[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 4 commits: validDerivPred: Reject exotic constraints in IrredPreds

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC


Commits:
0158c5f1 by Ryan Scott at 2023-04-17T18:43:27-04:00
validDerivPred: Reject exotic constraints in IrredPreds

This brings the `IrredPred` case in sync with the treatment of `ClassPred`s as
described in `Note [Valid 'deriving' predicate]` in `GHC.Tc.Validity`. Namely,
we should reject `IrredPred`s that are inferred from `deriving` clauses whose
arguments contain other type constructors, as described in `(VD2) Reject exotic
constraints` of that Note.  This has the nice property that `deriving` clauses
whose inferred instance context mention `TypeError` will now emit the type
error in the resulting error message, which better matches existing intuitions
about how `TypeError` should work.

While I was in town, I noticed that much of `Note [Valid 'deriving' predicate]`
was duplicated in a separate `Note [Exotic derived instance contexts]` in
`GHC.Tc.Deriv.Infer`. I decided to fold the latter Note into the former so that
there is a single authority on describing the conditions under which an
inferred `deriving` constraint can be considered valid.

This changes the behavior of `deriving` in a way that existing code might
break, so I have made a mention of this in the GHC User's Guide. It seems very,
very unlikely that much code is relying on this strange behavior, however, and
even if there is, there is a clear, backwards-compatible migration path using
`StandaloneDeriving`.

Fixes #22696.

- - - - -
10364818 by Krzysztof Gogolewski at 2023-04-17T18:44:03-04:00
Misc cleanup

- Use dedicated list functions
- Make cloneBndrs and cloneRecIdBndrs monadic
- Fix invalid haddock comments in libraries/base

- - - - -
a8bd4732 by Matthew Pickering at 2023-04-18T08:20:49-04:00
Convert interface file loading errors into proper diagnostics

This patch converts all the errors to do with loading interface files
into proper structured diagnostics.

* DriverMessage: Sometimes in the driver we attempt to load an interface
  file so we embed the IfaceMessage into the DriverMessage.
* TcRnMessage: Most the time we are loading interface files during
  typechecking, so we embed the IfaceMessage

This patch also removes the TcRnInterfaceLookupError constructor which
is superceded by the IfaceMessage, which is now structured compared to
just storing an SDoc before.

- - - - -
e05b0ee6 by sheaf at 2023-04-18T08:20:54-04:00
Don't panic in ltPatersonSize

The function GHC.Tc.Utils.TcType.ltPatersonSize would panic when it
encountered a type family on the RHS, as usually these are not allowed
(type families are not allowed on the RHS of class instances or of
quantified constraints). However, it is possible to still encounter
type families on the RHS after doing a bit of constraint solving, as
seen in test case T23171. This could trigger the panic in the call to
ltPatersonSize in GHC.Tc.Solver.Canonical.mk_strict_superclasses, which
is involved in avoiding loopy superclass constraints.

This patch simply changes ltPatersonSize to return "I don't know, because
there's a type family involved" in these cases.

Fixes #23171

- - - - -


30 changed files:

- compiler/GHC/CmmToAsm/X86/CodeGen.hs
- compiler/GHC/Core/Make.hs
- compiler/GHC/Core/Opt/SetLevels.hs
- compiler/GHC/Core/Opt/Specialise.hs
- compiler/GHC/Core/Opt/WorkWrap/Utils.hs
- compiler/GHC/Core/Subst.hs
- compiler/GHC/Driver/Config/Diagnostic.hs
- compiler/GHC/Driver/Config/Tidy.hs
- compiler/GHC/Driver/Errors.hs
- compiler/GHC/Driver/Errors/Ppr.hs
- compiler/GHC/Driver/Errors/Types.hs
- compiler/GHC/Driver/Make.hs
- compiler/GHC/Driver/MakeFile.hs
- compiler/GHC/Iface/Errors.hs
- + compiler/GHC/Iface/Errors/Ppr.hs
- + compiler/GHC/Iface/Errors/Types.hs
- compiler/GHC/Iface/Load.hs
- compiler/GHC/Iface/Recomp.hs
- compiler/GHC/IfaceToCore.hs
- compiler/GHC/Linker/Loader.hs
- compiler/GHC/Runtime/Loader.hs
- compiler/GHC/StgToJS/Linker/Utils.hs
- compiler/GHC/Tc/Deriv/Infer.hs
- compiler/GHC/Tc/Errors/Ppr.hs
- compiler/GHC/Tc/Errors/Types.hs
- compiler/GHC/Tc/Gen/Splice.hs
- compiler/GHC/Tc/Utils/Backpack.hs
- compiler/GHC/Tc/Utils/Env.hs
- compiler/GHC/Tc/Utils/Monad.hs
- compiler/GHC/Tc/Utils/TcType.hs


The diff was not included because it is too large.


View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/44f834339cf9d7cb94c8cb348bc468147506f5ad...e05b0ee65fde4f220e51365648e8c497b2f2fa8e

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View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/44f834339cf9d7cb94c8cb348bc468147506f5ad...e05b0ee65fde4f220e51365648e8c497b2f2fa8e
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