If a module cannot be found because it is ignored or from an unusable
package, report this to the user and the reason it is unusable.

Currently, GHC displays the standard "Cannot find module error". For
example:

```
<no location info>: error:
    Could not find module ‘Control.Monad.Random’
    Perhaps you meant
      Control.Monad.Reader (from mtl-2.2.2)
      Control.Monad.Cont (from mtl-2.2.2)
      Control.Monad.Error (from mtl-2.2.2)
```

GHC does, however, indicate unusable/ignored packages with the -v flag:

```
package MonadRandom-0.5.1-1421RgpXdhC8e8UI7D3emA is unusable due to
missing dependencies:
  fail-4.9.0.0-BAHmj60kS5K7NVhhKpm9J5
```

With this change, I took that message and added it to the output of the
"Cannot find module" message.

Reviewers: bgamari, dfeuer

Reviewed By: bgamari

Subscribers: Phyx, dfeuer, rwbarton, thomie, carter

GHC Trac Issues: #4806

Differential Revision: https://phabricator.haskell.org/D4783

Adam Gundry authored 6 years ago and Ben Gamari committed 6 years ago

filterImports needed a small adjustment to correctly handle record field
definitions arising from modules with DuplicateRecordFields enabled.

Previously hiding fields was not possible with DuplicateRecordFields enabled.

Test Plan: new test rename/should_compile/T14487

Reviewers: bgamari

Subscribers: simonpj, rwbarton, thomie, carter

GHC Trac Issues: #14487

Differential Revision: https://phabricator.haskell.org/D4805

Due to #15061.

Due to #15063.

See #15281

This reverts commit 86210b23.

Vladislav Zavialov authored 6 years ago and Ben Gamari committed 6 years ago

According to an accepted proposal
https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/002
4-no-kind-vars.rst

    With -Wcompat, warn if a kind variable is brought into scope
    implicitly in a type with an explicit forall. This applies to type
    signatures and to other contexts that allow a forall with the
    forall-or-nothing rule in effect (for example, class instances).

Test Plan: Validate

Reviewers: goldfire, hvr, bgamari, RyanGlScott

Reviewed By: goldfire

Subscribers: RyanGlScott, rwbarton, thomie, carter

GHC Trac Issues: #15264

Differential Revision: https://phabricator.haskell.org/D4834

Ben Gamari authored 6 years ago and Ben Gamari committed 6 years ago

Fixes #12970 and will provide a reasonable migration path for the
eventual remove of this function.

Test Plan: Validate

Reviewers: ekmett, hvr

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #12970

Differential Revision: https://phabricator.haskell.org/D4857

This appears to inexplicably break the OS X build, which fails with:
```
make[1]: *** No rule to make target `utils/unlit/fs.c', needed by
         `utils/unlit/dist/build/.depend.c_asm'.  Stop.
make[1]: *** Waiting for unfinished jobs....
make: *** [all] Error 2
```

This reverts commit 8ee9c574.

Until now GHC only supported basic constant folding (lit op lit, expr op
0, etc.).

This patch uses laws of +/-/* (associativity, commutativity,
distributivity) to support some constant folding into nested
expressions.

Examples of new transformations:

   - simple nesting: (10 + x) + 10 becomes 20 + x
   - deep nesting: 5 + x + (y + (z + (t + 5))) becomes 10 + (x + (y + (z + t)))
   - distribution: (5 + x) * 6 becomes 30 + 6*x
   - simple factorization: 5 + x + (x + (x + (x + 5))) becomes 10 + (4 *x)
   - siblings: (5 + 4*x) - (3*x + 2) becomes 3 + x

Test Plan: validate

Reviewers: simonpj, austin, bgamari

Reviewed By: bgamari

Subscribers: thomie

GHC Trac Issues: #9136

Differential Revision: https://phabricator.haskell.org/D2858

(cherry picked from commit fea04def)

As pointed out in #12951, this was a temporary measure to allow GHC to be
bootstrapped on Windows with GHC 7.10. This release is now out of our bootstrap
support window so let's remove it.

Fixes #15134.

Reviewers: dfeuer, hvr, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #15134

Differential Revision: https://phabricator.haskell.org/D4737

Preserve HsPars while typechecking

Test Plan: T15242

Reviewers: bgamari, alanz, simonpj

Reviewed By: alanz, simonpj

Subscribers: simonpj, AndreasK, rwbarton, thomie, carter

GHC Trac Issues: #15242

Differential Revision: https://phabricator.haskell.org/D4822

Ben Gamari authored 6 years ago and Ben Gamari committed 6 years ago

Test Plan: Validate using LLVM assembler

Reviewers: carter, erikd, simonmar

Reviewed By: simonmar

Subscribers: rwbarton, thomie

GHC Trac Issues: #15207

Differential Revision: https://phabricator.haskell.org/D4781

Ben Gamari authored 6 years ago and Ben Gamari committed 6 years ago

Test Plan: Validate on i386

Reviewers: simonmar

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #15255

Differential Revision: https://phabricator.haskell.org/D4855

Ben Gamari authored 6 years ago and Ben Gamari committed 6 years ago

Test Plan: Validate

Reviewers: hvr

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #15062

Differential Revision: https://phabricator.haskell.org/D4854

Adam Gundry authored 6 years ago and Ben Gamari committed 6 years ago

Test Plan: ./validate

Reviewers: bgamari

Subscribers: rwbarton, thomie, erikd, carter

GHC Trac Issues: #15257

Differential Revision: https://phabricator.haskell.org/D4853

This is a small change in user-facing behavior. When we
have a unification variable left over in a CUSK, we previously
would issue an error. But, we can just quantify. This also
teaches kcLHsQTyVars to use quantifyTyVars instead of its own,
ad-hoc quantification scheme.

Fixes #15273.

test case: polykinds/T11648b

Add support for built-in Natural literals in Core.

- Replace MachInt,MachWord, LitInteger, etc. with a single LitNumber
  constructor with a LitNumType field
- Support built-in Natural literals
- Add desugar warning for negative literals
- Move Maybe(..) from GHC.Base to GHC.Maybe for module dependency
  reasons

This patch introduces only a few rules for Natural literals (compared
to Integer's rules). Factorization of the built-in rules for numeric
literals will be done in another patch as this one is already big to
review.

Test Plan:
  validate
  test build with integer-simple

Reviewers: hvr, bgamari, goldfire, Bodigrim, simonmar

Reviewed By: bgamari

Subscribers: phadej, simonpj, RyanGlScott, carter, hsyl20, rwbarton,
thomie

GHC Trac Issues: #14170, #14465

Differential Revision: https://phabricator.haskell.org/D4212

Kirill Zaborsky authored 6 years ago and Ben Gamari committed 6 years ago

Test Plan: ./validate

Reviewers: bgamari, simonpj

Reviewed By: bgamari, simonpj

Subscribers: simonpj, rwbarton, thomie, carter

GHC Trac Issues: #13833

Differential Revision: https://phabricator.haskell.org/D4823

Adam Gundry authored 6 years ago and Ben Gamari committed 6 years ago

Test Plan: new tests rename/should_compile/{T14747,T15149}

Reviewers: simonpj, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #14747, #15149

Differential Revision: https://phabricator.haskell.org/D4821

Fixes #15040.

Reviewers: bgamari, simonmar

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4772

This patch adds "quantified constraint" context in error message when
UndecidableInstances checking fails for quantified constraints.
See Trac #15231:comment#1.

This patch also pretty-prints the instance head for better error messages.

Test Plan: make test TEST="T15231"

Reviewers: bgamari, simonpj

Reviewed By: simonpj

Subscribers: simonpj, rwbarton, thomie, carter

GHC Trac Issues: #15231

Differential Revision: https://phabricator.haskell.org/D4819

Reviewers: adamgundry, bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4826

Vladislav Zavialov authored 6 years ago and Ben Gamari committed 6 years ago

Unicode characters in Parser.y cause build failures
on systems where the locale does not support Unicode.

See https://mail.haskell.org/pipermail/ghc-devs/2018-June/015874.html

Test Plan: ./validate

Reviewers: bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, mpickering, carter

Differential Revision: https://phabricator.haskell.org/D4850

This seems to fix a number of segmentation faults.

There are some rather suspicious failures in the 64-bit case. See #15184 for
details.

Nathan Collins authored 6 years ago and Ben Gamari committed 6 years ago

The docs said that it took a file argument, as in
`-dth-dec-file=<file>`, but it does not take a file argument!

Lest we end up with a non-functional user/group lookup, resulting in #15230.

Consider (Trac #15215)
  data T a = MkT ...
  data S a = ...T...MkT....

If there is an error in the definition of 'T' we add a
"fake type constructor" to the type environment, so that we
can continue to typecheck 'S'.  But we /were not/ adding
a fake anything for 'MkT' and so there was an internal
error when we met 'MkT' in the body of 'S'.

The fix is to add fake tycons for all the 'implicits' of 'T'.
This is done by mk_fake_tc in TcTyClsDecls.checkValidTyCl,
which now returns a /list/ of TyCons rather than just one.

On the way I did some refactoring:

* Rename TcTyDecls.tcAddImplicits to tcAddTyConsToGblEnv
  and make it /include/ the TyCons themeselves as well
  as their implicits

* Some incidental refactoring about tcRecSelBinds. The main
  thing is that I've avoided creating a HsValBinds that we
  immediately decompose.  That meant moving some deck chairs
  around.

NB: The new error message for the regression test T15215
has the opaque error "Illegal constraint in a type:", flagged
in Trac #14845.  But that's the fault of the latter ticket.
The fix here not to blame.

This is a continuation of

    commit 9d600ea6
    Author: Simon Peyton Jones <simonpj@microsoft.com>
    Date:   Fri Jun 1 16:36:57 2018 +0100

        Expand type synonyms when Linting a forall

That patch pointed out that there was a lurking hole in
typeKind, where it could return an ill-scoped kind, because
of not expanding type synonyms enough.

This patch fixes it, quite nicely

* Use occCheckExpand to expand those synonyms (it was always
  designed for that exact purpose), and call it from
         Type.typeKind
         CoreUtils.coreAltType
         CoreLint.lintTYpe

* Consequently, move occCheckExpand from TcUnify.hs to
  Type.hs, and generalise it to take a list of type variables.

I also tidied up lintType a bit.

This patch uses (forall (a::*). a) for the type to
use when recovering from an error in a binding.

Previously (Trac #15276) we had (forall r (a :: TYPE r). a),
which is ill-kinded.

It's quite hard to provoke an error arising from this, because
it only happens in programs that have a type error anyway,
but in a subequent patch I make typeKind fall over if it returns
an ill-scoped kind, and that makes ghci/scripts/T13202 crash
without this fix.

Fix UNREG build failure for 32-bit targets.

This change is an equivalent of commit
0238a6c7
("UNREG: PprC: add support for of W32 literals")

The change allows combining two subwords into one word
on 32-bit targets. Tested on nios2-unknown-linux-gnu.

GHC Trac Issues: #15237

Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>

The ghc.mk file is generated by `./boot` and should be excluded from git
via .gitignore, since the file `ghc.mk` may have different line ends on
windows.

The file GNUmakefile and dir dist, dist-install should also be excluded
via .gitignore, just as other libraries.

Test Plan: [skip ci]

Reviewers: bgamari

Reviewed By: bgamari

Subscribers: osa1, rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4814

See https://ghc.haskell.org/trac/ghc/ticket/12578.