This matches the behavior and error of cmd/compile.

Fixes #34946.

Change-Id: I329ef358deea63d8425f76f1d54c95749b96c365
Reviewed-on: https://go-review.googlesource.com/c/go/+/202484
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

R=go1.11

This CL also introduces a new TODO in parser.go. To be
addressed in a separate CL to make this easier to review.

Also: Make parser's test harness easier to use by ignoring
auto-inserted (invisible) semicolons when computing error
positions. Adjusted testdata/commas.src accordingly.

Fixes #23434.

Change-Id: I050592d11d5f984f71185548394c000eea509205
Reviewed-on: https://go-review.googlesource.com/87898
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

R=go1.11

To fix this, this CL borrows code from the new syntax
package which has a better tuned parser at this point.

Fixes #11377.

Change-Id: Ib9212c945903d6f62abcc59ef5a5767d4ef36981
Reviewed-on: https://go-review.googlesource.com/87495
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

This change stabilizes the result of Sort when the error list contains
multiple items for same position. To stabilize the result, newly also
the Msg field is considered.

The motivation is to avoid diffs of sorted scanner.ErrorList output
in repository tracked logs like:

-testdata/foo.go:19:44: "bar"
 testdata/foo.go:19:44: "qux"
+testdata/foo.go:19:44: "bar"

The change was approved at [0] before submitting.

As a side effect, one file in go/parser/testdata must be updated as
well. For this file the parser produces two different errors:

testdata/issue3106.src:22:5: expected ';', found 'if'
testdata/issue3106.src:22:5: expected operand, found 'if'

Before comparing the actual and expected errors, the former are
filtered to keep only one error per source line[1]. With the new
(*ErrorList).Less the outcome is the other error than before which is
kept after the call to RemoveMultiplies.

[0]: https://groups.google.com/d/msg/golang-nuts/5ChC0XiIwlU/rol_yb2gTj4J
[1]:
https://github.com/golang/go/blob/9d0239771a2ddd77be0ba64c2782e1328a378190/src/go/parser/error_test.go#L160

Change-Id: Ib72c98a891cdeef34705c22dfbeb0408dcdfddf8
Reviewed-on: https://go-review.googlesource.com/8340
Reviewed-by: Robert Griesemer <gri@golang.org>

Preparation was in CL 134570043.
This CL contains only the effect of 'hg mv src/pkg/* src'.
For more about the move, see golang.org/s/go14nopkg.