8000 [3.10] bpo-44600: Fix line numbers for pattern matching cleanup code … · python/cpython@01601aa · GitHub
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[3.10] bpo-44600: Fix line numbers for pattern matching cleanup code (GH-27346) (GH-27356)
(cherry picked from commit 4214f47) Co-authored-by: Charles Burkland <charles.aburkland@gmail.com> Automerge-Triggered-By: GH:brandtbucher
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3 files changed

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‎Lib/test/test_patma.py

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Original file line numberDiff line numberDiff line change
@@ -3,6 +3,7 @@
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import dataclasses
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import enum
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import inspect
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import sys
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import unittest
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@@ -3056,6 +3057,81 @@ class Keys:
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self.assertIs(z, None)
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class TestTracing(unittest.TestCase):
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def _test_trace(self, func, expected_linenos, *f_args):
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actual_linenos = set()
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def trace(frame, event, arg):
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if frame.f_code.co_name == func.__name__:
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relative_lineno = frame.f_lineno - func.__code__.co_firstlineno
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actual_linenos.add(relative_lineno)
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return trace
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sys.settrace(trace)
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func(*f_args)
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sys.settrace(None)
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self.assertSetEqual(actual_linenos, expected_linenos)
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def test_default_case_traces_correctly_a(self):
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def default_no_assign(command): # 0
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match command.split(): # 1
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case ["go", direction] if direction in "nesw": # 2
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return f"go {direction}" # 3
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case ["go", _]: # 4
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return "no go" # 5
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case _: # 6
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return "default" # 7
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self._test_trace(default_no_assign, {0, 1, 2, 3}, "go n")
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self._test_trace(default_no_assign, {0, 1, 2, 4, 5}, "go x")
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self._test_trace(default_no_assign, {0, 1, 2, 4, 6, 7}, "spam")
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def test_default_case_traces_correctly_b(self):
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def default_wildcard_assign(command): # 0
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match command.split(): # 1
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case ["go", direction] if direction in "nesw": # 2
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return f"go {direction}" # 3
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case ["go", _]: # 4
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return "no go" # 5
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case x: # 6
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return x # 7
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self._test_trace(default_wildcard_assign, {0, 1, 2, 3}, "go n")
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self._test_trace(default_wildcard_assign, {0, 1, 2, 4, 5}, "go x")
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self._test_trace(default_wildcard_assign, {0, 1, 2, 4, 6, 7}, "spam")
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def test_default_case_traces_correctly_c(self):
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def no_default(command): # 0
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match command.split(): # 1
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case ["go", direction] if direction in "nesw": # 2
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return f"go {direction}" # 3
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case ["go", _]: # 4
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return "no go" # 5
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self._test_trace(no_default, {0, 1, 2, 3}, "go n")
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self._test_trace(no_default, {0, 1, 2, 4, 5}, "go x")
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self._test_trace(no_default, {0, 1, 2, 4}, "spam")
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def test_default_case_traces_correctly_d(self):
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def only_default_no_assign(command): # 0
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match command.split(): # 1
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case _: # 2
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return "default" # 3
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self._test_trace(only_default_no_assign, {0, 1, 2, 3}, "go n")
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self._test_trace(only_default_no_assign, {0, 1, 2, 3} , "go x")
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self._test_trace(only_default_no_assign, {0, 1, 2, 3} EDBE , "spam")
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def test_default_case_traces_correctly_e(self):
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def only_default_wildcard_assign(command): # 0
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match command.split(): # 1
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case x: # 2
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return x # 3
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self._test_trace(only_default_wildcard_assign, {0, 1, 2, 3}, "go n")
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self._test_trace(only_default_wildcard_assign, {0, 1, 2, 3} , "go x")
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self._test_trace(only_default_wildcard_assign, {0, 1, 2, 3}, "spam")
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if __name__ == "__main__":
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"""
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# From inside environment using this Python, with pyperf installed:

‎Misc/NEWS.d/next/Security/2021-07-25-20-04-54.bpo-44600.0WMldg.rst

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Fix incorrect line numbers while tracing some failed patterns in :ref:`match <match>` statements. Patch by Charles Burkland.

‎Python/compile.c

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Original file line numberDiff line numberDiff line change
@@ -6398,17 +6398,25 @@ compiler_match_inner(struct compiler *c, stmt_ty s, pattern_context *pc)
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}
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VISIT_SEQ(c, stmt, m->body);
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ADDOP_JUMP(c, JUMP_FORWARD, end);
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// If the pattern fails to match, we want the line number of the
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// cleanup to be associated with the failed pattern, not the last line
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// of the body
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SET_LOC(c, m->pattern);
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RETURN_IF_FALSE(emit_and_reset_fail_pop(c, pc));
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}
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if (has_default) {
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if (cases == 1) {
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// No matches. Done with the subject:
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ADDOP(c, POP_TOP);
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}
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// A trailing "case _" is common, and lets us save a bit of redundant
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// pushing and popping in the loop above:
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m = asdl_seq_GET(s->v.Match.cases, cases - 1);
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SET_LOC(c, m->pattern);
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if (cases == 1) {
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// No matches. Done with the subject:
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ADDOP(c, POP_TOP);
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}
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else {
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// Show line coverage for default case (it doesn't create bytecode)
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ADDOP(c, NOP);
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}
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if (m->guard) {
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RETURN_IF_FALSE(compiler_jump_if(c, m->guard, end, 0));
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}

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