…20133)

## Summary

Add regression benchmarks for the problematic cases in
astral-sh/ty#758. I'd like to merge this
before #20128 to measure the
impact (local tests show that this will "solve" both cases).

* main:
  Fix mdtest ignore python code blocks (#20139)
  [ty] add support for cyclic legacy generic protocols (#20125)
  [ty] add cycle detection for find_legacy_typevars (#20124)
  Use new diff rendering format in tests (#20101)
  [ty] Fix 'too many cycle iterations' for unions of literals (#20137)
  [ty] No boundness analysis for implicit instance attributes (#20128)
  Bump 0.12.11 (#20136)
  [ty] Benchmarks for problematic implicit instance attributes cases (#20133)
  [`pyflakes`] Fix `allowed-unused-imports` matching for top-level modules (`F401`) (#20115)
  Move GitLab output rendering to `ruff_db` (#20117)
  [ty] Evaluate reachability of non-definitely-bound to Ambiguous (#19579)
  [ty] Introduce a representation for the top/bottom materialization of an invariant generic (#20076)
  [`flake8-async`] Implement `blocking-http-call-httpx` (`ASYNC212`) (#20091)
  [ty] print diagnostics with fully qualified name to disambiguate some cases (#19850)
  [`ruff`] Preserve relative whitespace in multi-line expressions (`RUF033`) (#19647)

…stral-sh#20133)

## Summary

Add regression benchmarks for the problematic cases in
astral-sh/ty#758. I'd like to merge this
before astral-sh#20128 to measure the
impact (local tests show that this will "solve" both cases).

…h#20128)

## Summary

With this PR, we stop performing boundness analysis for implicit
instance attributes:

```py
class C:
    def __init__(self):
        if False:   
            self.x = 1

C().x  # would previously show an error, with this PR we pretend the attribute exists
```

This PR is potentially just a temporary measure until we find a better
fix. But I have already invested a lot of time trying to find the root
cause of astral-sh/ty#758 (and [this
example](astral-sh/ty#758 (comment)),
which I'm not entirely sure is related) and I still don't understand
what is going on. This PR fixes the performance problems in both of
these problems (in a rather crude way).

The impact of the proposed change on the ecosystem is small, and the
three new diagnostics are arguably true positives (previously hidden
because we considered the code unreachable, based on e.g. `assert`ions
that depended on implicit instance attributes). So this seems like a
reasonable fix for now.

Note that we still support cases like these:

```py
class D:
    if False:  # or any other expression that statically evaluates to `False`
        x: int = 1

D().x  # still an error


class E:
    if False:  # or any other expression that statically evaluates to `False`
        def f(self):
            self.x = 1

E().x  # still an error
```

closes astral-sh/ty#758

## Test Plan

Updated tests, benchmark results

## Summary

This is a simpler approach to the performance issues mentioned in
#23520.

isort's profiling results suggested that #22794 added a slow-converging
calculation rather than adding a specific hotspot to the type inferer.
What makes type inference for loop variables more troublesome than other
types of type inference is the calculation of reachability.
For other types, such as implicit attribute type inference, reachability
analysis is not performed for each attribute binding (reverted due to
performance issues: #20128,
astral-sh/ty#2117). They are all treated as
reachable.
Loop variables perform this heavy calculation (omitting reachability
analysis from the `LoopHeader` branch of `infer_loop_header_definition`
and `place_from_bindings_impl` will significantly improve performance).
It appears that slow convergence for one variable in a loop block will
also slow down the inference of all other definitions in the block that
depend on it.

To alleviate the issue, this PR reduces the value of
`MAX_RECURSIVE_UNION_LITERALS` from 10 to 5. This will result in faster
convergence when the loop variable grows like `Literal[0, 1, ...]`.
Local measurements show that this PR alone improved the isort inspection
time by about 37%.
I chose 5 as the new value because I felt it offered a good balance
between type inference precision and performance, based on the following
measurement results:

| Threshold | Mean | vs 10 |
|-----------|--------|---------|
| 4         | 0.89s  | -38%        |
| 5         | 0.91s  | -37%        |
| 6         | 1.05s  | -27%        |
| 7         | 1.06s  | -27%        |
| 8         | 1.23s  | -14%        |
| 9         | 1.26s  | -13%        |
| 10 (current)    | 1.43s  | — |

It has been observed that this PR and another mitigation, #23520, are
compatible, resulting in a total performance recovery of about 40-50%.

## Test Plan

N/A