Golang debug/macho: Mach-O format's truncation of DWARF section names longer than 16 chars makes some sections unrecognizable to debug/dwarf

Go version

This affects Go 1.23.x only. The test passes on Go 1.24.x and at tip.

Output of `go env` in your module/workspace:

GOOS='darwin'
GOARCH='arm64'

What did you do?

Looked at the failing builds on the build dashboard, e.g., https://ci.chromium.org/b/8713515151815260705, and tried to run the the test locally on darwin/arm64. It reproduced the failure.

Note that the darwin-arm64-longtest builder where this reproduces was added recently in #73488. The same test passes on darwin-amd64-longtest builders (e.g., https://ci.chromium.org/ui/p/golang/builders/ci/go1.23-darwin-amd64-longtest/b8713515151301513937/test-results?q=cmd%2Fgo.TestScript%2Fbuild_trimpath_cgo).

What did you see happen?

Test fails with:

script_test.go:159: FAIL: testdata/script/build_trimpath_cgo.txt:13: go run ./list-dwarf hello.exe: exit status 1

Full log:

# Go 1.25-ish
$ GOTOOLCHAIN=local go test -v -count=1 -run='^TestScript$/^build_trimpath_cgo$' cmd/go
[...]
--- PASS: TestScript (0.04s)
    --- PASS: TestScript/build_trimpath_cgo (7.40s)
PASS
ok      cmd/go  4.394s

$ GOTOOLCHAIN=go1.24.3 go test -v -count=1 -run='^TestScript$/^build_trimpath_cgo$' cmd/go
[...]
PASS
ok      cmd/go  4.572s

$ GOTOOLCHAIN=go1.23.9 go test -v -count=1 -run='^TestScript$/^build_trimpath_cgo$' cmd/go
=== RUN   TestScript
vcs-test.golang.org rerouted to http://127.0.0.1:63038
https://vcs-test.golang.org rerouted to https://127.0.0.1:63039
go test proxy running at GOPROXY=http://127.0.0.1:63040/mod
=== RUN   TestScript/build_trimpath_cgo
=== PAUSE TestScript/build_trimpath_cgo
=== CONT  TestScript/build_trimpath_cgo
    script_test.go:135: 2025-05-29T23:06:13Z
    script_test.go:137: $WORK=/var/folders/s_/5sjqzr0j6xggz_xtzmq_8r4m00jwcj/T/cmd-go-test-3448253444/tmpdir137029120/build_trimpath_cgo3434210657
    script_test.go:159: 
        PATH=/var/folders/s_/5sjqzr0j6xggz_xtzmq_8r4m00jwcj/T/cmd-go-test-3448253444/tmpdir137029120/testbin:/Users/gopher/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.23.9.darwin-arm64/bin:[...]:/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin:[...]:/Library/Apple/usr/bin:/usr/local/go/bin:/Users/gopher/go/bin:/Users/gopher/bin
        HOME=/no-home
        CCACHE_DISABLE=1
        GOARCH=arm64
        TESTGO_GOHOSTARCH=arm64
        GOCACHE=/Users/gopher/Library/Caches/go-build
        GOCOVERDIR=
        GODEBUG=
        GOEXE=
        GOEXPERIMENT=
        GOOS=darwin
        TESTGO_GOHOSTOS=darwin
        GOPROXY=http://127.0.0.1:63040/mod
        GOPRIVATE=
        GOROOT=/Users/gopher/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.23.9.darwin-arm64
        GOTRACEBACK=system
        TESTGO_GOROOT=/Users/gopher/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.23.9.darwin-arm64
        TESTGO_EXE=/var/folders/s_/5sjqzr0j6xggz_xtzmq_8r4m00jwcj/T/cmd-go-test-3448253444/tmpdir137029120/testbin/go
        TESTGO_VCSTEST_HOST=127.0.0.1:63038
        TESTGO_VCSTEST_TLS_HOST=127.0.0.1:63039
        TESTGO_VCSTEST_CERT=/var/folders/s_/5sjqzr0j6xggz_xtzmq_8r4m00jwcj/T/cmd-go-test-3448253444/vcstest199468596/cert.pem
        TESTGONETWORK=panic
        GOSUMDB=localhost.localdev/sumdb+00000c67+AcTrnkbUA+TU4heY3hkjiSES/DSQniBqIeQ/YppAUtK6
        GONOPROXY=
        GONOSUMDB=
        GOVCS=*:all
        devnull=/dev/null
        goversion=1.23.9
        CMDGO_TEST_RUN_MAIN=true
        HGRCPATH=
        GOTOOLCHAIN=auto
        newline=

        WORK=/var/folders/s_/5sjqzr0j6xggz_xtzmq_8r4m00jwcj/T/cmd-go-test-3448253444/tmpdir137029120/build_trimpath_cgo3434210657
        TEST_TELEMETRY_DIR=/var/folders/s_/5sjqzr0j6xggz_xtzmq_8r4m00jwcj/T/cmd-go-test-3448253444/tmpdir137029120/build_trimpath_cgo3434210657/telemetry
        TMPDIR=/var/folders/s_/5sjqzr0j6xggz_xtzmq_8r4m00jwcj/T/cmd-go-test-3448253444/tmpdir137029120/build_trimpath_cgo3434210657/tmp
        GOPATH=/var/folders/s_/5sjqzr0j6xggz_xtzmq_8r4m00jwcj/T/cmd-go-test-3448253444/tmpdir137029120/build_trimpath_cgo3434210657/gopath
        PWD=/var/folders/s_/5sjqzr0j6xggz_xtzmq_8r4m00jwcj/T/cmd-go-test-3448253444/tmpdir137029120/build_trimpath_cgo3434210657/gopath/src

        # This test builds a cgo binary and verifies the source directory path
        # does not appear in the binary, either literally or in compressed DWARF.
        # TODO(golang.org/issue/36072): ideally we should build a binary from identical
        # sources in different directories and verify the binary and all intermediate
        # files are identical. (0.000s)
        > [short] skip
        [condition not met]
        > [!cgo] skip
        [condition not met]
        # Check that the source path appears when -trimpath is not used. (1.242s)
        > go build -o hello.exe .
        > grep -q gopath[/\\]src hello.exe
        > go run ./list-dwarf hello.exe
        [stderr]
        2025/05/29 19:06:14 decoding dwarf section info at offset 0x5f2af: DW_FORM_strx with no .debug_str_offsets section
        exit status 1
    script_test.go:159: FAIL: testdata/script/build_trimpath_cgo.txt:13: go run ./list-dwarf hello.exe: exit status 1
--- FAIL: TestScript (0.04s)
    --- FAIL: TestScript/build_trimpath_cgo (1.25s)
FAIL
FAIL    cmd/go  1.795s
FAIL

What did you expect to see?

Passing test on Go 1.23 release branch, or skipped test if the failure is understood and it's better to skip.

The same test was also failing for @matloob in #70669 and was fixed in Go 1.24, but this appears to be a different issue in the same test.

CC @golang/command-line, @thanm. (Also FYI @mknyszek.)

Comment From: gabyhelp

Related Issues

Related Code Changes

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

Comment From: cherrymui

DW_FORM_strx with no .debug_str_offsets section

May be related to https://github.com/go-delve/delve/issues/3797 . Perhaps we want to backport CL 608995 .

On the other hand, Go 1.23 is going to be out of support soon, once Go 1.25 is released. Maybe don't bother.

Comment From: dmitshur

Thanks @cherrymui, that was it. I can confirm that release-branch.go1.23 with CL 608995 applied fixes the "DW_FORM_strx with no .debug_str_offsets section" error, though the test doesn't pass right away because it begins to run into #70669. Applying CL 633038 on top fixes the "invalid memory address or nil pointer dereference" panic, and with the two CLs the TestScript/build_trimpath_cgo test begins to pass. all.bash passes locally too.

I'll close this issue since it doesn't need more investigation: we know that the problem is that Go 1.23 doesn't have fixes for https://github.com/go-delve/delve/issues/3797 and for #70669, they're available in Go 1.24 and newer. This wasn't uncovered earlier because it only reproduces on darwin/arm64 without -short flag, and we didn't have a darwin-arm64-longtest builder when Go 1.23 was being developed.

@gopherbot Please create a backport issue for Go 1.23. We either need to fix debug/macho's DWARF handling of section names longer than 16 chars, or otherwise add a skip for this test since it can't work without that fix. The fix probably doesn't meet the bar to be backported, so we can skip the test.

Comment From: gopherbot

Backport issue(s) opened: #74721 (for 1.23).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.