[1.3] The default null values from the Thermostat cluster are not correctly set

[kkasperczyk-no]

Reproduction steps

It seems that the default NULL value for the attributes from Thermostat cluster like LocalTemperature or OutdoorTemperature is not correctly set. I have this attributes filled with NULL value in the .zap file and I have not modified them in my application, but the IsNull check returns false and the value is 0.

Even more interesting is that after performing read operation for these attributes using CHIPTool I got:

[1715586371.626553][74241:74243] CHIP:DMG: ReportDataMessage =
[1715586371.626561][74241:74243] CHIP:DMG: {
[1715586371.626567][74241:74243] CHIP:DMG: AttributeReportIBs =
[1715586371.626579][74241:74243] CHIP:DMG: [
[1715586371.626585][74241:74243] CHIP:DMG: AttributeReportIB =
[1715586371.626596][74241:74243] CHIP:DMG: {
[1715586371.626602][74241:74243] CHIP:DMG: AttributeDataIB =
[1715586371.626610][74241:74243] CHIP:DMG: {
[1715586371.626618][74241:74243] CHIP:DMG: DataVersion = 0x6972abdc,
[1715586371.626625][74241:74243] CHIP:DMG: AttributePathIB =
[1715586371.626633][74241:74243] CHIP:DMG: {
[1715586371.626641][74241:74243] CHIP:DMG: Endpoint = 0x1,
[1715586371.626649][74241:74243] CHIP:DMG: Cluster = 0x201,
[1715586371.626657][74241:74243] CHIP:DMG: Attribute = 0x0000_0001,
[1715586371.626664][74241:74243] CHIP:DMG: }
[1715586371.626674][74241:74243] CHIP:DMG:
[1715586371.626684][74241:74243] CHIP:DMG: Data = -1,
[1715586371.626690][74241:74243] CHIP:DMG: },
[1715586371.626705][74241:74243] CHIP:DMG:
[1715586371.626714][74241:74243] CHIP:DMG: },
[1715586371.626730][74241:74243] CHIP:DMG:
[1715586371.626738][74241:74243] CHIP:DMG: ],
[1715586371.626753][74241:74243] CHIP:DMG:
[1715586371.626762][74241:74243] CHIP:DMG: SuppressResponse = true,
[1715586371.626772][74241:74243] CHIP:DMG: InteractionModelRevision = 11
[1715586371.626781][74241:74243] CHIP:DMG: }
[1715586371.626848][74241:74243] CHIP:TOO: Endpoint: 1 Cluster: 0x0000_0201 Attribute 0x0000_0001 DataVersion: 1769122780
[1715586371.626868][74241:74243] CHIP:TOO: OutdoorTemperature: -1

I don't know when the behavior changed, but on the 1.2.0.1 tag it was working fine, and the read value in the CHIPTool was null.

It can be worked around by setting null value to these attributes on init and then read works as expected, but this is probably not the best solution.

Bug prevalence

Always

GitHub hash of the SDK that was being used

v1.3.0.0 tag

Platform

core

Platform Version(s)

1.3

Type

Spec Compliance Issue

Anything else?

No response

[bzbarsky-apple]

The XML says: type="temperature"

The type definition says: <type id="0xD8" description="Temperature" name="temperature" size="2" analog="true" signed="true" />

The ZAP output for that null default is 0xFFFF, which is NOT how one represents null for a signed 2-byte type.

This needs to be fixed in https://github.com/project-chip/zap/issues

Looks like #30758 changed the type in the XML from int16s to temperature, and we have no useful test coverage.