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util.inspect/console.log: classes print as bare integers, holes as NaN, resolved promises as pending #9415
Description
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
fix(runtime): inspect decodes classes, holes and promise state (Perry…
fix(runtime): inspect decodes classes, holes and promise state (#9415)…
proggeramlug commentedon Sep 2, 2026
Fixed by PR #9461: classes print
[class Name](the INT32/class-ref tag ambiguity, resolved via the sharedvalue_reprclassifier that #9472 also standardized #9465's fix onto), holes render<N empty items>/undefinedinstead ofNaNin both array walks and Map/Set, and promise state is read (Promise { 1 },<rejected>).test_gap_9415_inspect_class_hole_promise.ts. Verified on main0a1c137d90with a fresh build: fixture byte-identical tonode --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).