cmd/go: packages in different GOPATH are not rebuilt when modified

[gopherbot]

by diogin:

What steps will reproduce the problem?


1. Set GOPATH to two different paths:

D:\>echo %GOPATH%
D:\code;D:\devel\trunk

2. Create a folder "dddd" under "D:\devel\trunk\src", and create a
file "dddd.go" in it with the following content:

package dddd

func F() {
    println("ccc")
}

3. Create a folder "demo" under "D:\code\src", whose code imports
"dddd":

package main

import (
    "dddd"
)

func main() {
    dddd.F()
}

4. Step 3 prints a "ccc". Then change the string in "dddd\dddd.go"
to "eee", and "go install demo" again, the string printed is still
"ccc".


What is the expected output?

Shoud print "eee".

What do you see instead?

Print "ccc".

Which compiler are you using (5g, 6g, 8g, gccgo)?

8g

Which operating system are you using?

Windows/386

Which version are you using?  (run 'go version')

1.0.2

[alexbrainman]

Comment 1:

Cannot reproduce. But your description is bit vague. Here everything is important:
working directory, file / directory name case and such. Please, provide list of exact
commands to reproduce. Thank you.
Alex

Status changed to WaitingForReply.

[gopherbot]

Comment 2 by diogin:

Hello, you can reproduce exactly following these steps:
D:\>echo %GOPATH%
D:\code;D:\devel\trunk
D:\>type D:\code\src\demo\main.go
package main
import "dddd"
func main() {
    dddd.F()
}
D:\>type D:\devel\trunk\src\dddd\dddd.go
package dddd
func F() {
    println("ccc")
}
D:\>go install demo
D:\>demo
ccc
// here, edit the content to "eee"
D:\>type D:\devel\trunk\src\dddd\dddd.go
package dddd
func F() {
    println("eee")
}
D:\>go install demo
D:\>demo
ccc
D:\>

[gopherbot]

Comment 3 by diogin:

I add "D:\code\bin" to my PATH.

[peterGo]

Comment 4:

It's easy to reproduce this issue.
The build flags are shared by the build, install, run, and test commands:
    -a    force rebuilding of packages that are already up-to-date.
Command go
Compile packages and dependencies
http://golang.org/cmd/go/#Compile_packages_and_dependencies
For example,
    D:\>go install -a demo

[peterGo]

Comment 5:

It's easy to reproduce this issue.
The build flags are shared by the build, install, run, and test commands:
    -a    force rebuilding of packages that are already up-to-date.
Command go
Compile packages and dependencies
http://golang.org/cmd/go/#Compile_packages_and_dependencies
For example, to solve the problem, run,
    D:\>go install -a demo

[peterGo]

Comment 6:

I'm able to reproduce this issue on Windows 7. I'm unable to reproduce this issue on
Linux Mint 13. Therefore, it's most likely to be a Windows issue.

[alexbrainman]

Comment 7:

I can reproduce your problem now, thank you. And I can reproduce it on both windows and
linux.
Trying to understand why it is happening. Here is the code:
http://code.google.com/p/go/source/browse/src/cmd/go/pkg.go#515
If you look at the comment just above:
// ... If a package p is not in the same tree as any
// package named on the command-line, assume it is up-to-date
// no matter what the modification times on the source files indicate.
// This avoids rebuilding $GOROOT packages when people are
// working outside the Go root, and it effectively makes each tree
// listed in $GOPATH a separate compilation world.
// See issue #3149.
Given that comment, in addition to extract from
http://code.google.com/p/go/source/detail?r=a461bcce05f6
commit message:
* Do not recompile packages across roots (Fixes  issue #3149 .)
I surmise it is working as intended. So I should be closing this issue as such. But, as
a fellow programer, I can see this behavior confusing in your scenario. Perhaps this
needs to be documented somewhere at the very least.
Leaving it for others to decide what to do.
Alex

Status changed to Accepted.

[rsc]

Comment 8:

We should make sure the docs are clear.

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

[rsc]

Comment 9:

Labels changed: added go1.1.

[rsc]

Comment 10:

Labels changed: added size-l.

[rsc]

Comment 11:

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

[robpike]

Comment 12:

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

[rsc]

Comment 13:

Labels changed: added feature.

[robpike]

Comment 14:

Status changed to WorkingAsIntended.