SONARPY-1561: Infer types of variables used as decorators. (#1668)

python-checks/src/test/resources/checks/confusingTypeChecking/nonCallableCalled.py

@@ -1,4 +1,4 @@
-from typing import Set, FrozenSet, Union, Coroutine
+from typing import Set, FrozenSet, Union, Coroutine, Callable
 import asyncio
 
 def empty_union(x: Union['A', 'B']):
@@ -37,3 +37,15 @@ async def bar(func: Coroutine):
   await asyncio.gather(
     func()
   )
+
+
+def decorators(decorator: Callable, non_callable: str):
+
+    @non_callable()  # Noncompliant
+    def foo():
+        ...
+
+    @decorator()
+    def bar():
+        ...
+

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

@@ -80,6 +80,13 @@ class A(Base): ...
   a = A()
   a() # OK
 
+
+def decorators():
+  x = 42
+  @x() # Noncompliant
+  def foo():
+    ...
+
 #######################################
 # Valid case: Calling a callable object
 #######################################
@@ -97,6 +104,19 @@ def call_function():
     func()
     max()
 
+#############################
+# Valid case: Call a decorator
+#############################
+
+def decorators():
+    class Dec:
+        def __call__(self, *args):
+            ...
+
+    @Dec("foo")
+    def foo():
+        ...
+
 #############################
 # Valid case: Call a method
 #############################

python-frontend/src/main/java/org/sonar/python/cfg/ControlFlowGraphBuilder.java

@@ -164,10 +164,7 @@ private PythonCfgBlock build(Statement statement, PythonCfgBlock currentBlock) {
       case WITH_STMT:
         return buildWithStatement((WithStatement) statement, currentBlock);
       case CLASSDEF:
-        ClassDef classDef = (ClassDef) statement;
-        PythonCfgBlock block = build(classDef.body().statements(), currentBlock);
-        block.addElement(classDef.name()); // represents binding to class name
-        return block;
+        return buildClassDefStatement((ClassDef) statement, currentBlock);
       case RETURN_STMT:
         return buildReturnStatement((ReturnStatement) statement, currentBlock);
       case RAISE_STMT:
@@ -186,13 +183,28 @@ private PythonCfgBlock build(Statement statement, PythonCfgBlock currentBlock) {
         return buildBreakStatement((BreakStatement) statement, currentBlock);
       case MATCH_STMT:
         return buildMatchStatement((MatchStatement) statement, currentBlock);
+      case FUNCDEF:
+        return buildFuncDefStatement((FunctionDef) statement, currentBlock);
       default:
         currentBlock.addElement(statement);
     }
 
     return currentBlock;
   }
 
+  private PythonCfgBlock buildClassDefStatement(ClassDef classDef, PythonCfgBlock currentBlock) {
+    PythonCfgBlock block = build(classDef.body().statements(), currentBlock);
+    block.addElement(classDef.name()); // represents binding to class name
+    classDef.decorators().stream().forEach(currentBlock::addElement);
+    return block;
+  }
+
+  private static PythonCfgBlock buildFuncDefStatement(FunctionDef functionDef, PythonCfgBlock currentBlock) {
+    currentBlock.addElement(functionDef);
+    functionDef.decorators().stream().forEach(currentBlock::addElement);
+    return currentBlock;
+  }
+
   private PythonCfgBlock buildMatchStatement(MatchStatement statement, PythonCfgBlock successor) {
     List<CaseBlock> caseBlocks = statement.caseBlocks();
     PythonCfgBlock matchingBlock = null;

python-frontend/src/test/java/org/sonar/plugins/python/api/cfg/ControlFlowGraphTest.java

@@ -20,6 +20,7 @@
 package org.sonar.plugins.python.api.cfg;
 
 import java.util.Arrays;
+import java.util.List;
 import java.util.stream.Collectors;
 import org.junit.jupiter.api.Test;
 import org.mockito.Mockito;
@@ -706,6 +707,34 @@ void if_stmt_test_predecessors() {
       "after_if(succ = [END], pred = [before, if_body])");
   }
 
+  @Test
+  void decorators() {
+    ControlFlowGraph cfg = cfg(
+      "class Dec:",
+      "    def a():",
+      "        ...",
+      "dec = Dec()",
+      "@dec.a()",
+      "def foo():",
+      "    ..."
+    );
+    List<Tree> elements = cfg.start().elements();
+    assertThat(elements).hasSize(5);
+    assertThat(elements).extracting(Tree::getKind).containsExactly(Kind.NAME, Kind.FUNCDEF, Kind.ASSIGNMENT_STMT, Kind.DECORATOR, Kind.FUNCDEF);
+
+    cfg = cfg(
+      "class Dec:",
+      "    def __call__(self):",
+      "        ...",
+      "@Dec",
+      "class OtherClass:",
+      "    ..."
+    );
+    elements = cfg.start().elements();
+    assertThat(elements).hasSize(5);
+    assertThat(elements).extracting(Tree::getKind).containsExactly(Kind.NAME, Kind.FUNCDEF, Kind.DECORATOR, Kind.NAME, Kind.EXPRESSION_STMT);
+  }
+
   @Test
   void parameters() {
     FileInput fileInput = PythonTestUtils.parse("def f(p1, p2): pass");

python-frontend/src/test/java/org/sonar/python/types/TypeInferenceTest.java

@@ -24,26 +24,31 @@
 import org.sonar.plugins.python.api.symbols.ClassSymbol;
 import org.sonar.plugins.python.api.tree.AssignmentStatement;
 import org.sonar.plugins.python.api.tree.CallExpression;
+import org.sonar.plugins.python.api.tree.Decorator;
 import org.sonar.plugins.python.api.tree.Expression;
 import org.sonar.plugins.python.api.tree.ExpressionStatement;
 import org.sonar.plugins.python.api.tree.FileInput;
+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.ReturnStatement;
 import org.sonar.plugins.python.api.tree.Tree;
 import org.sonar.plugins.python.api.types.BuiltinTypes;
 import org.sonar.plugins.python.api.types.InferredType;
 import org.sonar.python.PythonTestUtils;
 import org.sonar.python.semantic.SymbolImpl;
+import org.sonar.python.semantic.SymbolTableBuilder;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.sonar.python.PythonTestUtils.getLastDescendant;
 import static org.sonar.python.PythonTestUtils.lastExpression;
 import static org.sonar.python.PythonTestUtils.lastExpressionInFunction;
-import static org.sonar.python.PythonTestUtils.lastStatement;import static org.sonar.python.PythonTestUtils.parse;
+import static org.sonar.python.PythonTestUtils.lastStatement;
+import static org.sonar.python.PythonTestUtils.parse;
+import static org.sonar.python.PythonTestUtils.pythonFile;
 import static org.sonar.python.types.InferredTypes.BOOL;
 import static org.sonar.python.types.InferredTypes.COMPLEX;
 import static org.sonar.python.types.InferredTypes.DECL_INT;
-import static org.sonar.python.types.InferredTypes.DECL_LIST;
 import static org.sonar.python.types.InferredTypes.DECL_STR;
 import static org.sonar.python.types.InferredTypes.DICT;
 import static org.sonar.python.types.InferredTypes.FLOAT;
@@ -759,4 +764,36 @@ void user_defined_attributes_reassigned() {
     ).type()).isEqualTo(DECL_INT);
   }
 
+  @Test
+  void decorators() {
+    Decorator decorator = lastDecorator(
+      "class A:",
+      "  def dec_method():",
+      "    ...",
+      "my_dec = A()",
+      "@my_dec.dec_method()",
+      "def a_function():",
+      "  ...");
+    CallExpression ce = (CallExpression) decorator.expression();
+    QualifiedExpression qe = (QualifiedExpression) ce.callee();
+    assertThat(typeName(qe.qualifier().type())).isEqualTo("A");
+    assertThat(qe.name().symbol().fullyQualifiedName()).isEqualTo("some_package.some_module.A.dec_method");
+    assertThat(ce.calleeSymbol().fullyQualifiedName()).isEqualTo("some_package.some_module.A.dec_method");
+
+    decorator = lastDecorator(
+      "class A:",
+      "  def __call__():",
+      "    ...",
+      "@A",
+      "class OtherClass:",
+      "  ...");
+    Name name = (Name) decorator.expression();
+    assertThat(name.type()).isEqualTo(anyType());
+    assertThat(name.symbol().fullyQualifiedName()).isEqualTo("some_package.some_module.A");
+  }
+
+  private static Decorator lastDecorator(String... code) {
+    FileInput fileInput = parse(new SymbolTableBuilder("some_package", pythonFile("some_module")), code);
+    return PythonTestUtils.getLastDescendant(fileInput, t -> t.is(Tree.Kind.DECORATOR));
+  }
 }