SONARPY-902 S930 (ArgumentNumberCheck) should not report on instance … (#1065)

Author: andrea-guarino-sonarsource

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

@@ -22,6 +22,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Collectors;
 import javax.annotation.Nullable;
@@ -35,13 +36,16 @@
 import org.sonar.plugins.python.api.tree.Argument;
 import org.sonar.plugins.python.api.tree.CallExpression;
 import org.sonar.plugins.python.api.tree.Expression;
+import org.sonar.plugins.python.api.tree.FunctionDef;
 import org.sonar.plugins.python.api.tree.Name;
 import org.sonar.plugins.python.api.tree.QualifiedExpression;
 import org.sonar.plugins.python.api.tree.RegularArgument;
 import org.sonar.plugins.python.api.tree.Tree;
 import org.sonar.python.semantic.FunctionSymbolImpl;
 import org.sonar.python.tree.TreeUtils;
 
+import static org.sonar.plugins.python.api.symbols.Usage.Kind.PARAMETER;
+
 @Rule(key = "S930")
 public class ArgumentNumberCheck extends PythonSubscriptionCheck {
 
@@ -66,7 +70,7 @@ public void initialize(Context context) {
 
   private static void checkPositionalParameters(SubscriptionContext ctx, CallExpression callExpression, FunctionSymbol functionSymbol) {
     int self = 0;
-    if (functionSymbol.isInstanceMethod() && callExpression.callee().is(Tree.Kind.QUALIFIED_EXPR)) {
+    if (functionSymbol.isInstanceMethod() && callExpression.callee().is(Tree.Kind.QUALIFIED_EXPR) && !isCalledAsClassMethod((QualifiedExpression) callExpression.callee())) {
       self = 1;
     }
     Map<String, FunctionSymbol.Parameter> positionalParamsWithoutDefault = positionalParamsWithoutDefault(functionSymbol);
@@ -101,6 +105,25 @@ private static void checkPositionalParameters(SubscriptionContext ctx, CallExpre
     }
   }
 
+  private static boolean isCalledAsClassMethod(QualifiedExpression callee) {
+    return TreeUtils.getSymbolFromTree(callee.qualifier())
+      .filter(ArgumentNumberCheck::isParamOfClassMethod)
+      .isPresent();
+  }
+
+  // no need to check that's the first parameter (i.e. cls)
+  // the assumption is that another method can be called only using the first parameter of a class method
+  private static boolean isParamOfClassMethod(Symbol symbol) {
+    return symbol.usages().stream().anyMatch(usage -> usage.kind() == PARAMETER && isParamOfClassMethod(usage.tree()));
+  }
+
+  private static boolean isParamOfClassMethod(Tree tree) {
+    FunctionDef functionDef = (FunctionDef) TreeUtils.firstAncestorOfKind(tree, Tree.Kind.FUNCDEF);
+    return Optional.ofNullable(TreeUtils.getFunctionSymbolFromDef(functionDef))
+      .filter(functionSymbol -> functionSymbol.decorators().stream().anyMatch(dec -> dec.equals("classmethod")))
+      .isPresent();
+  }
+
   private static Map<String, FunctionSymbol.Parameter> positionalParamsWithoutDefault(FunctionSymbol functionSymbol) {
     int unnamedIndex = 0;
     Map<String, FunctionSymbol.Parameter> result = new HashMap<>();

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

@@ -90,6 +90,10 @@ def class_meth(cls, p1, p2): pass
       def static_meth(p1, p2): pass
       def foo(p1): pass
       foo(42)
+      @classmethod
+      def bar_class_method(cls):
+        cls.bar_instance_method(cls)
+      def bar_instance_method(self): pass
 
     A.class_meth(42) # FN {{'class_meth' expects 2 positional arguments, but 1 was provided}}