Fix run-away for mutually referential instance attributes (#20645)

Author: MichaReiser

Cargo.lock

@@ -146,7 +146,7 @@ regex-automata = { version = "0.4.9" }
 rustc-hash = { version = "2.0.0" }
 rustc-stable-hash = { version = "0.1.2" }
 # When updating salsa, make sure to also update the revision in `fuzz/Cargo.toml`
-salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "29ab321b45d00daa4315fa2a06f7207759a8c87e", default-features = false, features = [
+salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "ef9f9329be6923acd050c8dddd172e3bc93e8051", default-features = false, features = [
     "compact_str",
     "macros",
     "salsa_unstable",

Cargo.toml

@@ -2363,6 +2363,55 @@ reveal_type(B().x)  # revealed: Unknown | Literal[1]
 reveal_type(A().x)  # revealed: Unknown | Literal[1]
 ```
 
+And cycles between many attributes:
+
+```py
+class ManyCycles:
+    def __init__(self: "ManyCycles"):
+        self.x1 = 0
+        self.x2 = 0
+        self.x3 = 0
+        self.x4 = 0
+        self.x5 = 0
+        self.x6 = 0
+        self.x7 = 1
+
+    def f1(self: "ManyCycles"):
+        self.x1 = self.x2 + self.x3 + self.x4 + self.x5 + self.x6 + self.x7
+        self.x2 = self.x1 + self.x3 + self.x4 + self.x5 + self.x6 + self.x7
+        self.x3 = self.x1 + self.x2 + self.x4 + self.x5 + self.x6 + self.x7
+        self.x4 = self.x1 + self.x2 + self.x3 + self.x5 + self.x6 + self.x7
+        self.x5 = self.x1 + self.x2 + self.x3 + self.x4 + self.x6 + self.x7
+        self.x6 = self.x1 + self.x2 + self.x3 + self.x4 + self.x5 + self.x7
+        self.x7 = self.x1 + self.x2 + self.x3 + self.x4 + self.x5 + self.x6
+
+    def f2(self: "ManyCycles"):
+        self.x1 = self.x2 + self.x3 + self.x4 + self.x5 + self.x6 + self.x7
+        self.x2 = self.x1 + self.x3 + self.x4 + self.x5 + self.x6 + self.x7
+        self.x3 = self.x1 + self.x2 + self.x4 + self.x5 + self.x6 + self.x7
+        self.x4 = self.x1 + self.x2 + self.x3 + self.x5 + self.x6 + self.x7
+        self.x5 = self.x1 + self.x2 + self.x3 + self.x4 + self.x6 + self.x7
+        self.x6 = self.x1 + self.x2 + self.x3 + self.x4 + self.x5 + self.x7
+        self.x7 = self.x1 + self.x2 + self.x3 + self.x4 + self.x5 + self.x6
+
+    def f3(self: "ManyCycles"):
+        self.x1 = self.x2 + self.x3 + self.x4 + self.x5 + self.x6 + self.x7
+        self.x2 = self.x1 + self.x3 + self.x4 + self.x5 + self.x6 + self.x7
+        self.x3 = self.x1 + self.x2 + self.x4 + self.x5 + self.x6 + self.x7
+        self.x4 = self.x1 + self.x2 + self.x3 + self.x5 + self.x6 + self.x7
+        self.x5 = self.x1 + self.x2 + self.x3 + self.x4 + self.x6 + self.x7
+        self.x6 = self.x1 + self.x2 + self.x3 + self.x4 + self.x5 + self.x7
+        self.x7 = self.x1 + self.x2 + self.x3 + self.x4 + self.x5 + self.x6
+
+        reveal_type(self.x1)  # revealed: Unknown | int
+        reveal_type(self.x2)  # revealed: Unknown | int
+        reveal_type(self.x3)  # revealed: Unknown | int
+        reveal_type(self.x4)  # revealed: Unknown | int
+        reveal_type(self.x5)  # revealed: Unknown | int
+        reveal_type(self.x6)  # revealed: Unknown | int
+        reveal_type(self.x7)  # revealed: Unknown | int
+```
+
 This case additionally tests our union/intersection simplification logic:
 
 ```py

crates/ty_python_semantic/resources/mdtest/attributes.md

@@ -1,2 +1,2 @@
-spark  # too many iterations (in `exported_names` query)
-steam.py  # hangs (single threaded)
+spark  # too many iterations (in `exported_names` query), `should not be able to access instance member `spark` of type variable IndexOpsLike@astype in inferable position`
+steam.py  # dependency graph cycle when querying TypeVarInstance < 'db >::lazy_default_(Id(2e007)), set cycle_fn/cycle_initial to fixpoint iterate.

crates/ty_python_semantic/resources/primer/bad.txt

@@ -30,7 +30,7 @@ ty_python_semantic = { path = "../crates/ty_python_semantic" }
 ty_vendored = { path = "../crates/ty_vendored" }
 
 libfuzzer-sys = { git = "https://github.com/rust-fuzz/libfuzzer", default-features = false }
-salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "29ab321b45d00daa4315fa2a06f7207759a8c87e", default-features = false, features = [
+salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "ef9f9329be6923acd050c8dddd172e3bc93e8051", default-features = false, features = [
     "compact_str",
     "macros",
     "salsa_unstable",