go-projectile-derive-gopath false positives

[peter-mogensen]

About half of my projects don't use a global GOPATH, but use GOPATH=pwd to contain everything in one directory.
go-projectile-set-gopath works OK for that purpose initially, but when switching from a buffer PROJ-ROOT1 (which has a main.go) to another buffer PROJ-ROOT2/main.go go-projectile-derive-gopath seems to fail.

The problem is that "rel" correctly ends up being "main.go", but since a main.go is also to be found in PROJ-ROOT1 (locate-file rel (split-string path path-separator t)) evaluated to "t" which causes GOPATH to be the old PROJ-ROOT1

[peter-mogensen]

A suggestion for an alternative implementation:

(defun go-projectile-better-derive-gopath (&optional path)
  "Attempt to derive GOPATH for the current buffer.
PATH defaults to GOPATH via getenv, used to determine if buffer is in current GOPATH already."
  (let* (
         (path (or path (getenv "GOPATH")))
         (buf (file-truename (or buffer-file-name default-directory)))
         (dir (locate-dominating-file buf "src"))
         )
    (message "P %S B %S D %S" path buf dir)
    (if dir
        (let* (
               (bufl (split-string dir "/" t))
               (pathl (split-string path "/" t))
               )
          (message "P %S B %S" pathl bufl)
          (while (string= (car pathl) (car bufl))
            (progn
              (setq pathl (cdr pathl))
              (setq bufl (cdr bufl))
              )
            )
          (if pathl
              (file-truename (directory-file-name dir))
            path
            )
          )
      )
    )
  )

[peter-mogensen]

Ahh... no ... this is more complex.
You also don't want to derive a GOPATH if the file is in GOROOT. Else you'll switch GOPATH when using tags navigation to move to a definition of a stdlib function.