tree 596317cfb0f609844177bba6ad47d9e0f2342f5c
parent 1d1727260058c6d58ebfdeb982c4657342282355
author Albert Teoh <albert.teoh@gmail.com> 1564852908 -0400
committer Rebecca Stambler <rstambler@golang.org> 1565020873 +0000

gopls: return file error if file open fails

The bug manifests itself when a non-existent file is passed in as an
argument to gopls, causing a nil pointer dereference panic. This is due
to an attempt to reference the "mapper" attribute, which is not set if
the file is not found.

The resolution is to check for an informative error that is set on the
file instance after "getFile" is called and return it immediately to the
caller to allow the error to propagate up to the main() function and
print the error to stdout.

Testing:
--------

Non-existent file:
$ gopls -rpc.trace -v check gopls/doesnotexist.go
check: file:///Users/albertteoh/repo/tools/gopls/doesnotexist.go: open /Users/albertteoh/repo/tools/gopls/doesnotexist.go: no such file or directory

Existing go file:
$ gopls -rpc.trace -v check internal/lsp/definition.go
2019/08/03 13:33:00 Info:go/packages.Load
	packages = 2
2019/08/03 13:33:00 Info:go/packages.Load
	package = golang.org/x/tools/internal/lsp
...

Fixes golang/go#33445

Change-Id: Ib56d8a4b7f23f4882b75cf684c5d18a49d27b824
Reviewed-on: https://go-review.googlesource.com/c/tools/+/188857
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>