Type fixes for ffi

moor/example/test_vm.dart

@@ -1,11 +0,0 @@
-import 'dart:io';
-
-import 'package:moor/moor_vm.dart';
-
-void main() async {
-  final executor = VMDatabase(File('test.db'), logStatements: true);
-
-  await executor.doWhenOpened((_) async {
-    await executor.close();
-  });
-}

moor/lib/src/vm/api/database.dart

@@ -15,12 +15,10 @@ part 'result.dart';
 
 const _openingFlags = Flags.SQLITE_OPEN_READWRITE | Flags.SQLITE_OPEN_CREATE;
 
-final _nullPtr = fromAddress(0);
-
 class Database {
   final DatabasePointer _db;
   final List<PreparedStatement> _preparedStmt = [];
-  bool _isClosed;
+  bool _isClosed = false;
 
   Database._(this._db);
 
@@ -37,7 +35,7 @@ class Database {
     final pathC = CString.allocate(fileName);
 
     final resultCode =
-        bindings.sqlite3_open_v2(pathC, dbOut, _openingFlags, _nullPtr.cast());
+        bindings.sqlite3_open_v2(pathC, dbOut, _openingFlags, fromAddress(0));
     final dbPointer = dbOut.load<DatabasePointer>();
 
     dbOut.free();
@@ -91,15 +89,15 @@ class Database {
     final errorOut = allocate<CString>();
 
     final result = bindings.sqlite3_exec(
-        _db, sqlPtr, _nullPtr.cast(), _nullPtr.cast(), errorOut);
+        _db, sqlPtr, fromAddress(0), fromAddress(0), errorOut);
 
     sqlPtr.free();
 
-    final errorPtr = errorOut.load<Pointer>();
+    final errorPtr = errorOut.load<CString>();
     errorOut.free();
 
     String errorMsg;
-    if (errorPtr.address != 0) {
+    if (errorPtr != null) {
       errorMsg = CString.fromC(errorPtr.cast());
       // the message was allocated from sqlite, we need to free it
       bindings.sqlite3_free(errorPtr.cast());
@@ -118,7 +116,7 @@ class Database {
     final sqlPtr = CString.allocate(sql);
 
     final resultCode =
-        bindings.sqlite3_prepare_v2(_db, sqlPtr, -1, stmtOut, _nullPtr.cast());
+        bindings.sqlite3_prepare_v2(_db, sqlPtr, -1, stmtOut, fromAddress(0));
     sqlPtr.free();
 
     final stmt = stmtOut.load<StatementPointer>();
@@ -126,7 +124,7 @@ class Database {
 
     if (resultCode != Errors.SQLITE_OK) {
       // we don't need to worry about freeing the statement. If preparing the
-      // statement was unsuccessful, stmtOut.load() will be the null pointer
+      // statement was unsuccessful, stmtOut.load() will be null
       throw SqliteException._fromErrorCode(_db, resultCode);
     }
 

moor/lib/src/vm/bindings/bindings.dart

@@ -31,9 +31,9 @@ class _SQLiteBindings {
   int Function(
     DatabasePointer database,
     CString query,
-    Pointer callback,
-    Pointer cbFirstArg,
-    Pointer errorMsgOut,
+    Pointer<Void> callback,
+    Pointer<Void> cbFirstArg,
+    Pointer<CString> errorMsgOut,
   ) sqlite3_exec;
 
   int Function(StatementPointer statement) sqlite3_step;

moor/lib/src/vm/bindings/signatures.dart

@@ -13,7 +13,7 @@ typedef sqlite3_open_v2_native_t = Int32 Function(
 
 typedef sqlite3_close_v2_native_t = Int32 Function(DatabasePointer database);
 
-typedef sqlite3_free_native = Function(Pointer<Void> pointer);
+typedef sqlite3_free_native = Void Function(Pointer<Void> pointer);
 
 typedef sqlite3_prepare_v2_native_t = Int32 Function(
     DatabasePointer database,
@@ -25,8 +25,8 @@ typedef sqlite3_prepare_v2_native_t = Int32 Function(
 typedef sqlite3_exec_native = Int32 Function(
     DatabasePointer database,
     CString query,
-    Pointer callback,
-    Pointer firstCbArg,
+    Pointer<Void> callback,
+    Pointer<Void> firstCbArg,
     Pointer<CString> errorOut);
 
 typedef sqlite3_step_native_t = Int32 Function(StatementPointer statement);

moor/lib/src/vm/ffi/blob.dart

@@ -7,7 +7,7 @@ import 'dart:typed_data';
 class CBlob extends Pointer<Uint8> {
   /// Allocate a [CBlob] not managed in and populates it with [dartBlob].
   factory CBlob.allocate(Uint8List dartBlob) {
-    final ptr = allocate(count: dartBlob.length);
+    final ptr = allocate<Int8>(count: dartBlob.length);
     for (var i = 0; i < dartBlob.length; ++i) {
       ptr.elementAt(i).store(dartBlob[i]);
     }

moor/lib/src/vm/vm_database.dart

@@ -90,6 +90,8 @@ class VMDatabase extends _DatabaseUser {
   VMDatabase(File file, {bool logStatements = false})
       : super(logStatements, file);
 
+  VMDatabase.memory({bool logStatements = false}) : super(logStatements, null);
+
   @override
   TransactionExecutor beginTransaction() {
     throw UnsupportedError('Transactions are not yet supported on the Dart VM');