Fix panic with CAST without type name

src/lexer/sql/test.rs

@@ -295,6 +295,11 @@ fn missing_join_clause() {
     );
 }
 
+#[test]
+fn cast_without_typename() {
+    parse_cmd(b"SELECT CAST(a AS ) FROM t");
+}
+
 #[test]
 fn unknown_table_option() {
     expect_parser_err_msg(b"CREATE TABLE t(x)o", "unknown table option: o");

src/parser/ast/fmt.rs

@@ -577,7 +577,9 @@ impl ToTokens for Expr {
                 s.append(TK_LP, None)?;
                 expr.to_tokens(s)?;
                 s.append(TK_AS, None)?;
-                type_name.to_tokens(s)?;
+                if let Some(ref type_name) = type_name {
+                    type_name.to_tokens(s)?;
+                }
                 s.append(TK_RP, None)
             }
             Expr::Collate(expr, collation) => {

src/parser/ast/mod.rs

@@ -296,7 +296,7 @@ pub enum Expr {
         /// expression
         expr: Box<Expr>,
         /// `AS` type name
-        type_name: Type,
+        type_name: Option<Type>,
     },
     /// `COLLATE`: expression
     Collate(Box<Expr>, String),
@@ -404,7 +404,7 @@ impl Expr {
         Expr::Collate(Box::new(x), from_token(ct, c))
     }
     /// Constructor
-    pub fn cast(x: Expr, type_name: Type) -> Expr {
+    pub fn cast(x: Expr, type_name: Option<Type>) -> Expr {
         Expr::Cast {
             expr: Box::new(x),
             type_name,

src/parser/parse.y

@@ -912,7 +912,7 @@ expr(A) ::= expr(X) COLLATE ids(C). {
 }
 %ifndef SQLITE_OMIT_CAST
 expr(A) ::= CAST LP expr(E) AS typetoken(T) RP. {
-  A = Expr::cast(E, T.unwrap()); // FIXME mandatory ?
+  A = Expr::cast(E, T);
 }
 %endif  SQLITE_OMIT_CAST