Translate CAST AS BINARY via COLLATE BINARY

Replace 'CAST(x AS BLOB)' with 'CAST(x AS TEXT) COLLATE BINARY' for
MySQL BINARY cast targets (both CAST(...) and CONVERT(...) forms). The
previous BLOB form caused TEXT-vs-BLOB equality to always return FALSE
due to SQLite's storage-class ordering.

Refs #31.

Author: JanJakes

packages/mysql-on-sqlite/src/sqlite/class-wp-pdo-mysql-on-sqlite.php

@@ -4287,6 +4287,13 @@ private function translate_simple_expr_body( WP_Parser_Node $node ): string {
 			);
 		}
 
+		// Translate "CAST(expr AS type)" to its SQLite equivalent.
+		if ( null !== $token && WP_MySQL_Lexer::CAST_SYMBOL === $token->id ) {
+			$expr      = $node->get_first_child_node( 'expr' );
+			$cast_type = $node->get_first_child_node( 'castType' );
+			return $this->translate_cast_expr( $expr, $cast_type );
+		}
+
 		/**
 		 * Translate MySQL CONVERT() expression.
 		 *
@@ -4295,23 +4302,44 @@ private function translate_simple_expr_body( WP_Parser_Node $node ): string {
 		 *   2. CONVERT(expr USING charset): Converts the character set.
 		 */
 		if ( null !== $token && WP_MySQL_Lexer::CONVERT_SYMBOL === $token->id ) {
-			$expr      = $this->translate( $node->get_first_child_node( 'expr' ) );
+			$expr      = $node->get_first_child_node( 'expr' );
 			$cast_type = $node->get_first_child_node( 'castType' );
 
 			if ( null !== $cast_type ) {
 				// CONVERT(expr, type): Translate to cast expression.
 				// TODO: Emulate UNSIGNED cast. SQLite has no unsigned integer type.
-				return sprintf( 'CAST(%s AS %s)', $expr, $this->translate( $cast_type ) );
+				return $this->translate_cast_expr( $expr, $cast_type );
 			} else {
 				// CONVERT(expr USING charset): Keep "expr" as is (no SQLite support).
 				// TODO: Consider rejecting UTF-8-incompatible charasets.
-				return $expr;
+				return $this->translate( $expr );
 			}
 		}
 
 		return $this->translate_sequence( $node->get_children() );
 	}
 
+	/**
+	 * Translate a MySQL CAST expression to SQLite.
+	 *
+	 * Shared by the CAST(expr AS type) and CONVERT(expr, type) forms.
+	 *
+	 * @param  WP_Parser_Node $expr      The "expr" AST node.
+	 * @param  WP_Parser_Node $cast_type The "castType" AST node.
+	 * @return string                    The translated SQLite expression.
+	 */
+	private function translate_cast_expr( WP_Parser_Node $expr, WP_Parser_Node $cast_type ): string {
+		/*
+		 * Translate "CAST(expr AS BINARY)" to "CAST(expr AS TEXT) COLLATE BINARY".
+		 * Emitting "CAST(expr AS BLOB)" would break equality against TEXT values
+		 * due to SQLite's storage-class ordering (BLOB > TEXT).
+		 */
+		if ( $cast_type->has_child_token( WP_MySQL_Lexer::BINARY_SYMBOL ) ) {
+			return sprintf( 'CAST(%s AS TEXT) COLLATE BINARY', $this->translate( $expr ) );
+		}
+		return sprintf( 'CAST(%s AS %s)', $this->translate( $expr ), $this->translate( $cast_type ) );
+	}
+
 	/**
 	 * Translate a MySQL LIKE expression to SQLite.
 	 *

packages/mysql-on-sqlite/tests/WP_SQLite_Driver_Translation_Tests.php

@@ -104,7 +104,7 @@ public function testSelect(): void {
 	public function testConvert(): void {
 		// CONVERT(expr, type) → CAST(expr AS type)
 		$this->assertQuery(
-			"SELECT CAST('abc' AS BLOB) AS `CONVERT('abc', BINARY)`",
+			"SELECT CAST('abc' AS TEXT) COLLATE BINARY AS `CONVERT('abc', BINARY)`",
 			"SELECT CONVERT('abc', BINARY)"
 		);
 
@@ -172,6 +172,18 @@ public function testBinary(): void {
 			"SELECT ( `a` || `b` ) COLLATE BINARY = 'x' AS `BINARY (a || b) = 'x'` FROM `t`",
 			"SELECT BINARY (a || b) = 'x' FROM t"
 		);
+
+		// "CAST(expr AS BINARY)" → "CAST(expr AS TEXT) COLLATE BINARY"
+		$this->assertQuery(
+			"SELECT CAST('abc' AS TEXT) COLLATE BINARY AS `CAST('abc' AS BINARY)`",
+			"SELECT CAST('abc' AS BINARY)"
+		);
+
+		// "CAST(expr AS BINARY) = expr" → "CAST(expr AS TEXT) COLLATE BINARY = expr"
+		$this->assertQuery(
+			"SELECT CAST('abc' AS TEXT) COLLATE BINARY = 'abc' AS `CAST('abc' AS BINARY) = 'abc'`",
+			"SELECT CAST('abc' AS BINARY) = 'abc'"
+		);
 	}
 
 	public function testInsert(): void {