fix: Restore implicit alias assignment for views in subquery scopes

Commit 5c2581f added a uniqueness guard to implicit alias assignment
that treated the entire AST as a single scope. This broke views where
the same view is referenced in multiple subqueries (e.g. OUTER APPLY),
since only the first occurrence got an alias and the rest triggered
"Use of tables without using an alias" errors.

Revert to the v0.4.0 behavior of unconditionally assigning
BaseIdentifier as the implicit alias — SQL subquery scopes allow
duplicate alias names. Add regression test for the multi-scope case.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: stevehansen

src/SqlInliner.Tests/AdditionalTests.cs

@@ -47,4 +47,32 @@ public void ViewWithoutAliasGetsDefaultAlias()
         referenced.Alias.ShouldNotBeNull();
         referenced.Alias!.Value.ShouldBe("VPeople");
     }
+
+    [Test]
+    public void SameViewInMultipleSubqueriesGetsImplicitAlias()
+    {
+        var connection = new DatabaseConnection();
+        connection.AddViewDefinition(DatabaseConnection.ToObjectName("dbo", "VStatus"),
+            "CREATE VIEW dbo.VStatus AS SELECT Id, Code FROM dbo.Statuses");
+
+        // VStatus is referenced twice in separate subqueries — both without explicit alias
+        const string viewSql = @"
+            CREATE VIEW dbo.VTest AS
+            SELECT
+                (SELECT TOP 1 VStatus.Code FROM dbo.VStatus WHERE VStatus.Id = t.StatusA) AS StatusA,
+                (SELECT TOP 1 VStatus.Code FROM dbo.VStatus WHERE VStatus.Id = t.StatusB) AS StatusB
+            FROM dbo.Items t";
+
+        var (view, errors) = DatabaseView.FromSql(connection, viewSql);
+        errors.Count.ShouldBe(0);
+        view.ShouldNotBeNull();
+
+        // Both references should get an implicit alias
+        foreach (var v in view!.References.Views)
+            v.Alias.ShouldNotBeNull();
+
+        // Should inline without errors
+        var inliner = new DatabaseViewInliner(connection, viewSql, InlinerOptions.Recommended());
+        inliner.Errors.ShouldBeEmpty();
+    }
 }

src/SqlInliner/DatabaseView.cs

@@ -62,25 +62,8 @@ public static (DatabaseView?, IList<ParseError>) FromSql(DatabaseConnection conn
 
             // TODO: Verify that we have all required properties on the ReferencesVisitor
 
-            var usedAliases = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
-            foreach (var reference in references.NamedTableReferences)
-            {
-                if (reference.Alias != null)
-                    usedAliases.Add(reference.Alias.Value);
-            }
-
             foreach (var view in references.Views)
-            {
-                if (view.Alias == null)
-                {
-                    var implicitAlias = view.SchemaObject.BaseIdentifier.Value;
-                    if (!usedAliases.Contains(implicitAlias))
-                    {
-                        view.Alias = new Identifier { Value = implicitAlias };
-                        usedAliases.Add(implicitAlias);
-                    }
-                }
-            }
+                view.Alias ??= view.SchemaObject.BaseIdentifier;
 
             foreach (var columnReference in references.ColumnReferences)
             {