From 38fa8c1e9bb24e53292ed82b7094309240a96ab5 Mon Sep 17 00:00:00 2001
From: Robert Griesemer <gri@golang.org>
Date: Wed, 17 Jul 2019 17:25:21 -0700
Subject: [PATCH] go/types: fix instantiated type name computation (for now)

This needs more work eventually.

Change-Id: I33fce18c454113620df9bb1db71a60b38b0a1306
---
 src/go/types/subst.go         |  9 ++++-----
 src/go/types/testdata/tmp.go2 |  9 ++++++---
 src/go/types/typestring.go    | 28 +++++++++++++++++-----------
 3 files changed, 27 insertions(+), 19 deletions(-)

diff --git a/src/go/types/subst.go b/src/go/types/subst.go
index c0224fe691..155619f6fa 100644
--- a/src/go/types/subst.go
+++ b/src/go/types/subst.go
@@ -127,7 +127,8 @@ func (s *subster) typ(typ Type) (res Type) {
 				panic("cannot handle instantiation of types with methods yet")
 			}
 			// TODO(gri) review name creation and factor out
-			name := t.obj.name + typeArgsString(s.targs)
+			name := TypeString(t, nil) + "<" + typeListString(s.targs) + ">"
+			//s.check.dump("NAME = %s", name)
 			tname, found := s.check.typMap[name]
 			if !found {
 				// TODO(gri) what is the correct position to use here?
@@ -208,15 +209,13 @@ func (s *subster) varList(in []*Var) (out []*Var, copied bool) {
 	return
 }
 
-func typeArgsString(targs []Type) string {
+func typeListString(targs []Type) string {
 	var buf bytes.Buffer
-	buf.WriteByte('<')
 	for i, arg := range targs {
 		if i > 0 {
 			buf.WriteString(", ")
 		}
-		buf.WriteString(TypeString(arg, nil))
+		WriteType(&buf, arg, nil)
 	}
-	buf.WriteByte('>')
 	return buf.String()
 }
diff --git a/src/go/types/testdata/tmp.go2 b/src/go/types/testdata/tmp.go2
index a75d304ffb..308c438b4e 100644
--- a/src/go/types/testdata/tmp.go2
+++ b/src/go/types/testdata/tmp.go2
@@ -11,7 +11,10 @@ func f(type P) (x P) List(P) {
 }
 
 var (
-	_ []int = f(0)
-	_ []float32 = f(float32)(10)
-	//_ []List(int) = f(List(int){})
+	//_ []int = f(0)
+	//_ []float32 = f(float32)(10)
+        // TODO(gri) fix next line
+	// [](List(int)) = f(List(int){})
+        // _ List(List(int)) = [](List(int)){}
+        // _ = [](List(int)){}
 )
diff --git a/src/go/types/typestring.go b/src/go/types/typestring.go
index 9e291922ca..46e254d293 100644
--- a/src/go/types/typestring.go
+++ b/src/go/types/typestring.go
@@ -9,6 +9,7 @@ package types
 import (
 	"bytes"
 	"fmt"
+	"strings"
 )
 
 // A Qualifier controls how named package-level objects are printed in
@@ -236,16 +237,16 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 
 	case *Named:
 		writeTypeName(buf, t.obj, qf)
-		if t.obj != nil && len(t.obj.tparams) > 0 {
-			buf.WriteByte('(')
-			for i, tpar := range t.obj.tparams {
-				if i > 0 {
-					buf.WriteString(", ")
-				}
-				writeTypeName(buf, tpar, qf)
-			}
-			buf.WriteByte(')')
-		}
+		// if t.obj != nil && len(t.obj.tparams) > 0 {
+		// 	buf.WriteByte('(')
+		// 	for i, tpar := range t.obj.tparams {
+		// 		if i > 0 {
+		// 			buf.WriteString(", ")
+		// 		}
+		// 		writeTypeName(buf, tpar, qf)
+		// 	}
+		// 	buf.WriteByte(')')
+		// }
 
 	case *Parameterized:
 		writeTypeName(buf, t.tname, qf)
@@ -289,7 +290,12 @@ func writeType(buf *bytes.Buffer, typ Type, qf Qualifier, visited []Type) {
 func writeTypeName(buf *bytes.Buffer, obj *TypeName, qf Qualifier) {
 	s := "<Named w/o object>"
 	if obj != nil {
-		if obj.pkg != nil {
+		// Don't prefix an instantiated type (which is marked by a closing '>')
+		// with yet another package name - the instantiated type is already fully
+		// qualified. See code in subst.go.
+		// TODO(gri) Need to factor out '>' or named type string generation;
+		// this dependency is too subtle.
+		if obj.pkg != nil && !strings.HasSuffix(obj.name, ">") {
 			writePackage(buf, obj.pkg, qf)
 		}
 		// TODO(gri): function-local named types should be displayed