cmd/cover: spurious 0/1 coverage entry for forward-declared functions

[axw]

What steps will reproduce the problem?
1. go test -coverprofile=c.out os
2. go tool cover -func=c.out | grep sigpipe

What is the expected output?

os/file_posix.go:   sigpipe         0.0%
...
total:          (statements)        65.6% (393/599)

What do you see instead?

os/file_posix.go:   sigpipe         0.0%
...
total:          (statements)        65.5% (393/600)

Which compiler are you using (5g, 6g, 8g, gccgo)?

6g

Which operating system are you using?

GNU/Linux

Which version are you using?  (run 'go version')

go version go1.2 linux/amd64

Please provide any additional information below.

I came across this while comparing the output of go tool cover and gocov, finding a
discrepancy in totals. I modified funcOutput in go.tools/cmd/cover/func.go to also print
the raw function coverage counts as well as percentages; in this way, I confirmed that
sigpipe had 0/1 lines covered, and was contributing to the total.

[rsc]

Comment 1:

Labels changed: added release-none, removed go1.3maybe.

[rsc]

Comment 2:

Labels changed: added repo-tools.

[gopherbot]

Change https://golang.org/cl/77152 mentions this issue: cmd/cover: do not report coverage for assembly functions