code review 5697062: go/printer: fix printing of variadic function calls

src/pkg/go/printer/nodes.go

 // Copyright 2009 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.
 
 // This file implements printing of AST nodes; specifically
 // expressions, statements, declarations, and files. It uses
 // the print functionality implemented in printer.go.
 
 package printer
 
@@ skipping 786 matching lines @@
                         p.expr0(x.High, depth+1, multiLine)
                 }
                 p.print(x.Rbrack, token.RBRACK)
 
         case *ast.CallExpr:
                 if len(x.Args) > 1 {
                         depth++
                 }
                 p.expr1(x.Fun, token.HighestPrec, depth, multiLine)
                 p.print(x.Lparen, token.LPAREN)
-                p.exprList(x.Lparen, x.Args, depth, commaSep|commaTerm, multiLine, x.Rparen)
                 if x.Ellipsis.IsValid() {
+                        p.exprList(x.Lparen, x.Args, depth, commaSep, multiLine, x.Ellipsis)
                         p.print(x.Ellipsis, token.ELLIPSIS)
+                        if x.Rparen.IsValid() && p.lineFor(x.Ellipsis) < p.lineFor(x.Rparen) {
+                                p.print(token.COMMA, formfeed)
+                        }
+                } else {
+                        p.exprList(x.Lparen, x.Args, depth, commaSep|commaTerm, multiLine, x.Rparen)
                 }
                 p.print(x.Rparen, token.RPAREN)
 
         case *ast.CompositeLit:
                 // composite literal elements that are composite literals themselves may have the type omitted
                 if x.Type != nil {
                         p.expr1(x.Type, token.HighestPrec, depth, multiLine)
                 }
                 p.print(x.Lbrace, token.LBRACE)
                 p.exprList(x.Lbrace, x.Elts, 1, commaSep|commaTerm, multiLine, x.Rbrace)
@@ skipping 688 matching lines @@
                         if prev != tok || getDoc(d) != nil {
                                 min = 2
                         }
                         p.linebreak(p.lineFor(d.Pos()), min, ignore, false)
                         p.decl(d, ignoreMultiLine)
                 }
         }
 
         p.print(newline)
 }