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This patch adds foldl' to GhcPrelude and changes must occurences
of foldl to foldl'. This leads to better performance especially
for quick builds where GHC does not perform strictness analysis.

It does change strictness behaviour when we use foldl' to turn
a argument list into function applications. But this is only a
drawback if code looks ONLY at the last argument but not at the first.
And as the benchmarks show leads to fewer allocations in practice
at O2.

Compiler performance for Nofib:

O2 Allocations:
        -1 s.d.                -----            -0.0%
        +1 s.d.                -----            -0.0%
        Average                -----            -0.0%

O2 Compile Time:
        -1 s.d.                -----            -2.8%
        +1 s.d.                -----            +1.3%
        Average                -----            -0.8%

O0 Allocations:
        -1 s.d.                -----            -0.2%
        +1 s.d.                -----            -0.1%
        Average                -----            -0.2%

Test Plan: ci

Reviewers: goldfire, bgamari, simonmar, tdammers, monoidal

Reviewed By: bgamari, monoidal

Subscribers: tdammers, rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4929

When parsing a nested comment or nested doc comment in the lexer, if we
see a line starting with '#' we attempt to parse a #line pragma. This
fixes how ghc handles output of the C preproccesor (-cpp flag) when the
original source has C comments or pragmas inside haskell comments.

Updates haddock submodule.

Test Plan: ./validate

Reviewers: bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #314

Differential Revision: https://phabricator.haskell.org/D4934

In https://github.com/gentoo-haskell/gentoo-haskell/issues/704
user explicitly uses -Wl,--relax for most built binaries.

Most of the time this works fine except for capi haskell code
similar to the following:

```haskell
{-# LANGUAGE CApiFFI #-}
module Z where

import Foreign.C

foreign import capi "unistd.h close" c_close :: CInt -> IO CInt
```

In this case compilation fails as:

```
$ inplace/bin/ghc-stage2 -c Z.hs -optl-Wl,--relax -fforce-recomp
ld: --relax and -r may not be used together
```

GHC's driver already disables relaxation on sparc as there relaxation
is already a default mode.

This change disables relaxation on partial linking for all platforms
where linker is binutils linker.

Reported-by: wmyrda
Bug: https://github.com/gentoo-haskell/gentoo-haskell/issues/704Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>

Test Plan: pass -optl-Wl,--relax in test above

Reviewers: bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4888

Trac #15505 showed that, when we have a type error, we
could have an unfilled-in coercion hole.  We don't want an
assertion error in that case.

The underlying cause is that tcClassDecl1 should call
solveEqualities to fully solve all top-level equalities
(or fail in the attempt).

I also refactored the ClassDecl case for tcTyClDecl1 into
a new function tcClassDecl1.  That makes it symmetrical
with the others.

Trac #15487 correctly reported that the qualification
of a Name in an ambiguous-occurrence error message was
wrong.  This patch fixes it.

It's easily done, in RnUtils.addNameClashErrRn

The problem was that in complaining about M.x we must
enusre that 'M' part is the same as that used in
pprNameProvenance.

We were failing to keep correct strictness info when eta-expanding
join points; Trac #15517.   The situation was something like

  \q v eta ->
     let j x = error "blah
         -- STR Lx   bottoming!
     in case y of
           A -> j x eta
           B -> blah
           C -> j x eta

So we spot j as a join point and eta-expand it.  But we must
also adjust the stricness info, else it vlaimes to bottom after
one arg is applied but now it has become two.

I fixed this in two places:

 - In CoreOpt.joinPointBinding_maybe, adjust strictness info

 - In SimplUtils.tryEtaExpandRhs, return consistent values
   for arity and bottom-ness

* Move the definition of `StableName` from `System.Mem.StableName`
  to a new `GHC.StableName` module.

* Expose the `StableName` data constructor from `GHC.StableName`.
  Once we have `UnliftedArray#`, this will enable `StableName`s to
  be stored in `UnliftedArray`s (from `primitive`) without unsafe
  coercions.

Reviewers: hvr, bgamari, andrewthad, osa1

Reviewed By: osa1

Subscribers: osa1, rwbarton, carter

GHC Trac Issues: #15535

Differential Revision: https://phabricator.haskell.org/D5078

In TcErrors, cec_suppress is used to suppress low-priority
errors in favour of truly insoluble ones.

But I was failing to initialise it correcly at top level, which
resulted in Trac #15539.  Easy to fix.

A few regression tests have fewer errors reported, but that seems to
be an improvement.

Summary: Write tests with fewer lines. See comments of nomeata in
https://phabricator.haskell.org/D5038.

Test Plan: make test TESTS='T9441a T9441b T9441c'

Reviewers: nomeata, dfeuer, bgamari

Reviewed By: nomeata

Subscribers: rwbarton, carter

GHC Trac Issues: #9441

Differential Revision: https://phabricator.haskell.org/D5076

Two tests - a ghci script and a compile fail test have been added.

This allows you to use the ghc-in-ghci script in Make even if you
haven't built stage2, and also with Hadrian.  Because of the way -I
works, it will prefer Make/stage2.

Summary:
After commit ef26182e,
the type variable binders in GADT constructor type signatures
are now quantified in toposorted order, instead of always having
all the universals before all the existentials. Unfortunately, that
commit forgot to update some code (which was assuming the latter
scenario) in `DsExpr` which desugars record updates. This wound
up being the cause of #15499.

This patch makes up for lost time by desugaring record updates in
a way such that the desugared expression applies type arguments to
the right-hand side constructor in the correct order—that is, the
order in which they were quantified by the user.

Test Plan: make test TEST=T15499

Reviewers: simonpj, bgamari

Reviewed By: simonpj

Subscribers: rwbarton, carter

GHC Trac Issues: #15499

Differential Revision: https://phabricator.haskell.org/D5060

Summary: (This is documented in `+RTS -?` but wasn't documented in the user's guide)

Reviewers: simonmar, bgamari, monoidal

Reviewed By: monoidal

Subscribers: rwbarton, carter

Differential Revision: https://phabricator.haskell.org/D5065

because since #15050, these are no longer used in pattern SIGnatures,
but still in other places where meta-variables should only be unified
with TYpe VARiables.

I also found mentions of `SigTv` in parts of the renamer and desugarer
that do not seem to directly relate to `SigTv` as used in the type
checker, but rather to uses of `forall a.` in type signatures. I renamed
these to `ScopedTv`.

Differential Revision: https://phabricator.haskell.org/D5074

Summary:
When `(.) @Int` is used without enabling `TypeApplications`,
the resulting error message will pretty-print the (symbolic)
`RdrName` `(.)`. However, it does so without parenthesizing it, which
causes the pretty-printed expression to appear as `.@Int`. Yuck.

Since the expression in a type application will always be prefix,
we can fix this issue by using `pprPrefixOcc` instead of plain ol'
`ppr`.

Test Plan: make test TEST=T15527

Reviewers: bgamari, monoidal, simonpj

Reviewed By: monoidal, simonpj

Subscribers: rwbarton, carter

GHC Trac Issues: #15527

Differential Revision: https://phabricator.haskell.org/D5071

Removes documentation suggesting that 30 and 31-bit code generation is supported
(in support of https://github.com/ghc/ghc/commit/290889927244c79479c4347dfa6c851a134dd6e0).

This allows to run ghc-in-ghci when :set -XTypeApplications is in
.ghciconfig.

Summary: Fortunately the bug is not present in master.

Test Plan: make test TEST=T15523

Reviewers: bgamari, RyanGlScott

Reviewed By: RyanGlScott

Subscribers: RyanGlScott, rwbarton, carter

GHC Trac Issues: #15523

Differential Revision: https://phabricator.haskell.org/D5070

Summary: Fixes #15486.

Test Plan: Validate

Reviewers: monoidal

Reviewed By: monoidal

Subscribers: rwbarton, carter

GHC Trac Issues: #15486

Differential Revision: https://phabricator.haskell.org/D5050

Summary:
When `\case` expressions are parsed normally, their
alternatives are marked as `CaseAlt` (which means that they are
pretty-printed without a `\` character in front of them, unlike for
lambda expressions). However, `\case` expressions created by way of
Template Haskell (in `Convert`) inconsistently designated the case
alternatives as `LambdaExpr`, causing them to be pretty-printed
poorly (as shown in #15518). The fix is simple: use `CaseAlt`
consistently.

Test Plan: make test TEST=T15518

Reviewers: goldfire, bgamari

Subscribers: rwbarton, carter

GHC Trac Issues: #15518

Differential Revision: https://phabricator.haskell.org/D5069

Summary:
When GHC reports that it cannot solve a constraint in error
messages, it often reports what given constraints it has in scope.
Unfortunately, sometimes redundant constraints (like `* ~ *`, from
#15361) can sneak in. The fix is simple: blast away these redundant
constraints using `mkMinimalBySCs`.

Test Plan: make test TEST=T15361

Reviewers: simonpj, bgamari

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #15361

Differential Revision: https://phabricator.haskell.org/D5002

Summary: If this is not checked, SrcSpans are sometimes mangled by CPP.

Test Plan: ./validate

Reviewers: bgamari, dfeuer

Reviewed By: bgamari

Subscribers: dfeuer, rwbarton, thomie, carter

GHC Trac Issues: #15279

Differential Revision: https://phabricator.haskell.org/D4866

Summary:
In order to disambiguate names from different modules, qualify all names
that don't originate in the current module.

Also update docs for QueryQualifyName

Test Plan: validate

Reviewers: simonpj, bgamari

Reviewed By: simonpj

Subscribers: rwbarton, thomie, carter, tdammers

GHC Trac Issues: #15269

Differential Revision: https://phabricator.haskell.org/D4852

Summary:
Since the LLVM backend is slow enough that *slowtest can't run
in the allocated time on Circle CI, let's just use *test. If that still
doesn't fit in the allocated 5 hours, we can try running just the
compiler tests.

Test Plan: Circle CI validation for LLVM

Reviewers: bgamari

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

Differential Revision: https://phabricator.haskell.org/D5033

Summary: Add testcase for  #9441

Test Plan: make test TESTS="T9441a T9441b T9441c"

Reviewers: dfeuer, simonpj, thomie, austin, bgamari

Reviewed By: dfeuer

Subscribers: rwbarton, carter

GHC Trac Issues: #9441

Differential Revision: https://phabricator.haskell.org/D5038

Summary:
- Avoid import *; this helps tools such as pyflakes.
The last occurrence in runtests.py is not easy to remove
as it's used by .T files.
- Use False/True instead of 0/1.

Test Plan: validate

Reviewers: bgamari, thomie, simonmar

Reviewed By: thomie

Subscribers: rwbarton, carter

Differential Revision: https://phabricator.haskell.org/D5062

Summary:
- remove clean_cmd
- framework_failures was undefined
- times_file was not used
- if_verbose_dump was called only when verbose >= 1; remove the check
- simplify normalise_whitespace

Test Plan: validate

Reviewers: bgamari, thomie

Reviewed By: thomie

Subscribers: rwbarton, carter

Differential Revision: https://phabricator.haskell.org/D5061

Summary:
Previously we just created a cartesian product of the library
paths of the plugin package and the libraries of the package.
Of course, some of these combinations result in a filepath of
a file doesn't exists, leading to #15475.

Instead of making `haskFile` return Nothing in case a file
doesn't exist (which would hide errors), we look at all the
possible dylib locations and ensure that at least one of those
locations is an existing file. If the list turns out to be
empty however, we panic.

Reviewers: mpickering, bgamari

Reviewed By: mpickering

Subscribers: monoidal, rwbarton, carter

GHC Trac Issues: #15475

Differential Revision: https://phabricator.haskell.org/D5048

- Rewrite module documentation
- Rewrite class documentation