Linker error when linking libwebrtc.a against C++ code on Linux OS after building with build.md instructions

[e-p-foley]

https://github.com/webrtc-sdk/webrtc-build/blame/3f144c5c0e145ea8e714cec6955abbff68c3caf1/docs/build.md#L222

Issue Observed:

Linker error when linking libwebrtc.a against C++ code on Linux OS after building with build.md instructions:

gn gen out/Linux-x64 --args="target_os="linux" target_cpu="x64" is_debug=false rtc_include_tests=false rtc_use_h264=false is_component_build=false use_rtti=true use_custom_libcxx=false rtc_enable_protobuf=false"

Error:

/usr/bin/ld: unknown architecture of input file webrtc-checkout/src/out/Linux-x64/obj/libwebrtc.a(peer_connection_interface.o)' is incompatible with i386:x86-64 output
/usr/bin/ld: unknown architecture of input file webrtc-checkout/src/out/Linux-x64/obj/libwebrtc.a(rtc_certificate.o)' is incompatible with i386:x86-64 output

Steps to reproduce:

1. mkdir webrtc-checkout

2. cd webrtc-checkout

3. fetch --nohooks webrtc

4. gclient sync

5. cd src

6. gn gen out/Linux-x64 --args="target_os="linux" target_cpu="x64" is_debug=false rtc_include_tests=false rtc_use_h264=false is_component_build=false use_rtti=true use_custom_libcxx=false rtc_enable_protobuf=false"

7. ninja -C out/Linux-x64

8. g++ -o test test.cpp peer_connection.o // test.cpp print "hello world"

Environment Configuration :

lscpu

Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Address sizes: 48 bits physical, 48 bits virtual
Byte Order: Little Endian
CPU(s): 32
On-line CPU(s) list: 0-31
Vendor ID: AuthenticAMD
Model name: AMD Ryzen 9 7950X 16-Core Processor
CPU family: 25
Model: 97
Thread(s) per core: 2
Core(s) per socket: 16
Socket(s): 1
Stepping: 2
BogoMIPS: 8999.77

Base machine Windows 11 pro, but running everything in WSL with OS:

Ubuntu 24.04.1 LTS

gcc -v

Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-linux-gnu/13/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 13.3.0-6ubuntu2~24.04' --with-bugurl=file:///usr/share/doc/gcc-13/README.Bugs --enable-

ld --verbose

GNU ld (GNU Binutils for Ubuntu) 2.42
Supported emulations:
elf_x86_64
elf32_x86_64
elf_i386
elf_iamcu
i386pep
i386pe
using internal linker script:
OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64",
"elf64-x86-64")
OUTPUT_ARCH(i386:x86-64)

When inspecting generated *.o files they do look compatible with an x86_64 arch:

ar -t obj/libwebrtc.a
ar -x obj/libwebrtc.a
*file .o

I see format:

ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), not stripped