include extra context in compiler and linker errors

[mvdan]

For example, from a recent bug report:

zdzCF.B: relocation target type.path/to/package/types.ZU31i not defined
zdzCF.F: relocation target type.path/to/package/types.ZHdpV not defined
zHIRS.ZCZ_Z.func1: relocation target type.path/to/package/types.ZHdpV not defined
z3hTq.C.func1.2: relocation target type.path/to/package/types.Z8uvN not defined
z3hTq.C.func1.2: relocation target type.path/to/package/types.ZU31i not defined
z3hTq.B.func1.2: relocation target type.path/to/package/types.Z8uvN not defined
z3hTq.B.func1.2: relocation target type.path/to/package/types.ZU31i not defined
exit status 2
exit status 2

If I was debugging this failure manually, I'd have to do a bunch of debugging to figure out what original bit of code the obfuscated names like ZU31i actually refer to.

This is unnecessary, and the errors are unnecessarily hostile to the average user. We should, at least, provide context as to what was the original name of each of these.

We could probably reuse the work from #5 here. We would print the usual build error, and then print its un-garbled version too if any garbled identifiers were found.

[mvdan]

Reversing is already good enough to do this. For example, for #315:

$ wgo1 garble build
# github.com/fatedier/frp/client/proxy
E5ewj7pj.go:27: pxy.swzbE4SL.Plugin undefined (type *HliYu5gW.TCPProxyConf has no field or method Plugin)
ck6BOo76.go:1: pxy.swzbE4SL.Plugin undefined (type *HliYu5gW.TCPProxyConf has no field or method Plugin)
ck6BOo76.go:1: pxy.swzbE4SL.PluginParams undefined (type *HliYu5gW.TCPProxyConf has no field or method PluginParams)
M8vRqyjN.go:13: pxy.swzbE4SL.Plugin undefined (type *HliYu5gW.TCPMuxProxyConf has no field or method Plugin)
TQQwyS7C.go:1: pxy.swzbE4SL.Plugin undefined (type *HliYu5gW.TCPMuxProxyConf has no field or method Plugin)
TQQwyS7C.go:1: pxy.swzbE4SL.PluginParams undefined (type *HliYu5gW.TCPMuxProxyConf has no field or method PluginParams)
BXLs4XhX.go:13: pxy.swzbE4SL.Plugin undefined (type *HliYu5gW.HTTPProxyConf has no field or method Plugin)
FJYiROJ6.go:1: pxy.swzbE4SL.Plugin undefined (type *HliYu5gW.HTTPProxyConf has no field or method Plugin)
FJYiROJ6.go:1: pxy.swzbE4SL.PluginParams undefined (type *HliYu5gW.HTTPProxyConf has no field or method PluginParams)
LfBuznMY.go:13: pxy.swzbE4SL.Plugin undefined (type *HliYu5gW.HTTPSProxyConf has no field or method Plugin)
LfBuznMY.go:13: too many errors
exit status 2
exit status 2
$ wgo1 garble build |& wgo1 garble reverse
# github.com/fatedier/frp/client/proxy
E5ewj7pj.go:27: pxy.swzbE4SL.Plugin undefined (type *github.com/fatedier/frp/pkg/config.TCPProxyConf has no field or method Plugin)
github.com/fatedier/frp/client/proxy/proxy.go:136: pxy.swzbE4SL.Plugin undefined (type *github.com/fatedier/frp/pkg/config.TCPProxyConf has no field or method Plugin)
github.com/fatedier/frp/client/proxy/proxy.go:136: pxy.swzbE4SL.PluginParams undefined (type *github.com/fatedier/frp/pkg/config.TCPProxyConf has no field or method PluginParams)
github.com/fatedier/frp/client/proxy/proxy.go:1523: pxy.swzbE4SL.Plugin undefined (type *github.com/fatedier/frp/pkg/config.TCPMuxProxyConf has no field or method Plugin)
github.com/fatedier/frp/client/proxy/proxy.go:165: pxy.swzbE4SL.Plugin undefined (type *github.com/fatedier/frp/pkg/config.TCPMuxProxyConf has no field or method Plugin)
github.com/fatedier/frp/client/proxy/proxy.go:165: pxy.swzbE4SL.PluginParams undefined (type *github.com/fatedier/frp/pkg/config.TCPMuxProxyConf has no field or method PluginParams)
github.com/fatedier/frp/client/proxy/proxy.go:1813: pxy.swzbE4SL.Plugin undefined (type *github.com/fatedier/frp/pkg/config.HTTPProxyConf has no field or method Plugin)
github.com/fatedier/frp/client/proxy/proxy.go:194: pxy.swzbE4SL.Plugin undefined (type *github.com/fatedier/frp/pkg/config.HTTPProxyConf has no field or method Plugin)
github.com/fatedier/frp/client/proxy/proxy.go:194: pxy.swzbE4SL.PluginParams undefined (type *github.com/fatedier/frp/pkg/config.HTTPProxyConf has no field or method PluginParams)
github.com/fatedier/frp/client/proxy/proxy.go:2103: pxy.swzbE4SL.Plugin undefined (type *github.com/fatedier/frp/pkg/config.HTTPSProxyConf has no field or method Plugin)
github.com/fatedier/frp/client/proxy/proxy.go:2103: too many errors
exit status 2
exit status 2

Edit: looks like just the field names aren't reversed, but still, the rest is helpful.

[capnspacehook]

Fields names are reversed as of 0150aa8 right?

[capnspacehook]

Also, is there any reason we wouldn't want to automatically reverse the error message(s) instead of making the user reverse the error messages themselves?

[mvdan]

Fields names are reversed as of 0150aa8 right?

Yep, I fixed that shortly after posting the comment.

Also, is there any reason we wouldn't want to automatically reverse the error message(s) instead of making the user reverse the error messages themselves?

That's what this issue is about :) My last comment just says that reverse is now good enough that hooking it up to build errors is now possible. Before, we were blocked because reverse wasn't good enough.

[mvdan]

Dropping this from the milestone because it doesn't seem urgent.