zig cc passes `--gc-sections` to the underlying linker, which then
causes undefined symbol errors when compiling with cgo but without C
code. Add `-Wl,--no-gc-sections` to make it work with zig cc. Minimal
example:
**main.go**
package main
import _ "runtime/cgo"
func main() {}
Run (works after the patch, doesn't work before):
CC="zig cc" go build main.go
Among the existing code, `src/runtime/testdata/testprognet` fails to
build:
src/runtime/testdata/testprognet$ CC="zig cc" go build .
net(.text): relocation target __errno_location not defined
net(.text): relocation target getaddrinfo not defined
net(.text): relocation target freeaddrinfo not defined
net(.text): relocation target gai_strerror not defined
runtime/cgo(.text): relocation target stderr not defined
runtime/cgo(.text): relocation target fwrite not defined
runtime/cgo(.text): relocation target vfprintf not defined
runtime/cgo(.text): relocation target fputc not defined
runtime/cgo(.text): relocation target abort not defined
runtime/cgo(.text): relocation target pthread_create not defined
runtime/cgo(.text): relocation target nanosleep not defined
runtime/cgo(.text): relocation target pthread_detach not defined
runtime/cgo(.text): relocation target stderr not defined
runtime/cgo(.text): relocation target strerror not defined
runtime/cgo(.text): relocation target fprintf not defined
runtime/cgo(.text): relocation target abort not defined
runtime/cgo(.text): relocation target pthread_mutex_lock not defined
runtime/cgo(.text): relocation target pthread_cond_wait not defined
runtime/cgo(.text): relocation target pthread_mutex_unlock not defined
runtime/cgo(.text): relocation target pthread_cond_broadcast not defined
runtime/cgo(.text): relocation target malloc not defined
With the patch both examples build as expected.
@ianlancetaylor suggested:
> It would be fine with me if somebody wants to send a cgo patch that
passes -Wl,--no-gc-sections, with a fallback if that option is not
supported.
... and this is what we are doing. Tested with zig
0.10.0-dev.2252+a4369918b
This is a continuation of CL 405414: the original one broke AIX and iOS
builds. To fix that, added `unknown option` to the list of strings
under lookup.
Fixes golang#52690