src$ git diff
diff --git a/src/go/ast/ast.go b/src/go/ast/ast.go
index 1e089b9e70..2dc0f43dcd 100644
--- a/src/go/ast/ast.go
+++ b/src/go/ast/ast.go
@@ -1035,23 +1035,19 @@ func (*FuncDecl) declNode() {}
 // and Comment comments directly associated with nodes, the remaining comments
 // are "free-floating" (see also issues #18593, #20744).
 type File struct {
-       Doc        *CommentGroup   // associated documentation; or nil
-       Package    token.Pos       // position of "package" keyword
-       Name       *Ident          // package name
-       Decls      []Decl          // top-level declarations; or nil
-       Scope      *Scope          // package scope (this file only)
-       Imports    []*ImportSpec   // imports in this file
-       Unresolved []*Ident        // unresolved identifiers in this file
-       Comments   []*CommentGroup // list of all comments in the source file
+       StartPos, EndPos token.Pos       // start and end of file
+       Doc              *CommentGroup   // associated documentation; or nil
+       Package          token.Pos       // position of "package" keyword
+       Name             *Ident          // package name
+       Decls            []Decl          // top-level declarations; or nil
+       Scope            *Scope          // package scope (this file only)
+       Imports          []*ImportSpec   // imports in this file
+       Unresolved       []*Ident        // unresolved identifiers in this file
+       Comments         []*CommentGroup // list of all comments in the source file
 }
 
-func (f *File) Pos() token.Pos { return f.Package }
-func (f *File) End() token.Pos {
-       if n := len(f.Decls); n > 0 {
-               return f.Decls[n-1].End()
-       }
-       return f.Name.End()
-}
+func (f *File) Pos() token.Pos { return f.StartPos }
+func (f *File) End() token.Pos { return f.EndPos }
 
 // A Package node represents a set of source files
 // collectively building a Go package.
diff --git a/src/go/ast/filter.go b/src/go/ast/filter.go
index 2fc73c4b99..cfdaa074f8 100644
--- a/src/go/ast/filter.go
+++ b/src/go/ast/filter.go
@@ -484,5 +484,6 @@ func MergePackageFiles(pkg *Package, mode MergeMode) *File {
        }
 
        // TODO(gri) need to compute unresolved identifiers!
-       return &File{doc, pos, NewIdent(pkg.Name), decls, pkg.Scope, imports, nil, comments}
+       // TODO: use least start and max end pos?
+       return &File{token.NoPos, token.NoPos, doc, pos, NewIdent(pkg.Name), decls, pkg.Scope, imports, nil, comments}
 }
diff --git a/src/go/parser/parser.go b/src/go/parser/parser.go
index 18041ff808..354d429623 100644
--- a/src/go/parser/parser.go
+++ b/src/go/parser/parser.go
@@ -2887,6 +2887,8 @@ func (p *parser) parseFile() *ast.File {
        }
 
        f := &ast.File{
+               StartPos: token.Pos(p.file.Base()),
+               EndPos:   token.Pos(p.file.Base() + p.file.Size()),
                Doc:      doc,
                Package:  pos,
                Name:     ident,