testing: T.Setenv can be called after T.Parallel

[noi]

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

$ go version
go version go1.19.1 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="$HOME/.cache/go-build"
GOENV="$HOME/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="$HOME/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="$HOME/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.19.1"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="$HOME/dev/go.mod"
GOWORK=""
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 -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1463438795=/tmp/go-build -gno-record-gcc-switches"

What did you do?

T.Setenv will panic if it be called after T.Parallel but it can be called in T.Run.

Sample code:
https://go.dev/play/p/54VhJKYpb_q

What did you expect to see?

I think it should panic even in T.Run.

What did you see instead?

Those tests become flaky without panic.

Others

I'm trying to fix this issue now.

[ianlancetaylor]

I'm not sure what is wrong with calling t.Setenv in a function passed to t.Run. It would be wrong if the function calls t.Parallel, but if it doesn't, it should work reliably. It may not do what you want, but it shouldn't be flaky. Do I misunderstand?

[ZekeLu]

I think noi@ means that a sub test is flaky when it calls t.Setenv while its parent has called t.Parallel. This looks plausible.

[ianlancetaylor]

Ah, yes, I see. We need to walk the parent list or something.

[noi]

Thank you for your replying!
I'm sorry for confusing you by my bad English. ZekeLu is right, I wanted to say like that.

I'm trying to fix this issue by passing isAncestorParalell to sub test in t.Run.

[gopherbot]

Change https://go.dev/cl/431101 mentions this issue: testing: fix T.Setenv for not calling to it in parallel tests

[noi]

I sent my changes, so I would appreciate it if you could review it when you have time🙇‍♂️

[gopherbot]

Change https://go.dev/cl/434115 mentions this issue: testing: update description of Setenv