From: Robert Griesemer <gri@golang.org>
Date: Thu, 18 Feb 2021 05:31:41 +0000 (-0800)
Subject: [dev.typeparams] cmd/compile/internal/types: review of typestring.go
X-Git-Tag: go1.17beta1~1473^2~11
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=d6bdd1aeef;p=gostls13.git

[dev.typeparams] cmd/compile/internal/types: review of typestring.go

The changes between (equivalent, and reviewed) go/types/typestring.go
and typestring.go can be seen by comparing patchset 1 and 3. The actual
change is just removing the "// UNREVIEWED" marker plus an adjustment
to writeTParamList (we now always write type constraints).

Change-Id: Ieb109c17756addc954e1ca0da606fa5b335ff30d
Reviewed-on: https://go-review.googlesource.com/c/go/+/293472
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
---

diff --git a/src/cmd/compile/internal/types2/typestring.go b/src/cmd/compile/internal/types2/typestring.go
index 4d778df43f..47b2c259e5 100644
--- a/src/cmd/compile/internal/types2/typestring.go
+++ b/src/cmd/compile/internal/types2/typestring.go
@@ -1,4 +1,3 @@
-// UNREVIEWED
 // Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
@@ -314,33 +313,16 @@ func writeTypeList(buf *bytes.Buffer, list []Type, qf Qualifier, visited []Type)
 }
 
 func writeTParamList(buf *bytes.Buffer, list []*TypeName, qf Qualifier, visited []Type) {
-	// bound returns the type bound for tname. The result is never nil.
-	bound := func(tname *TypeName) Type {
-		// be careful to avoid crashes in case of inconsistencies
-		if t, _ := tname.typ.(*TypeParam); t != nil && t.bound != nil {
-			return t.bound
-		}
-		return &emptyInterface
-	}
-
-	// If a single type bound is not the empty interface, we have to write them all.
-	var writeBounds bool
-	for _, p := range list {
-		// bound(p) should be an interface but be careful (it may be invalid)
-		b := asInterface(bound(p))
-		if b != nil && !b.Empty() {
-			writeBounds = true
-			break
-		}
-	}
-	writeBounds = true // always write the bounds for new type parameter list syntax
-
 	buf.WriteString("[")
 	var prev Type
 	for i, p := range list {
-		b := bound(p)
+		// TODO(gri) support 'any' sugar here.
+		var b Type = &emptyInterface
+		if t, _ := p.typ.(*TypeParam); t != nil && t.bound != nil {
+			b = t.bound
+		}
 		if i > 0 {
-			if writeBounds && b != prev {
+			if b != prev {
 				// type bound changed - write previous one before advancing
 				buf.WriteByte(' ')
 				writeType(buf, prev, qf, visited)
@@ -355,7 +337,7 @@ func writeTParamList(buf *bytes.Buffer, list []*TypeName, qf Qualifier, visited
 			buf.WriteString(p.name)
 		}
 	}
-	if writeBounds && prev != nil {
+	if prev != nil {
 		buf.WriteByte(' ')
 		writeType(buf, prev, qf, visited)
 	}