Fix scoping of JavaScript function names

Function declarations add their name to the outer scope, but not the
inner scope. Function expressions add their name to the inner scope,
unless the name is actually picked from the outer scope rather than
given after the function token.

We don't add the name to any scope in the case of functions declared in
QML elements because the QML element will receive the function as
appropriately named, and typed, property. It is always better to use
that one than to use a JavaScript local.

This causes some additional ecmascript tests to pass.

Pick-to: 6.2
Fixes: QTBUG-96625
Change-Id: I0b8ee98917d102a99fb6b9bd918037c71867a4a5
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

2 files changed, 31 insertions, 11 deletions

diff --git a/src/qml/compiler/qv4compilerscanfunctions.cpp b/src/qml/compiler/qv4compilerscanfunctions.cpp
index 9dec968a91..ee259b968b 100644
--- a/src/qml/compiler/qv4compilerscanfunctions.cpp
+++ b/src/qml/compiler/qv4compilerscanfunctions.cpp
@@ -382,8 +382,11 @@ bool ScanFunctions::visit(ExpressionStatement *ast)
         if (!_allowFuncDecls)
             _cg->throwSyntaxError(expr->functionToken, QStringLiteral("conditional function or closure declaration"));
 
-        if (!enterFunction(expr, /*enterName*/ true))
+        if (!enterFunction(expr, expr->identifierToken.length > 0
+                                ? FunctionNameContext::Inner
+                                : FunctionNameContext::None)) {
             return false;
+        }
         Node::accept(expr->formals, this);
         Node::accept(expr->body, this);
         leaveEnvironment();
@@ -399,7 +402,9 @@ bool ScanFunctions::visit(ExpressionStatement *ast)
 
 bool ScanFunctions::visit(FunctionExpression *ast)
 {
-    return enterFunction(ast, /*enterName*/ false);
+    return enterFunction(ast, ast->identifierToken.length > 0
+                                ? FunctionNameContext::Inner
+                                : FunctionNameContext::None);
 }
 
 bool ScanFunctions::visit(ClassExpression *ast)
@@ -496,12 +501,12 @@ bool ScanFunctions::visit(ArrayPattern *ast)
     return false;
 }
 
-bool ScanFunctions::enterFunction(FunctionExpression *ast, bool enterName)
+bool ScanFunctions::enterFunction(FunctionExpression *ast, FunctionNameContext nameContext)
 {
     Q_ASSERT(_context);
     if (_context->isStrict && (ast->name == QLatin1String("eval") || ast->name == QLatin1String("arguments")))
         _cg->throwSyntaxError(ast->identifierToken, QStringLiteral("Function name may not be eval or arguments in strict mode"));
-    return enterFunction(ast, ast->name.toString(), ast->formals, ast->body, enterName);
+    return enterFunction(ast, ast->name.toString(), ast->formals, ast->body, nameContext);
 }
 
 void ScanFunctions::endVisit(FunctionExpression *)
@@ -536,7 +541,7 @@ void ScanFunctions::endVisit(PatternProperty *)
 
 bool ScanFunctions::visit(FunctionDeclaration *ast)
 {
-    return enterFunction(ast, /*enterName*/ true);
+    return enterFunction(ast, FunctionNameContext::Outer);
 }
 
 void ScanFunctions::endVisit(FunctionDeclaration *)
@@ -674,7 +679,9 @@ void ScanFunctions::endVisit(WithStatement *)
     leaveEnvironment();
 }
 
-bool ScanFunctions::enterFunction(Node *ast, const QString &name, FormalParameterList *formals, StatementList *body, bool enterName)
+bool ScanFunctions::enterFunction(
+        Node *ast, const QString &name, FormalParameterList *formals, StatementList *body,
+        FunctionNameContext nameContext)
 {
     Context *outerContext = _context;
     enterEnvironment(ast, ContextType::Function, name);
@@ -685,7 +692,7 @@ bool ScanFunctions::enterFunction(Node *ast, const QString &name, FormalParamete
     if (outerContext) {
         outerContext->hasNestedFunctions = true;
         // The identifier of a function expression cannot be referenced from the enclosing environment.
-        if (enterName) {
+        if (nameContext == FunctionNameContext::Outer) {
             if (!outerContext->addLocalVar(name, Context::FunctionDefinition, VariableScope::Var, expr)) {
                 _cg->throwSyntaxError(ast->firstSourceLocation(), QStringLiteral("Identifier %1 has already been declared").arg(name));
                 return false;
@@ -711,8 +718,10 @@ bool ScanFunctions::enterFunction(Node *ast, const QString &name, FormalParamete
     }
 
 
-    if (!enterName && (!name.isEmpty() && (!formals || !formals->containsName(name))))
+    if (nameContext == FunctionNameContext::Inner
+            && (!name.isEmpty() && (!formals || !formals->containsName(name)))) {
         _context->addLocalVar(name, Context::ThisFunctionName, VariableScope::Var);
+    }
     _context->formals = formals;
 
     if (body && !_context->isStrict)
diff --git a/src/qml/compiler/qv4compilerscanfunctions_p.h b/src/qml/compiler/qv4compilerscanfunctions_p.h
index 0336398cac..073ee5c2a4 100644
--- a/src/qml/compiler/qv4compilerscanfunctions_p.h
+++ b/src/qml/compiler/qv4compilerscanfunctions_p.h
@@ -89,9 +89,19 @@ public:
     void leaveEnvironment();
 
     void enterQmlFunction(QQmlJS::AST::FunctionExpression *ast)
-    { enterFunction(ast, false); }
+    { enterFunction(ast, FunctionNameContext::None); }
 
 protected:
+    // Function declarations add their name to the outer scope, but not the
+    // inner scope. Function expressions add their name to the inner scope,
+    // unless the name is actually picked from the outer scope rather than
+    // given after the function token. QML functions don't add their name
+    // anywhere because the name is already recorded in the QML element.
+    // This enum is used to control the behavior of enterFunction().
+    enum class FunctionNameContext {
+        None, Inner, Outer
+    };
+
     using Visitor::visit;
     using Visitor::endVisit;
 
@@ -118,7 +128,8 @@ protected:
     bool visit(QQmlJS::AST::FieldMemberExpression *) override;
     bool visit(QQmlJS::AST::ArrayPattern *) override;
 
-    bool enterFunction(QQmlJS::AST::FunctionExpression *ast, bool enterName);
+    bool enterFunction(QQmlJS::AST::FunctionExpression *ast,
+                       FunctionNameContext nameContext);
 
     void endVisit(QQmlJS::AST::FunctionExpression *) override;
 
@@ -161,7 +172,7 @@ protected:
 protected:
     bool enterFunction(QQmlJS::AST::Node *ast, const QString &name,
                        QQmlJS::AST::FormalParameterList *formals,
-                       QQmlJS::AST::StatementList *body, bool enterName);
+                       QQmlJS::AST::StatementList *body, FunctionNameContext nameContext);
 
     void calcEscapingVariables();
 // fields: