Add formatting of type parameters in class and function definitions (#6161)

Part of #5062 
Closes https://github.com/astral-sh/ruff/issues/5931

Implements formatting of a sequence of type parameters in a dedicated
struct for reuse by classes, functions, and type aliases (preparing for
#5929). Adds formatting of type parameters in class and function
definitions — previously, they were just elided.

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/list.py

@@ -21,3 +21,14 @@ b3 = [
     aksjdhflsakhdflkjsadlfajkslhfdkjsaldajlahflashdfljahlfksajlhfajfjfsaahflakjslhdfkjalhdskjfa,
     aksjdhflsakhdflkjsadlfajkslhfdkjsaldajlahflashdfljahlfksajlhfajfjfsaahflakjslhdfkjalhdskjfa
 ]
+
+# Comment placement in non-empty lists
+c1 = [ # trailing open bracket
+    # leading item
+    1,
+
+    # between
+
+    2, # trailing item
+    # leading close bracket
+] # trailing close bracket

crates/ruff_python_formatter/resources/test/fixtures/ruff/statement/class_definition.py

@@ -43,6 +43,14 @@ class TestTrailingComment2: # trailing comment
     pass
 
 
+class TestTrailingComment3[T]: # trailing comment
+    pass
+
+
+class TestTrailingComment4[T](A): # trailing comment
+    pass
+
+
 class Test:
     """Docstring"""
 
@@ -144,3 +152,57 @@ class AltCLIPOutput(
     # Copied from transformers.models.clip.modeling_clip.CLIPOutput with CLIP->AltCLIP
 ):
     ...
+
+
+class TestTypeParams[Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb, Cccccccccccccccccccccc]:
+    pass
+
+
+class TestTypeParams[Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, *Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb, **Cccccccccccccccccccccc]:
+    pass
+
+
+class TestTypeParams[Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa]:
+    pass
+
+
+class TestTypeParams[*Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa]:
+    pass
+
+
+class TestTypeParams[**Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa]:
+    pass
+
+
+class TestTypeParams[**P, *Ts, T]:
+    pass
+
+
+class TestTypeParams[ # trailing bracket comment
+    # leading comment
+    A,
+
+    # in between comment
+
+    B,
+    # another leading comment
+    C,
+    D, # trailing comment
+    # leading bracket comment
+]:
+    pass
+
+
+
+class TestTypeParams[Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa](B, C, D):
+    pass
+
+
+
+class TestTypeParams[Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa](Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb, Cccccccccccccccccccccccc, Ddddddddddddddddddddddddd):
+    pass
+
+
+
+class TestTypeParams[A, B, C](meta=Aaaaaaaaaaaaaaaaaaaaaa):
+    pass

crates/ruff_python_formatter/resources/test/fixtures/ruff/statement/function.py

@@ -66,6 +66,52 @@ def argument_with_long_type_annotation(
 
 def test(): ...
 
+# Type parameter empty line spacing
+def test[
+    # comment
+    A,
+
+    # another
+
+    B,
+](): ...
+
+
+# Type parameter comments
+def type_param_comments[ # trailing bracket comment
+    # leading comment
+    A,
+
+    # in between comment
+
+    B,
+    # another leading comment
+    C,
+    D, # trailing comment
+    # leading bracket comment
+]():
+    # body comment
+    pass
+
+
+# Note empty type parameters is not valid syntax, e.g.
+# def test[](): ...
+
+
+# Different type parameter wrappings
+
+def single_line[Aaaaaaaaaaaaaaaaaaaaaaaaaaaaa, Bbbbbbbbbbbbbbb, Ccccccccccccccccc]():
+    pass
+
+def params_on_their_own_line[Aaaaaaaaaaaaaaaaaaaaaaaaaaaaa, Bbbbbbbbbbbbbbb, Ccccccccccc, Ddddddddddddd, Eeeeeeee]():
+    pass
+
+def param_per_line[Aaaaaaaaaaaaaaaaaaaaaaaaaaaaa, Bbbbbbbbbbbbbbb, Ccccccccccccccccc, Ddddddddddddd, Eeeeeeeeeeeeeeeee, ffffffffffff]():
+    pass
+
+def single_line_trailing_comma[A, B, C,]():
+    pass
+
 # Comment
 def with_leading_comment(): ...