Allow expression-only custom protovalidate rules (#4152)

Author: bufdev

CHANGELOG.md

@@ -13,6 +13,8 @@
 - Add `textDocument/documentSymbol` support for `buf lsp serve`.
 - Fix LSP navigation for cached modules which could cause import paths to become unresolvable.
 - Update default value of `--timeout` flag to 0, which results in no timeout by default.
+- Update `PROTOVALIDATE` lint rule to allow for custom rules that do not have `id` or `message`
+  fields.
 
 ## [v1.59.0] - 2025-10-20
 

private/bufpkg/bufcheck/bufcheckserver/internal/buflintvalidate/cel.go

@@ -145,8 +145,6 @@ func checkCEL(
 				break
 			}
 			idToConstraintIndices[celID] = append(idToConstraintIndices[celID], i)
-		} else {
-			add(i, "%s has an empty %s.id. IDs should always be specified.", parentNameCapitalized, celName)
 		}
 		if len(strings.TrimSpace(celConstraint.GetExpression())) == 0 {
 			add(i, "%s has an empty %s.expression. Expressions should always be specified.", parentNameCapitalized, celName)
@@ -155,14 +153,6 @@ func checkCEL(
 		ast, compileIssues := celEnv.Compile(celConstraint.GetExpression())
 		switch {
 		case ast.OutputType().IsAssignableType(cel.BoolType):
-			if celConstraint.GetMessage() == "" {
-				add(
-					i,
-					"%s has an empty %s.message for an expression that evaluates to a boolean. If an expression evaluates to a boolean, a message should always be specified.",
-					parentNameCapitalized,
-					celName,
-				)
-			}
 		case ast.OutputType().IsAssignableType(cel.StringType):
 			if celConstraint.GetMessage() != "" {
 				add(

private/bufpkg/bufcheck/lint_test.go

@@ -627,14 +627,12 @@ func TestRunProtovalidate(t *testing.T) {
 		bufanalysistesting.NewFileAnnotation(t, "cel_field.proto", 116, 5, 120, 6, "PROTOVALIDATE"),
 		bufanalysistesting.NewFileAnnotation(t, "cel_field.proto", 156, 5, 160, 6, "PROTOVALIDATE"),
 		bufanalysistesting.NewFileAnnotation(t, "cel_message.proto", 22, 3, 26, 5, "PROTOVALIDATE"),
-		bufanalysistesting.NewFileAnnotation(t, "cel_message.proto", 28, 3, 32, 5, "PROTOVALIDATE"),
 		bufanalysistesting.NewFileAnnotation(t, "cel_message.proto", 34, 3, 38, 5, "PROTOVALIDATE"),
 		bufanalysistesting.NewFileAnnotation(t, "cel_message.proto", 40, 3, 44, 5, "PROTOVALIDATE"),
 		bufanalysistesting.NewFileAnnotation(t, "cel_message.proto", 46, 3, 50, 5, "PROTOVALIDATE"),
 		bufanalysistesting.NewFileAnnotation(t, "cel_message.proto", 52, 3, 56, 5, "PROTOVALIDATE"),
 		bufanalysistesting.NewFileAnnotation(t, "cel_message.proto", 58, 3, 62, 5, "PROTOVALIDATE"),
 		bufanalysistesting.NewFileAnnotation(t, "cel_message.proto", 58, 3, 62, 5, "PROTOVALIDATE"),
-		bufanalysistesting.NewFileAnnotation(t, "cel_message.proto", 64, 3, 68, 5, "PROTOVALIDATE"),
 		bufanalysistesting.NewFileAnnotation(t, "cel_message.proto", 70, 3, 74, 5, "PROTOVALIDATE"),
 		bufanalysistesting.NewFileAnnotation(t, "cel_message.proto", 76, 3, 80, 5, "PROTOVALIDATE"),
 		bufanalysistesting.NewFileAnnotation(t, "cel_message.proto", 82, 5, 86, 7, "PROTOVALIDATE"),

private/bufpkg/bufcheck/testdata/lint/protovalidate/proto/cel_message.proto

@@ -24,7 +24,7 @@ message MessageTest {
     message: "message",
     expression: "this == this"
   };
-  // empty id
+  // empty id UPDATE this is now OK
   option (buf.validate.message).cel = {
     id: "",
     message: "message",
@@ -60,7 +60,7 @@ message MessageTest {
     message: "uh",
     expression: "foo + bar",
   };
-  // missing message with a bool expression
+  // missing message with a bool expression UPDATE: this is now OK
   option (buf.validate.message).cel = {
     id: "id5",
     message: "",