cmd/compile: miscompilation in star-tex.org/x/cmd/star-tex #59432
Description
What version of Go are you using (go version)?
$ go version go version devel go1.21-f62c9701b4 Tue Apr 4 07:17:19 2023 +0000 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/binet/.cache/go-build" GOENV="/home/binet/.config/go/env" GOEXE="" GOEXPERIMENT="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="linux" GOINSECURE="" GOMODCACHE="/home/binet/dev/go/gocode/pkg/mod" GONOPROXY="gitlab.cern.ch/tile-in-one/tio-go,gitlab.cern.ch/tile-in-one/tio-0021/*" GONOSUMDB="gitlab.cern.ch/tile-in-one/tio-go,gitlab.cern.ch/tile-in-one/tio-0021/*" GOOS="linux" GOPATH="/home/binet/dev/go/gocode" GOPRIVATE="gitlab.cern.ch/tile-in-one/tio-go" GOPROXY="https://proxy.golang.org,direct" GOROOT="/home/binet/sdk/go" GOSUMDB="sum.golang.org" GOTMPDIR="" GOTOOLDIR="/home/binet/sdk/go/pkg/tool/linux_amd64" GOVCS="" GOVERSION="devel go1.21-f62c9701b4 Tue Apr 4 07:17:19 2023 +0000" GCCGO="gccgo" GOAMD64="v1" AR="ar" CC="gcc" CXX="g++" CGO_ENABLED="1" GOMOD="/dev/null" GOWORK="" CGO_CFLAGS="-O2 -g" CGO_CPPFLAGS="" CGO_CXXFLAGS="-O2 -g" CGO_FFLAGS="-O2 -g" CGO_LDFLAGS="-O2 -g" PKG_CONFIG="pkg-config" GOGCCFLAGS="-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build2001148705=/tmp/go-build -gno-record-gcc-switches"
What did you do?
since 1c783f7, star-tex test is failing:
$> cd star-tex.org/x/tex/cmd/star-tex
$> go test
--- FAIL: TestProcess (0.00s)
--- FAIL: TestProcess/hello.tex (0.00s)
main_test.go:43: could not process TeX document: xtex.pasError(-2)
FAIL
exit status 1
ie: it was working with Go-1.18.x, but not anymore starting with Go-1.19.x.
What did you expect to see?
a sucessfully working test.
What did you see instead?
a failing test.
bisecting Go, I've found out the first revision of go test that triggered the failing test.
star-tex is relying on web2go to automatically transpile Donald Knuth's WEB tex.web file to Go.
the result is under x/tex/internal/xtex.
it's machine generated so, not super easy on the eye:
the failure is actually coming from:
- https://git.sr.ht/~sbinet/star-tex/tree/v0.4.0/item/internal/xtex/xtex.go#L1674
which, of course, shouldn't happen by just recompiling the same piece of code but with differentgo buildversions.
looking at 1c783f7 CL, a possible hint at the root cause generating this issue might be in how some of the C-trickeries performed in tex.web are translated into Go, meaning "unsafe":
- https://git.sr.ht/~sbinet/star-tex/tree/v0.4.0/item/internal/xtex/xtex.go#L136
- https://git.sr.ht/~sbinet/star-tex/tree/v0.4.0/item/internal/xtex/xtex.go#L145
- https://git.sr.ht/~sbinet/star-tex/tree/v0.4.0/item/internal/xtex/xtex.go#L149
- https://git.sr.ht/~sbinet/star-tex/tree/v0.4.0/item/internal/xtex/xtex.go#L163
(perhaps the interplay of unsafe.Pointer and uintptr at L145 and L149 ?)