Mark `sys.version_info[0] < 3` and similar comparisons as outdated (#13175)

## Summary

Closes https://github.com/astral-sh/ruff/issues/12993.

crates/ruff_linter/resources/test/fixtures/pyupgrade/UP036_0.py

@@ -225,3 +225,33 @@ if sys.version_info > (3,0):
 
     "this is\
     allowed too"
+
+if sys.version_info[0] == 3:
+    print("py3")
+
+if sys.version_info[0] <= 3:
+    print("py3")
+
+if sys.version_info[0] < 3:
+    print("py3")
+
+if sys.version_info[0] >= 3:
+    print("py3")
+
+if sys.version_info[0] > 3:
+    print("py3")
+
+if sys.version_info[0] == 2:
+    print("py3")
+
+if sys.version_info[0] <= 2:
+    print("py3")
+
+if sys.version_info[0] < 2:
+    print("py3")
+
+if sys.version_info[0] >= 2:
+    print("py3")
+
+if sys.version_info[0] > 2:
+    print("py3")

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

@@ -57,7 +57,9 @@ impl Violation for OutdatedVersionBlock {
     fn message(&self) -> String {
         let OutdatedVersionBlock { reason } = self;
         match reason {
-            Reason::Outdated => format!("Version block is outdated for minimum Python version"),
+            Reason::AlwaysFalse | Reason::AlwaysTrue => {
+                format!("Version block is outdated for minimum Python version")
+            }
             Reason::Invalid => format!("Version specifier is invalid"),
         }
     }
@@ -65,7 +67,9 @@ impl Violation for OutdatedVersionBlock {
     fn fix_title(&self) -> Option<String> {
         let OutdatedVersionBlock { reason } = self;
         match reason {
-            Reason::Outdated => Some("Remove outdated version block".to_string()),
+            Reason::AlwaysFalse | Reason::AlwaysTrue => {
+                Some("Remove outdated version block".to_string())
+            }
             Reason::Invalid => None,
         }
     }
@@ -73,7 +77,8 @@ impl Violation for OutdatedVersionBlock {
 
 #[derive(Debug, PartialEq, Eq)]
 enum Reason {
-    Outdated,
+    AlwaysTrue,
+    AlwaysFalse,
     Invalid,
 }
 
@@ -123,7 +128,11 @@ pub(crate) fn outdated_version_block(checker: &mut Checker, stmt_if: &StmtIf) {
                         Ok(true) => {
                             let mut diagnostic = Diagnostic::new(
                                 OutdatedVersionBlock {
-                                    reason: Reason::Outdated,
+                                    reason: if op.is_lt() || op.is_lt_e() {
+                                        Reason::AlwaysFalse
+                                    } else {
+                                        Reason::AlwaysTrue
+                                    },
                                 },
                                 branch.test.range(),
                             );
@@ -152,33 +161,40 @@ pub(crate) fn outdated_version_block(checker: &mut Checker, stmt_if: &StmtIf) {
                 value: ast::Number::Int(int),
                 ..
             }) => {
-                if op == &CmpOp::Eq {
+                let reason = match (int.as_u8(), op) {
-                    match int.as_u8() {
+                    (Some(2), CmpOp::Eq) => Reason::AlwaysFalse,
-                        Some(2) => {
+                    (Some(3), CmpOp::Eq) => Reason::AlwaysTrue,
-                            let mut diagnostic = Diagnostic::new(
+                    (Some(2), CmpOp::NotEq) => Reason::AlwaysTrue,
-                                OutdatedVersionBlock {
+                    (Some(3), CmpOp::NotEq) => Reason::AlwaysFalse,
-                                    reason: Reason::Outdated,
+                    (Some(2), CmpOp::Lt) => Reason::AlwaysFalse,
-                                },
+                    (Some(3), CmpOp::Lt) => Reason::AlwaysFalse,
-                                branch.test.range(),
+                    (Some(2), CmpOp::LtE) => Reason::AlwaysFalse,
-                            );
+                    (Some(3), CmpOp::LtE) => Reason::AlwaysTrue,
-                            if let Some(fix) = fix_always_false_branch(checker, stmt_if, &branch) {
+                    (Some(2), CmpOp::Gt) => Reason::AlwaysTrue,
-                                diagnostic.set_fix(fix);
+                    (Some(3), CmpOp::Gt) => Reason::AlwaysFalse,
-                            }
+                    (Some(2), CmpOp::GtE) => Reason::AlwaysTrue,
-                            checker.diagnostics.push(diagnostic);
+                    (Some(3), CmpOp::GtE) => Reason::AlwaysTrue,
-                        }
+                    (None, _) => Reason::Invalid,
-                        Some(3) => {
+                    _ => return,
-                            let mut diagnostic = Diagnostic::new(
+                };
-                                OutdatedVersionBlock {
+                match reason {
-                                    reason: Reason::Outdated,
+                    Reason::AlwaysTrue => {
-                                },
+                        let mut diagnostic =
-                                branch.test.range(),
+                            Diagnostic::new(OutdatedVersionBlock { reason }, branch.test.range());
-                            );
                         if let Some(fix) = fix_always_true_branch(checker, stmt_if, &branch) {
                             diagnostic.set_fix(fix);
                         }
                         checker.diagnostics.push(diagnostic);
                     }
-                        None => {
+                    Reason::AlwaysFalse => {
+                        let mut diagnostic =
+                            Diagnostic::new(OutdatedVersionBlock { reason }, branch.test.range());
+                        if let Some(fix) = fix_always_false_branch(checker, stmt_if, &branch) {
+                            diagnostic.set_fix(fix);
+                        }
+                        checker.diagnostics.push(diagnostic);
+                    }
+                    Reason::Invalid => {
                         checker.diagnostics.push(Diagnostic::new(
                             OutdatedVersionBlock {
                                 reason: Reason::Invalid,
@@ -186,8 +202,6 @@ pub(crate) fn outdated_version_block(checker: &mut Checker, stmt_if: &StmtIf) {
                             comparison.range(),
                         ));
                     }
-                        _ => {}
-                    }
                 }
             }
             _ => (),

crates/ruff_linter/src/rules/pyupgrade/snapshots/ruff_linter__rules__pyupgrade__tests__UP036_0.py.snap

@@ -801,3 +801,207 @@ UP036_0.py:219:4: UP036 [*] Version block is outdated for minimum Python version
 226     |-    "this is\
     225 |+"this is\
 227 226 |     allowed too"
+228 227 | 
+229 228 | if sys.version_info[0] == 3:
+
+UP036_0.py:229:4: UP036 [*] Version block is outdated for minimum Python version
+    |
+227 |     allowed too"
+228 | 
+229 | if sys.version_info[0] == 3:
+    |    ^^^^^^^^^^^^^^^^^^^^^^^^ UP036
+230 |     print("py3")
+    |
+    = help: Remove outdated version block
+
+ℹ Unsafe fix
+226 226 |     "this is\
+227 227 |     allowed too"
+228 228 | 
+229     |-if sys.version_info[0] == 3:
+230     |-    print("py3")
+    229 |+print("py3")
+231 230 | 
+232 231 | if sys.version_info[0] <= 3:
+233 232 |     print("py3")
+
+UP036_0.py:232:4: UP036 [*] Version block is outdated for minimum Python version
+    |
+230 |     print("py3")
+231 | 
+232 | if sys.version_info[0] <= 3:
+    |    ^^^^^^^^^^^^^^^^^^^^^^^^ UP036
+233 |     print("py3")
+    |
+    = help: Remove outdated version block
+
+ℹ Unsafe fix
+229 229 | if sys.version_info[0] == 3:
+230 230 |     print("py3")
+231 231 | 
+232     |-if sys.version_info[0] <= 3:
+233     |-    print("py3")
+    232 |+print("py3")
+234 233 | 
+235 234 | if sys.version_info[0] < 3:
+236 235 |     print("py3")
+
+UP036_0.py:235:4: UP036 [*] Version block is outdated for minimum Python version
+    |
+233 |     print("py3")
+234 | 
+235 | if sys.version_info[0] < 3:
+    |    ^^^^^^^^^^^^^^^^^^^^^^^ UP036
+236 |     print("py3")
+    |
+    = help: Remove outdated version block
+
+ℹ Unsafe fix
+232 232 | if sys.version_info[0] <= 3:
+233 233 |     print("py3")
+234 234 | 
+235     |-if sys.version_info[0] < 3:
+236     |-    print("py3")
+237 235 | 
+238 236 | if sys.version_info[0] >= 3:
+239 237 |     print("py3")
+
+UP036_0.py:238:4: UP036 [*] Version block is outdated for minimum Python version
+    |
+236 |     print("py3")
+237 | 
+238 | if sys.version_info[0] >= 3:
+    |    ^^^^^^^^^^^^^^^^^^^^^^^^ UP036
+239 |     print("py3")
+    |
+    = help: Remove outdated version block
+
+ℹ Unsafe fix
+235 235 | if sys.version_info[0] < 3:
+236 236 |     print("py3")
+237 237 | 
+238     |-if sys.version_info[0] >= 3:
+239     |-    print("py3")
+    238 |+print("py3")
+240 239 | 
+241 240 | if sys.version_info[0] > 3:
+242 241 |     print("py3")
+
+UP036_0.py:241:4: UP036 [*] Version block is outdated for minimum Python version
+    |
+239 |     print("py3")
+240 | 
+241 | if sys.version_info[0] > 3:
+    |    ^^^^^^^^^^^^^^^^^^^^^^^ UP036
+242 |     print("py3")
+    |
+    = help: Remove outdated version block
+
+ℹ Unsafe fix
+238 238 | if sys.version_info[0] >= 3:
+239 239 |     print("py3")
+240 240 | 
+241     |-if sys.version_info[0] > 3:
+242     |-    print("py3")
+243 241 | 
+244 242 | if sys.version_info[0] == 2:
+245 243 |     print("py3")
+
+UP036_0.py:244:4: UP036 [*] Version block is outdated for minimum Python version
+    |
+242 |     print("py3")
+243 | 
+244 | if sys.version_info[0] == 2:
+    |    ^^^^^^^^^^^^^^^^^^^^^^^^ UP036
+245 |     print("py3")
+    |
+    = help: Remove outdated version block
+
+ℹ Unsafe fix
+241 241 | if sys.version_info[0] > 3:
+242 242 |     print("py3")
+243 243 | 
+244     |-if sys.version_info[0] == 2:
+245     |-    print("py3")
+246 244 | 
+247 245 | if sys.version_info[0] <= 2:
+248 246 |     print("py3")
+
+UP036_0.py:247:4: UP036 [*] Version block is outdated for minimum Python version
+    |
+245 |     print("py3")
+246 | 
+247 | if sys.version_info[0] <= 2:
+    |    ^^^^^^^^^^^^^^^^^^^^^^^^ UP036
+248 |     print("py3")
+    |
+    = help: Remove outdated version block
+
+ℹ Unsafe fix
+244 244 | if sys.version_info[0] == 2:
+245 245 |     print("py3")
+246 246 | 
+247     |-if sys.version_info[0] <= 2:
+248     |-    print("py3")
+249 247 | 
+250 248 | if sys.version_info[0] < 2:
+251 249 |     print("py3")
+
+UP036_0.py:250:4: UP036 [*] Version block is outdated for minimum Python version
+    |
+248 |     print("py3")
+249 | 
+250 | if sys.version_info[0] < 2:
+    |    ^^^^^^^^^^^^^^^^^^^^^^^ UP036
+251 |     print("py3")
+    |
+    = help: Remove outdated version block
+
+ℹ Unsafe fix
+247 247 | if sys.version_info[0] <= 2:
+248 248 |     print("py3")
+249 249 | 
+250     |-if sys.version_info[0] < 2:
+251     |-    print("py3")
+252 250 | 
+253 251 | if sys.version_info[0] >= 2:
+254 252 |     print("py3")
+
+UP036_0.py:253:4: UP036 [*] Version block is outdated for minimum Python version
+    |
+251 |     print("py3")
+252 | 
+253 | if sys.version_info[0] >= 2:
+    |    ^^^^^^^^^^^^^^^^^^^^^^^^ UP036
+254 |     print("py3")
+    |
+    = help: Remove outdated version block
+
+ℹ Unsafe fix
+250 250 | if sys.version_info[0] < 2:
+251 251 |     print("py3")
+252 252 | 
+253     |-if sys.version_info[0] >= 2:
+254     |-    print("py3")
+    253 |+print("py3")
+255 254 | 
+256 255 | if sys.version_info[0] > 2:
+257 256 |     print("py3")
+
+UP036_0.py:256:4: UP036 [*] Version block is outdated for minimum Python version
+    |
+254 |     print("py3")
+255 | 
+256 | if sys.version_info[0] > 2:
+    |    ^^^^^^^^^^^^^^^^^^^^^^^ UP036
+257 |     print("py3")
+    |
+    = help: Remove outdated version block
+
+ℹ Unsafe fix
+253 253 | if sys.version_info[0] >= 2:
+254 254 |     print("py3")
+255 255 | 
+256     |-if sys.version_info[0] > 2:
+257     |-    print("py3")
+    256 |+print("py3")