cmd/go: always rebuild GOPATH code that looks out of date

We used to put a rebuilding barrier between GOPATHs, so that if
you had GOPATH=dir1:dir2 and you had "p" in dir1/src/p
and "q" in dir2/src/q, with "p" importing "q", then when you
ran 'go install p', it would see that it was working in dir1
and (since nothing from dir2 was explicitly mentioned)
would assume that everything in dir2 is up-to-date, provided
it is built at all.

This has the confusing behavior that if "q" hasn't been built ever,
then if you update sources in q and run 'go install p', the right
thing happens (q is rebuilt and then p), but after that, if you update
sources in q and run 'go install p', nothing happens: the installed
q is assumed up-to-date.

People using code conventions with multiple GOPATH entries
(for example, with commands in one place and libraries in another,
or vendoring conventions that try to avoid rewriting import paths)
run into this without realizing it and end up with incorrect build
results.

The original motivation here was to avoid rebuild standard packages
since a system-installed GOROOT might be unwritable.
The change introduced to separate GOROOT also separated
individual GOPATH entries. Later changes added a different, more
aggressive earlier shortcut for GOROOT in release settings,
so the code here is now only applying to (and confusing)
multiple GOPATH entries. Remove it.

Fixes #10509.

Change-Id: I687a3baa81eff4073b0d67f9acbc5a3ab192eda5
Reviewed-on: https://go-review.googlesource.com/9155
Reviewed-by: Ian Lance Taylor <iant@golang.org>

0 files changed, 0 insertions, 0 deletions