Don't mark parameters of empty methods with no body as unused (PY-7028)

python/src/com/jetbrains/python/inspections/PyUnusedLocalInspectionVisitor.java

@@ -29,9 +29,7 @@ import com.jetbrains.python.psi.search.PyOverridingMethodsSearch;
 import com.jetbrains.python.psi.search.PySuperMethodsSearch;
 import org.jetbrains.annotations.NotNull;
 
-import java.util.Collection;
-import java.util.HashSet;
-import java.util.Set;
+import java.util.*;
 
 /**
  * @author oleg
@@ -215,7 +213,8 @@ public class PyUnusedLocalInspectionVisitor extends PyInspectionVisitor {
     final UnusedLocalFilter[] filters = Extensions.getExtensions(UnusedLocalFilter.EP_NAME);
     // Register problems
 
-    Set<PyFunction> functionsWithInheritors = new  HashSet<PyFunction>();
+    final Set<PyFunction> functionsWithInheritors = new HashSet<PyFunction>();
+    final Map<PyFunction, Boolean> emptyFunctions = new HashMap<PyFunction, Boolean>();
 
     for (PsiElement element : myUnusedElements) {
       boolean ignoreUnused = false;
@@ -275,6 +274,14 @@ public class PyUnusedLocalInspectionVisitor extends PyInspectionVisitor {
             else if (ignoreUnusedParameters(func, functionsWithInheritors)) {
               continue;
             }
+            Boolean isEmpty = emptyFunctions.get(func);
+            if (isEmpty == null) {
+              isEmpty = isEmptyFunction(func);
+              emptyFunctions.put(func, isEmpty);
+            }
+            if (isEmpty) {
+              continue;
+            }
           }
           final LocalQuickFix[] fixes = mayBeField
                                   ? new LocalQuickFix[] { new AddFieldQuickFix(name, containingClass, name) }
@@ -393,4 +400,40 @@ public class PyUnusedLocalInspectionVisitor extends PyInspectionVisitor {
       return getName();
     }
   }
+
+  private static boolean isEmptyFunction(@NotNull PyFunction f) {
+    final PyStatementList statementList = f.getStatementList();
+    if (statementList == null) {
+      return true;
+    }
+    final PyStatement[] statements = statementList.getStatements();
+    if (statements.length == 0) {
+      return true;
+    }
+    else if (statements.length == 1) {
+      if (isStringLiteral(statements[0]) || isPassOrRaise(statements[0])) {
+        return true;
+      }
+    }
+    else if (statements.length == 2) {
+      if (isStringLiteral(statements[0]) && (isPassOrRaise(statements[1]))) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  private static boolean isPassOrRaise(PyStatement stmt) {
+    return stmt instanceof PyPassStatement || stmt instanceof PyRaiseStatement;
+  }
+
+  private static boolean isStringLiteral(PyStatement stmt) {
+    if (stmt instanceof PyExpressionStatement) {
+      final PyExpression expr = ((PyExpressionStatement)stmt).getExpression();
+      if (expr instanceof PyStringLiteralExpression) {
+        return true;
+      }
+    }
+    return false;
+  }
 }

python/testData/inspections/FieldFromUnusedParameter.py

@@ -1,3 +1,3 @@
 class A:
     def __init__(self, <weak_warning descr="Parameter 'foo' value is not used">f<caret>oo</weak_warning>):
-        pass
+        print('hello')

python/testData/inspections/FieldFromUnusedParameterKeyword.py

@@ -1,3 +1,3 @@
 class A:
     def __init__(self, <weak_warning descr="Parameter 'foo' value is not used">f<caret>oo=True</weak_warning>):
-        pass
+        print('hello')

python/testData/inspections/FieldFromUnusedParameterKeyword_after.py

@@ -1,3 +1,4 @@
 class A:
     def __init__(self, foo=True):
+        print('hello')
         self.foo = foo

python/testData/inspections/FieldFromUnusedParameter_after.py

@@ -1,3 +1,4 @@
 class A:
     def __init__(self, foo):
+        print('hello')
         self.foo = foo

python/testData/inspections/PyUnusedLocalVariableInspection/test.py

@@ -112,7 +112,7 @@ def test():
         print v
 
 def foo(<weak_warning descr="Parameter 'a' value is not used">a = 123</weak_warning>): # fail Do not use getText() as parameter name
-    pass
+    print('hello')
 
 def loopie():
     for x in range(5): pass
@@ -123,9 +123,9 @@ def locals_inside():
     do_smth_with(locals())
 
 class Stat(object):
-  @staticmethod
-  def woof(<weak_warning descr="Parameter 'dog' value is not used">dog="bark"</weak_warning>): # fail
-    pass
+    @staticmethod
+    def woof(<weak_warning descr="Parameter 'dog' value is not used">dog="bark"</weak_warning>): # fail
+        print('hello')
 
 class A:
     def __init__(self, *args): #pass
@@ -261,3 +261,25 @@ def test_only_name_in_local_class():
     class <weak_warning descr="Local class 'C' is not used">C</weak_warning>:
         pass
     return x
+
+
+# PY-7028
+def test_unused_params_in_empty_function_1(x, y, z):
+    pass
+
+
+# PY-7028
+def test_unused_params_in_empty_function_2(x, y, z):
+    raise Exception()
+
+
+# PY-7028
+def test_unused_params_in_empty_function_3(x, y, z):
+    """Docstring."""
+
+
+# PY-7028
+def test_unused_params_in_empty_function_4(x, y, z):
+    """Docstring."""
+    raise Exception()
+