An experiment: allow structs to be copied even if they
contain unexported fields. This gives packages the
ability to return opaque values in their APIs, like reflect
does for reflect.Value but without the kludgy hacks reflect
resorts to.
In general, we trust programmers not to do silly things
like *x = *y on a package's struct pointers, just as we trust
programmers not to do unicode.Letter = unicode.Digit,
but packages that want a harder guarantee can introduce
an extra level of indirection, like in the changes to os.File
in this CL or by using an interface type.
All in one CL so that it can be rolled back more easily if
we decide this is a bad idea.
Originally discussed in March 2011.
https://groups.google.com/group/golang-dev/t/3f5d30938c7c45ef
R=golang-dev, adg, dvyukov, r, bradfitz, jan.mercl, gri
CC=golang-dev
https://golang.org/cl/5372095
The change to assign.go is because the gcc testsuite fails to
handle .* in a normal way: it matches against the entire
compiler output, not just a single line.
assign.go:15:6: error: incompatible types in assignment (implicit assignment of 'sync.Mutex' hidden field 'key')
assign.go:19:6: error: incompatible types in assignment (implicit assignment of 'sync.Mutex' hidden field 'key')
assign.go:23:6: error: incompatible types in assignment (implicit assignment of 'sync.Mutex' hidden field 'key')
assign.go:27:6: error: incompatible types in assignment (implicit assignment of 'sync.Mutex' hidden field 'key')
chan/perm.go:14:5: error: incompatible types in assignment
chan/perm.go:15:5: error: incompatible types in assignment
chan/perm.go:16:6: error: incompatible types in assignment
chan/perm.go:17:6: error: incompatible types in assignment
chan/perm.go:24:7: error: invalid send on receive-only channel
chan/perm.go:25:12: error: invalid send on receive-only channel
chan/perm.go:31:4: error: invalid receive on send-only channel
chan/perm.go:32:9: error: invalid receive on send-only channel
chan/perm.go:38:2: error: invalid send on receive-only channel
chan/perm.go:42:2: error: invalid receive on send-only channel
initializerr.go:14:17: error: reference to undefined variable 'X'
initializerr.go:14:19: error: mixture of field and value initializers
initializerr.go:15:26: error: duplicate value for field 'Y'
initializerr.go:16:10: error: too many values in struct composite literal
initializerr.go:18:19: error: index expression is not integer constant
initializerr.go:17:11: error: too many elements in composite literal
R=rsc
DELTA=12 (0 added, 0 deleted, 12 changed)
OCL=29657
CL=29665
when assigning a multifield object
(structs or arrays of structs) they
must not contain any fields that could
not be assigned individually.
R=ken
OCL=29192
CL=29194
