x/mobile: Undefined symbols _res_9_nclose with Go 1.20

[xDragonZ]

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

$ go version
go version go1.20 darwin/arm64

Does this issue reproduce with the latest release?

Using MacOS with Go 1.20 error, no issue in 1.19.5

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

go env Output

$ go env
GO111MODULE=""
GOARCH="arm64"
GOBIN=""
GOCACHE="/Users/name/Library/Caches/go-build"
GOENV="/Users/name/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/name/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/name/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="go1.20"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
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 -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/hr/1lxcf_8s41dfqq139phd6twm0000gn/T/go-build1419606280=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

After compiling using gomobile bind -v -ldflags='-s -w' -target=ios -o libtest.xcframework github.com/example/test in terminal and import the libtest.xcframework library to xcode, it will show error in xcode when trying to compile ios app

What did you expect to see?

What did you see instead?

Undefined symbols for architecture arm64:
"_res_9_nclose", referenced from:
_internal/syscall/unix.libresolv_res_9_nclose_trampoline.abi0 in Libtest(go.o)
"_res_9_ninit", referenced from:
_internal/syscall/unix.libresolv_res_9_ninit_trampoline.abi0 in Libtest(go.o)
"_res_9_nsearch", referenced from:
_internal/syscall/unix.libresolv_res_9_nsearch_trampoline.abi0 in Libtest(go.o)
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Related: #58159

[bcmills]

(attn @golang/ios)

[bcmills]

import the library to xcode

Import how? (Is there something you need to configure in xcode to set the linker flags for the final executable?)

[xDragonZ]

Import xcframework to xcode project target. No, nothing to configure in xcode

[bcmills]

@xDragonZ, try adding libresolv.9.tbd and/or libresolv.tbd in the Linked Frameworks and Libraries section.
(See https://mozilla.github.io/firefox-browser-architecture/experiments/2017-09-06-rust-on-ios.html.)

[xDragonZ]

Thank you 🫡 finally got it working.

Passing extldflags=-lresolv to gomobile doesn't works but adding libresolv.tbd able to compile the ios app without error now.

[bcmills]

Great! Want to send a CL to update the documentation?
(Probably goes in one of the files in https://cs.opensource.google/go/x/mobile/+/master:cmd/gomobile/ ..?)

[gurupras]

Could you please share how you got this working? Running into the same issue and somehow adding libresolv.tbd and libresolv.9.tbd (for me it shows under Apple SDK and not IOS SDK; not sure if that matters) does nothing.

[xDragonZ]

@gurupras you need to add it to "Frameworks & Libraries" section too