[pyupgrade] Extend version detection to include sys.version_info.major (UP036) (#18633)

## Summary

Resolves #18165 

Added pattern `["sys", "version_info", "major"]` to the existing matches
for `sys.version_info` to ensure consistent handling of both the base
object and its major version attribute.

## Test Plan
`cargo nextest run` and `cargo insta test`

---------

Co-authored-by: Brent Westbrook <brentrwestbrook@gmail.com>

crates/ruff_linter/resources/test/fixtures/pyupgrade/UP036_5.py

@@ -71,3 +71,47 @@ if sys.version_info <= (3, 14, 0):
 
 if sys.version_info <= (3, 14, 15):
     print()
+
+# https://github.com/astral-sh/ruff/issues/18165
+
+if sys.version_info.major >= 3:
+    print("3")
+else:
+    print("2")
+
+if sys.version_info.major > 3:
+    print("3")
+else:
+    print("2")
+
+if sys.version_info.major <= 3:
+    print("3")
+else:
+    print("2")
+
+if sys.version_info.major < 3:
+    print("3")
+else:
+    print("2")
+
+if sys.version_info.major == 3:
+    print("3")
+else:
+    print("2")
+
+# Semantically incorrect, skip fixing
+
+if sys.version_info.major[1] > 3:
+    print(3)
+else:
+    print(2)
+
+if sys.version_info.major > (3, 13):
+    print(3)
+else:
+    print(2)
+
+if sys.version_info.major[:2] > (3, 13):
+    print(3)
+else:
+    print(2)

crates/ruff_linter/src/rules/pyupgrade/rules/outdated_version_block.rs

@@ -14,6 +14,7 @@ use crate::checkers::ast::Checker;
 use crate::fix::edits::{adjust_indentation, delete_stmt};
 use crate::{Edit, Fix, FixAvailability, Violation};
 use ruff_python_ast::PythonVersion;
+use ruff_python_semantic::SemanticModel;
 
 /// ## What it does
 /// Checks for conditional blocks gated on `sys.version_info` comparisons
@@ -103,14 +104,7 @@ pub(crate) fn outdated_version_block(checker: &Checker, stmt_if: &StmtIf) {
             continue;
         };
 
-        // Detect `sys.version_info`, along with slices (like `sys.version_info[:2]`).
-        if !checker
-            .semantic()
-            .resolve_qualified_name(map_subscript(left))
-            .is_some_and(|qualified_name| {
-                matches!(qualified_name.segments(), ["sys", "version_info"])
-            })
-        {
+        if !is_valid_version_info(checker.semantic(), left) {
             continue;
         }
 
@@ -456,6 +450,21 @@ fn extract_version(elts: &[Expr]) -> Option<Vec<Int>> {
     Some(version)
 }
 
+/// Returns `true` if the expression is related to `sys.version_info`.
+///
+/// This includes:
+/// - Direct access: `sys.version_info`
+/// - Subscript access: `sys.version_info[:2]`, `sys.version_info[0]`
+/// - Major version attribute: `sys.version_info.major`
+fn is_valid_version_info(semantic: &SemanticModel, left: &Expr) -> bool {
+    semantic
+        .resolve_qualified_name(map_subscript(left))
+        .is_some_and(|name| matches!(name.segments(), ["sys", "version_info"]))
+        || semantic
+            .resolve_qualified_name(left)
+            .is_some_and(|name| matches!(name.segments(), ["sys", "version_info", "major"]))
+}
+
 #[cfg(test)]
 mod tests {
     use test_case::test_case;

crates/ruff_linter/src/rules/pyupgrade/snapshots/ruff_linter__rules__pyupgrade__tests__UP036_5.py.snap

@@ -157,3 +157,123 @@ UP036_5.py:48:24: UP036 Version specifier is invalid
    |                        ^^^^^^^^^^^^^^^ UP036
 49 |     print()
    |
+
+UP036_5.py:77:4: UP036 [*] Version block is outdated for minimum Python version
+   |
+75 | # https://github.com/astral-sh/ruff/issues/18165
+76 |
+77 | if sys.version_info.major >= 3:
+   |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^ UP036
+78 |     print("3")
+79 | else:
+   |
+   = help: Remove outdated version block
+
+ℹ Unsafe fix
+74 74 | 
+75 75 | # https://github.com/astral-sh/ruff/issues/18165
+76 76 | 
+77    |-if sys.version_info.major >= 3:
+78    |-    print("3")
+79    |-else:
+80    |-    print("2")
+   77 |+print("3")
+81 78 | 
+82 79 | if sys.version_info.major > 3:
+83 80 |     print("3")
+
+UP036_5.py:82:4: UP036 [*] Version block is outdated for minimum Python version
+   |
+80 |     print("2")
+81 |
+82 | if sys.version_info.major > 3:
+   |    ^^^^^^^^^^^^^^^^^^^^^^^^^^ UP036
+83 |     print("3")
+84 | else:
+   |
+   = help: Remove outdated version block
+
+ℹ Unsafe fix
+79 79 | else:
+80 80 |     print("2")
+81 81 | 
+82    |-if sys.version_info.major > 3:
+83    |-    print("3")
+84    |-else:
+85    |-    print("2")
+   82 |+print("2")
+86 83 | 
+87 84 | if sys.version_info.major <= 3:
+88 85 |     print("3")
+
+UP036_5.py:87:4: UP036 [*] Version block is outdated for minimum Python version
+   |
+85 |     print("2")
+86 |
+87 | if sys.version_info.major <= 3:
+   |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^ UP036
+88 |     print("3")
+89 | else:
+   |
+   = help: Remove outdated version block
+
+ℹ Unsafe fix
+84 84 | else:
+85 85 |     print("2")
+86 86 | 
+87    |-if sys.version_info.major <= 3:
+88    |-    print("3")
+89    |-else:
+90    |-    print("2")
+   87 |+print("3")
+91 88 | 
+92 89 | if sys.version_info.major < 3:
+93 90 |     print("3")
+
+UP036_5.py:92:4: UP036 [*] Version block is outdated for minimum Python version
+   |
+90 |     print("2")
+91 |
+92 | if sys.version_info.major < 3:
+   |    ^^^^^^^^^^^^^^^^^^^^^^^^^^ UP036
+93 |     print("3")
+94 | else:
+   |
+   = help: Remove outdated version block
+
+ℹ Unsafe fix
+89 89 | else:
+90 90 |     print("2")
+91 91 | 
+92    |-if sys.version_info.major < 3:
+93    |-    print("3")
+94    |-else:
+95    |-    print("2")
+   92 |+print("2")
+96 93 | 
+97 94 | if sys.version_info.major == 3:
+98 95 |     print("3")
+
+UP036_5.py:97:4: UP036 [*] Version block is outdated for minimum Python version
+   |
+95 |     print("2")
+96 |
+97 | if sys.version_info.major == 3:
+   |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^ UP036
+98 |     print("3")
+99 | else:
+   |
+   = help: Remove outdated version block
+
+ℹ Unsafe fix
+94  94  | else:
+95  95  |     print("2")
+96  96  | 
+97      |-if sys.version_info.major == 3:
+98      |-    print("3")
+99      |-else:
+100     |-    print("2")
+    97  |+print("3")
+101 98  | 
+102 99  | # Semantically incorrect, skip fixing
+103 100 |