Fix bug in conflict counting.

[ci skip]

`new-test` _is_ implemented now. `new-install` isn't.

Refine "doingTH" check to include checking for QuasiQuotes

The conflict set that represents the option to not choose a value for a goal,
'initial', has two purposes:

1. 'initial' contributes to a node's conflict set, because it is unioned with
   the other conflict sets under the same choice node, if the current variable
   is contained in all of them.
2. 'initial' contributes to the conflict count.  When it is unioned with the
   other conflict sets, it is also added to the ConflictMap.

Previously, 'initial' was treated as the first of a node's children for (1) and
the last of the children for (2).  This refactoring treats 'initial' as the last
child in both cases, to make the code clearer, and renames it to 'lastCS'.
There should be no change in behavior.

In Explore.hs, the solver calculates a conflict set corresponding to the option
to not choose a value for each goal, called 'initial'.  That conflict set should
be added to the ConflictMap when the current goal causes a conflict.  However,
there was a bug, and the solver added 'initial' to the ConflictMap at every
level.

The bug meant that the solver preferred all goals that it had already chosen.
If a new goal started to cause conflicts, it would take a while for the solver
to start preferring the new goal over the ones that it had previously seen.
See #4595 for an example where this problem caused longer backjumps and slowed
down the solver.

Testing

I ran "cabal install --dry-run" for all packages on Hackage with master and the branch with a 90 second timeout, GHC 8.0.1, and index state 2017-07-08T04:20:18Z. Then I filtered out all packages where both runs had the same result (success or failure) and the times were within 10%. I repeated that process three times to eliminate packages that had different run times due to noise. Then I ran "cabal install --dry-run --max-backjumps=-1" on the remaining packages and averaged three runs.

Since this branch changes a goal-ordering heuristic, I expected a lot of changes in run time in either direction. Out of 105 changes, 83 were faster, 20 were slower, and 2 involved a timeout on both branches. (The two that timed out had different run times before I removed the backjump limit.)

package                          master result   master time (seconds)   branch result   branch time (seconds)   speedup
AesonBson                        solution         3.06                   solution         2.59                    1.18
DisTract                         no solution      1.48                   no solution      1.34                    1.1
GPipe-Examples                   timeout         90.01                   no solution      2.11                    -
GuiTV                            solution         2.54                   solution        16.05                    0.16
Phsu                             solution         3.49                   solution         1.83                    1.9
Ranka                            no solution      2.05                   no solution      1.65                    1.25
Rlang-QQ                         no solution      2.97                   no solution      1.89                    1.57
SourceGraph                      timeout         90.04                   no solution     11.53                    -
Validation                       no solution      2.1                    no solution      6.59                    0.32
WebCont                          no solution      2.04                   no solution      1.6                     1.28
acme-everything                  timeout         90.02                   timeout         90                       -
aeson-t                          solution         2.04                   solution         1.81                    1.13
alsa-gui                         no solution      1.62                   no solution      1.86                    0.87
aviation-cessna172-diagrams      no solution      2.56                   no solution      2.29                    1.12
aws-dynamodb-conduit             no solution      2.22                   no solution      1.83                    1.22
azure-servicebus                 no solution      5.18                   no solution      2.87                    1.8
bamboo-theme-mini-html5          no solution      2.51                   no solution      2                       1.26
bitcoin-payment-channel          solution         3.42                   solution         2.73                    1.25
bittorrent                       no solution      2.75                   no solution      2.4                     1.15
blaze-builder-enumerator         no solution      1.62                   no solution      1.88                    0.86
blunt                            solution         2.99                   solution         2.5                     1.19
cash                             no solution      1.33                   no solution      1.53                    0.87
cheapskate-terminal              no solution      2.04                   no solution      1.62                    1.26
clckwrks-plugin-bugs             no solution      3.85                   no solution      5.78                    0.67
cmdtheline                       no solution      1.96                   no solution      1.63                    1.2
colchis                          no solution      1.99                   no solution      2.23                    0.89
collada-types                    no solution      1.86                   no solution      1.66                    1.12
convertible-text                 solution         1.61                   solution         1.83                    0.88
cqrs-example                     no solution      2.64                   no solution      2.32                    1.14
dixi                             solution         4.44                   solution         4.03                    1.1
ethereum-client-haskell          no solution      1.84                   no solution      2.45                    0.75
flowdock                         no solution      2.46                   no solution      3.19                    0.77
geniserver                       no solution      5.34                   no solution      4.84                    1.1
ghc-imported-from                solution         4.59                   solution         2.9                     1.58
gps2htmlReport                   solution         3.08                   solution         5.58                    0.55
guarded-rewriting                solution         1.54                   solution         1.34                    1.14
hack2-handler-happstack-server   no solution      1.76                   no solution      2                       0.88
halma-telegram-bot               solution         4.27                   solution         3.37                    1.27
happs-tutorial                   no solution      2.08                   no solution      1.86                    1.12
happstack                        no solution      3.08                   no solution      5.86                    0.53
happstack-facebook               timeout         90.01                   timeout         90.03                    -
haskelldb-hsql-mysql             no solution      1.73                   no solution      1.5                     1.16
hdbi                             no solution      1.92                   no solution      1.66                    1.15
hdbi-postgresql                  no solution      3.05                   no solution      1.95                    1.56
hdbi-sqlite                      no solution      1.91                   no solution      1.69                    1.13
hexpat-iteratee                  no solution      2.61                   no solution      1.84                    1.42
hist-pl                          no solution      2.69                   no solution      2.36                    1.14
hscd                             no solution      2.53                   no solution      1.59                    1.59
http-client-lens                 no solution      3.63                   no solution      1.96                    1.85
hubris                           no solution      3.62                   no solution      1.63                    2.22
infinity                         no solution      1.34                   no solution      1.5                     0.89
iteratee-parsec                  no solution      2.01                   no solution      1.74                    1.16
json-togo                        no solution      1.86                   no solution      1.65                    1.13
lat                              no solution      2.87                   no solution      1.86                    1.55
liquidhaskell                    solution         3.34                   solution         2.25                    1.48
manatee-core                     no solution      1.79                   no solution      1.6                     1.12
manatee-curl                     no solution      8.44                   no solution      2.73                    3.09
manatee-editor                   no solution      5.05                   no solution      2.81                    1.8
manatee-filemanager              no solution     29.09                   no solution      2.96                    9.82
manatee-imageviewer              no solution      1.78                   no solution      1.57                    1.13
manatee-mplayer                  no solution      8.98                   no solution      4.05                    2.22
manatee-terminal                 no solution      3.19                   no solution      2.41                    1.32
minimung                         no solution      1.86                   no solution      1.57                    1.19
monoids                          no solution      3.02                   no solution      2.68                    1.13
mprover                          no solution      1.89                   no solution      1.54                    1.23
ms                               no solution      8.04                   no solution      4.35                    1.85
music-sibelius                   solution         3.1                    solution         2.5                     1.24
nerf                             solution        22.54                   solution         3.09                    7.29
nomyx-api                        solution         5.46                   solution         4.39                    1.24
nomyx-library                    solution         2.08                   solution         1.86                    1.11
nomyx-server                     no solution      4.83                   no solution      3.92                    1.23
opaleye-classy                   no solution      2.07                   no solution      3.58                    0.58
openflow                         no solution      1.95                   no solution      1.66                    1.18
ot                               no solution      3.37                   no solution      1.95                    1.73
paypal-api                       no solution      1.89                   no solution      1.64                    1.15
pdf-slave-server                 no solution      3.21                   no solution      2.15                    1.49
phooey                           solution         2.55                   solution        16.24                    0.16
pipes-cereal-plus                solution         1.85                   solution         1.65                    1.12
pocket-dns                       no solution      2.71                   no solution      2.08                    1.3
pontarius-mediaserver            no solution      2.29                   no solution      2.7                     0.85
precis                           no solution      2.53                   no solution      3.23                    0.78
prove-everywhere-server          no solution      2.19                   no solution      1.92                    1.14
quickbooks                       no solution      5.86                   no solution      5.17                    1.13
rbpcp-api                        solution         2.35                   solution         2.13                    1.11
react-haskell                    timeout         90.02                   no solution     71.21                    -
regex-xmlschema                  no solution      1.34                   no solution      1.51                    0.89
remote-json-server               solution         2.1                    solution         1.8                     1.16
scholdoc-citeproc                no solution      3                      no solution      1.92                    1.57
scion-browser                    no solution      5.21                   no solution      4.65                    1.12
semdoc                           no solution      4.21                   no solution      3.04                    1.39
servant-auth-token-rocksdb       no solution      4.68                   no solution      2.32                    2.02
snaplet-auth-acid                no solution      2.25                   no solution      1.99                    1.13
snaplet-stripe                   no solution      3.46                   no solution      2.97                    1.16
sssp                             no solution      3.3                    no solution      2.79                    1.18
target                           solution         2.8                    solution         2.11                    1.32
tls-extra                        no solution      2.74                   no solution      2.36                    1.16
twentefp-rosetree                no solution      1.69                   no solution      1.97                    0.86
twitter-enumerator               no solution     28.39                   no solution      2.16                   13.15
wai-middleware-cache             no solution      1.95                   no solution      1.56                    1.25
wai-middleware-catch             no solution      1.9                    no solution      1.54                    1.24
wai-middleware-route             solution        11.9                    solution         1.62                    7.34
xml2json                         no solution      2.27                   no solution      1.68                    1.35
yesod-auth-account-fork          solution         3.33                   solution         2.87                    1.16
yesod-comments                   no solution     25.6                    no solution     14.44                    1.77
yesod-pure                       solution         7.99                   solution         4.45                    1.79

These tests are copied from cabal-testsuite/PackageTests/TemplateHaskell with
only minor changes.

In several places we need to know whether any modules in the component being
built use template haskell, because if they do we need to make sure the object
files that will be needed are built.
Previously, we checked whether TemplateHaskell was present in the extensions
declared in the cabal file. Now we also check for QuasiQuotes.

This patch adds usesTemplateHaskellOrQQ to Distribution.Types.BuildInfo and
Distribution.PackageDescription. The checks "doingTH" checks in
Distribuion.Simple.GHC, Distribution.Simple.GHCJS, and Distribution.Simple.LHC
now delegate to usesTemplateHaskellOrQQ rather than each having identical checks
inline.

Hackage requires the .cabal file to be named consistently with the package name,
but `cabal check` didn't detect this yet.

Example output:

    $ cabal check
    The following errors will cause portability problems on other environments:
    * The filename ./doo.cabal does not match package name (expected: foobar.cabal)

    Hackage would reject this package.

Note: this new check is implicitly/accidentally tested by an existing (unrelated)
test in `cabal-testsuite`.

Remove extra space from ChangeLog generation

I don't know if it was there for a reason, but it looks like it wasn't.

[ci skip]

fixing documentation links

- corret hugs documentation liks
- add StrictData and Strict ghc flag links
- update documentation links for PolymorphicComponents, Generics, GADTs and MonoPatBinds
issue #4582

This reverts commit 0a28ab6a.

fixing broken links

[ci skip]

[ci skip]

an empty target is an empty string

Speed up equal files check

Try update-alternatives ld

Speed up Distribution.Compat.CopyFile.filesEqual by checking size of files before checking their contents

Alexei Pastuchov authored 7 years ago and Алексей Пастухов committed 7 years ago

https://github.com/haskell/cabal/issues/4582

Solver: Add individual flags to conflict sets.

[ci skip]

Enhance `--allow-{newer,older}` syntax

This extends the capabilities of `--allow-{newer,older}` to allow for more
fine-grained scoping to control more precisely which packages and constraints
a relaxation is applied to. See updated documentation for more details.

Move Distribution.Client.Compat.Prelude to Distribution.Compat.Prelude

The idea here is to break the dependency that has crept in from the
"Solver" into the "Client". (If there's ever going to be a separate
solver then the dependency would become a big problem.)