go/printer: align ImportPaths in ImportDecls if PackageName is given.

Fixes #1044.

R=gri
CC=golang-dev
https://golang.org/cl/1958047

src/pkg/go/printer/nodes.go

@@ -1192,25 +1192,25 @@ func (p *printer) stmt(stmt ast.Stmt, nextIsRBrace bool, multiLine *bool) {
 // ----------------------------------------------------------------------------
 // Declarations
 
-// The parameter n is the number of specs in the group. If indent is set,
+// The parameter n is the number of specs in the group. If doIndent is set,
 // multi-line identifier lists in the spec are indented when the first
 // linebreak is encountered.
 // Sets multiLine to true if the spec spans multiple lines.
 //
-func (p *printer) spec(spec ast.Spec, n int, indent bool, multiLine *bool) {
+func (p *printer) spec(spec ast.Spec, n int, doIndent bool, multiLine *bool) {
 	switch s := spec.(type) {
 	case *ast.ImportSpec:
 		p.setComment(s.Doc)
 		if s.Name != nil {
 			p.expr(s.Name, multiLine)
-			p.print(blank)
+			p.print(vtab)
 		}
 		p.expr(s.Path, multiLine)
 		p.setComment(s.Comment)
 
 	case *ast.ValueSpec:
 		p.setComment(s.Doc)
-		p.identList(s.Names, indent, multiLine) // always present
+		p.identList(s.Names, doIndent, multiLine) // always present
 		if n == 1 {
 			if s.Type != nil {
 				p.print(blank)

src/pkg/go/printer/testdata/declarations.golden

@@ -25,6 +25,15 @@ import (
 	b	"io"
 )
 
+import (
+	"unrenamed"
+	renamed	"renameMe"
+	.	"io"
+	_	"io"
+	"io"
+	.	"os"
+)
+
 // no newlines between consecutive single imports, but
 // respect extra line breaks in the source (at most one empty line)
 import _	"io"
@@ -51,6 +60,17 @@ import (
 	"bar"	// a comment
 )
 
+// comments + renames
+import (
+	"unrenamed"	// a comment
+	renamed		"renameMe"
+	.		"io"		/* a comment */
+	_		"io/ioutil"	// a comment
+	"io"		// testing alignment
+	.		"os"
+	// a comment
+)
+
 // a case that caused problems in the past (comment placement)
 import (
 	.	"fmt"

src/pkg/go/printer/testdata/declarations.input

@@ -25,6 +25,15 @@ import (
 	b "io"
 )
 
+import (
+       "unrenamed"
+       renamed "renameMe"
+       . "io"
+       _ "io"
+       "io"
+       . "os"
+)
+
 // no newlines between consecutive single imports, but
 // respect extra line breaks in the source (at most one empty line)
 import _ "io"
@@ -51,6 +60,17 @@ import (
 	"bar"  // a comment
 )
 
+// comments + renames
+import (
+       "unrenamed" // a comment
+       renamed "renameMe"
+       . "io" /* a comment */
+       _ "io/ioutil" // a comment
+       "io" // testing alignment
+       . "os"
+       // a comment
+)
+
 // a case that caused problems in the past (comment placement)
 import (
 	. "fmt"