SQLite: Fix parsing of INSERT DEFAULT VALUES syntax (sqlc-dev#4010)

This commit fixes issue sqlc-dev#3998 where SQLite's parser couldn't handle
the valid SQL syntax "INSERT INTO table DEFAULT VALUES".

The fix involves:
1. Updating the ANTLR grammar to properly support DEFAULT VALUES
   as part of the INSERT statement structure
2. Adding handling in convert.go for the DEFAULT VALUES case
3. Regenerating the parser from the updated grammar

Fixes sqlc-dev#3998

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: kyleconroy

internal/endtoend/testdata/insert_default_values/sqlite/go/db.go

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

internal/endtoend/testdata/insert_default_values/sqlite/go/models.go

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

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

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

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

@@ -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/endtoend/testdata/insert_default_values/sqlite/schema.sql

@@ -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: