Additional build-time variable overrides in cros-go.eclass

[Clayton Whitelaw]

It looks like the cros-go eclass is hard-coded to substitute only `main.Version` when a special variable is present. I would like to set more than just this one value.

I can see a few possibilities, in order of less constraints:

• An associative array named something like CROS_GO_VARIABLES or something like that that maps `pkg.var => value`  and passes each into ldflags as an argument to -X.
• An array named CROS_GO_LDFLAGS that lets you pass in whatever ldflags you want.
• "ldflags=${CROS_GO_LDFLAGS[@]}"
• An array named CROS_GO_BUILD_OPTS that lets you pass anything into the cros_go build step
• cros_go build -v ... "${CROS_GO_BUILD_OPTS[@]}" ...

Any preferences, or other eclasses that serve as an example to follow?

[Clayton Whitelaw]

I asked +Jack Rosenthal in person and he pointed me to flag-o-matic. Seems like it's targeted at C/C++ toolchains, but it would support this use case.

It also sounds like in any case it's okay to add something more simple/general like in the second and third options I mentioned previously.

[Clayton Whitelaw]

Looks like the ldflags are different between Go and C/C++ judging by the usage of "-X", so flag-o-matic is probably not a match and I'll probably go with adding CROS_GO_LDFLAGS.