun035: one eta expansion
* Ambiguity check at higher rank. Now that we have simple
subsumption, a type like
f :: (forall a. Eq a => Int) -> Int
is no longer ambiguous, because we could write
g :: (forall a. Eq a => Int) -> Int
g = f
and it'd typecheck just fine. But f's type is a bit
suspicious, and we might want to consider making the
ambiguity check do a check on each sub-term. Meanwhile,
these tests are accepted, whereas they were previously
rejected as ambiguous:
T7220a
T15438
T10503
T9222
* Some more interesting error message wibbles
T13381: Fine: one error (Int ~ Exp Int)
rather than two (Int ~ Exp Int, Exp Int ~ Int)
T9834: Small change in error (improvement)
T10619: Improved
T2414: Small change, due to order of unification, fine
T2534: A very simple case in which a change of unification order
means we get tow unsolved constraints instead of one
tc211: bizarre impredicative tests; just accept this for now
Updates Cabal and haddock submodules.
Metric Increase:
T12150
T12234
T5837
haddock.base
Metric Decrease:
haddock.compiler
haddock.Cabal
haddock.base
Merge note: This appears to break the
`UnliftedNewtypesDifficultUnification` test. It has been marked as
broken in the interest of merging.
(cherry picked from commit 66b7b195cb3dce93ed5078b80bf568efae904cc5)
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In tab-completion for the `:break` command, only those
identifiers should be shown, that are accepted in the
`:break` command. Hence these identifiers must be
- defined in an interpreted module
- top-level
- currently in scope
- listed in a `ModBreaks` value as a possible breakpoint.
The identifiers my be qualified or unqualified.
To get all possible top-level breakpoints for tab-completeion
with the correct qualification do:
1. Build the list called `pifsBreaks` of all pairs of
(Identifier, module-filename) from the `ModBreaks` values.
Here all identifiers are unqualified.
2. Build the list called `pifInscope` of all pairs of
(Identifiers, module-filename) with identifiers from
the `GlobalRdrEnv`. Take only those identifiers that are
in scope and have the correct prefix.
Here the identifiers may be qualified.
3. From the `pifInscope` list seclect all pairs that can be
found in the `pifsBreaks` list, by comparing only the
unqualified part of the identifier.
The remaining identifiers can be used for tab-completion.
This ensures, that we show only identifiers, that can be used
in a `:break` command.
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We used to have another factor, ufKeenessFactor, which would scale the
discounts before they were subtracted from the size. This was justified
with the following comment:
-- We multiple the raw discounts (args_discount and result_discount)
-- ty opt_UnfoldingKeenessFactor because the former have to do with
-- *size* whereas the discounts imply that there's some extra
-- *efficiency* to be gained (e.g. beta reductions, case reductions)
-- by inlining.
However, this is highly suspect since it means that we subtract a
*scaled* size from an absolute size, resulting in crazy (e.g. negative)
scores in some cases (#15304). We consequently killed off
ufKeenessFactor and bumped up the ufUseThreshold to compensate.
Adjustment of unfolding use threshold
=====================================
Since this removes a discount from our inlining heuristic, I revisited our
default choice of -funfolding-use-threshold to minimize the change in
overall inlining behavior. Specifically, I measured runtime allocations
and executable size of nofib and the testsuite performance tests built
using compilers (and core libraries) built with several values of
-funfolding-use-threshold.
This comes as a result of a quantitative comparison of testsuite
performance and code size as a function of ufUseThreshold, comparing
GHC trees using values of 50, 60, 70, 80, 90, and 100. The test set
consisted of nofib and the testsuite performance tests.
A full summary of these measurements are found in the description of
!2608
Comparing executable sizes (relative to the base commit) across all
nofib tests, we see that sizes are similar to the baseline:
gmean min max median
thresh
50 -6.36% -7.04% -4.82% -6.46%
60 -5.04% -5.97% -3.83% -5.11%
70 -2.90% -3.84% -2.31% -2.92%
80 -0.75% -2.16% -0.42% -0.73%
90 +0.24% -0.41% +0.55% +0.26%
100 +1.36% +0.80% +1.64% +1.37%
baseline +0.00% +0.00% +0.00% +0.00%
Likewise, looking at runtime allocations we see that 80 gives slightly
better optimisation than the baseline:
gmean min max median
thresh
50 +0.16% -0.16% +4.43% +0.00%
60 +0.09% -0.00% +3.10% +0.00%
70 +0.04% -0.09% +2.29% +0.00%
80 +0.02% -1.17% +2.29% +0.00%
90 -0.02% -2.59% +1.86% +0.00%
100 +0.00% -2.59% +7.51% -0.00%
baseline +0.00% +0.00% +0.00% +0.00%
Finally, I had to add a NOINLINE in T4306 to ensure that `upd` is
worker-wrappered as the test expects. This makes me wonder whether the
inlining heuristic is now too liberal as `upd` is quite a large
function. The same measure was taken in T12600.
Wall clock time compiling Cabal with -O0
thresh 50 60 70 80 90 100 baseline
build-Cabal 93.88 89.58 92.59 90.09 100.26 94.81 89.13
Also, this change happens to avoid the spurious test output in
`plugin-recomp-change` and `plugin-recomp-change-prof` (see #17308).
Metric Decrease:
hie002
T12234
T13035
T13719
T14683
T4801
T5631
T5642
T9020
T9872d
T9961
Metric Increase:
T12150
T12425
T13701
T14697
T15426
T1969
T3064
T5837
T6048
T9203
T9872a
T9872b
T9872c
T9872d
haddock.Cabal
haddock.base
haddock.compiler
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Previously, if we had a [W] (a :: k1) ~ (rhs :: k2), we would
spit out a [D] k1 ~ k2 and part the W as irreducible, hoping for
a unification. But we needn't do this. Instead, we now spit out
a [W] co :: k2 ~ k1 and then use co to cast the rhs of the original
Wanted. This means that we retain the connection between the
spat-out constraint and the original.
The problem with this new approach is that we cannot use the
casted equality for substitution; it's too like wanteds-rewriting-
wanteds. So, we forbid CTyEqCans that mention coercion holes.
All the details are in Note [Equalities with incompatible kinds]
in TcCanonical.
There are a few knock-on effects, documented where they occur.
While debugging an error in this patch, Simon and I ran into
infelicities in how patterns and matches are printed; we made
small improvements.
This patch includes mitigations for #17828, which causes spurious
pattern-match warnings. When #17828 is fixed, these lines should
be removed.
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If ImpredicativeTypes is not enabled, then `:print <term>` will fail if the
type of <term> has nested `forall`s or `=>`s.
This is because the GHCi debugger's internals will attempt to unify a
metavariable with the type of <term> and then display the result, but if the
type has nested `forall`s or `=>`s, then unification will fail.
As a result, `:print` will bail out and the unhelpful result will be
`<term> = (_t1::t1)` (where `t1` is a metavariable).
Beware: <term> can have nested `forall`s even if its definition doesn't use
RankNTypes! Here is an example from #14828:
class Functor f where
fmap :: (a -> b) -> f a -> f b
Somewhat surprisingly, `:print fmap` considers the type of fmap to have
nested foralls. This is because the GHCi debugger sees the type
`fmap :: forall f. Functor f => forall a b. (a -> b) -> f a -> f b`.
We could envision deeply instantiating this type to get the type
`forall f a b. Functor f => (a -> b) -> f a -> f b`,
but this trick wouldn't work for higher-rank types.
Instead, we adopt a simpler fix: enable `ImpredicativeTypes` when using
`:print` and friends in the GHCi debugger. This is allows metavariables
to unify with types that have nested (or higher-rank) `forall`s/`=>`s,
which makes `:print fmap` display as
`fmap = (_t1::forall a b. Functor f => (a -> b) -> f a -> f b)`, as expected.
Although ImpredicativeTypes is a somewhat unpredictable from a type inference
perspective, there is no danger in using it in the GHCi debugger, since all
of the terms that the GHCi debugger deals with have already been typechecked.
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(#2950)
GHCi is split up into 2 major parts: The user-interface (UI)
and the byte-code interpreter. With `-fexternal-interpreter`
they even run in different processes. Communication between
the UI and the Interpreter (called `iserv`) is done using
messages over a pipe. This is called `Remote GHCI` and
explained in the Note [Remote GHCi] in `compiler/ghci/GHCi.hs`.
To process a `:force` command the UI sends a `Seq` message
to the `iserv` process. Then `iserv` does the effective
evaluation of the value. When during this process a breakpoint
is hit, the `iserv` process has no additional information to
enhance the `Ignoring breakpoint` output with the breakpoint
location.
To be able to print additional breakpoint information,
there are 2 possible implementation choices:
1. Store the needed information in the `iserv` process.
2. Print the `Ignoring breakpoint` from the UI process.
For option 1 we need to store the breakpoint info redundantely
in 2 places and this is bad. Therfore option 2 was implemented
in this MR:
- The user enters a `force` command
- The UI sends a `Seq` message to the `iserv` process.
- If processing of the `Seq` message hits a breakpoint,
the `iserv` process returns control to the UI process.
- The UI looks up the source location of the breakpoint,
and prints the enhanced `Ignoring breakpoint` output.
- The UI sends a `ResumeSeq` message to the `iserv` process,
to continue forcing.
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(Commit message written by Omer, most of the code is written by Simon
and Richard)
See Note [Implementing unsafeCoerce] for how unsafe equality proofs and
the new unsafeCoerce# are implemented.
New notes added:
- [Checking for levity polymorphism] in CoreLint.hs
- [Implementing unsafeCoerce] in base/Unsafe/Coerce.hs
- [Patching magic definitions] in Desugar.hs
- [Wiring in unsafeCoerce#] in Desugar.hs
Only breaking change in this patch is unsafeCoerce# is not exported from
GHC.Exts, instead of GHC.Prim.
Fixes #17443
Fixes #16893
NoFib
-----
--------------------------------------------------------------------------------
Program Size Allocs Instrs Reads Writes
--------------------------------------------------------------------------------
CS -0.1% 0.0% -0.0% -0.0% -0.0%
CSD -0.1% 0.0% -0.0% -0.0% -0.0%
FS -0.1% 0.0% -0.0% -0.0% -0.0%
S -0.1% 0.0% -0.0% -0.0% -0.0%
VS -0.1% 0.0% -0.0% -0.0% -0.0%
VSD -0.1% 0.0% -0.0% -0.0% -0.1%
VSM -0.1% 0.0% -0.0% -0.0% -0.0%
anna -0.0% 0.0% -0.0% -0.0% -0.0%
ansi -0.1% 0.0% -0.0% -0.0% -0.0%
atom -0.1% 0.0% -0.0% -0.0% -0.0%
awards -0.1% 0.0% -0.0% -0.0% -0.0%
banner -0.1% 0.0% -0.0% -0.0% -0.0%
bernouilli -0.1% 0.0% -0.0% -0.0% -0.0%
binary-trees -0.1% 0.0% -0.0% -0.0% -0.0%
boyer -0.1% 0.0% -0.0% -0.0% -0.0%
boyer2 -0.1% 0.0% -0.0% -0.0% -0.0%
bspt -0.1% 0.0% -0.0% -0.0% -0.0%
cacheprof -0.1% 0.0% -0.0% -0.0% -0.0%
calendar -0.1% 0.0% -0.0% -0.0% -0.0%
cichelli -0.1% 0.0% -0.0% -0.0% -0.0%
circsim -0.1% 0.0% -0.0% -0.0% -0.0%
clausify -0.1% 0.0% -0.0% -0.0% -0.0%
comp_lab_zift -0.1% 0.0% -0.0% -0.0% -0.0%
compress -0.1% 0.0% -0.0% -0.0% -0.0%
compress2 -0.1% 0.0% -0.0% -0.0% -0.0%
constraints -0.1% 0.0% -0.0% -0.0% -0.0%
cryptarithm1 -0.1% 0.0% -0.0% -0.0% -0.0%
cryptarithm2 -0.1% 0.0% -0.0% -0.0% -0.0%
cse -0.1% 0.0% -0.0% -0.0% -0.0%
digits-of-e1 -0.1% 0.0% -0.0% -0.0% -0.0%
digits-of-e2 -0.1% 0.0% -0.0% -0.0% -0.0%
dom-lt -0.1% 0.0% -0.0% -0.0% -0.0%
eliza -0.1% 0.0% -0.0% -0.0% -0.0%
event -0.1% 0.0% -0.0% -0.0% -0.0%
exact-reals -0.1% 0.0% -0.0% -0.0% -0.0%
exp3_8 -0.1% 0.0% -0.0% -0.0% -0.0%
expert -0.1% 0.0% -0.0% -0.0% -0.0%
fannkuch-redux -0.1% 0.0% -0.0% -0.0% -0.0%
fasta -0.1% 0.0% -0.5% -0.3% -0.4%
fem -0.1% 0.0% -0.0% -0.0% -0.0%
fft -0.1% 0.0% -0.0% -0.0% -0.0%
fft2 -0.1% 0.0% -0.0% -0.0% -0.0%
fibheaps -0.1% 0.0% -0.0% -0.0% -0.0%
fish -0.1% 0.0% -0.0% -0.0% -0.0%
fluid -0.1% 0.0% -0.0% -0.0% -0.0%
fulsom -0.1% 0.0% +0.0% +0.0% +0.0%
gamteb -0.1% 0.0% -0.0% -0.0% -0.0%
gcd -0.1% 0.0% -0.0% -0.0% -0.0%
gen_regexps -0.1% 0.0% -0.0% -0.0% -0.0%
genfft -0.1% 0.0% -0.0% -0.0% -0.0%
gg -0.1% 0.0% -0.0% -0.0% -0.0%
grep -0.1% 0.0% -0.0% -0.0% -0.0%
hidden -0.1% 0.0% -0.0% -0.0% -0.0%
hpg -0.1% 0.0% -0.0% -0.0% -0.0%
ida -0.1% 0.0% -0.0% -0.0% -0.0%
infer -0.1% 0.0% -0.0% -0.0% -0.0%
integer -0.1% 0.0% -0.0% -0.0% -0.0%
integrate -0.1% 0.0% -0.0% -0.0% -0.0%
k-nucleotide -0.1% 0.0% -0.0% -0.0% -0.0%
kahan -0.1% 0.0% -0.0% -0.0% -0.0%
knights -0.1% 0.0% -0.0% -0.0% -0.0%
lambda -0.1% 0.0% -0.0% -0.0% -0.0%
last-piece -0.1% 0.0% -0.0% -0.0% -0.0%
lcss -0.1% 0.0% -0.0% -0.0% -0.0%
life -0.1% 0.0% -0.0% -0.0% -0.0%
lift -0.1% 0.0% -0.0% -0.0% -0.0%
linear -0.1% 0.0% -0.0% -0.0% -0.0%
listcompr -0.1% 0.0% -0.0% -0.0% -0.0%
listcopy -0.1% 0.0% -0.0% -0.0% -0.0%
maillist -0.1% 0.0% -0.0% -0.0% -0.0%
mandel -0.1% 0.0% -0.0% -0.0% -0.0%
mandel2 -0.1% 0.0% -0.0% -0.0% -0.0%
mate -0.1% 0.0% -0.0% -0.0% -0.0%
minimax -0.1% 0.0% -0.0% -0.0% -0.0%
mkhprog -0.1% 0.0% -0.0% -0.0% -0.0%
multiplier -0.1% 0.0% -0.0% -0.0% -0.0%
n-body -0.1% 0.0% -0.0% -0.0% -0.0%
nucleic2 -0.1% 0.0% -0.0% -0.0% -0.0%
para -0.1% 0.0% -0.0% -0.0% -0.0%
paraffins -0.1% 0.0% -0.0% -0.0% -0.0%
parser -0.1% 0.0% -0.0% -0.0% -0.0%
parstof -0.1% 0.0% -0.0% -0.0% -0.0%
pic -0.1% 0.0% -0.0% -0.0% -0.0%
pidigits -0.1% 0.0% -0.0% -0.0% -0.0%
power -0.1% 0.0% -0.0% -0.0% -0.0%
pretty -0.1% 0.0% -0.1% -0.1% -0.1%
primes -0.1% 0.0% -0.0% -0.0% -0.0%
primetest -0.1% 0.0% -0.0% -0.0% -0.0%
prolog -0.1% 0.0% -0.0% -0.0% -0.0%
puzzle -0.1% 0.0% -0.0% -0.0% -0.0%
queens -0.1% 0.0% -0.0% -0.0% -0.0%
reptile -0.1% 0.0% -0.0% -0.0% -0.0%
reverse-complem -0.1% 0.0% -0.0% -0.0% -0.0%
rewrite -0.1% 0.0% -0.0% -0.0% -0.0%
rfib -0.1% 0.0% -0.0% -0.0% -0.0%
rsa -0.1% 0.0% -0.0% -0.0% -0.0%
scc -0.1% 0.0% -0.1% -0.1% -0.1%
sched -0.1% 0.0% -0.0% -0.0% -0.0%
scs -0.1% 0.0% -0.0% -0.0% -0.0%
simple -0.1% 0.0% -0.0% -0.0% -0.0%
solid -0.1% 0.0% -0.0% -0.0% -0.0%
sorting -0.1% 0.0% -0.0% -0.0% -0.0%
spectral-norm -0.1% 0.0% -0.0% -0.0% -0.0%
sphere -0.1% 0.0% -0.0% -0.0% -0.0%
symalg -0.1% 0.0% -0.0% -0.0% -0.0%
tak -0.1% 0.0% -0.0% -0.0% -0.0%
transform -0.1% 0.0% -0.0% -0.0% -0.0%
treejoin -0.1% 0.0% -0.0% -0.0% -0.0%
typecheck -0.1% 0.0% -0.0% -0.0% -0.0%
veritas -0.0% 0.0% -0.0% -0.0% -0.0%
wang -0.1% 0.0% -0.0% -0.0% -0.0%
wave4main -0.1% 0.0% -0.0% -0.0% -0.0%
wheel-sieve1 -0.1% 0.0% -0.0% -0.0% -0.0%
wheel-sieve2 -0.1% 0.0% -0.0% -0.0% -0.0%
x2n1 -0.1% 0.0% -0.0% -0.0% -0.0%
--------------------------------------------------------------------------------
Min -0.1% 0.0% -0.5% -0.3% -0.4%
Max -0.0% 0.0% +0.0% +0.0% +0.0%
Geometric Mean -0.1% -0.0% -0.0% -0.0% -0.0%
Test changes
------------
- break006 is marked as broken, see #17833
- The compiler allocates less when building T14683 (an unsafeCoerce#-
heavy happy-generated code) on 64-platforms. Allocates more on 32-bit
platforms.
- Rest of the increases are tiny amounts (still enough to pass the
threshold) in micro-benchmarks. I briefly looked at each one in a
profiling build: most of the increased allocations seem to be because
of random changes in the generated code.
Metric Decrease:
T14683
Metric Increase:
T12150
T12234
T12425
T13035
T14683
T5837
T6048
Co-Authored-By: Richard Eisenberg <rae@cs.brynmawr.edu>
Co-Authored-By: Ömer Sinan Ağacan <omeragacan@gmail.com>
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This patch implements the [sugggestion from Simon (PJ)](https://gitlab.haskell.org/ghc/ghc/issues/14628#note_146559):
- Make `TcErrors.getSkolemInfo` return a `SkolemInfo` rather than an `Implication`.
- If `getSkolemInfo` gets `RuntimeUnk`s, just return a new data constructor in `SkolemInfo`, called `RuntimeUnkSkol`.
- In `TcErrors.pprSkols` print something sensible for a `RuntimeUnkSkol`.
The `getSkolemInfo` function paniced while formating suggestions to add type annotations (subfunction `suggestAddSig`)
to a *"Couldn't match type ‘x’ with ‘y’"* error message.
The `getSkolemInfo` function didn't find any Implication value and paniced.
With this patch the `getSkolemInfo` function does no longer panic, if it finds `RuntimeUnkSkol`s.
As the panic occured while processing an error message, we don't need to implement any new error message!
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Due to #17557.
Also accepting spurious performance change.
Metric Decrease:
T1969
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Due to #17557.
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`:steplocal` enables only breakpoints in the current top-level binding.
When a normal breakpoint is hit, then the module name and the break id from the `BRK_FUN` byte code
allow us to access the corresponding entry in a ModBreak table. From this entry we then get the SrcSpan
(see compiler/main/InteractiveEval.hs:bindLocalsAtBreakpoint).
With this source-span we can then determine the current top-level binding, needed for the steplocal command.
However, if we break at an exception or at an error, we don't have an BRK_FUN byte-code, so we don't have any source information.
The function `bindLocalsAtBreakpoint` creates an `UnhelpfulSpan`, which doesn't allow us to determine the current top-level binding.
To avoid a `panic`, we have to check for `UnhelpfulSpan` in the function `ghc/GHCi/UI.hs:stepLocalCmd`.
Hence a :steplocal command after a break-on-exception or a break-on-error is not possible.
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See #16205.
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To display the free variables for a single breakpoint, GHCi pulls out the
information from the fields `modBreaks_breakInfo` and `modBreaks_vars`
of the `ModBreaks` data structure. For a specific breakpoint this gives 2
lists of types 'Id` (`Var`) and `OccName`. They are used to create the Id's
for the free variables and must be kept in sync:
If we remove an element from the Names list, then we also must remove the
corresponding element from the OccNames list.
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Previously we would hackily evaluate a textual code snippet to compute
actions to disable I/O buffering and flush the stdout/stderr handles.
This broke in a number of ways (#15336, #16563).
Instead we now ship a module (`GHC.GHCi.Helpers`) with `base` containing
the needed actions. We can then easily refer to these via `Orig` names.
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After a :cd command and after setting some package flags,
GHCi unloads all loaded modules by resetting the list of targets.
This patch deletes eventually defined debugger breakpoints, before GHCi resets the target list.
The common code is factored out into the new function clearAllTargets.
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This patch adds two new commands `:enable` and `:disable` to the GHCi debugger.
Opposite to `:set stop <n> :continue` a breakpoint disabled with `:disable` will
not loose its previously set stop command.
A new field breakEnabled is added to the BreakLocation data structure to
track the enable/disable state. When a breakpoint is disabled with a `:disable`
command, the following happens:
The corresponding BreakLocation data element is searched dictionary of the
`breaks` field of the GHCiStateMonad. If the break point is found and not
already in the disabled state, the breakpoint is removed from bytecode.
The BreakLocation data structure is kept in the breaks list and the new
breakEnabled field is set to false.
The `:enable` command works similar.
The breaks field in the GHCiStateMonad was changed from an association list
to int `IntMap`.
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`:info Coercible` now outputs the correct section number of the GHCi User's guide together with the secion title.
`:forward x` gives the correct syntax hint.
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When GHC attempts to unify a metavariable with a type containing
foralls, it will be rejected as an occurrence of impredicativity.
GHC was /not/ extending the same treatment to predicate types, such
as in the following (erroneous) example from #11514:
```haskell
foo :: forall a. (Show a => a -> a) -> ()
foo = undefined
```
This will attempt to instantiate `undefined` at
`(Show a => a -> a) -> ()`, which is impredicative. This patch
catches impredicativity arising from predicates in this fashion.
Since GHC is pickier about impredicative instantiations, some test
cases needed to be updated to be updated so as not to fall afoul of
the new validity check. (There were a surprising number of
impredicative uses of `undefined`!) Moreover, the `T14828` test case
now has slightly less informative types shown with `:print`. This is
due to a a much deeper issue with the GHCi debugger (see #14828).
Fixes #11514.
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As noted in #16205 this configuration reliably segfaults.
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A bunch of tests for `integer-simple` were now broken for a foolish reason:
unlike the `integer-gmp` case, there is no CorePrep optimization for turning
small integers directly into applications of `S#`.
Rather than port this optimization to `integer-simple` (which would involve
moving a bunch of `integer-simple` names into `PrelNames`), I switched
as many tests as possible to use `Int`.
The printing of `Integer` is already tested in `print037`.
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This means that `:p` no longer leaks the implementation details of
`Integer` with `integer-simple`. The `print037` test case should
exercise all possible code paths for GHCi's code around printing
`Integer`s (both in `integer-simple` and `integer-gmp`).
`ghc` the package now also has a Cabal `integer-simple` flag (like the
`integer-gmp` one).
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Towards fixing #16043.
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