cmd/link: cgo fails to link on macos 13 beta (arm64)

[ptxmac]

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

$ go version
go version go1.18.3 darwin/arm64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

tl;dr: 13.0 Beta (22A5266r) on Apple silicon (arm64)

go env Output

$ go env
GO111MODULE=""
GOARCH="arm64"
GOBIN=""
GOCACHE="/Users/ptx/Library/Caches/go-build"
GOENV="/Users/ptx/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/ptx/go/pkg/mod"
GONOPROXY=
GONOSUMDB=
GOOS="darwin"
GOPATH="/Users/ptx/go"
GOPRIVATE=
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_arm64"
GOVCS=""
GOVERSION="go1.18.3"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/dev/null"
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 -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/xf/5whnbpls5d31z5dyrpdf_zh80000gn/T/go-build3396597166=/tmp/go-build -gno-record-gcc-switches -fno-common"
GOROOT/bin/go version: go version go1.18.3 darwin/arm64
GOROOT/bin/go tool compile -V: compile version go1.18.3
uname -v: Darwin Kernel Version 22.0.0: Tue May 24 20:30:32 PDT 2022; root:xnu-8792.0.50.111.3~5/RELEASE_ARM64_T8103
ProductName:	macOS
ProductVersion:	13.0
BuildVersion:	22A5266r
lldb --version: lldb-1400.0.17.202
Apple Swift version 5.7 (swiftlang-5.7.0.113.202 clang-1400.0.16.2)

What did you do?

Attempt to compile the following program:

package main

// #include <stdio.h>
import "C"

func main() {
	C.putchar('a')
}

What did you expect to see?

This should Just-Work™ and create a valid arm64 binary

What did you see instead?

A long list of linker warnings followed by an error:

$ go build -v main.go
# command-line-arguments
/usr/local/go/pkg/tool/darwin_arm64/link: running clang failed: exit status 1
ld: warning: pointer not aligned at address 0x100090467 ('_type.*' + 1127 from /var/folders/xf/5whnbpls5d31z5dyrpdf_zh80000gn/T/go-link-1884331981/go.o)
  ...snip around 2000 lines of minor variations of this warning
ld: warning: pointer not aligned at address 0x10009CA17 ('_type.*' + 51735 from /var/folders/xf/5whnbpls5d31z5dyrpdf_zh80000gn/T/go-link-1884331981/go.o)
ld: unaligned pointer(s) for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

[cherrymui]

Thanks for reporting. I'll see if I can get macOS 13 beta on my machine and try this.

Please note that this is the beta version of the OS and things may change before the final release. Thanks.

[ptxmac]

Fully aware of the pain of using beta software 😄

Happy to test nightly builds of go if there's any commits that might solve this problem

[cherrymui]

I couldn't find how to install macOS 13 beta despite that I have enrolled the Apple Beta Program. However, I'm able to reproduce the issue by using Xcode 14 beta on macOS 12.5 beta. I see two issues here:

• According to the man page (even the one from Xcode 14 beta), the unaligned pointer check should be default to "suppress" (as we pass -arch arm64), but it is not. Even explicitly passing -unaligned_pointers suppress still couldn't suppress it. It looks to me this is broken in the system linker (ld64-816).

• The address of the symbol _type.* is indeed weird. I see

0000000000070000 s _runtime.types
0000000000070001 s _type.*

for the go.o object file. It doesn't really affect program execution. But I think it is a good idea to just align that address.

I send a CL for the second part. With that the cgo program builds and runs fine.

[gopherbot]

Change https://go.dev/cl/411912 mentions this issue: cmd/link: set alignment for carrier symbols

[ptxmac]

I'm able to reproduce the issue by using Xcode 14 beta on macOS 12.5 beta

Oh that's good news - then I should be able to use another version of xcode.

[cherrymui]

@ptxmac could you try if Go tip (which now includes the CL) works on the new OS with the new Xcode? Thanks!

[ptxmac]

Just tested with

$ gotip version
go version devel go1.19-ecc268a Thu Jun 16 01:03:59 2022 +0000 darwin/arm64

Just perfect! - Thanks!

[gopherbot]

Change https://go.dev/cl/412734 mentions this issue: cmd/link: consider alignment in carrier symbol size calculation

[nikk-gr]

It looks like beta 3 update solved this issue