x/tools/cmd/goimports: truncates input file despite no -w flag #28270
Description
Please answer these questions before submitting your issue. Thanks!
What version of Go are you using (go version)?
go version go1.11.1 linux/amd64
Using goimports as of https://go-review.googlesource.com/c/tools/+/142697, specifically patch set 5:
git fetch https://go.googlesource.com/tools refs/changes/97/142697/5 && git checkout FETCH_HEAD
Does this issue reproduce with the latest release?
Yes
What operating system and processor architecture are you using (go env)?
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/myitcv/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/myitcv/gostuff"
GOPROXY=""
GORACE=""
GOROOT="/home/myitcv/gos"
GOTMPDIR=""
GOTOOLDIR="/home/myitcv/gos/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
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 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build893028818=/tmp/go-build -gno-record-gcc-switches"
What did you do?
goimports was "hanging" on this input file so I switched out of my editor and ran this sequence of commands:
$ goimports main.go
(killed with Ctrl-c)
$ gofmt main.go
...
$ goimports -help
...
$ goimports -v -trace main.go
(killed with Ctrl-c)
$ goimports -v main.go
This last call ran very fast; too fast because main.go had, by this point, been truncated to zero length.
Unfortunately I can't provide a precise repo because the contents of the truncated file have been lost 😄
What did you expect to see?
The input file not to be truncated; no -w flag was provided.
What did you see instead?
Per above.
cc @ianthehat @heschik