[red_knot] Crash on analysing stub file with explicitly derived class

[LordAro]

Found just while playing around with red_knot ( b4d9d26 )

test.py

class Foo(object):
    pass

works fine

Renaming it to test.pyi results in:

 $ ./../target/debug/red_knot && echo $?
0
 $ mv test.py test.pyi
 $ ./../target/debug/red_knot && echo $?
thread '<unnamed>' panicked at crates/red_knot_python_semantic/src/types/infer.rs:177:25:
no entry found for key
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Rayon: detected unexpected panic; aborting
Aborted (core dumped)

Seems to crash with anything as the parent.

relevant part of RUST_BACKTRACE=full:

  19:     0x561605928fe5 - core::option::Option<T>::expect::hffc771cc74f800e9
                               at /build/rustc-kAv1jW/rustc-1.75.0+dfsg0ubuntu1~bpo0/library/core/src/option.rs:894:21
  20:     0x561605928fe5 - <std::collections::hash::map::HashMap<K,V,S> as core::ops::index::Index<&Q>>::index::hf84fbd63e8ba27dd
                               at /build/rustc-kAv1jW/rustc-1.75.0+dfsg0ubuntu1~bpo0/library/std/src/collections/hash/map.rs:1341:23
  21:     0x56160595a8e4 - red_knot_python_semantic::types::infer::TypeInference::expression_ty::h45e30f4ed3623f78
                               at /home/cpigott/dev/ruff/crates/red_knot_python_semantic/src/types/infer.rs:177:25
  22:     0x56160579d5e4 - <ruff_python_ast::expression::ExpressionRef as red_knot_python_semantic::semantic_model::HasTy>::ty::h7574fdc81220df66
                               at /home/cpigott/dev/ruff/crates/red_knot_python_semantic/src/semantic_model.rs:62:9
  23:     0x5616056603b5 - <ruff_python_ast::nodes::ExprName as red_knot_python_semantic::semantic_model::HasTy>::ty::h0bf9800421b11df7
                               at /home/cpigott/dev/ruff/crates/red_knot_python_semantic/src/semantic_model.rs:72:17
  24:     0x561605600139 - red_knot_workspace::lint::lint_maybe_undefined::hbf56527a89120b0f
                               at /home/cpigott/dev/ruff/crates/red_knot_workspace/src/lint.rs:117:11
  25:     0x561605600d9e - <red_knot_workspace::lint::SemanticVisitor as ruff_python_ast::visitor::Visitor>::visit_expr::h4e5d2046d4543b66
                               at /home/cpigott/dev/ruff/crates/red_knot_workspace/src/lint.rs:244:17
  26:     0x56160561fbfd - ruff_python_ast::visitor::walk_arguments::hcf8638d59de7f088
                               at /home/cpigott/dev/ruff/crates/ruff_python_ast/src/visitor.rs:597:9
  27:     0x5616055f9674 - ruff_python_ast::visitor::Visitor::visit_arguments::he4e1af453a0b6b0f
                               at /home/cpigott/dev/ruff/crates/ruff_python_ast/src/visitor.rs:58:9
  28:     0x5616056238bc - ruff_python_ast::visitor::walk_stmt::h8c2b40d349b01a24
                               at /home/cpigott/dev/ruff/crates/ruff_python_ast/src/visitor.rs:165:17
  29:     0x561605600d2a - <red_knot_workspace::lint::SemanticVisitor as ruff_python_ast::visitor::Visitor>::visit_stmt::h2cea15d01c9fd284
                               at /home/cpigott/dev/ruff/crates/red_knot_workspace/src/lint.rs:238:9
  30:     0x561605620f36 - ruff_python_ast::visitor::walk_body::hd1184b90f5a26118
                               at /home/cpigott/dev/ruff/crates/ruff_python_ast/src/visitor.rs:115:9
  31:     0x5616055f93f8 - ruff_python_ast::visitor::Visitor::visit_body::h1b0a1fbe97acb4d0
                               at /home/cpigott/dev/ruff/crates/ruff_python_ast/src/visitor.rs:94:9
  32:     0x561605602c32 - <red_knot_workspace::lint::lint_semantic::Configuration_ as salsa::function::Configuration>::execute::inner_::h18d04db1014d8c80
                               at /home/cpigott/dev/ruff/crates/red_knot_workspace/src/lint.rs:93:5

Looking forward to seeing where this goes!

[carljm]

Thanks for the report!

This looks related to #13176, but I'd expect that issue to cause a resolution to Type::Unbound, not a panic. Will take a look.

[carljm]

Found the bug, fix PR in progress.