From d4d627acce8ab0d2e0a98a7ad7c3956b05606dd6 Mon Sep 17 00:00:00 2001
From: sji <sji@sj-i.dev>
Date: Tue, 9 Aug 2022 00:45:14 +0900
Subject: [PATCH] Fix GH-9271: Conflicts between interface constants and trait
 constants should trigger fatal error

---
 Zend/tests/traits/constant_022.phpt | 19 +++++++++++++++++++
 Zend/zend_inheritance.c             | 11 ++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)
 create mode 100644 Zend/tests/traits/constant_022.phpt

diff --git a/Zend/tests/traits/constant_022.phpt b/Zend/tests/traits/constant_022.phpt
new file mode 100644
index 0000000000000..bf78b210bf45f
--- /dev/null
+++ b/Zend/tests/traits/constant_022.phpt
@@ -0,0 +1,19 @@
+--TEST--
+Conflicts between trait constants and interface constants trigger fatal errors
+--FILE--
+<?php
+
+trait MyTrait {
+    const A = 1;
+}
+interface I {
+    const A = 2;
+}
+
+class D implements I {
+    use MyTrait;
+}
+
+echo D::A;
+--EXPECTF--
+Fatal error: I and MyTrait define the same constant (A) in the composition of D. However, the definition differs and is considered incompatible. Class was composed in %s on line %d
diff --git a/Zend/zend_inheritance.c b/Zend/zend_inheritance.c
index 526da9111e88e..ff6b1f5e531bb 100644
--- a/Zend/zend_inheritance.c
+++ b/Zend/zend_inheritance.c
@@ -2256,7 +2256,7 @@ static bool do_trait_constant_check(zend_class_entry *ce, zend_class_constant *t
 }
 /* }}} */
 
-static void zend_do_traits_constant_binding(zend_class_entry *ce, zend_class_entry **traits) /* {{{ */
+static void zend_do_bind_trait_constants(zend_class_entry *ce, zend_class_entry **traits) /* {{{ */
 {
 	size_t i;
 
@@ -2426,9 +2426,10 @@ static void zend_do_bind_traits(zend_class_entry *ce, zend_class_entry **traits)
 		efree(exclude_tables);
 	}
 
-	/* then flatten the constants and properties into it, to, mostly to notify developer about problems */
-	zend_do_traits_constant_binding(ce, traits);
+	/* then flatten the properties into it, to, mostly to notify developer about problems */
 	zend_do_traits_property_binding(ce, traits);
+
+	/* trait constants are flattened after inheriting interfaces to handle conflicts with constants from interfaces */
 }
 /* }}} */
 
@@ -2983,6 +2984,10 @@ ZEND_API zend_class_entry *zend_do_link_class(zend_class_entry *ce, zend_string
 		} else if (parent && parent->num_interfaces) {
 			zend_do_inherit_interfaces(ce, parent);
 		}
+		if (ce->num_traits) {
+			/* trait constants are bound after processing interfaces to handle conflicts with constants from interfaces */
+			zend_do_bind_trait_constants(ce, traits_and_interfaces);
+		}
 		if (!(ce->ce_flags & (ZEND_ACC_INTERFACE|ZEND_ACC_TRAIT))
 			&& (ce->ce_flags & (ZEND_ACC_IMPLICIT_ABSTRACT_CLASS|ZEND_ACC_EXPLICIT_ABSTRACT_CLASS))
 				) {