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Crash on incompatible dictionary unpack #4959
Description
Type checking this code fragment causes a mypy crash:
from typing import Dict
def f() -> Dict[int, str]:
return {1: '', **d()}
def d() -> Dict[int, int]:
return {}Here's the traceback:
Traceback (most recent call last):
File "/Users/jukka/src/mypy/scripts/mypy", line 6, in <module>
main(__file__)
File "/Users/jukka/src/mypy/mypy/main.py", line 88, in main
res = type_check_only(sources, bin_dir, options, flush_errors) # noqa
File "/Users/jukka/src/mypy/mypy/main.py", line 143, in type_check_only
flush_errors=flush_errors)
File "/Users/jukka/src/mypy/mypy/build.py", line 183, in build
flush_errors, fscache)
File "/Users/jukka/src/mypy/mypy/build.py", line 268, in _build
graph = dispatch(sources, manager)
File "/Users/jukka/src/mypy/mypy/build.py", line 2253, in dispatch
process_graph(graph, manager)
File "/Users/jukka/src/mypy/mypy/build.py", line 2543, in process_graph
process_stale_scc(graph, scc, manager)
File "/Users/jukka/src/mypy/mypy/build.py", line 2659, in process_stale_scc
graph[id].type_check_first_pass()
File "/Users/jukka/src/mypy/mypy/build.py", line 1903, in type_check_first_pass
self.type_checker().check_first_pass()
File "/Users/jukka/src/mypy/mypy/checker.py", line 252, in check_first_pass
self.accept(d)
File "/Users/jukka/src/mypy/mypy/checker.py", line 351, in accept
stmt.accept(self)
File "/Users/jukka/src/mypy/mypy/nodes.py", line 539, in accept
return visitor.visit_func_def(self)
File "/Users/jukka/src/mypy/mypy/checker.py", line 607, in visit_func_def
self._visit_func_def(defn)
File "/Users/jukka/src/mypy/mypy/checker.py", line 611, in _visit_func_def
self.check_func_item(defn, name=defn.name())
File "/Users/jukka/src/mypy/mypy/checker.py", line 671, in check_func_item
self.check_func_def(defn, typ, name)
File "/Users/jukka/src/mypy/mypy/checker.py", line 834, in check_func_def
self.accept(item.body)
File "/Users/jukka/src/mypy/mypy/checker.py", line 351, in accept
stmt.accept(self)
File "/Users/jukka/src/mypy/mypy/nodes.py", line 804, in accept
return visitor.visit_block(self)
File "/Users/jukka/src/mypy/mypy/checker.py", line 1433, in visit_block
self.accept(s)
File "/Users/jukka/src/mypy/mypy/checker.py", line 351, in accept
stmt.accept(self)
File "/Users/jukka/src/mypy/mypy/nodes.py", line 919, in accept
return visitor.visit_return_stmt(self)
File "/Users/jukka/src/mypy/mypy/checker.py", line 2204, in visit_return_stmt
self.check_return_stmt(s)
File "/Users/jukka/src/mypy/mypy/checker.py", line 2235, in check_return_stmt
allow_none_return=allow_none_func_call)
File "/Users/jukka/src/mypy/mypy/checkexpr.py", line 2379, in accept
typ = node.accept(self)
File "/Users/jukka/src/mypy/mypy/nodes.py", line 1570, in accept
return visitor.visit_dict_expr(self)
File "/Users/jukka/src/mypy/mypy/checkexpr.py", line 2018, in visit_dict_expr
self.check_call(method, [arg], [nodes.ARG_POS], arg)
File "/Users/jukka/src/mypy/mypy/checkexpr.py", line 620, in check_call
object_type=object_type)
File "/Users/jukka/src/mypy/mypy/checkexpr.py", line 587, in check_call
messages=arg_messages)
File "/Users/jukka/src/mypy/mypy/checkexpr.py", line 1061, in check_argument_types
actual + 1, i + 1, callee, context, messages)
File "/Users/jukka/src/mypy/mypy/checkexpr.py", line 1097, in check_arg
caller_kind, context)
File "/Users/jukka/src/mypy/mypy/messages.py", line 643, in incompatible_argument
arg_name = context.arg_names[n - 1]
IndexError: list index out of range
Activity
Fine-grained: Add tests for unpacking expressions (and fix crash)
Fine-grained: Support Python 3 unpacking expressions (and fix crash) (#…