SONARPY-3247: S5953: fix FP on generic types defined with Python's "new" generic syntax (#462)

GitOrigin-RevId: 97637b177c0aa684b3b84047e7827bd21cbbca6a

Author: joke1196

python-checks/src/main/java/org/sonar/python/checks/UndefinedSymbolsCheck.java

@@ -20,15 +20,19 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import javax.annotation.Nullable;
 import org.sonar.check.Rule;
 import org.sonar.plugins.python.api.PythonSubscriptionCheck;
 import org.sonar.plugins.python.api.SubscriptionContext;
 import org.sonar.plugins.python.api.tree.BaseTreeVisitor;
 import org.sonar.plugins.python.api.tree.CallExpression;
+import org.sonar.plugins.python.api.tree.ClassDef;
 import org.sonar.plugins.python.api.tree.FileInput;
 import org.sonar.plugins.python.api.tree.ImportFrom;
 import org.sonar.plugins.python.api.tree.Name;
 import org.sonar.plugins.python.api.tree.Tree;
+import org.sonar.plugins.python.api.tree.TypeParams;
+import org.sonar.python.tree.TreeUtils;
 
 @Rule(key = "S5953")
 public class UndefinedSymbolsCheck extends PythonSubscriptionCheck {
@@ -68,11 +72,29 @@ private static class UnresolvedSymbolsVisitor extends BaseTreeVisitor {
 
     @Override
     public void visitName(Name name) {
-      if (name.isVariable() && name.symbol() == null && !name.name().startsWith("_")) {
+      if (name.isVariable() && name.symbol() == null && !name.name().startsWith("_") && !isTypeVar(name)) {
         nameIssues.computeIfAbsent(name.name(), k -> new ArrayList<>()).add(name);
       }
     }
 
+    private static boolean isTypeVar(Name name) {
+      return TreeUtils.firstAncestor(name, tree -> classWithTypeVar(tree, name)) != null;
+    }
+
+    private static boolean classWithTypeVar(Tree tree, Name name) {
+      if (tree instanceof ClassDef classDef) {
+        return hasTypeVar(classDef.typeParams(), name);
+      }
+      return false;
+    }
+
+    private static boolean hasTypeVar(@Nullable TypeParams typeParams, Name name) {
+      if (typeParams != null && !typeParams.typeParamsList().isEmpty()) {
+        return typeParams.typeParamsList().stream().anyMatch(typeParam -> typeParam.name().name().equals(name.name()));
+      }
+      return false;
+    }
+
     @Override
     public void visitImportFrom(ImportFrom importFrom) {
       hasWildcardImport |= importFrom.wildcard() != null;

python-checks/src/test/resources/checks/undefinedSymbols/undefinedSymbols.py

@@ -156,3 +156,9 @@ def undefined_generic_type[T: T](a: T) -> T:
     x: T = a
     a.foo()
 
+class TypeVarTest[T]:
+    def from_class_def(self):
+        a: list[T] = ...
+
+    def unknow_generic(self):
+        a: list[X] = ... # Noncompliant