testing: "B.Loop called with timer stopped" regression in 1.24.2

[jakebailey]

Go version

go version go1.24.2 linux/amd64

Output of go env in your module/workspace:

AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='gccgo'
GO111MODULE=''
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/home/jabaile/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/home/jabaile/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build515752239=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/home/jabaile/work/TypeScript-go/go.mod'
GOMODCACHE='/home/jabaile/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/jabaile/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/jabaile/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.24.2'
GOWORK=''
PKG_CONFIG='pkg-config'

What did you do?

$ git clone --depth=1 https://github.com/microsoft/typescript-go.git
$ cd typescript-go
$ go test -run=- -bench=BenchmarkGetNormalizedAbsolutePath -benchtime=1x ./internal/tspath

What did you see happen?

$ go1.24.2 test -run=- -bench=BenchmarkGetNormalizedAbsolutePath -benchtime=1x ./internal/tspath
--- FAIL: BenchmarkGetNormalizedAbsolutePath/non-normalized_inputs/GetNormalizedAbsolutePath
    benchmark.go:417: B.Loop called with timer stopped
--- FAIL: BenchmarkGetNormalizedAbsolutePath/non-normalized_inputs/GetNormalizedAbsolutePath_(old)
    benchmark.go:417: B.Loop called with timer stopped
--- FAIL: BenchmarkGetNormalizedAbsolutePath/non-normalized_inputs
--- FAIL: BenchmarkGetNormalizedAbsolutePath/normalized_inputs/GetNormalizedAbsolutePath
    benchmark.go:417: B.Loop called with timer stopped
--- FAIL: BenchmarkGetNormalizedAbsolutePath/normalized_inputs/GetNormalizedAbsolutePath_(old)
    benchmark.go:417: B.Loop called with timer stopped
--- FAIL: BenchmarkGetNormalizedAbsolutePath/normalized_inputs
--- FAIL: BenchmarkGetNormalizedAbsolutePath/normalized_inputs_(long)/GetNormalizedAbsolutePath
    benchmark.go:417: B.Loop called with timer stopped
--- FAIL: BenchmarkGetNormalizedAbsolutePath/normalized_inputs_(long)/GetNormalizedAbsolutePath_(old)
    benchmark.go:417: B.Loop called with timer stopped
--- FAIL: BenchmarkGetNormalizedAbsolutePath/normalized_inputs_(long)
--- FAIL: BenchmarkGetNormalizedAbsolutePath
FAIL
exit status 1
FAIL    github.com/microsoft/typescript-go/internal/tspath      0.009s
FAIL

What did you expect to see?

$ go1.24.1 test -run=- -bench=BenchmarkGetNormalizedAbsolutePath -benchtime=1x ./internal/tspath
goos: linux
goarch: amd64
pkg: github.com/microsoft/typescript-go/internal/tspath
cpu: Intel(R) Core(TM) i9-10900K CPU @ 3.70GHz
BenchmarkGetNormalizedAbsolutePath/non-normalized_inputs/GetNormalizedAbsolutePath-20                  1              1461 ns/op               0 B/op          0 allocs/op
BenchmarkGetNormalizedAbsolutePath/non-normalized_inputs/GetNormalizedAbsolutePath_(old)-20            1             11891 ns/op              96 B/op          5 allocs/op
BenchmarkGetNormalizedAbsolutePath/normalized_inputs/GetNormalizedAbsolutePath-20                      1              1252 ns/op               0 B/op          0 allocs/op
BenchmarkGetNormalizedAbsolutePath/normalized_inputs/GetNormalizedAbsolutePath_(old)-20                1             10325 ns/op             240 B/op          9 allocs/op
BenchmarkGetNormalizedAbsolutePath/normalized_inputs_(long)/GetNormalizedAbsolutePath-20               1              1147 ns/op               0 B/op          0 allocs/op
BenchmarkGetNormalizedAbsolutePath/normalized_inputs_(long)/GetNormalizedAbsolutePath_(old)-20                 1             12934 ns/op            2080 B/op         12 allocs/op
PASS
ok      github.com/microsoft/typescript-go/internal/tspath      0.010s

The -benchtime=1x doesn't affect anything; removing it shows the same problem (just slower).

[jakebailey]

No, this is our fault. We're calling b.Loop in a loop itself, which shouldn't work.

I'll fix this, but I guess this isn't a regression per se. Sorry!