[pydocstyle-D405] Allow using parameters as a sub-section header (#9894)

## Summary

This review contains a fix for
[D405](https://docs.astral.sh/ruff/rules/capitalize-section-name/)
(capitalize-section-name)
The problem is that Ruff considers the sub-section header as a normal
section if it has the same name as some section name. For instance, a
function/method has an argument named "parameters". This only applies if
you use Numpy style docstring.

See: [ISSUE](https://github.com/astral-sh/ruff/issues/9806)

The following will not raise D405 after the fix:
```python  
def some_function(parameters: list[str]):
    """A function with a parameters parameter

    Parameters
    ----------

    parameters:
        A list of string parameters
    """
    ...
```


## Test Plan

```bash
cargo test
```

---------

Co-authored-by: Mikko Leppänen <mikko.leppanen@vaisala.com>
Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>

crates/ruff_linter/resources/test/fixtures/pydocstyle/sections.py

@@ -562,3 +562,46 @@ def titlecase_sub_section_header():
 
         Returns:
     """
+
+
+def test_method_should_be_correctly_capitalized(parameters: list[str], other_parameters: dict[str, str]): # noqa: D213
+    """Test parameters and attributes sections are capitalized correctly.
+
+    Parameters
+    ----------
+    parameters:
+        A list of string parameters
+    other_parameters:
+        A dictionary of string attributes
+
+    Other Parameters
+    ----------
+    other_parameters:
+        A dictionary of string attributes
+    parameters:
+        A list of string parameters
+
+    """
+
+
+def test_lowercase_sub_section_header_should_be_valid(parameters: list[str], value: int):  # noqa: D213
+    """Test that lower case subsection header is valid even if it has the same name as section kind.
+
+    Parameters:
+    ----------
+    parameters:
+        A list of string parameters
+    value:
+        Some value
+    """
+
+
+def test_lowercase_sub_section_header_different_kind(returns: int):
+   """Test that lower case subsection header is valid even if it is of a different kind.
+
+   Parameters
+   -‐-----------------
+   returns:
+       some value
+
+   """

crates/ruff_linter/src/docstrings/sections.rs

@@ -130,6 +130,34 @@ impl SectionKind {
             Self::Yields => "Yields",
         }
     }
+
+    /// Returns `true` if a section can contain subsections, as in:
+    /// ```python
+    /// Yields
+    /// ------
+    /// int
+    ///     Description of the anonymous integer return value.
+    /// ```
+    ///
+    /// For NumPy, see: <https://numpydoc.readthedocs.io/en/latest/format.html>
+    ///
+    /// For Google, see: <https://google.github.io/styleguide/pyguide.html#38-comments-and-docstrings>
+    pub(crate) fn has_subsections(self) -> bool {
+        matches!(
+            self,
+            Self::Args
+                | Self::Arguments
+                | Self::OtherArgs
+                | Self::OtherParameters
+                | Self::OtherParams
+                | Self::Parameters
+                | Self::Raises
+                | Self::Returns
+                | Self::SeeAlso
+                | Self::Warns
+                | Self::Yields
+        )
+    }
 }
 
 pub(crate) struct SectionContexts<'a> {
@@ -462,13 +490,54 @@ fn is_docstring_section(
     //         args: The arguments to the function.
     //     """
     // ```
+    // Or `parameters` in:
+    // ```python
+    // def func(parameters: tuple[int]):
+    //     """Toggle the gizmo.
+    //
+    //     Parameters:
+    //     -----
+    //     parameters:
+    //         The arguments to the function.
+    //     """
+    // ```
     // However, if the header is an _exact_ match (like `Returns:`, as opposed to `returns:`), then
     // continue to treat it as a section header.
-    if let Some(previous_section) = previous_section {
+    if section_kind.has_subsections() {
-        if previous_section.indent_size < indent_size {
+        if let Some(previous_section) = previous_section {
             let verbatim = &line[TextRange::at(indent_size, section_name_size)];
-            if section_kind.as_str() != verbatim {
+
-                return false;
+            // If the section is more deeply indented, assume it's a subsection, as in:
+            // ```python
+            // def func(args: tuple[int]):
+            //     """Toggle the gizmo.
+            //
+            //     Args:
+            //         args: The arguments to the function.
+            //     """
+            // ```
+            if previous_section.indent_size < indent_size {
+                if section_kind.as_str() != verbatim {
+                    return false;
+                }
+            }
+
+            // If the section isn't underlined, and isn't title-cased, assume it's a subsection,
+            // as in:
+            // ```python
+            // def func(parameters: tuple[int]):
+            //     """Toggle the gizmo.
+            //
+            //     Parameters:
+            //     -----
+            //     parameters:
+            //         The arguments to the function.
+            //     """
+            // ```
+            if !next_line_is_underline && verbatim.chars().next().is_some_and(char::is_lowercase) {
+                if section_kind.as_str() != verbatim {
+                    return false;
+                }
             }
         }
     }

crates/ruff_linter/src/rules/pydocstyle/snapshots/ruff_linter__rules__pydocstyle__tests__D214_sections.py.snap

@@ -49,5 +49,7 @@ sections.py:558:5: D214 [*] Section is over-indented ("Returns")
 563     |-        Returns:
     563 |+    Returns:
 564 564 |     """
+565 565 | 
+566 566 | 
 
 

crates/ruff_linter/src/rules/pydocstyle/snapshots/ruff_linter__rules__pydocstyle__tests__D406_sections.py.snap

@@ -61,4 +61,31 @@ sections.py:216:5: D406 [*] Section name should end with a newline ("Raises")
 229 229 | 
 230 230 |     """
 
+sections.py:588:5: D406 [*] Section name should end with a newline ("Parameters")
+    |
+587 |   def test_lowercase_sub_section_header_should_be_valid(parameters: list[str], value: int):  # noqa: D213
+588 |       """Test that lower case subsection header is valid even if it has the same name as section kind.
+    |  _____^
+589 | | 
+590 | |     Parameters:
+591 | |     ----------
+592 | |     parameters:
+593 | |         A list of string parameters
+594 | |     value:
+595 | |         Some value
+596 | |     """
+    | |_______^ D406
+    |
+    = help: Add newline after "Parameters"
+
+ℹ Safe fix
+587 587 | def test_lowercase_sub_section_header_should_be_valid(parameters: list[str], value: int):  # noqa: D213
+588 588 |     """Test that lower case subsection header is valid even if it has the same name as section kind.
+589 589 | 
+590     |-    Parameters:
+    590 |+    Parameters
+591 591 |     ----------
+592 592 |     parameters:
+593 593 |         A list of string parameters
+
 

crates/ruff_linter/src/rules/pydocstyle/snapshots/ruff_linter__rules__pydocstyle__tests__D407_sections.py.snap

@@ -567,5 +567,32 @@ sections.py:558:5: D407 [*] Missing dashed underline after section ("Returns")
 563 563 |         Returns:
     564 |+    -------
 564 565 |     """
+565 566 | 
+566 567 | 
+
+sections.py:600:4: D407 [*] Missing dashed underline after section ("Parameters")
+    |
+599 |   def test_lowercase_sub_section_header_different_kind(returns: int):
+600 |      """Test that lower case subsection header is valid even if it is of a different kind.
+    |  ____^
+601 | | 
+602 | |    Parameters
+603 | |    -‐-----------------
+604 | |    returns:
+605 | |        some value
+606 | | 
+607 | |    """
+    | |______^ D407
+    |
+    = help: Add dashed line under "Parameters"
+
+ℹ Safe fix
+600 600 |    """Test that lower case subsection header is valid even if it is of a different kind.
+601 601 | 
+602 602 |    Parameters
+    603 |+   ----------
+603 604 |    -‐-----------------
+604 605 |    returns:
+605 606 |        some value
 
 

crates/ruff_linter/src/rules/pydocstyle/snapshots/ruff_linter__rules__pydocstyle__tests__D409_sections.py.snap

@@ -61,4 +61,39 @@ sections.py:216:5: D409 [*] Section underline should match the length of its nam
 227 227 |     Raises:
 228 228 |     My attention.
 
+sections.py:568:5: D409 [*] Section underline should match the length of its name ("Other Parameters")
+    |
+567 |   def test_method_should_be_correctly_capitalized(parameters: list[str], other_parameters: dict[str, str]): # noqa: D213
+568 |       """Test parameters and attributes sections are capitalized correctly.
+    |  _____^
+569 | | 
+570 | |     Parameters
+571 | |     ----------
+572 | |     parameters:
+573 | |         A list of string parameters
+574 | |     other_parameters:
+575 | |         A dictionary of string attributes
+576 | | 
+577 | |     Other Parameters
+578 | |     ----------
+579 | |     other_parameters:
+580 | |         A dictionary of string attributes
+581 | |     parameters:
+582 | |         A list of string parameters
+583 | | 
+584 | |     """
+    | |_______^ D409
+    |
+    = help: Adjust underline length to match "Other Parameters"
+
+ℹ Safe fix
+575 575 |         A dictionary of string attributes
+576 576 | 
+577 577 |     Other Parameters
+578     |-    ----------
+    578 |+    ----------------
+579 579 |     other_parameters:
+580 580 |         A dictionary of string attributes
+581 581 |     parameters:
+
 

crates/ruff_linter/src/rules/pydocstyle/snapshots/ruff_linter__rules__pydocstyle__tests__D413_sections.py.snap

@@ -161,5 +161,33 @@ sections.py:558:5: D413 [*] Missing blank line after last section ("Returns")
 563 563 |         Returns:
     564 |+    
 564 565 |     """
+565 566 | 
+566 567 | 
+
+sections.py:588:5: D413 [*] Missing blank line after last section ("Parameters")
+    |
+587 |   def test_lowercase_sub_section_header_should_be_valid(parameters: list[str], value: int):  # noqa: D213
+588 |       """Test that lower case subsection header is valid even if it has the same name as section kind.
+    |  _____^
+589 | | 
+590 | |     Parameters:
+591 | |     ----------
+592 | |     parameters:
+593 | |         A list of string parameters
+594 | |     value:
+595 | |         Some value
+596 | |     """
+    | |_______^ D413
+    |
+    = help: Add blank line after "Parameters"
+
+ℹ Safe fix
+593 593 |         A list of string parameters
+594 594 |     value:
+595 595 |         Some value
+    596 |+    
+596 597 |     """
+597 598 | 
+598 599 |