go/parser: Better comment for ParseFile.

The name ParseFile was kept as it indicates that
this function parses a Go 'SourceFile' per the
Go spec. Similarly, the other functions (ParseExpr,
ParseStmtList, ParseDeclList) parse the corresponding
constructs as defined in the Go spec.

Fixes #1311.

R=r, rsc
CC=golang-dev
https://golang.org/cl/3453042

src/pkg/go/parser/interface.go

@@ -111,14 +111,13 @@ func ParseDeclList(fset *token.FileSet, filename string, src interface{}) ([]ast
 }
 
 
-// TODO(gri) Change ParseFile to Parse and improve documentation (issue 1311).
-
-// ParseFile parses a Go source file and returns a File node.
+// ParseFile parses the source code of a single Go source file and returns
+// the corresponding ast.File node. The source code may be provided via
+// the filename of the source file, or via the src parameter.
 //
-// If src != nil, ParseFile parses the file source from src. src may
-// be provided in a variety of formats. At the moment the following types
-// are supported: string, []byte, and io.Reader. In this case, filename is
-// only used for source position information and error messages.
+// If src != nil, ParseFile parses the source from src and the filename is
+// only used when recording position information. The type of the argument
+// for the src parameter must be string, []byte, or io.Reader.
 //
 // If src == nil, ParseFile parses the file specified by filename.
 //