x/tools/cmd/goimports: add configuration mechanism for ignore list

[bradfitz]

Per the golang-nuts thread (https://groups.google.com/forum/#!msg/golang-nuts/in9IVmPc_fQ/BO4wzOylCAAJ), goimports should have a configuration mechanism to permit designated ignored directories.

[ghost]

Please make an unified mechanism. Then other src-scanning tools could also use it.

[bradfitz]

@pi, which other ones? Who should I talk to? Does one already exist?

[ghost]

godoc for example;
in analysys/analysys.go:

    // Enumerate packages in $GOPATH.
    for i, dir := range filepath.SplitList(build.Default.GOPATH) {
        root := filepath.Join(dir, "src") + string(os.PathSeparator)
....

And I doubt you should talk to anyone. You boss ;)

[gopherbot]

CL https://golang.org/cl/24971 mentions this issue.

[thomasf]

@bradfitz the other src tool that I use quite a bit is gorename.. It maybe takes about a minute to run it and it spews out errors about C code which isn't used by any Go code at all.. I'll guess that the answer of which source tool needs speed improvements differ depending on who uses what often.

Btw, It's probably better to have separate ignore files per tool for flexibility, one can always use symlinks to use a single file if the format is the same.

(and... thanks for the very much speedier goimports)

[bradfitz]

@thomasf, I filed #16427 to track that. Let's move any discussion there.