SQLite: Fix parsing of INSERT DEFAULT VALUES syntax

internal/endtoend/testdata/insert_default_values/sqlite/query.sql

@@ -0,0 +1,2 @@
+-- name: InsertWorkspace :exec
+INSERT INTO workspace DEFAULT VALUES;

internal/endtoend/testdata/insert_default_values/sqlite/schema.sql

@@ -0,0 +1,3 @@
+CREATE TABLE workspace (
+    id INTEGER PRIMARY KEY AUTOINCREMENT
+);

internal/endtoend/testdata/insert_default_values/sqlite/sqlc.json

@@ -0,0 +1,12 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "engine": "sqlite",
+      "path": "go",
+      "name": "querytest",
+      "schema": "schema.sql",
+      "queries": "query.sql"
+    }
+  ]
+}

internal/engine/sqlite/convert.go

@@ -875,7 +875,25 @@ func (c *cc) convertInsert_stmtContext(n *parser.Insert_stmtContext) ast.Node {
 		ReturningList: c.convertReturning_caluseContext(n.Returning_clause()),
 	}
 
-	if n.Select_stmt() != nil {
+	// Check if this is a DEFAULT VALUES insert
+	hasDefaultValues := false
+	for _, child := range n.GetChildren() {
+		if term, ok := child.(antlr.TerminalNode); ok {
+			if term.GetSymbol().GetTokenType() == parser.SQLiteParserDEFAULT_ {
+				hasDefaultValues = true
+				break
+			}
+		}
+	}
+
+	if hasDefaultValues {
+		// For DEFAULT VALUES, create an empty select statement
+		insert.SelectStmt = &ast.SelectStmt{
+			FromClause:  &ast.List{},
+			TargetList:  &ast.List{},
+			ValuesLists: &ast.List{Items: []ast.Node{&ast.List{}}}, // Single empty values list
+		}
+	} else if n.Select_stmt() != nil {
 		if ss, ok := c.convert(n.Select_stmt()).(*ast.SelectStmt); ok {
 			ss.ValuesLists = &ast.List{}
 			insert.SelectStmt = ss

internal/engine/sqlite/parser/SQLiteParser.g4

@@ -359,9 +359,9 @@ insert_stmt:
                 COMMA OPEN_PAR expr ( COMMA expr)* CLOSE_PAR
             )*
             | select_stmt
+            | DEFAULT_ VALUES_
         ) upsert_clause? returning_clause?
     )
-    | DEFAULT_ VALUES_
 ;
 
 upsert_clause: