surprising behavior with -instrument and godep

[jeremyschlatter]

I am debugging a program that has a dependency on package foo, and I want to step into function calls in foo. So I run:

$ godebug run -instrument=foo myProg.go

godebug runs without complaint. Yet, to my surprise, I still can't step into foo. Why? Because I had forgotten that I was using godep. I would have been fine if I had instead run:

$ godebug run -instrument=my/package/name/Godeps/_workspace/src/foo

It would be nice if godebug caught this for me. At a minimum, it could have noticed that I didn't import package foo anywhere, and warned me that it was useless to pass that package in the instrument flag.

Alternatively, maybe we should get rid of the -instrument flag entirely. Having it sacrifices some usability for performance, but I don't understand the tradeoff very well. How much performance would we lose by instrumenting everything? Can we make that better? How often does the flag cause surprising behavior?

[jsgv]

same issue. having to declare package path:

$ godebug run -instrument=github.com/jesusjjf/myproject/package1,github.com/jesusjjf/myproject/package2 myproject.go

+1 on godebug being able to detect automatically

Awesome tool!!

[benfleis]

+1 on the awesomeness of the tool +1 on some way to handle this