cmd/gc: missing declared and not used error

[griesemer]

http://play.golang.org/p/kSqOMI9a_6

Expected output:

prog.go:4: s declared and not used

But the compiler is silent.

This is an implementation restriction, and a compiler may be free to restrict or not.
That said, given the specification of the restriction, this is not consistent with the
usage checks that gc already does.

We may not be able to fix this since it may invalidate code that is now compiling.

[griesemer]

Comment 1:

Occurrences in std library:
https://golang.org/cl/13242058
https://golang.org/cl/13683044

[remyoudompheng]

Comment 2:

Status changed to Duplicate.

Merged into issue #3059.