Fix panic that can occur when interpreting options in lenient mode (#331)

The panic fix is tiny. But this commit is bigger because other
changes/improvements were called for: most of the code changes are to
improve error handling when in lenient mode. After I fixed the panic,
the test case was failing in a different way, due to an issue with how
errors (even in lenient mode) were still being passed to an error
reporter and causing the stage to fail.

This issue was introduced in #279. That PR moved things around, pushing
the responsibility of calling `interp.reporter.HandleError` down, so
that interpreting a single option could potentially report multiple
errors (instead of failing fast and only reporting the first).

But when in lenient mode, we don't actually want to send those errors to
the reporter: sending the error to the reporter meant the error would
get memoized and then returned in subsequent handle calls, which could
cause the process to fail when it should be lenient and also can cause
it to report the wrong error in lenient mode. So now we demarcate the
parts of the process where errors are tolerated (i.e. where lenience
mode is actually activated) with a new field on the interpreter that is
examined when errors are reported.

Author: jhump

internal/options.go

@@ -18,23 +18,24 @@ import (
 	"google.golang.org/protobuf/types/descriptorpb"
 
 	"github.com/bufbuild/protocompile/ast"
-	"github.com/bufbuild/protocompile/reporter"
 )
 
 type hasOptionNode interface {
 	OptionNode(part *descriptorpb.UninterpretedOption) ast.OptionDeclNode
 	FileNode() ast.FileDeclNode // needed in order to query for NodeInfo
 }
 
-func FindFirstOption(res hasOptionNode, handler *reporter.Handler, scope string, opts []*descriptorpb.UninterpretedOption, name string) (int, error) {
+type errorHandler func(span ast.SourceSpan, format string, args ...interface{}) error
+
+func FindFirstOption(res hasOptionNode, handler errorHandler, scope string, opts []*descriptorpb.UninterpretedOption, name string) (int, error) {
 	return findOption(res, handler, scope, opts, name, false, true)
 }
 
-func FindOption(res hasOptionNode, handler *reporter.Handler, scope string, opts []*descriptorpb.UninterpretedOption, name string) (int, error) {
+func FindOption(res hasOptionNode, handler errorHandler, scope string, opts []*descriptorpb.UninterpretedOption, name string) (int, error) {
 	return findOption(res, handler, scope, opts, name, true, false)
 }
 
-func findOption(res hasOptionNode, handler *reporter.Handler, scope string, opts []*descriptorpb.UninterpretedOption, name string, exact, first bool) (int, error) {
+func findOption(res hasOptionNode, handler errorHandler, scope string, opts []*descriptorpb.UninterpretedOption, name string, exact, first bool) (int, error) {
 	found := -1
 	for i, opt := range opts {
 		if exact && len(opt.Name) != 1 {
@@ -51,7 +52,7 @@ func findOption(res hasOptionNode, handler *reporter.Handler, scope string, opts
 			fn := res.FileNode()
 			node := optNode.GetName()
 			nodeInfo := fn.NodeInfo(node)
-			return -1, handler.HandleErrorf(nodeInfo, "%s: option %s cannot be defined more than once", scope, name)
+			return -1, handler(nodeInfo, "%s: option %s cannot be defined more than once", scope, name)
 		}
 		found = i
 	}

options/options.go

@@ -129,6 +129,16 @@ func TestOptionsInUnlinkedFiles(t *testing.T) {
 				assert.Equal(t, "foo.bar", fd.GetOptions().GetGoPackage())
 			},
 		},
+		{
+			name:     "file options, not custom",
+			contents: `option go_package = "foo.bar"; option must_link = "FOO";`,
+			uninterpreted: map[string]interface{}{
+				"test.proto:must_link": "FOO",
+			},
+			checkInterpreted: func(t *testing.T, fd *descriptorpb.FileDescriptorProto) {
+				assert.Equal(t, "foo.bar", fd.GetOptions().GetGoPackage())
+			},
+		},
 		{
 			name:     "message options",
 			contents: `message Test { option (must.link) = 1.234; option deprecated = true; }`,
@@ -244,6 +254,25 @@ func TestOptionsInUnlinkedFiles(t *testing.T) {
 	}
 }
 
+func TestOptionsInUnlinkedFileInvalid(t *testing.T) {
+	t.Parallel()
+	h := reporter.NewHandler(nil)
+	ast, err := parser.Parse(
+		"test.proto",
+		strings.NewReader(
+			`syntax = "proto2";
+			    package foo;
+			    option malformed_non_existent = true;
+			    option features.utf8_validation = NONE;`,
+		), h)
+	require.NoError(t, err, "failed to parse")
+	res, err := parser.ResultFromAST(ast, false, h)
+	require.NoError(t, err, "failed to produce descriptor proto")
+	_, err = options.InterpretUnlinkedOptions(res)
+	require.ErrorContains(t, err,
+		`test.proto:4:29: field "google.protobuf.FeatureSet.utf8_validation" was not introduced until edition 2023`)
+}
+
 func buildUninterpretedMapForFile(fd *descriptorpb.FileDescriptorProto, opts map[string]interface{}) {
 	buildUninterpretedMap(fd.GetName(), fd.GetOptions().GetUninterpretedOption(), opts)
 	for _, md := range fd.GetMessageType() {

options/options_test.go

@@ -686,7 +686,7 @@ func (r *result) addMessageBody(msgd *descriptorpb.DescriptorProto, body *ast.Me
 
 func (r *result) isMessageSetWireFormat(scope string, md *descriptorpb.DescriptorProto, handler *reporter.Handler) (*descriptorpb.UninterpretedOption, error) {
 	uo := md.GetOptions().GetUninterpretedOption()
-	index, err := internal.FindOption(r, handler, scope, uo, "message_set_wire_format")
+	index, err := internal.FindOption(r, handler.HandleErrorf, scope, uo, "message_set_wire_format")
 	if err != nil {
 		return nil, err
 	}

parser/result.go

@@ -112,7 +112,7 @@ func validateNoFeatures(res *result, syntax protoreflect.Syntax, scope string, o
 		// Editions is allowed to use features
 		return nil
 	}
-	if index, err := internal.FindFirstOption(res, handler, scope, opts, "features"); err != nil {
+	if index, err := internal.FindFirstOption(res, handler.HandleErrorf, scope, opts, "features"); err != nil {
 		return err
 	} else if index >= 0 {
 		optNode := res.OptionNode(opts[index])
@@ -135,7 +135,7 @@ func validateMessage(res *result, syntax protoreflect.Syntax, name protoreflect.
 		}
 	}
 
-	if index, err := internal.FindOption(res, handler, scope, md.Options.GetUninterpretedOption(), "map_entry"); err != nil {
+	if index, err := internal.FindOption(res, handler.HandleErrorf, scope, md.Options.GetUninterpretedOption(), "map_entry"); err != nil {
 		return err
 	} else if index >= 0 {
 		optNode := res.OptionNode(md.Options.GetUninterpretedOption()[index])
@@ -331,7 +331,7 @@ func validateEnum(res *result, syntax protoreflect.Syntax, name protoreflect.Ful
 
 	allowAlias := false
 	var allowAliasOpt *descriptorpb.UninterpretedOption
-	if index, err := internal.FindOption(res, handler, scope, ed.Options.GetUninterpretedOption(), "allow_alias"); err != nil {
+	if index, err := internal.FindOption(res, handler.HandleErrorf, scope, ed.Options.GetUninterpretedOption(), "allow_alias"); err != nil {
 		return err
 	} else if index >= 0 {
 		allowAliasOpt = ed.Options.UninterpretedOption[index]
@@ -481,7 +481,7 @@ func validateField(res *result, syntax protoreflect.Syntax, name protoreflect.Fu
 					return err
 				}
 			}
-			if index, err := internal.FindOption(res, handler, scope, fld.Options.GetUninterpretedOption(), "packed"); err != nil {
+			if index, err := internal.FindOption(res, handler.HandleErrorf, scope, fld.Options.GetUninterpretedOption(), "packed"); err != nil {
 				return err
 			} else if index >= 0 {
 				optNode := res.OptionNode(fld.Options.GetUninterpretedOption()[index])
@@ -491,7 +491,7 @@ func validateField(res *result, syntax protoreflect.Syntax, name protoreflect.Fu
 				}
 			}
 		} else if syntax == protoreflect.Proto3 {
-			if index, err := internal.FindOption(res, handler, scope, fld.Options.GetUninterpretedOption(), "default"); err != nil {
+			if index, err := internal.FindOption(res, handler.HandleErrorf, scope, fld.Options.GetUninterpretedOption(), "default"); err != nil {
 				return err
 			} else if index >= 0 {
 				optNode := res.OptionNode(fld.Options.GetUninterpretedOption()[index])

parser/validate.go

@@ -39,31 +39,36 @@ type ErrorWithPos interface {
 
 // Error creates a new ErrorWithPos from the given error and source position.
 func Error(span ast.SourceSpan, err error) ErrorWithPos {
-	return errorWithSpan{SourceSpan: span, underlying: err}
+	var ewp ErrorWithPos
+	if errors.As(err, &ewp) {
+		// replace existing position with given one
+		return &errorWithSpan{SourceSpan: span, underlying: ewp.Unwrap()}
+	}
+	return &errorWithSpan{SourceSpan: span, underlying: err}
 }
 
 // Errorf creates a new ErrorWithPos whose underlying error is created using the
 // given message format and arguments (via fmt.Errorf).
 func Errorf(span ast.SourceSpan, format string, args ...interface{}) ErrorWithPos {
-	return errorWithSpan{SourceSpan: span, underlying: fmt.Errorf(format, args...)}
+	return Error(span, fmt.Errorf(format, args...))
 }
 
 type errorWithSpan struct {
 	ast.SourceSpan
 	underlying error
 }
 
-func (e errorWithSpan) Error() string {
+func (e *errorWithSpan) Error() string {
 	sourcePos := e.GetPosition()
 	return fmt.Sprintf("%s: %v", sourcePos, e.underlying)
 }
 
-func (e errorWithSpan) GetPosition() ast.SourcePos {
+func (e *errorWithSpan) GetPosition() ast.SourcePos {
 	return e.Start()
 }
 
-func (e errorWithSpan) Unwrap() error {
+func (e *errorWithSpan) Unwrap() error {
 	return e.underlying
 }
 
-var _ ErrorWithPos = errorWithSpan{}
+var _ ErrorWithPos = (*errorWithSpan)(nil)

reporter/errors.go

@@ -153,13 +153,7 @@ func (h *Handler) HandleError(err error) error {
 // call to HandleError or HandleErrorf), that same error is returned and the
 // given error is not reported.
 func (h *Handler) HandleErrorWithPos(span ast.SourceSpan, err error) error {
-	if ewp, ok := err.(ErrorWithPos); ok {
-		// replace existing position with given one
-		err = errorWithSpan{SourceSpan: span, underlying: ewp.Unwrap()}
-	} else {
-		err = errorWithSpan{SourceSpan: span, underlying: err}
-	}
-	return h.HandleError(err)
+	return h.HandleError(Error(span, err))
 }
 
 // HandleErrorf handles an error with the given source position, creating the
@@ -191,14 +185,7 @@ func (h *Handler) HandleWarning(err ErrorWithPos) {
 // HandleWarningWithPos handles a warning with the given source position. This will
 // delegate to the handler's configured reporter.
 func (h *Handler) HandleWarningWithPos(span ast.SourceSpan, err error) {
-	ewp, ok := err.(ErrorWithPos)
-	if ok {
-		// replace existing position with given one
-		ewp = errorWithSpan{SourceSpan: span, underlying: ewp.Unwrap()}
-	} else {
-		ewp = errorWithSpan{SourceSpan: span, underlying: err}
-	}
-	h.HandleWarning(ewp)
+	h.HandleWarning(Error(span, err))
 }
 
 // HandleWarningf handles a warning with the given source position, creating the