ext/curl: Deprecate CURLOPT_DNS_USE_GLOBAL_CACHE constant

Libcurl `CURLOPT_DNS_USE_GLOBAL_CACHE` constant is no longer supported
since libcurl[^1] 7.62. This feature is also not thread-safe, and we have
special handling to emit warnings if it's used in ZTS builds.

Impact: Close to 1,100 hits on GitHub code search[^2]

[^1]: [CURLOPT_DNS_USE_GLOBAL_CACHE](https://curl.se/libcurl/c/CURLOPT_DNS_USE_GLOBAL_CACHE.html)
[^2]: [GitHub code search: `CURLOPT_DNS_USE_GLOBAL_CACHE`](https://github.com/search?q=CURLOPT_DNS_USE_GLOBAL_CACHE+language%3APHP+++NOT+is%3Aarchived+NOT+path%3A%2F%5Eext%5C%2F%2F&type=code)

Author: Ayesh

NEWS

@@ -133,6 +133,7 @@ PHP                                                                        NEWS
   . Deprecated the CURLOPT_BINARYTRANSFER constant. (divinity76)
   . Bumped required libcurl version to 7.61.0. (Ayesh)
   . Added feature_list key to the curl_version() return value. (Ayesh)
+  . Deprecated the CURLOPT_DNS_USE_GLOBAL_CACHE constant. (Ayesh Karunaratne)
 
 - Date:
   . Added DateTime[Immutable]::createFromTimestamp. (Marc Bennewitz)

UPGRADING

@@ -393,6 +393,8 @@ PHP 8.4 UPGRADE NOTES
 
 - Curl:
   . The CURLOPT_BINARYTRANSFER constant is deprecated.
+  . The CURLOPT_DNS_USE_GLOBAL_CACHE constant is deprecated. This feature
+    is not thread-safe, and is no longer supported since libcurl 7.62.
 
 - Date:
   . Calling DatePeriod::__construct(string $isostr, int $options = 0) is

ext/curl/curl.stub.php

@@ -74,9 +74,9 @@
 const CURLOPT_DNS_CACHE_TIMEOUT = UNKNOWN;
 /**
  * @var int
- * @cvalue CURLOPT_DNS_USE_GLOBAL_CACHE
+ * @deprecated has no effect since Curl 7.62.0
  */
-const CURLOPT_DNS_USE_GLOBAL_CACHE = UNKNOWN;
+const CURLOPT_DNS_USE_GLOBAL_CACHE = -1;
 /**
  * @var int
  * @cvalue CURLOPT_EGDSOCKET

ext/curl/curl_arginfo.h

@@ -1103,9 +1103,6 @@ static void _php_curl_set_default_options(php_curl *ch)
 	curl_easy_setopt(ch->cp, CURLOPT_INFILE,            (void *) ch);
 	curl_easy_setopt(ch->cp, CURLOPT_HEADERFUNCTION,    curl_write_header);
 	curl_easy_setopt(ch->cp, CURLOPT_WRITEHEADER,       (void *) ch);
-#ifndef ZTS
-	curl_easy_setopt(ch->cp, CURLOPT_DNS_USE_GLOBAL_CACHE, 1);
-#endif
 	curl_easy_setopt(ch->cp, CURLOPT_DNS_CACHE_TIMEOUT, 120);
 	curl_easy_setopt(ch->cp, CURLOPT_MAXREDIRS, 20); /* prevent infinite redirects */
 
@@ -1589,7 +1586,6 @@ static zend_result _php_curl_setopt(php_curl *ch, zend_long option, zval *zvalue
 		case CURLOPT_COOKIESESSION:
 		case CURLOPT_CRLF:
 		case CURLOPT_DNS_CACHE_TIMEOUT:
-		case CURLOPT_DNS_USE_GLOBAL_CACHE:
 		case CURLOPT_FAILONERROR:
 		case CURLOPT_FILETIME:
 		case CURLOPT_FORBID_REUSE:
@@ -1735,12 +1731,6 @@ static zend_result _php_curl_setopt(php_curl *ch, zend_long option, zval *zvalue
 					php_error_docref(NULL, E_WARNING, "CURLPROTO_FILE cannot be activated when an open_basedir is set");
 					return FAILURE;
 			}
-# if defined(ZTS)
-			if (option == CURLOPT_DNS_USE_GLOBAL_CACHE && lval) {
-				php_error_docref(NULL, E_WARNING, "CURLOPT_DNS_USE_GLOBAL_CACHE cannot be activated when thread safety is enabled");
-				return FAILURE;
-			}
-# endif
 			error = curl_easy_setopt(ch->cp, option, lval);
 			break;
 		case CURLOPT_SAFE_UPLOAD:
@@ -2075,6 +2065,7 @@ static zend_result _php_curl_setopt(php_curl *ch, zend_long option, zval *zvalue
 		}
 
 		case CURLOPT_BINARYTRANSFER:
+		case CURLOPT_DNS_USE_GLOBAL_CACHE:
 			/* Do nothing, just backward compatibility */
 			break;
 

ext/curl/interface.c

@@ -1,14 +1,15 @@
 --TEST--
 Bug #71144 (Sementation fault when using cURL with ZTS)
+Since Curl 7.62, CURLOPT_DNS_USE_GLOBAL_CACHE has no effect, and
+using the CURLOPT_DNS_USE_GLOBAL_CACHE constant is deprecated
+in PHP 8.4.
 --EXTENSIONS--
 curl
---SKIPIF--
-<?php if (!PHP_ZTS) { print "skip only for zts build"; } ?>
 --FILE--
 <?php
 $ch = curl_init();
 var_dump(curl_setopt($ch, CURLOPT_DNS_USE_GLOBAL_CACHE, 1));
 ?>
 --EXPECTF--
-Warning: curl_setopt(): CURLOPT_DNS_USE_GLOBAL_CACHE cannot be activated when thread safety is enabled in %sbug71144.php on line %d
-bool(false)
+Deprecated: Constant CURLOPT_DNS_USE_GLOBAL_CACHE is deprecated in %sbug71144.php on line %d
+bool(true)