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go/parser: document that parse functions need valid token.FileSet

+ panic with explicit error if no file set it provided

(Not providing a file set is invalid use of the API; panic
is the appropriate action rather than returning an error.)

Fixes #16018.

Change-Id: I207f5b2a2e318d65826bdd9522fce46d614c24ee
Reviewed-on: https://go-review.googlesource.com/24010
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Robert Griesemer 2016-06-10 10:27:37 -07:00
parent fee02d270b
commit e980a3d885

View File

@ -73,7 +73,7 @@ const (
//
// The mode parameter controls the amount of source text parsed and other
// optional parser functionality. Position information is recorded in the
// file set fset.
// file set fset, which must not be nil.
//
// If the source couldn't be read, the returned AST is nil and the error
// indicates the specific failure. If the source was read but syntax
@ -82,6 +82,10 @@ const (
// are returned via a scanner.ErrorList which is sorted by file position.
//
func ParseFile(fset *token.FileSet, filename string, src interface{}, mode Mode) (f *ast.File, err error) {
if fset == nil {
panic("parser.ParseFile: no token.FileSet provided (fset == nil)")
}
// get source
text, err := readSource(filename, src)
if err != nil {
@ -125,7 +129,8 @@ func ParseFile(fset *token.FileSet, filename string, src interface{}, mode Mode)
//
// If filter != nil, only the files with os.FileInfo entries passing through
// the filter (and ending in ".go") are considered. The mode bits are passed
// to ParseFile unchanged. Position information is recorded in fset.
// to ParseFile unchanged. Position information is recorded in fset, which
// must not be nil.
//
// If the directory couldn't be read, a nil map and the respective error are
// returned. If a parse error occurred, a non-nil but incomplete map and the
@ -169,9 +174,14 @@ func ParseDir(fset *token.FileSet, path string, filter func(os.FileInfo) bool, m
// ParseExprFrom is a convenience function for parsing an expression.
// The arguments have the same meaning as for Parse, but the source must
// be a valid Go (type or value) expression.
// be a valid Go (type or value) expression. Specifically, fset must not
// be nil.
//
func ParseExprFrom(fset *token.FileSet, filename string, src interface{}, mode Mode) (ast.Expr, error) {
if fset == nil {
panic("parser.ParseExprFrom: no token.FileSet provided (fset == nil)")
}
// get source
text, err := readSource(filename, src)
if err != nil {