cmd/cgo: warning on generated code when using -Wall

[FlorianUekermann]

using cgo with:

CC=clang
CGO_CFLAGS=-std=gnu11 -march=native -O3 -g -fPIC -Wall -pedantic -Wextra -Werror

results in the following error for me:

# runtime/cgo
gcc_libinit.c:66:38: error: unused parameter 'dummy' [-Werror,-Wunused-parameter]

This is not a major issue, but it would be nice if we didn't have to add -Wno-unused-parameter, since the warning may be desired in other C code. Looking at the code, it seems as if dummy may as well be unnamed.

[ianlancetaylor]

You can't simply leave the parameter unnamed, because this is C and C does not permit unnamed parameters. You have to mark the parameter with __attribute__((unused)). Patches welcome.

[gopherbot]

Change https://golang.org/cl/140797 mentions this issue: runtime/cgo: Annotate unused vairable with __attribute__((unused))