Rename Red Knot (#17820)

crates/ty_python_semantic/resources/mdtest/loops/while_loop.md

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+# While loops
+
+## Basic `while` loop
+
+```py
+def _(flag: bool):
+    x = 1
+    while flag:
+        x = 2
+
+    reveal_type(x)  # revealed: Literal[1, 2]
+```
+
+## `while` with `else` (no `break`)
+
+```py
+def _(flag: bool):
+    x = 1
+    while flag:
+        x = 2
+    else:
+        reveal_type(x)  # revealed: Literal[1, 2]
+        x = 3
+
+    reveal_type(x)  # revealed: Literal[3]
+```
+
+## `while` with `else` (may `break`)
+
+```py
+def _(flag: bool, flag2: bool):
+    x = 1
+    y = 0
+    while flag:
+        x = 2
+        if flag2:
+            y = 4
+            break
+    else:
+        y = x
+        x = 3
+
+    reveal_type(x)  # revealed: Literal[2, 3]
+    reveal_type(y)  # revealed: Literal[4, 1, 2]
+```
+
+## Nested `while` loops
+
+```py
+def flag() -> bool:
+    return True
+
+x = 1
+
+while flag():
+    x = 2
+
+    while flag():
+        x = 3
+        if flag():
+            break
+    else:
+        x = 4
+
+    if flag():
+        break
+else:
+    x = 5
+
+reveal_type(x)  # revealed: Literal[3, 4, 5]
+```
+
+## Boundness
+
+Make sure that the boundness information is correctly tracked in `while` loop control flow.
+
+### Basic `while` loop
+
+```py
+def _(flag: bool):
+    while flag:
+        x = 1
+
+    # error: [possibly-unresolved-reference]
+    x
+```
+
+### `while` with `else` (no `break`)
+
+```py
+def _(flag: bool):
+    while flag:
+        y = 1
+    else:
+        x = 1
+
+    # no error, `x` is always bound
+    x
+    # error: [possibly-unresolved-reference]
+    y
+```
+
+### `while` with `else` (may `break`)
+
+```py
+def _(flag: bool, flag2: bool):
+    while flag:
+        x = 1
+        if flag2:
+            break
+    else:
+        y = 1
+
+    # error: [possibly-unresolved-reference]
+    x
+    # error: [possibly-unresolved-reference]
+    y
+```
+
+## Condition with object that implements `__bool__` incorrectly
+
+```py
+class NotBoolable:
+    __bool__: int = 3
+
+# error: [unsupported-bool-conversion] "Boolean conversion is unsupported for type `NotBoolable`"
+while NotBoolable():
+    ...
+```