bpo-29593: Improve UnboundLocalError message. by Carreau · Pull Request #141 · python/cpython

the-knights-who-say-ni

Raymond Hettinger reported during PyCon Canada 2016 Keynote (~20m30 sec)
That unbound local error message was inaccurate, it state that :

> local variable 'xxx' referenced before assignment

Though it can be assigned and deleted.

    for a toy example:

       def foo():
          x = 1
          del x
          print(x)

       foo()

Do the same for free variable.

    def multiplier(n):
	def multiply(x):
	    return x * n
	del n
	return multiply

Carreau changed the title ~~Improve UnboundLocalError message.~~ bpo-29593: Improve UnboundLocalError message.

Feb 17, 2017

akruis pushed a commit to akruis/cpython that referenced this pull request

Nov 7, 2017

Call Py_DECREF(frame) with the right recursion_depth.

akruis pushed a commit to akruis/cpython that referenced this pull request

Mar 25, 2018

Call Py_DECREF(frame) with the right recursion_depth. Add a
changelog entry. The actual fix was part of commit cfd51a5.

akruis pushed a commit to akruis/cpython that referenced this pull request

Jun 19, 2018

Call Py_DECREF(frame) with the right recursion_depth.

(cherry picked from commit e520032)

SonicField added a commit to SonicField/cpython that referenced this pull request

Apr 26, 2026

Codifies three protocols developed across the emitAnyCall PURE conversion
arc (push 56-59) per pythia python#142/python#141/python#143 + supervisor + theologian
authorizations:

P8 — Phase 0' Coverage Extension to Perf-Regressing Benchmarks
Per pythia python#142 python#1 + supervisor 22:46:24Z + 22:47:40Z. Sentinel-only HIR
diff has empirical blind spot to single-bench regressions on unrelated
workloads (caught when emitAnyCall push 59 showed int_arith -10% with
exception-sentinel HIR-diff PASSING). Procedure: identify 24-bench >5%
benches, run Phase 0' HIR-diff on bench source per identified bench
(precise scrub, structural diff). Add to gate Step 7 post-processing.

P9 — Filesystem-First Cross-Check Before Fabrication HALT
Per medic 2026-04-22 build-claim false positive + medic 2026-04-25
22:50:53Z PYTHONJITDUMPFINALHIR false positive against generalist HIR
dumps that were filesystem-verified at /tmp + retracted at 22:53:44Z.
Procedure: identify implied artifact, ls + stat to confirm
existence/mtime, post QUERY (not HALT) if artifact exists, never cite
session-log absence as sole evidence. Costs ~30s vs ~5-10min false-
positive recovery cycle.

P10 — Variance Characterization Before (B) Investigation
Per W-EMITANYCALL-INT-ARITH-PERF closure 22:57:29Z + pythia python#143 python#1
amendment 23:21:18Z + supervisor 23:21:51Z. Mirrors agent-memory
feedback_falsifier_convergent_negative.md (per-agent reasoning side);
P10 codifies team-process side. Procedure (7 steps): identify >5%
benches, 3-run targeted re-runs for in-isolation variance, AT LEAST ONE
full-24-bench re-run for in-context variance (different statistical
populations: page-cache, branch-predictor, allocator history,
subprocess-position effects). Closure REQUIRES both isolated AND
in-context corroboration; if isolated clean but in-context reproduces
delta → real signal in sequence-context layer (cold-start/page-cache),
not at conversion layer.

Pythia python#143 python#4 caught these 3 protocols as 'LANDED in spec but
uncommitted at HEAD 0810be4 — exist only in working tree, not yet
history.' This commit closes that gap: protocols now in git history
before being cited as canonical (CC3 codification-on-authoring rule).

Spec doc: P1-P10 + 3 cross-cutting (CC1/CC2/CC3) + paired empirical
controls (PhxMem positive / HirType negative).

Bundle target: push 60 if Alex authorizes (A)/(B)/(C); separate
codification push if Alex direction is delayed >2hr per supervisor
23:21:51Z.