io/ioutil: TempDir should support patterns like TempFile does

[tv42]

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

$ go version
go version go1.13rc1 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="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/tv/.cache/go-build"
GOENV="/home/tv/.config/go/env"
GOEXE=""
GOFLAGS="-trimpath"
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/tv/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/tv/sdk/go1.13rc1"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/tv/sdk/go1.13rc1/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="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=/home/tv/tmp/go-build904900999=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I tried to make a temp directory with a predictable name suffix.

What did you expect to see?

A temp directory named /home/tv/.cache/foo/foo.<random string here>.ext

I expected ioutil.TempDir to follow the same new logic as TempFile now does. See
191efbc
#4896

What did you see instead?

A temp directory named /home/tv/.cache/foo/foo.*.ext<random string here>

[ianlancetaylor]

Changing the prefix argument to ioutil.TempDir into a pattern argument exactly like that of ioutil.TempFile seems like a reasonable change.

Does anybody see any problems with this?

[rsc]

Given that this is exactly what we did in #4896 for TempFile and no one raised any concerns when Ian asked two weeks ago, this seems like a likely accept.

Leaving open for a week for final comments.

[rsc]

Accepted.

[gopherbot]

Change https://golang.org/cl/198488 mentions this issue: io/ioutil: support predictable prefix+suffix for TempDir with *

[odeke-em]

Hey Russ, I just moved this issue from Backlog back to Go1.14 as I submitted a CL and it is just waiting on feedback on the example test before final review on merge.