A cross-platform debugger for Go

Re:A cross-platform debugger for Go by lighthawk on Monday April 20, 2015 @02:37PM (#9409990)

While I totally applaud this effort, how does it not lie? It inserts code into the actual source claiming it is on a line in the original file, but it is in a different line in the compiled version. That seems like it could be a problem at some point, and despite the serious utility in this, I'm not 100% convinced it is the right tool for the job.

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Re:A cross-platform debugger for Go by jschlatter on Monday April 20, 2015 @02:59PM (#9410127)

Author here. I agree that this could cause surprises. Are there specific cases you have in mind?

Two cases I have thought of are stack traces and logging that inspects the stack. In the former case, if you get a stack trace while debugging it will not mean much because the lines do not match those of your code. In the latter case, logging statements may print the wrong things if they depend on being called a certain number of stack frames below user code. glog does this, for example[1]. I don't have solutions to either case yet, but I have some ideas of how to start. I think the utility the tool provides is well worth those two issues, and I'm hopeful that both can be fixed.

[1] https://github.com/golang/glog/blob/master/glog.go#L536

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Re:A cross-platform debugger for Go by skybrian on Monday April 20, 2015 @06:13PM (#9411176)

A neat trick in some languages is to modify the source so that the line numbers don't change, for example by using semicolons instead of newlines and making sure a newline never appears in inserted instrumentation code. But I'm not sure if that's possible in Go.

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Re:A cross-platform debugger for Go by jschlatter on Monday April 20, 2015 @05:35PM (#9411006)

> Another is that you may inadvertently corrupt or change the behavior of the code in an unintentional way if you modify it incorrectly

I'm concerned about this, too. One of my next high priorities for godebug is to download many open source projects and search for behavior differences caused by the debugger. I would also like to generate new programs and test them as well.

> But, you get the easy 80% with this for sure. I'm just prodding you to work on the other 20%.

I will. I'm excited about the project and want to make it as useful as I can.

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Re:A cross-platform debugger for Go by andrewchambers on Monday April 20, 2015 @06:00PM (#9411125)

A compiler transforms source code. It doesn't have access to all programs either, yet we trust them most of the time.

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Re:A cross-platform debugger for Go by aleksi on Monday April 20, 2015 @03:14PM (#9410196)

Go has special comments for that: "//line filename:line"

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Re:A cross-platform debugger for Go by jschlatter on Monday April 20, 2015 @03:24PM (#9410260)

Thanks, I didn't know that. The go/token docs don't say much about it. Do you know if there is better documentation somewhere?

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Re:A cross-platform debugger for Go by rsc on Monday April 20, 2015 @03:52PM (#9410436)

http://golang.org/cmd/gc/

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Re:A cross-platform debugger for Go by vorg on Tuesday April 21, 2015 @12:00AM (#9412214)

I tried using this facility a few months ago based on this very short documentation but couldn't get it working, nor could I search out any further doco on it, so because it wasn't really important I gave up. Can I ask... have any of you ever successfully used this?

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Re:A cross-platform debugger for Go by aleksi on Tuesday April 21, 2015 @03:12AM (#9412639)

Yes, me. It works. :) Also it's used by "go test -cover".

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