cmd/go: go clean -testcache fails if GOCACHE directory does not exist

[mxk]

What version of Go are you using (go version)?

$ go version
go version go1.11.2 darwin/amd64

Does this issue reproduce with the latest release?

Yes. It may be affected by #26794 for 1.12, but looking at the code, I think the bug is still there.

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN="/Users/mxk/bin"
GOCACHE="/Users/mxk/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/mxk/.go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/Cellar/go/1.11.2/libexec"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.11.2/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/xg/rnkm_hgs5298dsx212f1_y2c0000gp/T/go-build752263492=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

cachedir=$(go env GOCACHE)
mv $cachedir $cachedir.old
go clean -testcache
mv $cachedir.old $cachedir

What did you expect to see?

No errors and an exit code of 0.

What did you see instead?

go clean -testcache: open /Users/mxk/Library/Caches/go-build/testexpire.txt: no such file or directory
exit code 1

The -testcache flag assumes that the cache directory exists. When that's not the case, there is nothing to clear, so the command should exit normally.

[agnivade]

/cc @bcmills

[bcmills]

I believe this was fixed by #28680. Please reopen if you can still reproduce it at head.

example.com$ gotip env GOCACHE
/tmp/tmp.pCKjol3k6h

example.com$ rm -r $(gotip env GOCACHE)

example.com$ gotip clean -testcache

[MatthiasScholz]

The issue does not seem to be fixed.

Running version:

• go version go1.13.5 linux/amd64

Gives the following error message:

go clean -testcache
go clean -testcache: open /.../.cache/go-build/testexpire.txt: no such file or directory

[ianlancetaylor]

Yes, I can recreate this if I rename the entire cache directory as the first comment suggests.

[jespino]

I can work on this.

I would like to confirm something. Is it, no fail and no warning, the expected behavior? Is it a correct assumption that is there is no testexpire.txt file, the test cache is already clean? Do we care about somebody accidentally removing the .cache/go-build/testexpire.txt file, but not the rest of the testcache files?

[bcmills]

@jespino, I think the error comes from here:

go/src/cmd/go/internal/clean/clean.go

Line 164 in 6145a80

f, err := lockedfile.Edit(filepath.Join(dir, "testexpire.txt"))

lockedfile.Edit creates the file if it does not already exist, so presumably the problem is that the parent directory of the file does not yet exist. If the cache directory does not exist at all, then it is necessarily already clean.

(Actually, that makes the fix pretty trivial — simpler to mail a fix than to explain it here.)

[gopherbot]

Change https://golang.org/cl/212099 mentions this issue: cmd/go/internal/clean: make 'go clean -testcache' a no-op if the cache directory is gone