Fix dialect properties

drift/lib/src/runtime/executor/helpers/engines.dart

@@ -292,7 +292,7 @@ class DelegatedDatabase extends _BaseExecutor {
   SqlDialect get dialect => SqlDialect.sqlite;
 
   @override
-  bool get supportsBigInt => false;
+  bool get supportsBigInt => true;
 
   final Lock _openingLock = Lock();
 

drift/lib/src/runtime/query_builder/generation_context.dart

@@ -24,7 +24,10 @@ class GenerationContext {
   final SqlTypeSystem typeSystem;
 
   /// The [SqlDialect] that should be respected when generating the query.
-  final SqlDialect dialect;
+  SqlDialect get dialect => executor?.executor.dialect ?? SqlDialect.sqlite;
+
+  /// Whether executor supports BigInt type
+  bool get supportsBigInt => executor?.executor.supportsBigInt ?? true;
 
   /// The actual [DatabaseConnectionUser] that's going to execute the generated
   /// query.
@@ -36,9 +39,6 @@ class GenerationContext {
   /// This is almost always the case, but not in a `CREATE VIEW` statement.
   final bool supportsVariables;
 
-  /// Whether executor supports BigInt type
-  bool get supportsBigInt => executor?.executor.supportsBigInt ?? false;
-
   final List<dynamic> _boundVariables = [];
 
   /// The values of [introducedVariables] that will be sent to the underlying
@@ -61,14 +61,12 @@ class GenerationContext {
   /// Constructs a [GenerationContext] by copying the relevant fields from the
   /// database.
   GenerationContext.fromDb(this.executor, {this.supportsVariables = true})
-      : typeSystem = executor?.typeSystem ?? SqlTypeSystem.defaultInstance,
-        // ignore: invalid_null_aware_operator, (doesn't seem to actually work)
-        dialect = executor?.executor?.dialect ?? SqlDialect.sqlite;
+      : typeSystem = executor?.typeSystem ?? SqlTypeSystem.defaultInstance;
 
   /// Constructs a custom [GenerationContext] by setting the fields manually.
   /// See [GenerationContext.fromDb] for a more convenient factory.
   GenerationContext(this.typeSystem, this.executor,
-      {this.dialect = SqlDialect.sqlite, this.supportsVariables = true});
+      {this.supportsVariables = true});
 
   /// Introduces a variable that will be sent to the database engine. Whenever
   /// this method is called, a question mark should be added to the [buffer] so

drift/lib/src/utils/lazy_database.dart

@@ -9,21 +9,36 @@ typedef DatabaseOpener = FutureOr<QueryExecutor> Function();
 /// A special database executor that delegates work to another [QueryExecutor].
 /// The other executor is lazily opened by a [DatabaseOpener].
 class LazyDatabase extends QueryExecutor {
-  late QueryExecutor _delegate;
+  /// Underlying executor
+  late final QueryExecutor _delegate;
+
   bool _delegateAvailable = false;
+  final SqlDialect _dialect;
 
   Completer<void>? _openDelegate;
 
   @override
   bool get supportsBigInt => _delegate.supportsBigInt;
 
+  @override
+  SqlDialect get dialect {
+    // Drift reads dialect before database opened, so we must know in advance
+    if (_delegateAvailable && _dialect != _delegate.dialect) {
+      throw Exception('LazyDatabase created with $_dialect, but underlying '
+          'database is ${_delegate.dialect}.');
+    }
+    return _dialect;
+  }
+
   /// The function that will open the database when this [LazyDatabase] gets
   /// opened for the first time.
   final DatabaseOpener opener;
 
   /// Declares a [LazyDatabase] that will run [opener] when the database is
-  /// first requested to be opened.
-  LazyDatabase(this.opener);
+  /// first requested to be opened. You must specify the same [dialect] as the
+  /// underlying database has
+  LazyDatabase(this.opener, {SqlDialect dialect = SqlDialect.sqlite})
+      : _dialect = dialect;
 
   Future<void> _awaitOpened() {
     if (_delegateAvailable) {