GitLab

Edward Z. Yang authored Dec 12, 2016 and Edward Z. Yang committed Dec 13, 2016

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Edward Z. Yang authored Dec 12, 2016 and Edward Z. Yang committed Dec 13, 2016

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Edward Z. Yang authored Dec 12, 2016 and Edward Z. Yang committed Dec 13, 2016

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Edward Z. Yang authored Dec 12, 2016 and Edward Z. Yang committed Dec 13, 2016

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Edward Z. Yang authored Dec 12, 2016 and Edward Z. Yang committed Dec 13, 2016

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Edward Z. Yang authored Dec 12, 2016 and Edward Z. Yang committed Dec 13, 2016

This is probably too much info for big instantiations, but it's
better than nothing.
Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Edward Z. Yang authored Dec 12, 2016 and Edward Z. Yang committed Dec 13, 2016

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

[ci skip]

First create then rename symlinks to fix #4156

[ci skip]

Update 'bootstrap.sh'.

Revert "Solver: Add missing call to 'simplifyVar'."

[ci skip]

Ben Gamari authored Dec 06, 2016 and Mikhail Glushenkov committed Dec 07, 2016

(cherry picked from commit e0bf43c3)

Nix integration

This reverts commit adc1fe96.

Migrate ConflictSet qpn ↦ ConflictSet

Print final conflict set when search is exhaustive

Before this change, the behavior in the exhaustive case was to filter
the log up until the first error with the final conflict set, leading to
possibly inconsistently filtered error messages.

Now we always use the conflict set from the first error to filter the
the log, and then display the final conflict set as an additional hint.

[ci skip]

[ci skip]

Solver: Fix space leak in 'addlinking' (issue #2899).

Add some missing occurrences of flib in cabal-install.

Solver: Add missing call to 'simplifyVar'.

Solver: Avoid removing goal choices from the tree when applying heuristics.

'simplifyVar' removes flag names from the 'Var' type, so that all flags within a
package are treated as one during backjumping. A more complete fix would involve
creating a 'SimpleVar' type.

The bug caused the conflict counting heuristic to never prefer flag goals. Flag
variables in the tree's goals had the flags' original names, and the flag
variables in the conflict map did not have names, so they could never be equal.

Since this fix changes the goal order, I wanted to test for an unexpected large
negative impact on solver runtime. I ran the solver on all packages on Hackage
individually with GHC 8.0.1 and looked for differences of more than 10% between
master and the branch. There were twelve packages. I reran those packages three
times and found ten with a significant difference in runtime. Here are the
average runtimes. None of them hit the backjump limit.

package                         master (seconds)   branch (seconds)   ratio
clash-ghc                        2.60              3.99               1.54
hack-middleware-clientsession    8.22              2.54               0.31
hackage-server                   1.46              1.85               1.26
hamusic                          5.47              4.55               0.83
haskore-synthesizer             10.13              7.64               0.75
language-gcl                     2.54              2.03               0.80
ms                              36.98              8.02               0.22
pipes-cereal-plus                1.51              1.66               1.10
thorn                            8.28              3.08               0.37
wai-handler-devel                1.72              1.91               1.11

I looked at the diff in the -v3 log for several of them and saw that the solver
was making some flag choices earlier, as expected.

This isn't much of an improvement, but it at least looks like a safe change.

The error displayed is the first error, which matches the first
conflict set in the non-exhaustive case. In the exhaustive case,
however, we display the last conflict set alongside the first error.

The change in the error message, »the rest of the dependency tree«,
should make it clearer that the error may not come from the final
branches of the dependency tree, but that there may be a lot of branches
being traversed between the first error and the final conflict set, so
they may not be congruent.

(Reasoning for displaying the first rather than the last error in the
non-exhaustive case: Both the first and the last error may be occur near
the leaves, so the conflict set may be incomplete. At the first
backjump, however, the conflicts are more likely to be relevant as the
solver has made fewer compromises at that point.
In the exhaustive case, this is not relevant as the final conflict set
is located at the root, so the conflict set contains all the conflicts
of a certain path through the tree. This is much more useful than the
first conflict set.)

Example:

```
> ./.stack-work/install/x86_64-linux-nix/ghc-8.0.1/8.0.1/bin/cabal install --dry-run cabal-install-1.24.0.0 cabal-install-1.22.9.0
Warning: The package list for 'hackage.haskell.org' is 46 days old.
Run 'cabal update' to get the latest list of available packages.
Resolving dependencies...
cabal: Could not resolve dependencies:
next goal: cabal-install (user goal)
rejecting: cabal-install-1.24.0.0 (constraint from user target requires
==1.22.9.0)
rejecting: cabal-install-1.22.9.0 (constraint from user target requires
==1.24.0.0)
rejecting: cabal-install-1.22.8.0, cabal-install-1.22.7.0,
cabal-install-1.22.6.0, cabal-install-1.22.5.0, cabal-install-1.22.4.0,
cabal-install-1.22.3.0, cabal-install-1.22.2.0, cabal-install-1.22.0.1,
cabal-install-1.22.0.0, cabal-install-1.20.2.0, cabal-install-1.20.1.0,
cabal-install-1.20.0.6, cabal-install-1.20.0.5, cabal-install-1.20.0.4,
cabal-install-1.20.0.3, cabal-install-1.20.0.2, cabal-install-1.20.0.1,
cabal-install-1.20.0.0, cabal-install-1.18.2.0, cabal-install-1.18.1.0,
cabal-install-1.18.0.8, cabal-install-1.18.0.7, cabal-install-1.18.0.6,
cabal-install-1.18.0.5, cabal-install-1.18.0.4, cabal-install-1.18.0.3,
cabal-install-1.18.0.2, cabal-install-1.18.0.1, cabal-install-1.18.0,
cabal-install-1.16.1.0, cabal-install-1.16.0.2, cabal-install-1.16.0.1,
cabal-install-1.16.0, cabal-install-0.14.1, cabal-install-0.14.0,
cabal-install-0.10.2, cabal-install-0.10.0, cabal-install-0.8.2,
cabal-install-0.8.0, cabal-install-0.6.4, cabal-install-0.6.2,
cabal-install-0.6.0, cabal-install-0.5.2, cabal-install-0.5.1,
cabal-install-0.5.0, cabal-install-0.4.0 (constraint from user target requires
==1.22.9.0)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: cabal-install (49)
```

Output the last error message in addition to the final conflict
set, and give a less technical description of the conflict set for the
user message.

An example for the expected output is:

> cabal install --dry-run DPM CurryDB DAV DSH Digit HList MagicHaskeller bamboo
cabal: Could not resolve dependencies:
trying: CurryDB-0.1.1.0 (user goal)
trying: base-4.8.0.0/installed-1b6... (dependency of CurryDB-0.1.1.0)
trying: unix-2.7.1.0/installed-e59... (dependency of process-1.2.3.0/installed-3b1...)
trying: directory-1.2.2.0/installed-b49... (dependency of process-1.2.3.0/installed-3b1...)
Dependency tree exhaustively searched.
I've had most trouble fulfilling the following goals: haskell98 (36850), base
(26359), directory (9599), HTF (5092), bamboo (3788), DPM (3452), unix (3208),
CurryDB (107)