SONARPY-997 Fix FP on S5632 for nonlocal variables (#1116)

Author: guillaume-dequenne

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

@@ -46,16 +46,19 @@ public void initialize(Context context) {
         return;
       }
       Expression raisedExpression = raiseStatement.expressions().get(0);
-      if (!raisedExpression.type().canBeOrExtend(BASE_EXCEPTION)) {
-        ctx.addIssue(raiseStatement, MESSAGE);
-        return;
-      }
       Symbol symbol = null;
       if (raisedExpression instanceof HasSymbol) {
         symbol = ((HasSymbol) raisedExpression).symbol();
       } else if (raisedExpression.is(Tree.Kind.CALL_EXPR)) {
         symbol = ((CallExpression) raisedExpression).calleeSymbol();
       }
+      if (hasGlobalOrNonLocalUsage(symbol)) {
+        return;
+      }
+      if (!raisedExpression.type().canBeOrExtend(BASE_EXCEPTION)) {
+        ctx.addIssue(raiseStatement, MESSAGE);
+        return;
+      }
       if (!mayInheritFromBaseException(symbol)) {
         ctx.addIssue(raiseStatement, MESSAGE);
       }
@@ -77,4 +80,8 @@ private static boolean mayInheritFromBaseException(@Nullable Symbol symbol) {
     // to handle other builtins like 'NotImplemented'
     return !BuiltinSymbols.all().contains(symbol.fullyQualifiedName());
   }
+
+  private static boolean hasGlobalOrNonLocalUsage(@Nullable Symbol symbol) {
+    return symbol != null && symbol.usages().stream().anyMatch(s -> s.tree().parent().is(Tree.Kind.GLOBAL_STMT, Tree.Kind.NONLOCAL_STMT));
+  }
 }

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

@@ -142,3 +142,14 @@ def raise_with_str_concat():
 
 def raise_builtin_exception_with_fqn_null():
   raise IOError()
+
+
+def no_fp_on_nonlocal_variables(x):
+    exception = None
+    def do_something():
+        nonlocal exception
+        if foo():
+            exception = ValueError("Hello")
+    do_something()
+    if exception:
+        raise exception