From: Rob Findley <rfindley@google.com>
Date: Tue, 22 Jun 2021 14:13:54 +0000 (-0400)
Subject: [dev.typeparams] go/types: adjust logic for method expression arg naming
X-Git-Tag: go1.18beta1~1818^2^2~300
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=62095c66e042024fc631a3e9514b637ae4b5ae10;p=gostls13.git

[dev.typeparams] go/types: adjust logic for method expression arg naming

CL 325369 improved this logic in types2. Port this improvement back to
go/types.

Change-Id: I5f859cbffd88bb3db09a81c2389269f7bd0869f9
Reviewed-on: https://go-review.googlesource.com/c/go/+/330069
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
---

diff --git a/src/go/types/call.go b/src/go/types/call.go
index 3a04121e98..039c7bbaf5 100644
--- a/src/go/types/call.go
+++ b/src/go/types/call.go
@@ -587,16 +587,15 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
 		if sig.params != nil {
 			params = sig.params.vars
 		}
-		// Be consistent about named/unnamed parameters.
-		needName := true
-		for _, param := range params {
-			if param.Name() == "" {
-				needName = false
-				break
-			}
-		}
+		// Be consistent about named/unnamed parameters. This is not needed
+		// for type-checking, but the newly constructed signature may appear
+		// in an error message and then have mixed named/unnamed parameters.
+		// (An alternative would be to not print parameter names in errors,
+		// but it's useful to see them; this is cheap and method expressions
+		// are rare.)
 		name := ""
-		if needName {
+		if len(params) > 0 && params[0].name != "" {
+			// name needed
 			name = sig.recv.name
 			if name == "" {
 				name = "_"