Updated parser to produce error when trying to reinitialize final variables in class constructors. …

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
diff --git a/runtime/vm/parser.cc b/runtime/vm/parser.cc
index f96c1a3ec17e9fb14636824aff397baba1ee81ab..023c4abce5232ced6b06d7a60e062427d0ed143f 100644
--- a/runtime/vm/parser.cc
+++ b/runtime/vm/parser.cc
@@ -3007,6 +3007,8 @@ AstNode* Parser::CheckDuplicateFieldInit(
     AstNode* init_value) {
   ASSERT(!field->is_static());
   AstNode* result = NULL;
+  const String& field_name = String::Handle(field->name());
+  String& initialized_name = String::Handle(Z);
 
   // The initializer_list is divided into two sections. The sections
   // are separated by a NULL entry: [f0, ... fn, NULL, fn+1, ...]
@@ -3021,6 +3023,13 @@ AstNode* Parser::CheckDuplicateFieldInit(
     if (initialized_field == NULL) {
       break;
     }
+
+    initialized_name ^= initialized_field->name();
+    if (initialized_name.Equals(field_name) && field->has_initializer()) {
+      ReportError(init_pos, "final field '%s' is already initialized.",
+                  field_name.ToCString());
+    }
+
     if (initialized_field->raw() == field->raw()) {
       // This final field has been initialized by an inlined
       // initializer expression. This is a runtime error.
@@ -5241,12 +5250,53 @@ void Parser::AddImplicitConstructor(const Class& cls) {
 }
 
 
+void Parser::CheckFinalInitializationConflicts(const ClassDesc* class_desc,
+                                               const MemberDesc* member) {
+  const ParamList* params = &member->params;
+  if (!params->has_field_initializer) {
+    return;
+  }
+
+  const ZoneGrowableArray<ParamDesc>& parameters = *params->parameters;
+  const GrowableArray<const Field*>& fields = class_desc->fields();
+
+  for (intptr_t p = 0; p < parameters.length(); p++) {
+    const ParamDesc& current_param = parameters[p];
+    if (!current_param.is_field_initializer) {
+      continue;
+    }
+
+    const String& param_name = *current_param.name;
+    String& field_name = String::Handle(Z);

[siva, 2017/06/19 18:11:14]

This handle allocation could be hoisted outside the outer for loop too.

+
+    for (intptr_t i = 0; i < fields.length(); i++) {
+      const Field* current_field = fields.At(i);
+      if (!current_field->is_final() || !current_field->has_initializer()) {
+        continue;
+      }
+
+      field_name ^= current_field->name();
+      if (param_name.Equals(field_name)) {
+        ReportError(current_param.name_pos,
+                    "final field '%s' is already initialized.",
+                    param_name.ToCString());
+      }
+    }
+  }
+}
+
+
 // Check for cycles in constructor redirection.
 void Parser::CheckConstructors(ClassDesc* class_desc) {
   // Check for cycles in constructor redirection.
   const GrowableArray<MemberDesc>& members = class_desc->members();
   for (int i = 0; i < members.length(); i++) {
     MemberDesc* member = &members[i];
+    if (member->IsConstructor()) {
+      // Check that our constructors don't try and reinitialize an initialized
+      // final variable.
+      CheckFinalInitializationConflicts(class_desc, member);
+    }
     if (member->redirect_name == NULL) {
       continue;
     }