From be6dee3c5d2c61d14e217808dcb16068cfd0d13b Mon Sep 17 00:00:00 2001
From: Ilija Tovilo <ilija.tovilo@me.com>
Date: Mon, 5 Aug 2024 10:42:04 +0200
Subject: [PATCH] Reset seen symbols when ending namespace (GH-15244)

Previously, seen symbols were never cleaned during the compilation of a single
file. This makes it impossible to use a class or function from a different
namespace if such a symbol is also declared within the same file. This is
inconsistent with how it would work when split into different files.
---
 NEWS                                          |  1 +
 UPGRADING                                     |  4 ++
 .../ns_end_resets_seen_symbols_1.phpt         | 58 +++++++++++++++++
 .../ns_end_resets_seen_symbols_2.phpt         | 62 +++++++++++++++++++
 Zend/zend_compile.c                           |  2 +
 5 files changed, 127 insertions(+)
 create mode 100644 Zend/tests/use_function/ns_end_resets_seen_symbols_1.phpt
 create mode 100644 Zend/tests/use_function/ns_end_resets_seen_symbols_2.phpt

diff --git a/NEWS b/NEWS
index f5801cf7a38..38dfed12eab 100644
--- a/NEWS
+++ b/NEWS
@@ -12,6 +12,7 @@ PHP                                                                        NEWS
   . Passing E_USER_ERROR to trigger_error() is now deprecated. (Girgias)
   . Fixed bug GH-15292 (Dynamic AVX detection is broken for MSVC). (nielsdos)
   . Using "_" as a class name is now deprecated. (Girgias)
+  . Exiting a namespace now clears seen symbols. (ilutov)
 
 - Curl:
   . Added constants CURL_HTTP_VERSION_3 (libcurl 7.66) and CURL_HTTP_VERSION_3ONLY
diff --git a/UPGRADING b/UPGRADING
index 528aaff6165..2a3e3d18554 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -248,6 +248,10 @@ PHP 8.4 UPGRADE NOTES
     RFC: https://wiki.php.net/rfc/deprecated_attribute
   . Implemented property hooks.
     RFC: https://wiki.php.net/rfc/property-hooks
+  . Exiting a namespace now clears seen symbols. This allows using a symbol in a
+    namespace block, even if a previous namespace block declared a symbol with
+    the same name.
+    See Zend/tests/use_function/ns_end_resets_seen_symbols_1.phpt.
 
 - Curl:
   . curl_version() returns an additional feature_list value, which is an
diff --git a/Zend/tests/use_function/ns_end_resets_seen_symbols_1.phpt b/Zend/tests/use_function/ns_end_resets_seen_symbols_1.phpt
new file mode 100644
index 00000000000..71f9c74f0c2
--- /dev/null
+++ b/Zend/tests/use_function/ns_end_resets_seen_symbols_1.phpt
@@ -0,0 +1,58 @@
+--TEST--
+Namespace end resets seen function symbols
+--FILE--
+<?php
+
+namespace {
+    function f() {
+        echo __FUNCTION__, "\n";
+    }
+    f();
+}
+
+namespace Ns {
+    function f() {
+        echo __FUNCTION__, "\n";
+    }
+    f();
+}
+
+namespace {
+    use function Ns\f;
+    f();
+}
+
+namespace Ns {
+    use function f;
+    f();
+}
+
+namespace {
+    f();
+}
+
+namespace Ns {
+    f();
+}
+
+namespace {
+    use function f;
+    f();
+}
+
+namespace Ns {
+    use function Ns\f;
+    f();
+}
+
+?>
+--EXPECTF--
+Warning: The use statement with non-compound name 'f' has no effect in %s on line 36
+f
+Ns\f
+Ns\f
+f
+f
+Ns\f
+f
+Ns\f
diff --git a/Zend/tests/use_function/ns_end_resets_seen_symbols_2.phpt b/Zend/tests/use_function/ns_end_resets_seen_symbols_2.phpt
new file mode 100644
index 00000000000..83925c14664
--- /dev/null
+++ b/Zend/tests/use_function/ns_end_resets_seen_symbols_2.phpt
@@ -0,0 +1,62 @@
+--TEST--
+Namespace end resets seen class symbols
+--FILE--
+<?php
+
+namespace {
+    class C {}
+    var_dump(new C);
+}
+
+namespace Ns {
+    class C {}
+    var_dump(new C);
+}
+
+namespace {
+    use Ns\C;
+    var_dump(new C);
+}
+
+namespace Ns {
+    use C;
+    var_dump(new C);
+}
+
+namespace {
+    var_dump(new C);
+}
+
+namespace Ns {
+    var_dump(new C);
+}
+
+namespace {
+    use C;
+    var_dump(new C);
+}
+
+namespace Ns {
+    use Ns\C;
+    var_dump(new C);
+}
+
+?>
+--EXPECTF--
+Warning: The use statement with non-compound name 'C' has no effect in %s on line 32
+object(C)#%d (0) {
+}
+object(Ns\C)#1 (0) {
+}
+object(Ns\C)#1 (0) {
+}
+object(C)#%d (0) {
+}
+object(C)#%d (0) {
+}
+object(Ns\C)#1 (0) {
+}
+object(C)#%d (0) {
+}
+object(Ns\C)#1 (0) {
+}
diff --git a/Zend/zend_compile.c b/Zend/zend_compile.c
index a650d81d163..cfd97e59b7e 100644
--- a/Zend/zend_compile.c
+++ b/Zend/zend_compile.c
@@ -377,6 +377,8 @@ static void zend_reset_import_tables(void) /* {{{ */
 		efree(FC(imports_const));
 		FC(imports_const) = NULL;
 	}
+
+	zend_hash_clean(&FC(seen_symbols));
 }
 /* }}} */