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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[BUG] CelValue runtime path mishandles fixed32/fixed64 and FieldMask field access","articleBody":"**Describe the bug**\n\nMy motivation is to build support for protokt (alternate protobuf codegen + runtime) in protovalidate-java, which uses CEL.\n\nI think I've encountered two independent bugs in the planner runtime; both surface when CEL navigates a `com.google.protobuf.Message` whose conversion goes through `ProtoCelValueConverter`: \n\n1. proto `fixed32`/`fixed64` fields resolve as signed int, breaking `uint` overloads: the CEL spec maps proto `fixed32`/`fixed64` to CEL `uint`, and the `CelValue` path via `ProtoCelValueConverter.fromProtoMessageFieldToCelValue` does not: it has cases for `UINT32`/`UINT64` but not `FIXED32`/`FIXED64`, so those fall through to `normalizePrimitive` and surface as `Integer`/`Long`.\n\n2. `FieldMask`-typed fields can't be navigated as messages: `BaseProtoCelValueConverter.fromWellKnownProto` converts `FieldMask` to a comma-separated string of its paths, which is different from cel-go and cel-java's `ProtoLiteAdapter.adaptValueToWellKnownProto`.\n\n**To Reproduce**\nCheck which components this affects:\n\n- [ ]  parser\n- [ ]  checker\n- [x]  runtime\n\nReproducers (in Kotlin to get dependencies inline):\n\n1.\n    ```kotlin\n    @file:Repository(\"https://repo1.maven.org/maven2\")\n    @file:DependsOn(\"dev.cel:cel:0.13.0\")\n    @file:DependsOn(\"com.google.protobuf:protobuf-java:4.30.1\")\n    \n    import com.google.protobuf.DescriptorProtos.DescriptorProto\n    import com.google.protobuf.DescriptorProtos.FieldDescriptorProto\n    import com.google.protobuf.DescriptorProtos.FileDescriptorProto\n    import com.google.protobuf.Descriptors.FileDescriptor\n    import com.google.protobuf.DynamicMessage\n    import dev.cel.bundle.CelFactory\n    import dev.cel.common.types.StructTypeReference\n    \n    // A minimal one-field message: `Msg { fixed32 f = 1; }`, built from a runtime\n    // descriptor so the reproducer needs no .proto compilation.\n    val fileProto =\n        FileDescriptorProto.newBuilder()\n            .setName(\"repro.proto\")\n            .setSyntax(\"proto3\")\n            .addMessageType(\n                DescriptorProto.newBuilder()\n                    .setName(\"Msg\")\n                    .addField(\n                        FieldDescriptorProto.newBuilder()\n                            .setName(\"f\")\n                            .setNumber(1)\n                            .setType(FieldDescriptorProto.Type.TYPE_FIXED32)\n                            .setLabel(FieldDescriptorProto.Label.LABEL_OPTIONAL)\n                    )\n            )\n            .build()\n    \n    val fileDescriptor = FileDescriptor.buildFrom(fileProto, arrayOf())\n    val msgDescriptor = fileDescriptor.findMessageTypeByName(\"Msg\")\n    \n    val cel =\n        CelFactory.plannerCelBuilder()\n            .addMessageTypes(msgDescriptor)\n            .addVar(\"msg\", StructTypeReference.create(\"Msg\"))\n            .build()\n    \n    // The checker types a proto fixed32 field as CEL `uint`; `msg.f \u003e 5u` type-checks.\n    val ast = cel.compile(\"msg.f \u003e 5u\").ast\n    val program = cel.createProgram(ast)\n    \n    val msg =\n        DynamicMessage.newBuilder(msgDescriptor)\n            .setField(msgDescriptor.findFieldByNumber(1), 6)\n            .build()\n    \n    val result = program.eval(mapOf(\"msg\" to msg))\n    println(\"msg.f \u003e 5u  -\u003e  $result\")\n    check(result == true) { \"expected true\" }\n    println(\"OK\")\n    ```\n\n    Throws `dev.cel.runtime.CelEvaluationException: evaluation error at \u003cinput\u003e:6: No matching overload for function '_\u003e_'. Overload candidates: greater_uint64.`. Potential fix: https://github.com/google/cel-java/pull/1073\n\n2. \n    ```kotlin\n    @file:Repository(\"https://repo1.maven.org/maven2\")\n    @file:DependsOn(\"dev.cel:cel:0.13.0\")\n    @file:DependsOn(\"com.google.protobuf:protobuf-java:4.30.1\")\n    \n    import com.google.protobuf.DescriptorProtos.DescriptorProto\n    import com.google.protobuf.DescriptorProtos.FieldDescriptorProto\n    import com.google.protobuf.DescriptorProtos.FileDescriptorProto\n    import com.google.protobuf.Descriptors.FileDescriptor\n    import com.google.protobuf.DynamicMessage\n    import com.google.protobuf.FieldMask\n    import dev.cel.bundle.CelFactory\n    import dev.cel.common.types.StructTypeReference\n    \n    // A minimal one-field message: `Msg { google.protobuf.FieldMask m = 1; }`.\n    val fileProto =\n        FileDescriptorProto.newBuilder()\n            .setName(\"repro.proto\")\n            .setSyntax(\"proto3\")\n            .addDependency(\"google/protobuf/field_mask.proto\")\n            .addMessageType(\n                DescriptorProto.newBuilder()\n                    .setName(\"Msg\")\n                    .addField(\n                        FieldDescriptorProto.newBuilder()\n                            .setName(\"m\")\n                            .setNumber(1)\n                            .setType(FieldDescriptorProto.Type.TYPE_MESSAGE)\n                            .setTypeName(\".google.protobuf.FieldMask\")\n                            .setLabel(FieldDescriptorProto.Label.LABEL_OPTIONAL)\n                    )\n            )\n            .build()\n    \n    val fileDescriptor =\n        FileDescriptor.buildFrom(fileProto, arrayOf(FieldMask.getDescriptor().file))\n    val msgDescriptor = fileDescriptor.findMessageTypeByName(\"Msg\")\n    \n    val cel =\n        CelFactory.plannerCelBuilder()\n            .addMessageTypes(msgDescriptor)\n            .addVar(\"msg\", StructTypeReference.create(\"Msg\"))\n            .build()\n    \n    // `msg.m.paths` selects the repeated `paths` field of the FieldMask.\n    val ast = cel.compile(\"msg.m.paths\").ast\n    val program = cel.createProgram(ast)\n    \n    val msg =\n        DynamicMessage.newBuilder(msgDescriptor)\n            .setField(\n                msgDescriptor.findFieldByNumber(1),\n                FieldMask.newBuilder().addPaths(\"a\").addPaths(\"b\").build()\n            )\n            .build()\n    \n    val result = program.eval(mapOf(\"msg\" to msg))\n    println(\"msg.m.paths  -\u003e  $result\")\n    check(result == listOf(\"a\", \"b\")) { \"expected [a, b]\" }\n    println(\"OK\")\n    ```\n\n    Throws `dev.cel.runtime.CelEvaluationException: evaluation error at \u003cinput\u003e:5: Error resolving field 'paths'. Field selections must be performed on messages or maps.`. Potential fix: https://github.com/google/cel-java/pull/1074\n\n**Additional context**\nFor the full context see https://github.com/bufbuild/protovalidate-java/pull/202 and https://github.com/open-toast/protokt/pull/402\n","author":{"url":"https://github.com/andrewparmet","@type":"Person","name":"andrewparmet"},"datePublished":"2026-06-02T16:11:59.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/1075/cel-java/issues/1075"}