Fix free of uninitialized memory in MATCH_ERROR

As suggested by Tyson Andre:
#5371 (comment)

Also fix line number of unhandled match error

Closes GH-5841.

Author: iluuu1994

Zend/tests/match/037.phpt

@@ -53,13 +53,13 @@ var_dump(match(3) {
 
 ?>
 --EXPECTF--
-string(%d) "UnhandledMatchError: Unhandled match value of type bool in %s037.php:5
+string(%d) "UnhandledMatchError: Unhandled match value of type bool in %s037.php:4
 Stack trace:
 #0 {main}"
-string(%d) "UnhandledMatchError: Unhandled match value of type int in %s037.php:13
+string(%d) "UnhandledMatchError: Unhandled match value of type int in %s037.php:12
 Stack trace:
 #0 {main}"
-string(%d) "UnhandledMatchError: Unhandled match value of type string in %s037.php:21
+string(%d) "UnhandledMatchError: Unhandled match value of type string in %s037.php:20
 Stack trace:
 #0 {main}"
 string(3) "foo"

Zend/zend_compile.c

@@ -5297,6 +5297,24 @@ void zend_compile_match(znode *result, zend_ast *ast)
 	uint32_t cond_count = 0;
 	uint32_t *jmp_end_opnums = safe_emalloc(sizeof(uint32_t), arms->children, 0);
 
+	// The generated default arm is emitted first to avoid live range issues where the tmpvar
+	// for the arm result is freed even though it has not been initialized yet.
+	if (!has_default_arm) {
+		if (!uses_jumptable) {
+			zend_update_jump_target_to_next(opnum_default_jmp);
+		}
+
+		if (jumptable) {
+			zend_op *opline = &CG(active_op_array)->opcodes[opnum_match];
+			opline->extended_value = get_next_op_number();
+		}
+
+		zend_op *opline = zend_emit_op(NULL, ZEND_MATCH_ERROR, &expr_node, NULL);
+		if (opline->op1_type == IS_CONST) {
+			Z_TRY_ADDREF_P(CT_CONSTANT(opline->op1));
+		}
+	}
+
 	for (uint32_t i = 0; i < arms->children; ++i) {
 		zend_ast *arm_ast = arms->child[i];
 		zend_ast *body_ast = arm_ast->child[1];
@@ -5358,22 +5376,6 @@ void zend_compile_match(znode *result, zend_ast *ast)
 		ZVAL_NULL(&result->u.constant);
 	}
 
-	if (!has_default_arm) {
-		if (!uses_jumptable) {
-			zend_update_jump_target_to_next(opnum_default_jmp);
-		}
-
-		if (jumptable) {
-			zend_op *opline = &CG(active_op_array)->opcodes[opnum_match];
-			opline->extended_value = get_next_op_number();
-		}
-
-		zend_op *opline = zend_emit_op(NULL, ZEND_MATCH_ERROR, &expr_node, NULL);
-		if (opline->op1_type == IS_CONST) {
-			Z_TRY_ADDREF_P(CT_CONSTANT(opline->op1));
-		}
-	}
-
 	for (uint32_t i = 0; i < arms->children; ++i) {
 		zend_update_jump_target_to_next(jmp_end_opnums[i]);
 	}

ext/opcache/tests/match/001.phpt

@@ -52,14 +52,14 @@ test:
      ; (after optimizer)
      ; %s
 0000 CV0($char) = RECV 1
-0001 MATCH CV0($char) "a": 0002, "b": 0003, "c": 0003, "d": 0004, "e": 0005, "f": 0005, "g": 0006, "h": 0007, "i": 0007, default: 0008
-0002 RETURN string("a")
-0003 RETURN string("b, c")
-0004 RETURN string("d")
-0005 RETURN string("e, f")
-0006 RETURN string("g")
-0007 RETURN string("h, i")
-0008 MATCH_ERROR CV0($char)
+0001 MATCH CV0($char) "a": 0003, "b": 0004, "c": 0004, "d": 0005, "e": 0006, "f": 0006, "g": 0007, "h": 0008, "i": 0008, default: 0002
+0002 MATCH_ERROR CV0($char)
+0003 RETURN string("a")
+0004 RETURN string("b, c")
+0005 RETURN string("d")
+0006 RETURN string("e, f")
+0007 RETURN string("g")
+0008 RETURN string("h, i")
 string(1) "a"
 string(4) "b, c"
 string(4) "b, c"