Allow SPDX license headers to exceed the line length (#10481)

Closes #10465.

crates/ruff_linter/resources/test/fixtures/pycodestyle/E501.py

@@ -82,3 +82,8 @@ class Bar:
     """
     This is a long sentence that ends with a shortened URL and, therefore, could easily be broken across multiple lines ([source](https://ruff.rs))
     """
+
+
+# OK
+# SPDX-FileCopyrightText: Copyright 2012-2015 Charlie Marsh <[email protected]>
+# SPDX-License-Identifier: a very long license identifier that exceeds the line length limit

crates/ruff_linter/src/rules/pycodestyle/overlong.rs

@@ -53,7 +53,7 @@ impl Overlong {
         };
 
         let mut chunks = line.split_whitespace();
-        let (Some(_), Some(second_chunk)) = (chunks.next(), chunks.next()) else {
+        let (Some(first_chunk), Some(second_chunk)) = (chunks.next(), chunks.next()) else {
             // Single word / no printable chars - no way to make the line shorter.
             return None;
         };
@@ -67,6 +67,15 @@ impl Overlong {
             }
         }
 
+        // Do not enforce the line length limit for SPDX license headers, which are machine-readable
+        // and explicitly _not_ recommended to wrap over multiple lines.
+        if matches!(
+            (first_chunk, second_chunk),
+            ("#", "SPDX-License-Identifier:" | "SPDX-FileCopyrightText:")
+        ) {
+            return None;
+        }
+
         // Obtain the start offset of the part of the line that exceeds the limit.
         let mut start_offset = line.start();
         let mut start_width = LineWidthBuilder::new(tab_size);

crates/ruff_linter/src/rules/pycodestyle/rules/line_too_long.rs

@@ -27,6 +27,9 @@ use crate::settings::LinterSettings;
 ///    line-length threshold. That is, a line will not be flagged as
 ///    overlong if a pragma comment _causes_ it to exceed the line length.
 ///    (This behavior aligns with that of the Ruff formatter.)
+/// 4. Ignores SPDX license identifiers and copyright notices
+///    (e.g., `# SPDX-License-Identifier: MIT`), which are machine-readable
+///    and should _not_ wrap over multiple lines.
 ///
 /// If [`lint.pycodestyle.ignore-overlong-task-comments`] is `true`, this rule will
 /// also ignore comments that start with any of the specified [`lint.task-tags`]