Merge 'translate/select: prevent multiple identical non-aliased table references ' from Preston Thorpe

closes https://github.com/tursodatabase/turso/issues/3505

Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>

Closes #3761

core/translate/planner.rs

@@ -986,9 +986,29 @@ fn parse_join(
         crate::bail_parse_error!("NATURAL JOIN cannot be combined with ON or USING clause");
     }
 
+    // this is called once for each join, so we only need to check the rightmost table
+    // against all previous tables for duplicates
+    let rightmost_table = table_references.joined_tables().last().unwrap();
+    let has_duplicate = table_references
+        .joined_tables()
+        .iter()
+        .take(table_references.joined_tables().len() - 1)
+        .any(|t| t.identifier == rightmost_table.identifier);
+
+    if has_duplicate
+        && !natural
+        && constraint
+            .as_ref()
+            .is_none_or(|c| !matches!(c, ast::JoinConstraint::Using(_)))
+    {
+        // Duplicate table names are only allowed for NATURAL or USING joins
+        crate::bail_parse_error!(
+            "table name {} specified more than once - use an alias to disambiguate",
+            rightmost_table.identifier
+        );
+    }
     let constraint = if natural {
         assert!(table_references.joined_tables().len() >= 2);
-        let rightmost_table = table_references.joined_tables().last().unwrap();
         // NATURAL JOIN is first transformed into a USING join with the common columns
         let mut distinct_names: Vec<ast::Name> = vec![];
         // TODO: O(n^2) maybe not great for large tables or big multiway joins

testing/select.test

@@ -1074,3 +1074,23 @@ do_execsql_test_on_specific_db {:memory:} rowid-select-from-clause-subquery-expl
 	SELECT rowid,a FROM (SELECT rowid,a FROM t);
 } {1|abc}
 
+# https://github.com/tursodatabase/turso/issues/3505 regression test
+do_execsql_test_in_memory_any_error ambiguous-self-join {
+    CREATE TABLE T(a);
+	INSERT INTO t VALUES (1), (2), (3); 
+	SELECT * fROM t JOIN t;
+}
+
+do_execsql_test_on_specific_db {:memory:} unambiguous-self-join {
+    CREATE TABLE T(a);
+	INSERT INTO t VALUES (1), (2), (3); 
+	SELECT * fROM t as ta JOIN t order by ta.a;
+} {1|1
+1|2
+1|3
+2|1
+2|2
+2|3
+3|1
+3|2
+3|3}