cmd/compile,debug/gosym: generics: compiler produces symbols that gosym can not parse

[aarzilli]

The symbol names currently produced by the compiler for generic function instantiations can not be parsed by debug/gosym (or any simple parser for that matter).

For example:

func testfunction[T any](arg T) {
	fmt.Println(arg)
}

func main() {
	testfunction(3)
}

Produces the symbol main.testfunction[.shape.int] for which gosym will return:

PackageName: "main"
ReceiverName: "testfunction[.shape"
BaseName: "int]"

instead of:

PackageName: "main"
ReceiverName: ""
BaseName: "testfunction[.shape.int]"

Parsing symbol names is further complicated by generic method instantiations:

type S[T any] struct {
	x T
}

func (s *S[T]) testfunction() {
	fmt.Println(s.x)
}

Will produce the symbol main.(*S[.shape.int]).testfunction, so just looking for the first . instead of the last one doesn't work either.

Referencing issue #37762 here since its making an effort to fix a bug in this area.

[cherrymui]

cc @griesemer @randall77 @danscales

[danscales]

@griesemer and I talked. Once some types2 change are complete that will give a better unique name for various types (in a week or two), we will discuss gosym compatibility and other issues related to naming instantiations of generic functions/methods, and come to a more formal decision on the format of names of function instantiations.

In this case, as you describe, the '.' that we are using when specifying the type args of a function instantiation is clearly confusing the current gosym code.

[gopherbot]

Change https://golang.org/cl/354689 mentions this issue: cmd/compile: adjust debug/gosym to deal with instantiated types/funcs/methods