rpc/jsonrpc: keep trace_call's unrequested trace empty and stop attaching the tracer for stateDiff - #23572
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trace_call returned the full call trace for stateDiff-only and vmTrace-only requests. Call was the only ad-hoc path missing the final reset that doCall, doCallBlock and RawTransaction all have. The reset is not redundant: the OE tracer appends call frames to the result regardless of the requested trace types, so a vmTrace-only request fills Trace as a side effect. The field stays an empty array rather than null. That is what OpenEthereum returns, what the other trace_* endpoints already return, and what cmd/rpcdaemon/postman/Trace_Testing.json asserts.
Call and RawTransaction attached the tracer for stateDiff-only requests as well, collecting a trace they then discard. doCall and doCallBlock already attach it only for trace and vmTrace. Both also passed the tracer hooks to the EVM unconditionally. With an empty trace-type list the tracer has no result to write into, so the first OnEnter dereferenced a nil pointer and the request failed with "method handler crashed". Reachable on trace_call and on trace_rawTransaction. Both paths now build a vm.Config the way the sibling paths do, so the hooks exist only when a trace is actually collected. parseOeTracerConfig stays outside the branch: trace_* must keep rejecting custom tracers whatever the requested trace types are.
ReplayTransaction built and populated a TraceCallResult that it never returned. doCall already rejects unrecognized trace types, so dropping the block keeps the error behaviour, now covered by a test. The trace docs said unrequested trace types are null. That holds for stateDiff and vmTrace but not for trace, which is an empty array.
lupin012
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August 27, 2026 08:53
lupin012
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AskAlexSharov,
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lystopad,
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yperbasis
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August 27, 2026 08:53
AskAlexSharov
approved these changes
Aug 27, 2026
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Closes #23326.
The report expected an unrequested
traceto benull; the reporter withdrew that, sincetracefollows OpenEthereum'sTraceResults.trace: Vec<Trace>and is an array, nevernull. The captured response shows the real defect: with["stateDiff"]thetracefield carries the full call trace.Three defects, all present on
release/3.6too:tracepopulated when not requested. With["stateDiff"]or["vmTrace"],trace_callreturns the full call trace.Callwas the only ad-hoc path missing the final reset thatdoCall,doCallBlockandRawTransactionhave.stateDiff-only requests.CallandRawTransactionattached it for all three trace types, collecting a trace they then discard.OnEnternil-dereferenced. Recovered per request, so the client getsmethod handler crashed. Reachable ontrace_callandtrace_rawTransaction.Changes
Call: resetTracewhentracewas not requested. Still needed after the tracer change, because the OE tracer appends call frames regardless of the requested types, sovmTrace-only fillsTraceas a side effect.CallandRawTransaction: build avm.Configlike the sibling paths, so the hooks exist only when a trace is collected. Closes both the wasted work and the panic.parseOeTracerConfigstays outside the branch, so custom tracers keep being rejected for any trace types.ReplayTransaction: drop aTraceCallResultit built, populated and never returned.doCallalready rejects unrecognized trace types.null, true forstateDiffandvmTracebut not fortrace.Behaviour change
trace_callwith["stateDiff"]or["vmTrace"]now returns"trace": []. This matches OpenEthereum, the othertrace_*endpoints, andcmd/rpcdaemon/postman/Trace_Testing.json, whose"trace_call - stateDiff only"case expects"trace": []and fails against the current code.Tests
Regression coverage for the three defects, plus non-regression on
["trace"], ontracecombined with the other types, and on a custom tracer rejected for astateDiff-only request.Also verified over HTTP with the old and new
rpcdaemonside by side against one dev-chain node:traceTypes["stateDiff"],["vmTrace"],["vmTrace","stateDiff"]tracelength 1tracelength 0[]method handler crashedtracelength 0["trace"],["trace","stateDiff"]tracelength 1tracelength 1trace_rawTransactionwith[]goes frommethod handler crashedto"trace": []; with["stateDiff"]it was already correct.