Add CI probe for Turso columnN binding shapes

Run a focused matrix of INSERT-SELECT-FROM-VALUES variants directly
against Turso (no driver) and print pass/fail for each. The matrix
isolates each suspected dimension separately:

  - top-level vs INSERT context
  - bare column1 vs `column1` (backtick)
  - with vs without CAST
  - with vs without WHERE true
  - VALUES vs SELECT alias vs CTE alias

The probe is decorated with continue-on-error so it cannot fail the
job, and it runs before PHPUnit so it always produces output even if
the main test step crashes.

The aim is to identify which exact shape Turso rejects so the fix
can be targeted rather than guessed at, since prior driver-side
rewrites caused a Turso SIGSEGV in testReconstructTable.

Author: JanJakes

.github/workflows/phpunit-tests-turso.yml

@@ -894,6 +894,58 @@ jobs:
           echo "close: ok\n";
           PHP
 
+      - name: Probe Turso columnN binding in INSERT-SELECT-FROM-VALUES
+        continue-on-error: true
+        env:
+          LD_PRELOAD: ${{ steps.preload.outputs.value }}
+        run: |
+          php <<'PHP'
+          <?php
+          // Probes Turso behaviour for the columnN reference pattern that the
+          // mysql-on-sqlite driver emits for INSERT...VALUES type casting.
+          // Each form is a small variation; we run them in isolation and
+          // print the outcome so we can see exactly which shape Turso rejects.
+          $pdo = new PDO('sqlite::memory:');
+          $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
+          $pdo->exec('CREATE TABLE t (v INTEGER)');
+
+          $cases = [
+              'top-level SELECT column1 FROM (VALUES)' =>
+                  'SELECT column1 FROM (VALUES (5))',
+              'top-level SELECT `column1` FROM (VALUES)' =>
+                  'SELECT `column1` FROM (VALUES (5))',
+              'top-level SELECT CAST(`column1`) FROM (VALUES)' =>
+                  'SELECT CAST(`column1` AS INTEGER) FROM (VALUES (5))',
+              'top-level SELECT CAST(`column1`) FROM (VALUES) WHERE true' =>
+                  'SELECT CAST(`column1` AS INTEGER) FROM (VALUES (5)) WHERE true',
+              'INSERT...SELECT column1 FROM (VALUES)' =>
+                  'INSERT INTO t (v) SELECT column1 FROM (VALUES (5))',
+              'INSERT...SELECT `column1` FROM (VALUES)' =>
+                  'INSERT INTO t (v) SELECT `column1` FROM (VALUES (5))',
+              'INSERT...SELECT CAST(`column1`) FROM (VALUES)' =>
+                  'INSERT INTO t (v) SELECT CAST(`column1` AS INTEGER) FROM (VALUES (5))',
+              'INSERT...SELECT CAST(`column1`) FROM (VALUES) WHERE true' =>
+                  'INSERT INTO t (v) SELECT CAST(`column1` AS INTEGER) FROM (VALUES (5)) WHERE true',
+              'INSERT...SELECT CAST(column1) FROM (VALUES) WHERE true (no backticks)' =>
+                  'INSERT INTO t (v) SELECT CAST(column1 AS INTEGER) FROM (VALUES (5)) WHERE true',
+              'INSERT...SELECT CAST(`column1`) FROM (SELECT...)' =>
+                  'INSERT INTO t (v) SELECT CAST(`column1` AS INTEGER) FROM (SELECT 5 AS `column1`) WHERE true',
+              'INSERT...SELECT CAST(`column1`) FROM CTE(VALUES)' =>
+                  "INSERT INTO t (v) WITH src(`column1`) AS (VALUES (5)) SELECT CAST(`column1` AS INTEGER) FROM src WHERE true",
+          ];
+          foreach ($cases as $label => $sql) {
+              try {
+                  $stmt = $pdo->query($sql);
+                  if ($stmt && stripos($sql, 'INSERT') === false) {
+                      $stmt->fetchAll();
+                  }
+                  echo "OK   $label\n";
+              } catch (Throwable $e) {
+                  echo "FAIL $label -> " . $e->getMessage() . "\n";
+              }
+              try { $pdo->exec('DELETE FROM t'); } catch (Throwable $_) {}
+          }
+
       - name: Install Composer dependencies (root)
         uses: ramsey/composer-install@v3
         with: