SONARPY-1883 Fix FP on S5756 on nested function in presence of try/except (#1813)

Author: guillaume-dequenne

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

@@ -299,4 +299,14 @@ def conditionally_reassigned_param_try_except(a, param):
             param = [1,2,3]
         param()
     except:
-        ...
+        ...
+
+
+def nested_function_in_try_catch():
+    foo = None
+    try:
+        ...
+    except:
+        ...
+    def bar():
+        foo()

python-frontend/src/main/java/org/sonar/python/semantic/v2/types/Definition.java

@@ -20,7 +20,9 @@
 package org.sonar.python.semantic.v2.types;
 
 import org.sonar.plugins.python.api.tree.Name;
+import org.sonar.plugins.python.api.tree.Tree;
 import org.sonar.python.semantic.v2.SymbolV2;
+import org.sonar.python.tree.TreeUtils;
 import org.sonar.python.types.v2.PythonType;
 
 /**
@@ -45,4 +47,9 @@ public Name lhsName() {
   public PythonType rhsType() {
     return lhsName.typeV2();
   }
+
+  @Override
+  Tree scopeTree(Name name) {
+    return TreeUtils.firstAncestor(name, t -> !t.equals(lhsName.parent()) && t.is(Tree.Kind.FUNCDEF, Tree.Kind.FILE_INPUT, Tree.Kind.CLASSDEF));
+  }
 }

python-frontend/src/main/java/org/sonar/python/semantic/v2/types/Propagation.java

@@ -20,6 +20,7 @@
 package org.sonar.python.semantic.v2.types;
 
 import java.util.HashSet;
+import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Stream;
 import org.sonar.plugins.python.api.tree.Expression;
@@ -29,6 +30,7 @@
 import org.sonar.python.semantic.v2.SymbolV2Utils;
 import org.sonar.python.semantic.v2.UsageV2;
 import org.sonar.python.tree.NameImpl;
+import org.sonar.python.tree.TreeUtils;
 import org.sonar.python.types.v2.PythonType;
 import org.sonar.python.types.v2.UnionType;
 
@@ -53,10 +55,13 @@ protected Propagation(SymbolV2 lhsSymbol, Name lhsName) {
    */
   boolean propagate(Set<SymbolV2> initializedVars) {
     PythonType rhsType = rhsType();
+    Tree scopeTree = scopeTree(lhsName);
     if (initializedVars.add(lhsSymbol)) {
       getSymbolNonDeclarationUsageTrees(lhsSymbol)
         .filter(NameImpl.class::isInstance)
         .map(NameImpl.class::cast)
+        // Avoid propagation to usages in nested scopes, as this may lead to FPs
+        .filter(n -> isInSameScope(n, scopeTree))
         .forEach(n -> n.typeV2(rhsType));
       return true;
     } else {
@@ -68,11 +73,20 @@ boolean propagate(Set<SymbolV2> initializedVars) {
       getSymbolNonDeclarationUsageTrees(lhsSymbol)
         .filter(NameImpl.class::isInstance)
         .map(NameImpl.class::cast)
+        .filter(n -> isInSameScope(n, scopeTree))
         .forEach(n -> n.typeV2(newType));
       return !newType.equals(currentType);
     }
   }
 
+  private boolean isInSameScope(Name n, Tree scopeTree) {
+    return Optional.ofNullable(scopeTree(n)).filter(scopeTree::equals).isPresent();
+  }
+
+  Tree scopeTree(Name name) {
+    return TreeUtils.firstAncestor(name, t ->  t.is(Tree.Kind.FUNCDEF, Tree.Kind.FILE_INPUT, Tree.Kind.CLASSDEF));
+  }
+
   public static Stream<Tree> getSymbolNonDeclarationUsageTrees(SymbolV2 symbol) {
     return symbol.usages()
       .stream()

python-frontend/src/test/java/org/sonar/python/semantic/v2/TypeInferenceV2Test.java

@@ -990,6 +990,24 @@ void try_except_list_attributes() {
 
   }
 
+  @Test
+  void tryExceptNestedScope() {
+    FileInput fileInput = inferTypes("""
+      try:
+          ...
+      except:
+          ...
+      
+      do_smth = None
+      
+      def something(param):
+          type(do_smth)
+      """);
+    List<CallExpression> calls = PythonTestUtils.getAllDescendant(fileInput, tree -> tree.is(Tree.Kind.CALL_EXPR));
+    RegularArgument doSmthArg = (RegularArgument) calls.get(0).arguments().get(0);
+    assertThat(doSmthArg.expression().typeV2()).isEqualTo(PythonType.UNKNOWN);
+  }
+
   @Test
   void inferTypeForQualifiedExpression() {
     var root = inferTypes("""