Description
What version of Go are you using (go version)?
$ go version go version go1.17 linux/amd64
Does this issue reproduce with the latest release?
Yes
What operating system and processor architecture are you using (go env)?
go env Output
$ go env GO111MODULE="" GOARCH="amd64" GOBIN="" GOCACHE="/home/xxx/.cache/go-build" GOENV="/home/xxx/.config/go/env" GOEXE="" GOEXPERIMENT="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="linux" GOINSECURE="" GOMODCACHE="/home/xxx/go/pkg/mod" GONOPROXY="" GONOSUMDB="" GOOS="linux" GOPATH="/home/xxx/go" GOPRIVATE="" GOPROXY="https://proxy.golang.org,direct" GOROOT="/usr/lib/go" GOSUMDB="sum.golang.org" GOTMPDIR="" GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64" GOVCS="" GOVERSION="go1.17" GCCGO="gccgo" AR="ar" CC="x86_64-pc-linux-gnu-gcc" CXX="x86_64-pc-linux-gnu-g++" CGO_ENABLED="1" GOMOD="/dev/null" 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-build1250957969=/tmp/go-build -gno-record-gcc-switches"
What did you do?
I used time.Format to format a time including milliseconds with layout string "15:04:05,000". Before go 1.17, the comma was not recognized as separator for milliseconds and the string ,000 was added to the format output verbatim. The result was for example 23:00:12,000. Since go 1.17, the comma is recognized as separator for milliseconds, but changed to a period in the output. The result now is for example 23:00:12.345. I expect the result respect the comma in the layout string and getting 23:00:12,345.
Having the zeros replaced with the actual milliseconds changed the behavior to previous versions but is an improvement from my perspective. But, the changed behavior regarding the comma as separator breaks existing code that relies on a comma being used, e.g., because it is parsed by some other system later on.
Example code: https://play.golang.org/p/Bq6p4dxqhgG
What did you expect to see?
23:00:12,345
(or 23:00:12,000 as in go <1.17)
What did you see instead?
23:00:12.345