cmd/go: include file name in error message for bad import

[gopherbot]

by peter.waller:

Mailing list discussion is here:

https://groups.google.com/forum/?fromgroups=#!topic/golang-dev/4oYo21jEGuU

At maximum verbosity, `go get` does not give enough information as to what is causing
the failure if it encounters an invalid import. Ideally, it would always report the
package/file/line number where the invalid import is located. Otherwise it could be
buried somewhere deep in a dependency tree.

Example:

   $ go get -d -v -n github.com/go-gl/...
    import "sdl": import path doesn't contain a slash
    package sdl: unrecognized import path "sdl"

There is something in the code that raises this error talking about the error detail
being irrelevant. I don't understand why.

http://golang.org/src/cmd/go/vcs.go#L322

[minux]

Comment 1:

Status changed to Accepted.

[rsc]

Comment 2:

Labels changed: added size-m.

[rsc]

Comment 3:

Labels changed: added priority-later, removed priority-triage.

[rsc]

Comment 4:

Labels changed: added go1.1maybe, removed go1.1.

[robpike]

Comment 5:

Labels changed: added go1.2maybe, removed go1.1maybe.

[rsc]

Comment 6:

Labels changed: added feature.

[robpike]

Comment 7:

Not in time for 1.2.

Labels changed: removed go1.2maybe.

[rsc]

Comment 8:

Labels changed: added go1.3maybe.

[rsc]

Comment 9:

Labels changed: removed feature.

[rsc]

Comment 10:

Labels changed: added release-none, removed go1.3maybe.

[rsc]

Comment 11:

Labels changed: added repo-main.

[ysmolski]

Example in the topic is not reproducible. So I made this:

% go get -d -v -n github.com/ysmolsky/import-error/...
github.com/ysmolsky/import-error (download)
# cd /Users/thorn/go/src/github.com/ysmolsky/import-error; git sync/update
package github.com/ysmolsky/import-error/t1
	imports sdl: unrecognized import path "sdl" (import path does not begin with hostname)

Reported error is somewhat better. It tells the package where problem happened. But it does not tell the file/line.

[matloob]

GOPATH go get is no longer supported. As of Go 1.24, if we try to do a go get that has a bad import, we get the following:

go: example.com/baz imports
	sdl: package sdl is not in std (/Users/matloob/devgo/src/sdl)

This should now be tracked in #41688, which is a newer issue that tracks adding line numbers to the import stacks printed by (*loadPkg).stackText. See specifically Jay's comment #41688 (comment)