go/types, types2: replace (internal) writePackage with packagePrefix

This makes it easier to use the package string prefix in some cases
(cleanup).

Change-Id: I0ae74bf8770999110e7d6e49eac4e42962e78596
Reviewed-on: https://go-review.googlesource.com/c/go/+/451795
Auto-Submit: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/cmd/compile/internal/types2/decl.go

@@ -5,7 +5,6 @@
 package types2
 
 import (
-	"bytes"
 	"cmd/compile/internal/syntax"
 	"fmt"
 	"go/constant"
@@ -311,10 +310,7 @@ func (check *Checker) cycleError(cycle []Object) {
 	// may refer to imported types. See issue #50788.
 	// TODO(gri) This functionality is used elsewhere. Factor it out.
 	name := func(obj Object) string {
-		var buf bytes.Buffer
-		writePackage(&buf, obj.Pkg(), check.qualifier)
-		buf.WriteString(obj.Name())
-		return buf.String()
+		return packagePrefix(obj.Pkg(), check.qualifier) + obj.Name()
 	}
 
 	// TODO(gri) Should we start with the last (rather than the first) object in the cycle

src/cmd/compile/internal/types2/object.go

@@ -512,7 +512,7 @@ func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
 
 	// For package-level objects, qualify the name.
 	if obj.Pkg() != nil && obj.Pkg().scope.Lookup(obj.Name()) == obj {
-		writePackage(buf, obj.Pkg(), qf)
+		buf.WriteString(packagePrefix(obj.Pkg(), qf))
 	}
 	buf.WriteString(obj.Name())
 
@@ -553,9 +553,9 @@ func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
 	WriteType(buf, typ, qf)
 }
 
-func writePackage(buf *bytes.Buffer, pkg *Package, qf Qualifier) {
+func packagePrefix(pkg *Package, qf Qualifier) string {
 	if pkg == nil {
-		return
+		return ""
 	}
 	var s string
 	if qf != nil {
@@ -564,9 +564,9 @@ func writePackage(buf *bytes.Buffer, pkg *Package, qf Qualifier) {
 		s = pkg.Path()
 	}
 	if s != "" {
-		buf.WriteString(s)
-		buf.WriteByte('.')
+		s += "."
 	}
+	return s
 }
 
 // ObjectString returns the string form of obj.
@@ -604,7 +604,7 @@ func writeFuncName(buf *bytes.Buffer, f *Func, qf Qualifier) {
 			buf.WriteByte(')')
 			buf.WriteByte('.')
 		} else if f.pkg != nil {
-			writePackage(buf, f.pkg, qf)
+			buf.WriteString(packagePrefix(f.pkg, qf))
 		}
 	}
 	buf.WriteString(f.name)

src/cmd/compile/internal/types2/typestring.go

@@ -388,9 +388,7 @@ func (w *typeWriter) tParamList(list []*TypeParam) {
 }
 
 func (w *typeWriter) typeName(obj *TypeName) {
-	if obj.pkg != nil {
-		writePackage(w.buf, obj.pkg, w.qf)
-	}
+	w.string(packagePrefix(obj.pkg, w.qf))
 	w.string(obj.name)
 }
 

src/go/types/decl.go

@@ -5,7 +5,6 @@
 package types
 
 import (
-	"bytes"
 	"fmt"
 	"go/ast"
 	"go/constant"
@@ -309,10 +308,7 @@ func (check *Checker) cycleError(cycle []Object) {
 	// may refer to imported types. See issue #50788.
 	// TODO(gri) Thus functionality is used elsewhere. Factor it out.
 	name := func(obj Object) string {
-		var buf bytes.Buffer
-		writePackage(&buf, obj.Pkg(), check.qualifier)
-		buf.WriteString(obj.Name())
-		return buf.String()
+		return packagePrefix(obj.Pkg(), check.qualifier) + obj.Name()
 	}
 
 	// TODO(gri) Should we start with the last (rather than the first) object in the cycle

src/go/types/object.go

@@ -469,7 +469,7 @@ func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
 
 	// For package-level objects, qualify the name.
 	if obj.Pkg() != nil && obj.Pkg().scope.Lookup(obj.Name()) == obj {
-		writePackage(buf, obj.Pkg(), qf)
+		buf.WriteString(packagePrefix(obj.Pkg(), qf))
 	}
 	buf.WriteString(obj.Name())
 
@@ -510,9 +510,9 @@ func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
 	WriteType(buf, typ, qf)
 }
 
-func writePackage(buf *bytes.Buffer, pkg *Package, qf Qualifier) {
+func packagePrefix(pkg *Package, qf Qualifier) string {
 	if pkg == nil {
-		return
+		return ""
 	}
 	var s string
 	if qf != nil {
@@ -521,9 +521,9 @@ func writePackage(buf *bytes.Buffer, pkg *Package, qf Qualifier) {
 		s = pkg.Path()
 	}
 	if s != "" {
-		buf.WriteString(s)
-		buf.WriteByte('.')
+		s += "."
 	}
+	return s
 }
 
 // ObjectString returns the string form of obj.
@@ -561,7 +561,7 @@ func writeFuncName(buf *bytes.Buffer, f *Func, qf Qualifier) {
 			buf.WriteByte(')')
 			buf.WriteByte('.')
 		} else if f.pkg != nil {
-			writePackage(buf, f.pkg, qf)
+			buf.WriteString(packagePrefix(f.pkg, qf))
 		}
 	}
 	buf.WriteString(f.name)

src/go/types/typestring.go

@@ -389,9 +389,7 @@ func (w *typeWriter) tParamList(list []*TypeParam) {
 }
 
 func (w *typeWriter) typeName(obj *TypeName) {
-	if obj.pkg != nil {
-		writePackage(w.buf, obj.pkg, w.qf)
-	}
+	w.string(packagePrefix(obj.pkg, w.qf))
 	w.string(obj.name)
 }