[dev.cmdgo] all: merge master (67f7e16) into dev.cmdgodev.cmdgo

Merge List:

+ 2021-08-27 67f7e16bcc encoding/gob: optimize decoding of []byte
+ 2021-08-27 2c60a99f72 cmd/compile/internal/syntax: make valid type parameter list in presence of errors
+ 2021-08-27 d350a66532 cmd/compile: eagerly CalcStructSize for synthetic ABI types
+ 2021-08-27 d7e2e2ec2b cmd/compile: delay fillinMethods to deal with mutually-recursive types
+ 2021-08-27 c927599783 cmd/compile: eliminate repetitive code
+ 2021-08-27 62f88b6dc8 cmd/compile: add types.RecalcSize
+ 2021-08-27 e7eee5e265 cmd/compile: remove ssagen/pgen_test.go
+ 2021-08-27 f153b6739b cmd/compile: use typecheck.InitUniverse in unit tests
+ 2021-08-26 967a8017f7 cmd/compile: move types init code into package types
+ 2021-08-26 af80af22b5 cmd/compile/internal/types2: do not declare new methods on instantiated types
+ 2021-08-26 03db2c2413 cmd/compile/internal/types2: implement TypeList.String (debugging support)
+ 2021-08-26 c9e05fdcf7 cmd/compile: fix reference to generic type needed by crawler
+ 2021-08-26 eb6a07fcf9 cmd/compile: unexport Type.Vargen
+ 2021-08-26 3836983779 cmd/compile/internal/types: unexport Type.Extra
+ 2021-08-26 1f8d4562de cmd/compile: change typecheck.iscmp into ir.Op.IsCmp

Change-Id: I95c040a0e984a13a3b12c50458148007221ee300

1 files changed, 7 insertions, 1 deletions

diff --git a/src/cmd/compile/internal/types2/signature.go b/src/cmd/compile/internal/types2/signature.go
index d28e7b8944..ddad1f0311 100644
--- a/src/cmd/compile/internal/types2/signature.go
+++ b/src/cmd/compile/internal/types2/signature.go
@@ -132,7 +132,7 @@ func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []
 				// Also: Don't report an error via genericType since it will be reported
 				//       again when we type-check the signature.
 				// TODO(gri) maybe the receiver should be marked as invalid instead?
-				if recv := asNamed(check.genericType(rname, false)); recv != nil {
+				if recv, _ := check.genericType(rname, false).(*Named); recv != nil {
 					recvTParams = recv.TParams().list()
 				}
 			}
@@ -211,6 +211,12 @@ func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []
 			switch T := rtyp.(type) {
 			case *Named:
 				T.expand(nil)
+				// The receiver type may be an instantiated type referred to
+				// by an alias (which cannot have receiver parameters for now).
+				if T.TArgs() != nil && sig.RParams() == nil {
+					check.errorf(recv.pos, "cannot define methods on instantiated type %s", recv.typ)
+					break
+				}
 				// spec: "The type denoted by T is called the receiver base type; it must not
 				// be a pointer or interface type and it must be declared in the same package
 				// as the method."