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pxf: write an Any as a body only when the body gives back the same bytes (protowire#501) #168
Description
trendvidia/protowire#501 (decided by the owner): a PXF encoder must write an Any as a type entry and body only when decoding that body gives exactly the stored value bytes. Otherwise it writes type_url and value. How it checks is the port's choice, and writing every Any raw conforms. Draft -01 § Any Blocks.
Why. A reader compares an Any by its bytes. A body that decodes to other bytes changes the message with no error. protowire-go's encoder changed 159,728 of 300,000 fuzzed Any values before protowire-go#232.
Cases that differ (measured on protowire-go): unknown fields at any level, field or map order, explicitly written zeros, a Timestamp no literal holds, and an unset @default or @required field. A chain of Anys past MaxNestingDepth should also come out raw rather than unreadable.
Not measured in this port, in either tier.
Done when: a test writes an Any holding each case above and reads the PXF back to the same value bytes.
Activity
bfrancojr commentedon Nov 3, 2026
Duplicate of #150 (filed earlier, same rule). This one adds the spec's wording from trendvidia/protowire#516. Either can be kept.
bfrancojr commentedon Nov 3, 2026
Status, 2026-11-03.
Full tier: done-when met.
AnyBodyReadBackTest(from #151, which fixed #150) writes an Any for each case listed here and reads the PXF back, with both decoders, to the same message:@defaultand an unset@requiredfield.aChainStopsAtTheDepthLimitandaChainPastTheLimitIsNotWalkedcover a chain of Anys pastMaxNestingDepth. #174 adds a test that an Any whose body would go past the limit stays astype_urlandvalue.Lite tier: can't be tested yet. The lite tier has no type resolver, so it writes every Any raw, which the rule allows. But I tried to add a lite test, and a lite schema with a
google.protobuf.Anyfield does not compile: the plugin referencescom.google.protobuf.AnyPxfMeta, which is never generated. Filed as trendvidia/protowire#539.Leaving this open until #539 lets the lite test run. Or close it as a duplicate of #150 if you'd rather track the lite half on #539 alone.
pxf-runtime: ship companions for google.protobuf Any, Struct and kin …