`trace.CoverageResults.__init__` does not copy the counts dict

Issue

CoverageResults.__init__ copies calledfuncs and callers via .copy() but assigns counts directly. This means self.counts is an alias to the caller's dict, and calling update() mutates the original dict passed to the constructor.

Reproducer

from trace import CoverageResults

# counts is NOT copied — original is mutated:
counts = {}
cr = CoverageResults(counts=counts)
cr.update(CoverageResults(counts={('file.py', 1): 5}))
print(counts)  # {('file.py', 1): 5} — mutated

# calledfuncs IS copied — original is not mutated:
calledfuncs = {}
cr = CoverageResults(calledfuncs=calledfuncs)
cr.update(CoverageResults(calledfuncs={('file.py', 'mod', 'func'): 1}))
print(calledfuncs)  # {} — not mutated

Impact

The documentation states that CoverageResults "should not be created directly by the user," so direct external impact is limited. However, the inconsistency also affects internal usage: Trace.results() passes its internal self.counts directly to the constructor, so calling update() on the returned CoverageResults will mutate the Trace object's internal state.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-146176
• gh-146183

Beginnen Sie in Lib/trace.py bei CoverageResults.init und Trace.results(), wo im Issue steht, dass das counts-Wörterbuch durchgereicht wird. Prüfen Sie das bestehende Aktualisierungsverhalten und ergänzen Sie Tests, die das Beibehalten des Wörterbuchs des Aufrufers abdecken; als erledigt gilt die Änderung, wenn das Aktualisieren eines CoverageResults nicht mehr das vom Konstruktor bereitgestellte Wörterbuch oder den internen Zustand des Trace-Objekts verändert.