x/tools/internal/gocommand: TestRmdirAfterGoList_Runner failures

[gopherbot]

#!watchflakes
default <- pkg == "golang.org/x/tools/internal/gocommand" && test == "TestRmdirAfterGoList_Runner"

Issue created automatically to collect these failures.

Example (log):

=== RUN   TestRmdirAfterGoList_Runner
    invoke_test.go:115: failed to remove temp dir: remove C:\b\s\w\ir\x\t\TestRmdirAfterGoList_Runner2474274036\001: The process cannot access the file because it is being used by another process.
    invoke_test.go:118: C:\b\s\w\ir\x\t\TestRmdirAfterGoList_Runner2474274036\001 d 001/ <nil>
--- FAIL: TestRmdirAfterGoList_Runner (0.55s)

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "golang.org/x/tools/internal/gocommand" && test == "TestRmdirAfterGoList_Runner"

2025-05-15 19:23 x_tools-go1.24-windows-amd64-longtest tools@ec0dab2f release-branch.go1.24@431f75a0 x/tools/internal/gocommand.TestRmdirAfterGoList_Runner (log)

=== RUN   TestRmdirAfterGoList_Runner
    invoke_test.go:115: failed to remove temp dir: remove C:\b\s\w\ir\x\t\TestRmdirAfterGoList_Runner2474274036\001: The process cannot access the file because it is being used by another process.
    invoke_test.go:118: C:\b\s\w\ir\x\t\TestRmdirAfterGoList_Runner2474274036\001 d 001/ <nil>
--- FAIL: TestRmdirAfterGoList_Runner (0.55s)

— watchflakes

[adonovan]

Well that was quick. The directory listing shows only the t.TempDir directory, ...\TestRmdirAfterGoList_RunnerXXX\001. That likely means that the directory itself, not some other file within it such as go.mod or p/X.go, could not be deleted (though it's possible there's a race between WalkDir and whatever asynchronous task is still running).

Looking within gocommand, the answer seems fairly obvious: the WaitDelay mechanism of exec.Command allows, under some circumstances, the Wait call to return before all the work is done. Assuming that occurs, then the go list child process may be running after Wait returns. Since it holds a reference to its working directory, this prevents its deletion on Windows.

As long as we're using WaitDelay, we can't assume the child process is done when Runner.RunRaw returns.

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
default <- pkg == "golang.org/x/tools/internal/gocommand" && test == "TestRmdirAfterGoList_Runner"

2025-05-16 16:55 x_tools-go1.24-windows-386 tools@5c7400c9 release-branch.go1.24@431f75a0 x/tools/internal/gocommand.TestRmdirAfterGoList_Runner (log)

=== RUN   TestRmdirAfterGoList_Runner
    invoke_test.go:115: failed to remove temp dir: remove C:\b\s\w\ir\x\t\TestRmdirAfterGoList_Runner477305817\001: The process cannot access the file because it is being used by another process.
    invoke_test.go:118: C:\b\s\w\ir\x\t\TestRmdirAfterGoList_Runner477305817\001 d 001/ <nil>
--- FAIL: TestRmdirAfterGoList_Runner (0.45s)

2025-05-16 16:59 x_tools-go1.23-windows-386 tools@2263a61d release-branch.go1.23@f77084d1 x/tools/internal/gocommand.TestRmdirAfterGoList_Runner (log)

=== RUN   TestRmdirAfterGoList_Runner
    invoke_test.go:115: failed to remove temp dir: remove C:\b\s\w\ir\x\t\TestRmdirAfterGoList_Runner841516109\001: The process cannot access the file because it is being used by another process.
    invoke_test.go:118: C:\b\s\w\ir\x\t\TestRmdirAfterGoList_Runner841516109\001 d 001/ <nil>
--- FAIL: TestRmdirAfterGoList_Runner (0.26s)

— watchflakes