If the target files contains `//line` directive and it indicates
a non-go file, the linter is going to handle it as a go file,
which results in failure.
The cause of this issue is that the linters (`Analyzer`s) are using
`pass.Fset.Position()`. This func returns the adjusted position using
`//line` directive.
The example project reported in #998 has `//line` directive that
indicates other non-go file.
According to the description of "Compiler Directives”
(https://golang.org/cmd/compile/#hdr-Compiler_Directives),
line directives is mainly used for reporting original positions to
the generators or something.
On linters of golangci-lint, `pass.Fset.Position()` is used just to
aggregate file names; we don't have to adjust positions.
This changes `Analyzer`s that use `pass.Fset.Position()` to aggregate
file names to use `pass.Fset.PositionFor()` with `adjusted == false`.
Relates: #998
Run all linters per package. It allows unloading package data when it's
processed. It dramatically reduces memory (and CPU because of GC) usage.
Relates: #337
Use go/packages instead of x/tools/loader: it allows to work
with go modules and speedups loading of packages with the help
of build cache.
A lot of linters became "fast": they are enabled by --fast now and
work in 1-2 seconds. Only unparam, interfacer and megacheck
are "slow" linters now.
Average project is analyzed 20-40% faster than before if all linters are
enabled! If we enable all linters except unparam, interfacer and
megacheck analysis is 10-20x faster!
Use build.Import instead of manual parser.ParseFile and paths traversal. It allows:
1. support build tags for all linters.
2. analyze files only for current GOOS/GOARCH: less false-positives.
3. analyze xtest packages (*_test) by golint: upstream golint and
gometalinter can't do it! And don't break analysis on the first xtest
package like it was before.
4. proper handling of xtest packages for linters like goconst where
package boundary is important: less false-positives is expected.
Also:
1. reuse AST parsing for golint and goconst: minor speedup.
2. allow to specify path (not only name) regexp for --skip-files and
--skip-dirs
3. add more default exclude filters for golint about commits:
`(comment on exported (method|function)|should have( a package)?
comment|comment should be of the form)`
4. print skipped dir in verbose (-v) mode
5. refactor per-linter tests: declare arguments in comments, run only
one linter and in combination with slow linter
