docs: clarify when to use assert vs Assert vs Assume vs CHECK_NONFATAL - #7615
docs: clarify when to use assert vs Assert vs Assume vs CHECK_NONFATAL#7615PastaPastaPasta wants to merge 1 commit into
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WalkthroughAdded assertion and check guidance to Estimated code review effort: 1 (Trivial) | ~5 minutes Merge Risk: 🔵 Low · up to The documentation change is mergeable with owner awareness, but it should clarify failed Suggested reviewers: 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
✨ Finishing Touches🧪 Generate unit tests (beta)
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Actionable comments posted: 2
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Inline comments:
In `@AGENTS.md`:
- Around line 32-38: Update the Assume release-behavior wording from “a silent
no-op in release” to “a failed Assume is silent in release” in AGENTS.md lines
32-38 and CLAUDE.md lines 32-38, preserving the statement that the expression is
always evaluated.
In `@doc/developer-notes.md`:
- Around line 468-500: Update the RPC assertion-linter guidance in the section
describing test/lint/lint-assertions.py to state that it only checks
single-line, semicolon-terminated assertion statements and excludes
src/rpc/server.cpp. Clarify that the lint does not reject every assert, Assert,
or Assume use under src/rpc/ and src/wallet/rpc*.
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AGENTS.mdCLAUDE.mddoc/developer-notes.md
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| persisted/consensus state - aborting has to be the safer outcome. It should | ||
| be rare and obviously justified, but do use it where it is genuinely needed | ||
| to document and enforce a precondition that keeps the code below it safe. | ||
| `Assert` returns its argument, so prefer it when you need the value. |
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| `Assert` returns its argument, so prefer it when you need the value. | |
| `Assert` returns its argument: `assert(ptr != nullptr); obj = *ptr;` becomes `obj = *Assert(ptr);` |
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I think when you need the valule is a bit wide definition. Any better options for wording?
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Applied your suggestion verbatim in AGENTS.md/CLAUDE.md (12e6389). Agreed "when you need the value" was too broad — the transformation example states it precisely, so doc/developer-notes.md now uses the same example-based wording: a check followed by a use of the checked value collapses into one expression.
🤖 Posted autonomously by Claude on behalf of pasta.
| persisted/consensus state - aborting has to be the safer outcome. It should | ||
| be rare and obviously justified, but do use it where it is genuinely needed | ||
| to document and enforce a precondition that keeps the code below it safe. | ||
| `Assert` returns its argument, so prefer it when you need the value. |
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| `Assert` returns its argument, so prefer it when you need the value. | |
| `Assert` returns its argument: `assert(ptr != nullptr); obj = *ptr;` becomes `obj = *Assert(ptr);` |
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Applied verbatim in 12e6389 (kept identical across AGENTS.md/CLAUDE.md).
🤖 Posted autonomously by Claude on behalf of pasta.
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The existing "Assertions and Checks" section lists the helpers in src/util/check.h but does not say which one to reach for by default, so new code picks assert() for invariants that are merely suspicious, and a violated bookkeeping assumption becomes a node crash. Rewrite the section around the cost of continuing: Assume is the default for "this is how things are supposed to be", assert/Assert is reserved for cases where continuing means undefined behavior or corrupt persisted state, and CHECK_NONFATAL covers logic bugs on paths with a caller to report to. Document the build/CI behavior of ABORT_ON_FAILED_ASSUME and that assertions must never validate peer, RPC or on-disk input. Add a matching summary to the agent guides and a TOC entry for the section.
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Final validation — Codex/Sol only (Phase 2 disabled)
The PR substantially improves Dash Core's assertion guidance, but two statements remain broad enough to misdirect contributors: the mandatory RPC rule includes non-request lifecycle code, and mere reachability from external input is described as a remote crash. The release-build description of Assume should also include the compiler optimization caveat already documented upstream.
Source: codex general reviewer backend gpt-5.6-sol; codex dash-core-commit-history reviewer backend gpt-5.6-sol; final verifier backend gpt-5.6-sol. openclaw-agent/cliproxy/gpt-5.6-sol is orchestration-only and not reviewer evidence.
Validated zero-blocker Codex/Sol precheck evidence was promoted to final because Phase 2 (Sonnet/Opus) is temporarily disabled. This is Codex/Sol-only final validation, not Codex + Sonnet/Opus coverage.
Review provenance
- Codex reviewers:
gpt-5.6-sol— general (completed),gpt-5.6-sol— dash-core-commit-history (completed) - Verifier:
gpt-5.6-sol— verifier - Sonnet/Opus: not run (Phase 2 disabled — temporary Codex/Sol-only final)
- Secondary pass: disabled (
temporary_phase2_sonnet_disable)
🟡 2 suggestion(s) | 💬 1 nitpick(s)
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These findings are from an automated code review. Verify each finding against the current code and only fix it if needed.
In `doc/developer-notes.md`:
- [SUGGESTION] doc/developer-notes.md:488-493: Limit the mandatory nonfatal-check rule to request-facing RPC paths
The unconditional rule for all RPC code conflicts with the repository's intentional lifecycle exception. `test/lint/lint-assertions.py` excludes `src/rpc/server.cpp`, where `StopRPC()` and `SetRPCWarmupFinished()` use assertions for initialization and shutdown invariants. Those functions do not run under an RPC request boundary that can convert `NonFatalCheckError` into a response, so replacing their assertions with throwing checks would not report anything to an RPC caller and could instead propagate an exception during startup or shutdown. State the requirement for request-facing RPC paths and mirror that qualification in `AGENTS.md` and `CLAUDE.md`.
- [SUGGESTION] doc/developer-notes.md:495-503: Describe attacker control rather than mere assertion reachability
An assertion is remotely triggerable only when external input can make its condition false, not merely because execution reaches it while processing that input. The preceding `ConnectBlock()` example demonstrates this distinction: peer block processing reaches `assert(pindex)`, but the peer does not control the internally supplied pointer. Wallet files and arbitrary on-disk corruption are likewise local inputs unless an attacker controlled the persisted data. The current wording could lead contributors to remove valid internal precondition checks from validation and Dash-specific paths without first tracing whether untrusted input can violate the invariant. Apply the same distinction to the condensed guidance in `AGENTS.md` and `CLAUDE.md`.
- [NITPICK] doc/developer-notes.md:465-472: Document optimization of side-effect-free Assume expressions
In a release build, `inline_assertion_check<false>` only forwards its argument and the returned value is normally discarded. Under the as-if rule, the compiler may therefore eliminate a side-effect-free expression and the call entirely. Saying the expression is always evaluated in every build can incorrectly imply guaranteed runtime evaluation and cost. Bitcoin Core's current developer notes explicitly document this caveat; the condensed claim in `AGENTS.md` and `CLAUDE.md` should be updated at the same time.
| * `CHECK_NONFATAL` / `NONFATAL_UNREACHABLE` report internal logic bugs to a | ||
| caller: they throw `NonFatalCheckError`, which RPC code catches and turns | ||
| into an error message asking the user to file a bug report, and the node | ||
| keeps running. Mandatory in RPC code, enforced (best-effort) by | ||
| `test/lint/lint-assertions.py` for `src/rpc/` and `src/wallet/rpc*`; use | ||
| `NONFATAL_UNREACHABLE()` instead of `assert(false)` there. |
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🟡 Suggestion: Limit the mandatory nonfatal-check rule to request-facing RPC paths
The unconditional rule for all RPC code conflicts with the repository's intentional lifecycle exception. test/lint/lint-assertions.py excludes src/rpc/server.cpp, where StopRPC() and SetRPCWarmupFinished() use assertions for initialization and shutdown invariants. Those functions do not run under an RPC request boundary that can convert NonFatalCheckError into a response, so replacing their assertions with throwing checks would not report anything to an RPC caller and could instead propagate an exception during startup or shutdown. State the requirement for request-facing RPC paths and mirror that qualification in AGENTS.md and CLAUDE.md.
| * `CHECK_NONFATAL` / `NONFATAL_UNREACHABLE` report internal logic bugs to a | |
| caller: they throw `NonFatalCheckError`, which RPC code catches and turns | |
| into an error message asking the user to file a bug report, and the node | |
| keeps running. Mandatory in RPC code, enforced (best-effort) by | |
| `test/lint/lint-assertions.py` for `src/rpc/` and `src/wallet/rpc*`; use | |
| `NONFATAL_UNREACHABLE()` instead of `assert(false)` there. | |
| * `CHECK_NONFATAL` / `NONFATAL_UNREACHABLE` report internal logic bugs to a | |
| caller: they throw `NonFatalCheckError`, which request-facing RPC dispatch | |
| catches and turns into an error message asking the user to file a bug report, | |
| and the node keeps running. Required on request-facing RPC paths, enforced | |
| (best-effort) by `test/lint/lint-assertions.py` for `src/rpc/` and | |
| `src/wallet/rpc*`; use `NONFATAL_UNREACHABLE()` instead of `assert(false)` | |
| there. |
source: ['codex']
| An assertion reachable from P2P messages, RPC arguments, wallet files, or | ||
| on-disk data is a remote crash. This cuts especially deep in Dash-specific | ||
| code: masternode, LLMQ, InstantSend, ChainLocks, governance and CoinJoin paths | ||
| process peer-chosen message contents and read state (EvoDB, quorum caches, DKG | ||
| sessions) possibly written by an older or buggy version. There, validate and | ||
| reject (misbehaving peer, `state.Invalid(...)`, early return) rather than | ||
| assert; use `Assume` for our *own* bookkeeping while still handling the | ||
| violated case; and reserve `assert` for the narrow spot where continuing would | ||
| corrupt EvoDB, the block index, or the wallet. |
There was a problem hiding this comment.
🟡 Suggestion: Describe attacker control rather than mere assertion reachability
An assertion is remotely triggerable only when external input can make its condition false, not merely because execution reaches it while processing that input. The preceding ConnectBlock() example demonstrates this distinction: peer block processing reaches assert(pindex), but the peer does not control the internally supplied pointer. Wallet files and arbitrary on-disk corruption are likewise local inputs unless an attacker controlled the persisted data. The current wording could lead contributors to remove valid internal precondition checks from validation and Dash-specific paths without first tracing whether untrusted input can violate the invariant. Apply the same distinction to the condensed guidance in AGENTS.md and CLAUDE.md.
| An assertion reachable from P2P messages, RPC arguments, wallet files, or | |
| on-disk data is a remote crash. This cuts especially deep in Dash-specific | |
| code: masternode, LLMQ, InstantSend, ChainLocks, governance and CoinJoin paths | |
| process peer-chosen message contents and read state (EvoDB, quorum caches, DKG | |
| sessions) possibly written by an older or buggy version. There, validate and | |
| reject (misbehaving peer, `state.Invalid(...)`, early return) rather than | |
| assert; use `Assume` for our *own* bookkeeping while still handling the | |
| violated case; and reserve `assert` for the narrow spot where continuing would | |
| corrupt EvoDB, the block index, or the wallet. | |
| An assertion whose condition can be made false by a P2P message or RPC | |
| argument is a remotely triggerable crash. Wallet files and on-disk state are | |
| also input that must be validated, although failures there are local unless an | |
| attacker controlled the persisted data. This distinction cuts especially deep | |
| in Dash-specific code: masternode, LLMQ, InstantSend, ChainLocks, governance and | |
| CoinJoin paths process peer-chosen message contents and read state (EvoDB, | |
| quorum caches, DKG sessions) possibly written by an older or buggy version. | |
| Validate and reject (`state.Invalid(...)`, an early return, or a misbehaving | |
| peer) whenever that input can violate the condition; use `Assume` for our *own* | |
| bookkeeping while still handling the violated case; and reserve `assert` for | |
| the narrow spot where continuing would corrupt EvoDB, the block index, or the | |
| wallet. |
source: ['codex']
| A bugged rate limiter may expose us to extra DoS pressure; aborting would | ||
| turn that into a guaranteed outage for every user running the release. Never | ||
| let an `Assume` be the thing that kills a production node. The expression is | ||
| always evaluated, in every build; failures abort only where | ||
| `-DABORT_ON_FAILED_ASSUME` is defined — `--enable-debug` and `--enable-fuzz` | ||
| builds, i.e. CI's `linux64_multiprocess` and fuzz jobs — and are silent in | ||
| release. That coverage is partial: an invariant you actually care about also | ||
| needs a test, and code downstream must still cope with the violated case. |
There was a problem hiding this comment.
💬 Nitpick: Document optimization of side-effect-free Assume expressions
In a release build, inline_assertion_check<false> only forwards its argument and the returned value is normally discarded. Under the as-if rule, the compiler may therefore eliminate a side-effect-free expression and the call entirely. Saying the expression is always evaluated in every build can incorrectly imply guaranteed runtime evaluation and cost. Bitcoin Core's current developer notes explicitly document this caveat; the condensed claim in AGENTS.md and CLAUDE.md should be updated at the same time.
| A bugged rate limiter may expose us to extra DoS pressure; aborting would | |
| turn that into a guaranteed outage for every user running the release. Never | |
| let an `Assume` be the thing that kills a production node. The expression is | |
| always evaluated, in every build; failures abort only where | |
| `-DABORT_ON_FAILED_ASSUME` is defined — `--enable-debug` and `--enable-fuzz` | |
| builds, i.e. CI's `linux64_multiprocess` and fuzz jobs — and are silent in | |
| release. That coverage is partial: an invariant you actually care about also | |
| needs a test, and code downstream must still cope with the violated case. | |
| A bugged rate limiter may expose us to extra DoS pressure; aborting would | |
| turn that into a guaranteed outage for every user running the release. Never | |
| let an `Assume` be the thing that kills a production node. Under normal C++ | |
| evaluation rules its expression is evaluated in every build. However, in a | |
| release build the compiler may optimize away a side-effect-free expression | |
| and the `Assume` call, skipping runtime evaluation. Failures abort only where | |
| `-DABORT_ON_FAILED_ASSUME` is defined — `--enable-debug` and `--enable-fuzz` | |
| builds, i.e. CI's `linux64_multiprocess` and fuzz jobs — and are silent in | |
| release. That coverage is partial: an invariant you actually care about also | |
| needs a test, and code downstream must still cope with the violated case. |
source: ['codex']
3 participants
Issue being fixed or feature implemented
The "Assertions and Checks" section in
doc/developer-notes.mdlists thehelpers in
src/util/check.has three equally-weighted options without sayingwhich to reach for by default. In practice
assert()gets used for invariantsthat are merely suspicious, turning a violated bookkeeping assumption into a
node crash. It also omits which builds abort on a failed
Assumeand thatassertions must never be derived from peer/RPC/on-disk input.
What was done?
Rewrote the section around one question — what does it cost to continue with
the invariant violated?
Assumeis the default: a violation is a real bug to investigate, butexecution stays well-defined (archetype: a rate-limit counter going
negative). Documented that
--enable-debug/--enable-fuzzdefine-DABORT_ON_FAILED_ASSUME(CI'slinux64_multiprocessand fuzz jobs), andthat this coverage is partial.
assert/Assertis reserved for cases where continuing means UB orcorrupt persisted/consensus state — rare, but still correct where a
precondition genuinely keeps the code below it safe.
CHECK_NONFATAL/NONFATAL_UNREACHABLEfor logic bugs with a caller toreport to; mandatory under
src/rpc/andsrc/wallet/rpc*pertest/lint/lint-assertions.py.write) are
AbortNode()/InitError()/error returns, not checks. Added aDash-specific note: asserting on peer-chosen messages or EvoDB/quorum state
converts a peer-triggered inconsistency into a network-wide remote crash.
static_assertbullet, and a condensed version in
CLAUDE.md/AGENTS.md(kept identical,as those files require).
No code changes.
How Has This Been Tested?
Documentation only. Claims were verified against the tree: the
ABORT_ON_FAILED_ASSUMEblocks inconfigure.ac, the CI job configs, thelint regex, and the
assert(pindex)example (Chainstate::ConnectBlock()).lint-whitespace.pyandlint-spelling.pyare clean for the touched files.Breaking Changes
None.
Checklist: