What version of Go are you using (go version)?

$ go version
go version devel go1.20-ff0877e180 Wed Dec 7 12:19:22 2022 -0500 linux/amd64

Does this issue reproduce with the latest release?

No, only with Go 1.20 / tip.

What operating system and processor architecture are you using (go env)?

linux/amd64

What did you do?

Here is a small program that has a main function and a test.

Try the following with it:

// step 1
go test -cover .

// step 2
rm -rf somedata ; mkdir somedata ; GOCOVERDIR=somedata go run -cover . ; go tool covdata percent -i=somedata

What did you expect to see?

Identical results for both runs.

What did you see instead?

$ go test -cover .
ok  	mainwithtest	0.020s	coverage: 50.0% of statements
$ rm -rf somedata ; mkdir somedata ; GOCOVERDIR=somedata go run -cover . ; go tool covdata percent -i=somedata
hi mom
	main	coverage: 50.0% of statements

Note the discrepancy with the package name. For go test -cover we get the import path (which seems correct), but for the go build -cover we're getting the package name and not import path. Seems that these two should be consistent.