mypyc crashes when working on ParamSpec.kwargs

[kasium]

Bug Report

When using mypyc on code using ParamSpec.kwargs, a crash occurs

To Reproduce

from __future__ import annotations

from typing import Any, Callable, ParamSpec, TypeVar

PARAM = ParamSpec("PARAM")
RET = TypeVar("RET")


def decorator() -> Callable[[Callable[PARAM, RET]], Callable[PARAM, RET]]:
    def _wrapper(function: Callable[PARAM, RET]) -> Callable[PARAM, RET]:
        def _inner(*args: PARAM.args, **kwargs: PARAM.kwargs) -> Any:
            data = {key: arg for key, arg in kwargs.items()}
            function(*args, **kwargs)

        return _inner

    return _wrapper

Expected Behavior

no crash

Actual Behavior

Traceback (most recent call last):
foo.py:13: AssertionError: PARAM.kwargs`-1

Your Environment

• Mypy version used: mypy 1.15.0 (compiled: yes)
• Mypy command-line flags: n/a
• Mypy configuration options from mypy.ini (and other config files): n/a
• Python version used: 3.13.0

[sterliakov]

Traceback from current master (a.py:12 is the data = ... line - dictcomp):

$ mypyc a.py
Traceback (most recent call last):
  File "/tmp/tmp.R3k7W0wi65/build/setup.py", line 5, in <module>
    ext_modules=mypycify(['a.py'], opt_level="3", debug_level="1", strict_dunder_typing=False),
  File "/home/stas/Documents/Work/mypy/mypyc/build.py", line 531, in mypycify
    groups, group_cfilenames = mypyc_build(
  File "/home/stas/Documents/Work/mypy/mypyc/build.py", line 436, in mypyc_build
    group_cfiles, ops_text = generate_c(
  File "/home/stas/Documents/Work/mypy/mypyc/build.py", line 244, in generate_c
    modules, ctext = emitmodule.compile_modules_to_c(
  File "/home/stas/Documents/Work/mypy/mypyc/codegen/emitmodule.py", line 428, in compile_modules_to_c
    modules = compile_modules_to_ir(result, mapper, compiler_options, errors)
  File "/home/stas/Documents/Work/mypy/mypyc/codegen/emitmodule.py", line 272, in compile_modules_to_ir
    scc_ir = compile_scc_to_ir(trees, result, mapper, compiler_options, errors)
  File "/home/stas/Documents/Work/mypy/mypyc/codegen/emitmodule.py", line 227, in compile_scc_to_ir
    modules = build_ir(scc, result.graph, result.types, mapper, compiler_options, errors)
  File "/home/stas/.local/share/uv/python/cpython-3.13.0-linux-x86_64-gnu/lib/python3.13/contextlib.py", line 85, in inner
    return func(*args, **kwds)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/main.py", line 95, in build_ir
    transform_mypy_file(builder, module)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/main.py", line 141, in transform_mypy_file
    builder.accept(node)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/builder.py", line 290, in accept
    node.accept(self.visitor)
  File "/home/stas/Documents/Work/mypy/mypy/nodes.py", line 813, in accept
    return visitor.visit_func_def(self)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/visitor.py", line 181, in visit_func_def
    transform_func_def(self.builder, fdef)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/function.py", line 101, in transform_func_def
    func_ir, func_reg = gen_func_item(builder, fdef, fdef.name, sig)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/function.py", line 324, in gen_func_item
    builder.accept(fitem.body)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/builder.py", line 290, in accept
    node.accept(self.visitor)
  File "/home/stas/Documents/Work/mypy/mypy/nodes.py", line 1280, in accept
    return visitor.visit_block(self)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/visitor.py", line 190, in visit_block
    transform_block(self.builder, block)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/statement.py", line 130, in transform_block
    builder.accept(stmt)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/builder.py", line 290, in accept
    node.accept(self.visitor)
  File "/home/stas/Documents/Work/mypy/mypy/nodes.py", line 813, in accept
    return visitor.visit_func_def(self)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/visitor.py", line 181, in visit_func_def
    transform_func_def(self.builder, fdef)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/function.py", line 101, in transform_func_def
    func_ir, func_reg = gen_func_item(builder, fdef, fdef.name, sig)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/function.py", line 324, in gen_func_item
    builder.accept(fitem.body)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/builder.py", line 290, in accept
    node.accept(self.visitor)
  File "/home/stas/Documents/Work/mypy/mypy/nodes.py", line 1280, in accept
    return visitor.visit_block(self)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/visitor.py", line 190, in visit_block
    transform_block(self.builder, block)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/statement.py", line 130, in transform_block
    builder.accept(stmt)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/builder.py", line 290, in accept
    node.accept(self.visitor)
  File "/home/stas/Documents/Work/mypy/mypy/nodes.py", line 813, in accept
    return visitor.visit_func_def(self)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/visitor.py", line 181, in visit_func_def
    transform_func_def(self.builder, fdef)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/function.py", line 101, in transform_func_def
    func_ir, func_reg = gen_func_item(builder, fdef, fdef.name, sig)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/function.py", line 324, in gen_func_item
    builder.accept(fitem.body)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/builder.py", line 290, in accept
    node.accept(self.visitor)
  File "/home/stas/Documents/Work/mypy/mypy/nodes.py", line 1280, in accept
    return visitor.visit_block(self)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/visitor.py", line 190, in visit_block
    transform_block(self.builder, block)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/statement.py", line 130, in transform_block
    builder.accept(stmt)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/builder.py", line 290, in accept
    node.accept(self.visitor)
  File "/home/stas/Documents/Work/mypy/mypy/nodes.py", line 1367, in accept
    return visitor.visit_assignment_stmt(self)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/visitor.py", line 202, in visit_assignment_stmt
    transform_assignment_stmt(self.builder, stmt)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/statement.py", line 199, in transform_assignment_stmt
    rvalue_reg = builder.accept(stmt.rvalue)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/builder.py", line 276, in accept
    res = node.accept(self.visitor)
  File "/home/stas/Documents/Work/mypy/mypy/nodes.py", line 2470, in accept
    return visitor.visit_dictionary_comprehension(self)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/visitor.py", line 323, in visit_dictionary_comprehension
    return transform_dictionary_comprehension(self.builder, expr)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/expression.py", line 1037, in transform_dictionary_comprehension
    comprehension_helper(builder, loop_params, gen_inner_stmts, o.line)
    ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/for_helpers.py", line 359, in comprehension_helper
    handle_loop(loop_params)
    ~~~~~~~~~~~^^^^^^^^^^^^^
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/for_helpers.py", line 319, in handle_loop
    for_loop_helper(
    ~~~~~~~~~~~~~~~^
        builder,
        ^^^^^^^^
    ...<5 lines>...
        line=line,
        ^^^^^^^^^^
    )
    ^
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/for_helpers.py", line 104, in for_loop_helper
    for_gen = make_for_loop_generator(
        builder, index, expr, body_block, normal_loop_exit, line, is_async=is_async
    )
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/for_helpers.py", line 496, in make_for_loop_generator
    target_type = builder.get_dict_item_type(expr.callee.expr)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/builder.py", line 995, in get_dict_item_type
    key_type = self.get_dict_key_type(expr)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/builder.py", line 979, in get_dict_key_type
    dict_base_types = self.get_dict_base_type(expr)
  File "/home/stas/Documents/Work/mypy/mypyc/irbuild/builder.py", line 973, in get_dict_base_type
    assert isinstance(t, Instance), t
           ~~~~~~~~~~^^^^^^^^^^^^^
a.py:12: AssertionError: PARAM.kwargs`-1