go/printer, gofmt: use blank to separate import rename from import path

Note that declarations.golden is not using spaces for alignment (so
that the alignment tabs are visible) which is why this change affects
the test cases significantly. gofmt uses spaces for alignment (by default)
and only tabs for indentation.

gofmt -w src misc (no changes)

Fixes #1673.

R=iant
CC=golang-dev
https://golang.org/cl/4388044

src/pkg/go/printer/nodes.go

@@ -1200,7 +1200,7 @@ func (p *printer) spec(spec ast.Spec, n int, doIndent bool, multiLine *bool) {
 		p.setComment(s.Doc)
 		if s.Name != nil {
 			p.expr(s.Name, multiLine)
-			p.print(vtab)
+			p.print(blank)
 		}
 		p.expr(s.Path, multiLine)
 		p.setComment(s.Comment)

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

@@ -7,10 +7,10 @@ package imports
 import "io"
 
 import (
-	_	"io"
+	_ "io"
 )
 
-import _	"io"
+import _ "io"
 
 import (
 	"io"
@@ -20,40 +20,40 @@ import (
 
 import (
 	"io"
-	aLongRename	"io"
+	aLongRename "io"
 
-	b	"io"
+	b "io"
 )
 
 import (
 	"unrenamed"
-	renamed	"renameMe"
-	.	"io"
-	_	"io"
+	renamed "renameMe"
+	. "io"
+	_ "io"
 	"io"
-	.	"os"
+	. "os"
 )
 
 // no newlines between consecutive single imports, but
 // respect extra line breaks in the source (at most one empty line)
-import _	"io"
-import _	"io"
-import _	"io"
+import _ "io"
+import _ "io"
+import _ "io"
 
-import _	"os"
-import _	"os"
-import _	"os"
+import _ "os"
+import _ "os"
+import _ "os"
 
 
-import _	"fmt"
-import _	"fmt"
-import _	"fmt"
+import _ "fmt"
+import _ "fmt"
+import _ "fmt"
 
 import "foo"	// a comment
 import "bar"	// a comment
 
 import (
-	_	"foo"
+	_ "foo"
 	// a comment
 	"bar"
 	"foo"	// a comment
@@ -63,17 +63,17 @@ import (
 // comments + renames
 import (
 	"unrenamed"	// a comment
-	renamed		"renameMe"
-	.		"io"		/* a comment */
-	_		"io/ioutil"	// a comment
+	renamed "renameMe"
+	. "io"		/* a comment */
+	_ "io/ioutil"	// a comment
 	"io"		// testing alignment
-	.		"os"
+	. "os"
 	// a comment
 )
 
 // a case that caused problems in the past (comment placement)
 import (
-	.	"fmt"
+	. "fmt"
 	"io"
 	"malloc"	// for the malloc count test only
 	"math"
@@ -81,9 +81,38 @@ import (
 	"testing"
 )
 
+// more import examples
+import (
+	"xxx"
+	"much longer name"	// comment
+	"short name"		// comment
+)
+
+import (
+	_ "xxx"
+	"much longer name"	// comment
+)
+
+import (
+	mymath "math"
+	"/foo/bar/long_package_path"	// a comment
+)
+
+import (
+	"package_a"	// comment
+	"package_b"
+	my_better_c "package_c"	// comment
+	"package_d"		// comment
+	my_e "package_e"	// comment
+
+	"package_a"	// comment
+	"package_bb"
+	"package_ccc"	// comment
+	"package_dddd"	// comment
+)
 
 // at least one empty line between declarations of different kind
-import _	"io"
+import _ "io"
 
 var _ int
 

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

@@ -81,6 +81,35 @@ import (
 	"testing"
 )
 
+// more import examples
+import (
+	"xxx"
+	"much longer name" // comment
+	"short name" // comment
+)
+
+import (
+	_ "xxx"
+	"much longer name" // comment
+)
+
+import (
+	mymath "math"
+	"/foo/bar/long_package_path" // a comment
+)
+
+import (
+	"package_a" // comment
+	"package_b"
+	my_better_c "package_c" // comment
+	"package_d" // comment
+	my_e "package_e" // comment
+
+	"package_a"    // comment
+	"package_bb"
+	"package_ccc"  // comment
+	"package_dddd" // comment
+)
 
 // at least one empty line between declarations of different kind
 import _ "io"