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util.inspect/console.log: classes print as bare integers, holes as NaN, resolved promises as pending #9415

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util.inspect/console.log: classes print as bare integers, holes as NaN, resolved promises as pending#9415

Description

@proggeramlug
proggeramlug
opened on Sep 1, 2026
console.log(class Klass {})       // node "[class Klass]"        perry "49"  (a bare integer)
console.log(new Array(3))         // node "[ <3 empty items> ]"  perry "[ NaN, NaN, NaN ]"
console.log(Promise.resolve(1))   // node "Promise { 1 }"        perry "Promise { <pending> }"

Three distinct inspect defects. The first is the worst: a class value prints as an integer (its class id leaking through), which is unrecognisable rather than merely differently formatted. The second turns holes into NaN, which is a wrong value, not a formatting choice. The third reports a settled promise as pending.

Debug output is how people diagnose everything else, so these make every other investigation harder.

Found by a differential stress-test of claude-code under perry.

Activity

  1. proggeramlug
    added 2 commits that reference this issue on Sep 1, 2026

    fix(runtime): inspect decodes classes, holes and promise state (Perry…

    385870a

    fix(runtime): inspect decodes classes, holes and promise state (#9415)…

    cf19b71

  2. proggeramlug commented on Sep 2, 2026

    @proggeramlug
    proggeramlug
    on Sep 2, 2026
    ContributorAuthor

    Fixed by PR #9461: classes print [class Name] (the INT32/class-ref tag ambiguity, resolved via the shared value_repr classifier that #9472 also standardized #9465's fix onto), holes render <N empty items>/undefined instead of NaN in both array walks and Map/Set, and promise state is read (Promise { 1 }, <rejected>). test_gap_9415_inspect_class_hole_promise.ts. Verified on main 0a1c137d90 with a fresh build: fixture byte-identical to node --experimental-strip-types (stdout, stderr, and exit code).
    The rest of the fall-through-to-double family is filed as #9462 (hole-leak source + typeof/String/console.table) and #9463 (%s/%o policy).

  3. proggeramlug
    closed this as completedon Sep 2, 2026
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