v1.26.2: panic in parseFileEntries5 (slice bounds out of range) when loading Go 1.26.x binaries on darwin/arm64, regression since v1.26.1

[andersonjohnf]

Version of Delve

• v1.26.2 (tagged) — broken
• master @ v1.26.3-0.20260421122345-0c15a4835a4b — still broken, same panic
• v1.26.1 — works

All three built with go1.26.2.

Platform

• macOS (darwin) on arm64 (Apple Silicon, M-series)
• Go 1.26.2

What happened

Launching a Go 1.26.2 binary under dlv dap (via the VS Code Go extension) causes Delve to panic in its DWARF 5 line-parser during binary-info load. In v1.26.2, the panic crashes the DAP session so the debugger fails to attach at all. In master, the panic is still present but the target process continues to launch because the panic happens in a worker goroutine that is no longer fatal to the parent load — however, debug info for the affected compilation unit is incomplete, so breakpoints and stepping silently misbehave in parts of the program.

Downgrading to v1.26.1 (built against the same Go 1.26.2 toolchain) restores full functionality, so the regression was introduced between v1.26.1 and v1.26.2.

Expected

dlv dap loads the binary info cleanly and the DAP session attaches, as it did under v1.26.1.

Actual — panic trace (v1.26.2, trimmed to the relevant frames)

Building ./main.go
panic: runtime error: slice bounds out of range [14:0]

goroutine 71 gp=0x4f87c72650e0 m=15 mp=0x4f87c7c00808 [running]:
panic({0x1037f68a0?, 0x4f87cb6eb980?})
    .../runtime/panic.go:879 +0x15c
runtime.panicBounds64(...)
runtime.panicBounds()
github.com/go-delve/delve/pkg/dwarf/line.parseFileEntries5(0x4f87c9961760, 0x4f87cac35320)
    .../delve@v1.26.2/pkg/dwarf/line/line_parser.go:315 +0x4d0
github.com/go-delve/delve/pkg/dwarf/line.Parse({0x4f87cd09fc20, 0xd}, 0x4f87cac35320, {0x0, 0x0, 0x0}, 0x0, 0x610000, 0x0, 0x8)
    .../delve@v1.26.2/pkg/dwarf/line/line_parser.go:104 +0x228
github.com/go-delve/delve/pkg/proc.(*BinaryInfo).loadDebugInfoMaps(...)
    .../delve@v1.26.2/pkg/proc/bininfo.go:2650 +0x7bc
github.com/go-delve/delve/pkg/proc.loadBinaryInfoMacho.gowrap2()
    .../delve@v1.26.2/pkg/proc/bininfo.go:2155 +0x30
runtime.goexit({})
created by github.com/go-delve/delve/pkg/proc.loadBinaryInfoMacho in goroutine 22
    .../delve@v1.26.2/pkg/proc/bininfo.go:2155 +0x55c

The panic fires in parseFileEntries5 at the slice operation on line 315 — a 14-byte read against a 0-length remainder of the DWARF section, suggesting the parser has advanced past the actual end of a file_name entry group while reading the DWARF 5 line-table header.

Steps to reproduce

1. On darwin/arm64 with Go 1.26.2, install Delve v1.26.2: go install github.com/go-delve/delve/cmd/dlv@v1.26.2.
2. Build any non-trivial Go 1.26.2 program (I hit it on a ~50-dep Go module using gin, firestore, pgx, livekit/protocol, and other common deps; happy to test a minimal repro if helpful).
3. Launch under dlv dap (e.g. via the VS Code Go extension's default Go debug config) against ./cmd/<binary>.
4. Panic fires before the DAP session attaches.

Downgrading to v1.26.1 with no other changes (go install github.com/go-delve/delve/cmd/dlv@v1.26.1) makes the problem go away.

[aarzilli]

A reproducer would be useful. Especially a built executable.

[Codelax]

Hello, got the same error. I was able to reproduce using https://github.com/scaleway/scaleway-cli.

• go build ./cmd/scw
• dlv exec ./scw

 ± dlv exec ./scw
panic: runtime error: slice bounds out of range [97:0]

As mentioned in the issue, downgrading with go install github.com/go-delve/delve/cmd/dlv@v1.26.1 works

Built binary does not fit in github (32M zipped), I uploaded here it if that suits you (30 days availability): https://transfert.free.fr/DaE2F8I
I was not able to reproduce with a more lite project.

[Kentzo]

FWIW I'm getting when using dlv dap too. Confirm that downgrading to dlv@1.26.1 does help.

[adicostil]

I got the same go 1.25.9, dlv 1.26.2 panic: runtime error: slice bounds out of range [55:0]

switched to prior version go install github.com/go-delve/delve/cmd/dlv@v1.26.1 and no error

[thedadams]

I am actively developing https://github.com/obot-platform/obot.

Steps to reproduce:

1. Clone that repo locally.
2. From the root of the directory, run go build -o bin/obot .
3. Now run dlv exec ./bin/obot and you will see the panic.

One interesting note: if you build with go build -ldflags="-s -w " -o bin/obot . then you will not see the panic with dlv exec ./bin/obot.

As others have stated, v1.26.1 doesn't have the same issue.

I am using a M1 Max MacBook Pro and Go 1.26.2.

EDIT: a colleague of mine pointed out that my interesting note may actually not be interesting at all.

[komapa]

The only thing that worked for me was CGO_ENABLED="0" and build the executable. Then dlv does not error as reported.

[aarzilli]

People here should try #4315.

[thedadams]

That change fixes the issue for me.