Elide return type check for directly provable instances of $this at compile time

Girgias · azjezz · commit 15c01db5afdc · 2026-06-16T20:35:01.000+01:00
diff --git a/Zend/tests/return_types/025_2.phpt b/Zend/tests/return_types/025_2.phpt
@@ -0,0 +1,14 @@
+--TEST--
+Return type of self is allowed in closure but $this return value must be checked as closure might not be bound to a class
+--FILE--
+<?php
+
+$c = function(): self { return $this; };
+try {
+	var_dump($c());
+} catch (Throwable $e) {
+	echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+?>
+--EXPECT--
+Error: Using $this when not in object context
diff --git a/Zend/zend_compile.c b/Zend/zend_compile.c
@@ -2642,6 +2642,58 @@ static void zend_compile_memoized_expr(znode *result, zend_ast *expr, uint32_t t
 }
 /* }}} */
 
+static bool zend_is_this_instance_of_name(const zend_string *type_name)
+{
+	if (zend_string_equals_ci(CG(active_class_entry)->name, type_name)) {
+		return true;
+	}
+	if (zend_string_equals_ci(type_name, ZSTR_KNOWN(ZEND_STR_SELF))) {
+		return true;
+	}
+	if (zend_string_equals_ci(type_name, ZSTR_KNOWN(ZEND_STR_PARENT))) {
+		return true;
+	}
+
+	ZEND_ASSERT((CG(active_class_entry)->ce_flags & ZEND_ACC_LINKED) == 0);
+	if (CG(active_class_entry)->num_interfaces) {
+		for (uint32_t i = 0; i < CG(active_class_entry)->num_interfaces; i++) {
+			if (zend_string_equals_ci(CG(active_class_entry)->interface_names[i].lc_name, type_name)) {
+				return true;
+			}
+		}
+	}
+	const zend_string *parent_name = CG(active_class_entry)->parent_name;
+	if (parent_name && zend_string_equals_ci(parent_name, type_name)) {
+		return true;
+	}
+
+	return false;
+}
+
+static bool zend_is_this_valid_for_return_type(zend_type type)
+{
+	/* Closures can be bound to a class scope, however it might not and this must type error */
+	if (CG(active_op_array)->fn_flags & ZEND_ACC_CLOSURE) {
+		return false;
+	}
+
+	if (ZEND_TYPE_FULL_MASK(type) & (MAY_BE_OBJECT|MAY_BE_STATIC)) {
+		return true;
+	}
+
+	const zend_type *single_type;
+	ZEND_TYPE_FOREACH(type, single_type) {
+		if (ZEND_TYPE_HAS_NAME(*single_type)) {
+			const zend_string *name = ZEND_TYPE_NAME(*single_type);
+			if (zend_is_this_instance_of_name(name)) {
+				return true;
+			}
+		}
+	} ZEND_TYPE_FOREACH_END();
+
+	return false;
+}
+
 static void zend_emit_return_type_check(
 		znode *expr, const zend_arg_info *return_info, bool implicit) /* {{{ */
 {
@@ -2696,16 +2748,16 @@ static void zend_emit_return_type_check(
 			/* we don't need run-time check */
 			return;
 		}
-		
+
 		/* If return type contains static and we are returning $this
 		 * (determined by checking if the previous opcode is ZEND_FETCH_THIS)
 		 * then we don't need to check the return type */
-		if (expr && ZEND_TYPE_CONTAINS_CODE(type, IS_STATIC)) {
-			const zend_op_array *op_array = CG(active_op_array);
-			zend_op previous = op_array->opcodes[op_array->last-1];
-			if (previous.opcode == ZEND_FETCH_THIS) {
-				return;
-			}
+		const zend_op_array *op_array = CG(active_op_array);
+		if (expr && op_array->last >= 1
+			&& op_array->opcodes[op_array->last-1].opcode == ZEND_FETCH_THIS
+			&& zend_is_this_valid_for_return_type(type)) {
+			ZEND_ASSERT((expr->op_type & (IS_VAR|IS_TMP_VAR)) && expr->u.op.var == op_array->opcodes[op_array->last-1].result.var);
+			return;
 		}
 
 		opline = zend_emit_op(NULL, ZEND_VERIFY_RETURN_TYPE, expr, NULL);
diff --git a/ext/opcache/tests/opt/verify_return_type/direct_extended_interface_verify_return_type_for_this_class.phpt b/ext/opcache/tests/opt/verify_return_type/direct_extended_interface_verify_return_type_for_this_class.phpt
@@ -31,17 +31,14 @@ $_main:
 0002 RETURN int(1)
 
 C::foo:
-     ; (lines=5, args=0, vars=0, tmps=1)
+     ; (lines=4, args=0, vars=0, tmps=1)
      ; (before optimizer)
      ; %s:7-9
      ; return  [] RANGE[0..0]
 0000 T0 = FETCH_THIS
-0001 VERIFY_RETURN_TYPE T0
-0002 RETURN T0
-0003 VERIFY_RETURN_TYPE
-0004 RETURN null
-LIVE RANGES:
-     0: 0001 - 0002 (tmp/var)
+0001 RETURN T0
+0002 VERIFY_RETURN_TYPE
+0003 RETURN null
 
 $_main:
      ; (lines=3, args=0, vars=0, tmps=0)
@@ -52,11 +49,8 @@ $_main:
 0002 RETURN int(1)
 
 C::foo:
-     ; (lines=3, args=0, vars=0, tmps=1)
+     ; (lines=2, args=0, vars=0, tmps=1)
      ; (after optimizer)
      ; %s:7-9
 0000 T0 = FETCH_THIS
-0001 VERIFY_RETURN_TYPE T0
-0002 RETURN T0
-LIVE RANGES:
-     0: 0001 - 0002 (tmp/var)
+0001 RETURN T0
diff --git a/ext/opcache/tests/opt/verify_return_type/direct_interface_verify_return_type_for_this_class.phpt b/ext/opcache/tests/opt/verify_return_type/direct_interface_verify_return_type_for_this_class.phpt
@@ -29,17 +29,14 @@ $_main:
 0001 RETURN int(1)
 
 C::foo:
-     ; (lines=5, args=0, vars=0, tmps=1)
+     ; (lines=4, args=0, vars=0, tmps=1)
      ; (before optimizer)
      ; %s:6-8
      ; return  [] RANGE[0..0]
 0000 T0 = FETCH_THIS
-0001 VERIFY_RETURN_TYPE T0
-0002 RETURN T0
-0003 VERIFY_RETURN_TYPE
-0004 RETURN null
-LIVE RANGES:
-     0: 0001 - 0002 (tmp/var)
+0001 RETURN T0
+0002 VERIFY_RETURN_TYPE
+0003 RETURN null
 
 $_main:
      ; (lines=2, args=0, vars=0, tmps=0)
diff --git a/ext/opcache/tests/opt/verify_return_type/parent_explicit_verify_return_type_for_this_class.phpt b/ext/opcache/tests/opt/verify_return_type/parent_explicit_verify_return_type_for_this_class.phpt
@@ -28,17 +28,14 @@ $_main:
 0000 RETURN int(1)
 
 C2::foo:
-     ; (lines=5, args=0, vars=0, tmps=1)
+     ; (lines=4, args=0, vars=0, tmps=1)
      ; (before optimizer)
      ; %s:6-8
      ; return  [] RANGE[0..0]
 0000 T0 = FETCH_THIS
-0001 VERIFY_RETURN_TYPE T0
-0002 RETURN T0
-0003 VERIFY_RETURN_TYPE
-0004 RETURN null
-LIVE RANGES:
-     0: 0001 - 0002 (tmp/var)
+0001 RETURN T0
+0002 VERIFY_RETURN_TYPE
+0003 RETURN null
 
 $_main:
      ; (lines=1, args=0, vars=0, tmps=0)
diff --git a/ext/opcache/tests/opt/verify_return_type/parent_verify_return_type_for_this_class.phpt b/ext/opcache/tests/opt/verify_return_type/parent_verify_return_type_for_this_class.phpt
@@ -28,17 +28,14 @@ $_main:
 0000 RETURN int(1)
 
 C2::foo:
-     ; (lines=5, args=0, vars=0, tmps=1)
+     ; (lines=4, args=0, vars=0, tmps=1)
      ; (before optimizer)
      ; %s:6-8
      ; return  [] RANGE[0..0]
 0000 T0 = FETCH_THIS
-0001 VERIFY_RETURN_TYPE T0
-0002 RETURN T0
-0003 VERIFY_RETURN_TYPE
-0004 RETURN null
-LIVE RANGES:
-     0: 0001 - 0002 (tmp/var)
+0001 RETURN T0
+0002 VERIFY_RETURN_TYPE
+0003 RETURN null
 
 $_main:
      ; (lines=1, args=0, vars=0, tmps=0)
diff --git a/ext/opcache/tests/opt/verify_return_type/self_explicit_verify_return_type_for_this_class.phpt b/ext/opcache/tests/opt/verify_return_type/self_explicit_verify_return_type_for_this_class.phpt
@@ -26,17 +26,14 @@ $_main:
 0000 RETURN int(1)
 
 C::foo:
-     ; (lines=5, args=0, vars=0, tmps=1)
+     ; (lines=4, args=0, vars=0, tmps=1)
      ; (before optimizer)
      ; %s:4-6
      ; return  [] RANGE[0..0]
 0000 T0 = FETCH_THIS
-0001 VERIFY_RETURN_TYPE T0
-0002 RETURN T0
-0003 VERIFY_RETURN_TYPE
-0004 RETURN null
-LIVE RANGES:
-     0: 0001 - 0002 (tmp/var)
+0001 RETURN T0
+0002 VERIFY_RETURN_TYPE
+0003 RETURN null
 
 $_main:
      ; (lines=1, args=0, vars=0, tmps=0)
diff --git a/ext/opcache/tests/opt/verify_return_type/self_verify_return_type_for_this_class.phpt b/ext/opcache/tests/opt/verify_return_type/self_verify_return_type_for_this_class.phpt
@@ -26,17 +26,14 @@ $_main:
 0000 RETURN int(1)
 
 C::foo:
-     ; (lines=5, args=0, vars=0, tmps=1)
+     ; (lines=4, args=0, vars=0, tmps=1)
      ; (before optimizer)
      ; %s:4-6
      ; return  [] RANGE[0..0]
 0000 T0 = FETCH_THIS
-0001 VERIFY_RETURN_TYPE T0
-0002 RETURN T0
-0003 VERIFY_RETURN_TYPE
-0004 RETURN null
-LIVE RANGES:
-     0: 0001 - 0002 (tmp/var)
+0001 RETURN T0
+0002 VERIFY_RETURN_TYPE
+0003 RETURN null
 
 $_main:
      ; (lines=1, args=0, vars=0, tmps=0)
diff --git a/ext/opcache/tests/opt/verify_return_type/self_verify_return_type_for_this_trait.phpt b/ext/opcache/tests/opt/verify_return_type/self_verify_return_type_for_this_trait.phpt
@@ -26,17 +26,14 @@ $_main:
 0000 RETURN int(1)
 
 T::foo:
-     ; (lines=5, args=0, vars=0, tmps=1)
+     ; (lines=4, args=0, vars=0, tmps=1)
      ; (before optimizer)
      ; %s:4-6
      ; return  [] RANGE[0..0]
 0000 T0 = FETCH_THIS
-0001 VERIFY_RETURN_TYPE T0
-0002 RETURN T0
-0003 VERIFY_RETURN_TYPE
-0004 RETURN null
-LIVE RANGES:
-     0: 0001 - 0002 (tmp/var)
+0001 RETURN T0
+0002 VERIFY_RETURN_TYPE
+0003 RETURN null
 
 $_main:
      ; (lines=1, args=0, vars=0, tmps=0)
@@ -45,11 +42,8 @@ $_main:
 0000 RETURN int(1)
 
 T::foo:
-     ; (lines=3, args=0, vars=0, tmps=1)
+     ; (lines=2, args=0, vars=0, tmps=1)
      ; (after optimizer)
      ; %s:4-6
 0000 T0 = FETCH_THIS
-0001 VERIFY_RETURN_TYPE T0
-0002 RETURN T0
-LIVE RANGES:
-     0: 0001 - 0002 (tmp/var)
+0001 RETURN T0
