[Dart] Enums with "bit_flags" cannot be used as bit flags

[jakobkordez]

Reading a bit_flags enum where multiple values are set throws an exception:

Unhandled exception:
RangeError (byteOffset): Index out of range: no indices are valid: 3
#0      _byteDataByteOffsetCheck (dart:typed_data-patch/typed_data_patch.dart:5419:5)
#1      _ByteDataView.getUint32 (dart:typed_data-patch/typed_data_patch.dart:5191:5)
#2      BufferContext._getUint32 (package:flat_buffers/flat_buffers.dart:68:41)
#3      BufferContext.derefObject (package:flat_buffers/flat_buffers.dart:40:43)
#4      TableReader.read (package:flat_buffers/flat_buffers.dart:1119:29)
...

Schema:

enum DigitalInputs: ubyte (bit_flags) {
    DI_CLK1,
    DI_CLK2,
    DI_S1,
    DI_S2,
}

table Holder {
    digital_inputs: DigitalInputs;
}

[kendegemaro]

According to the FlatBuffers Docs, this appears to be intended to me on the first look.

the values of this field indicate bits, meaning that any unsigned value N specified in the schema will end up representing 1<<N, or if you don't specify values at all, you'll get the sequence 1, 2, 4, 8, ...

In your case, this means the following:
DI_CLK1 = 1
DI_CLK2 = 2
DI_S1 = 4
DI_S2 = 8

If I understood you correctly, with "multiple values", e.g. 0b00000011, you get digital_inputs = 3 and the enum cannot be resolved to any of the defined values in DigitalInputs. Did you assign this value to your buffer using the FlatBuffers Library? Do you verify your buffer before/while you are reading it?

[jakobkordez]

This buffer was generated (DigitalInputs::DI_CLK1 | DigitalInputs::DI_CLK2) and verified in C++, then saved to a binary file and read in Dart.

Dart does not generate any verificaiton functions.