Honestly, I wouldn't consider this a bug, except that it crashes the daemon and prevents it from processing anything else. The ast module clearly warns "It is possible to crash the Python interpreter with a sufficiently large/complex string due to stack depth limitations in Python’s AST compiler.", so it might even be close to that limit as well.
But if there was a way of simply not processing such large nodes, or recovering, I think that would deserve a "fix".
version: 1.12.0+dev.fe15ee69b9225f808f8ed735671b73c31ae1bed8
Daemon crashed!
Traceback (most recent call last):
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/dmypy_server.py", line 236, in serve
resp = self.run_command(command, data)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/dmypy_server.py", line 285, in run_command
ret = method(self, **data)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/dmypy_server.py", line 353, in cmd_run
return self.check(sources, export_types, is_tty, terminal_width)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/dmypy_server.py", line 427, in check
res = self.initialize_fine_grained(sources, is_tty, terminal_width)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/dmypy_server.py", line 466, in initialize_fine_grained
result = mypy.build.build(sources=sources, options=self.options, fscache=self.fscache)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/build.py", line 193, in build
result = _build(
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/build.py", line 268, in _build
graph = dispatch(sources, manager, stdout)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/build.py", line 2897, in dispatch
graph = load_graph(sources, manager)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/build.py", line 3083, in load_graph
st = State(
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/build.py", line 2000, in __init__
self.parse_file(temporary=temporary)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/build.py", line 2176, in parse_file
self.tree = manager.parse_file(
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/build.py", line 841, in parse_file
tree = parse(source, path, id, self.errors, options=options)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/parse.py", line 27, in parse
tree = mypy.fastparse.parse(source, fnam=fnam, module=module, errors=errors, options=options)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 242, in parse
).visit(ast)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 417, in visit
return visitor(node)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 876, in visit_Module
body = self.fix_function_overloads(self.translate_stmt_list(mod.body, ismodule=True))
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 491, in translate_stmt_list
node = self.visit(stmt)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 417, in visit
return visitor(node)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 889, in visit_FunctionDef
return self.do_func_def(n)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 1023, in do_func_def
body = self.as_required_block(n.body, can_strip=True, is_coroutine=is_coroutine)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 606, in as_required_block
self.translate_stmt_list(stmts, can_strip=can_strip, is_coroutine=is_coroutine)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 491, in translate_stmt_list
node = self.visit(stmt)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 417, in visit
return visitor(node)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 1443, in visit_Expr
value = self.visit(n.value)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 417, in visit
return visitor(node)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 1497, in visit_BinOp
e = OpExpr(op, self.visit(n.left), self.visit(n.right))
...
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 417, in visit
return visitor(node)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 1497, in visit_BinOp
e = OpExpr(op, self.visit(n.left), self.visit(n.right))
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 417, in visit
return visitor(node)
File "/media/box/projects/moebius-n2212/v310/lib/python3.10/site-packages/mypy/fastparse.py", line 1492, in visit_BinOp
op = self.from_operator(n.op)
RecursionError: maximum recursion depth exceeded
Crash Report
I have been unable to use dmypy for a while due to recursion error, but finally took the time to figure out why. This seems to happen when processing a dependency, SymPy source file+line: https://github.com/sympy/sympy/blob/e676df8ded885babe62bd31bec5db8c96b7480e7/sympy/polys/numberfields/resolvent_lookup.py#L248.
It seems that the AST of the expression is just simply too deep to process before hitting recursion limit, estimating its a couple thousand nodes deep.
Honestly, I wouldn't consider this a bug, except that it crashes the daemon and prevents it from processing anything else. The ast module clearly warns "It is possible to crash the Python interpreter with a sufficiently large/complex string due to stack depth limitations in Python’s AST compiler.", so it might even be close to that limit as well.
But if there was a way of simply not processing such large nodes, or recovering, I think that would deserve a "fix".
Traceback
To Reproduce
Run dymy on https://github.com/sympy/sympy/blob/e676df8ded885babe62bd31bec5db8c96b7480e7/sympy/polys/numberfields/resolvent_lookup.py.
Your Environment
dmypy run -- sympy/polys/numberfields/resolvent_lookup.py