Receiver parameters generally aren't relevant to the function
signature type. In particular:
1. When checking whether a type's method implements an interface's
method, we specifically want to ignore the receiver parameters,
because they'll be different.
2. When checking interface type equality, interface methods always
use the same "fakethis" *struct{} type as their receiver.
3. Finally, method expressions and method values degenerate into
receiver-less function types.
The only case where we care about receiver types matching is in
addmethod, which is easily handled by adding an extra Eqtype check of
the receiver parameters. Also, added a test for this, since
(surprisingly) there weren't any.
As precedence, go/types.Identical ignores receiver parameters when
comparing go/types.Signature values.
Notably, this allows us to slightly simplify the "implements"
function, which is used for checking whether type/interface t
implements interface iface. Currently, cmd/compile actually works
around Eqtype's receiver parameter checking by creating new throwaway
TFUNC Types without the receiver parameter.
(Worse, the compiler currently only provides APIs to build TFUNC Types
from Nod syntax trees, so building those throwaway types also involves
first building throwaway syntax trees.)
Passes toolstash -cmp.
Change-Id: Ib07289c66feacee284e016bc312e8c5ff674714f
Reviewed-on: https://go-review.googlesource.com/20602
Reviewed-by: Robert Griesemer <gri@golang.org>
compile with the current compiler. Adjust expected error
message in method1.go to match 6g output.
R=rsc
DELTA=9 (2 added, 5 deleted, 2 changed)
OCL=33674
CL=33682
is recognized by the gccgo testsuite but is ignored by the
errchk script used with 6g.
method1.go:7:1: error: redefinition of 'M': parameter types changed
method1.go:6:1: note: previous definition of 'M' was here
method1.go:10:1: error: redefinition of 'f': parameter types changed
method1.go:9:1: note: previous definition of 'f' was here
method1.go:13:1: error: redefinition of 'g': parameter names changed
method1.go:12:1: note: previous definition of 'g' was here
R=rsc
DELTA=5 (0 added, 0 deleted, 5 changed)
OCL=18962
CL=19058
