pcre: Workaround bug #81101

The way to fix it is to disable certain match start optimizaions. The
observed performance impact appears negligible ATM, compared to the
functional regression revealed.

A possible side effect might occur if a pattern uses (*COMMIT) or
(*MARK), which is however not a very broadly used syntax in PHP. Still
this should be observed and handled by possibly adding a possibility to
reverse PCRE2_NO_START_OPTIMIZE on the user side.

One test shows a behavior change, where instead of int 0 the match
would produce an error and return false. Except strict comparison
is used, this should be acceptable.

Signed-off-by: Anatol Belski <ab@php.net>
(cherry picked from commit d188ca7688)
Signed-off-by: Anatol Belski <ab@php.net>

ext/pcre/php_pcre.c

@@ -595,7 +595,11 @@ static zend_always_inline size_t calculate_unit_length(pcre_cache_entry *pce, co
 PHPAPI pcre_cache_entry* pcre_get_compiled_regex_cache_ex(zend_string *regex, int locale_aware)
 {
 	pcre2_code			*re = NULL;
+#if 10 == PCRE2_MAJOR && 37 == PCRE2_MINOR
+	uint32_t			 coptions = PCRE2_NO_START_OPTIMIZE;
+#else
 	uint32_t			 coptions = 0;
+#endif
 	PCRE2_UCHAR	         error[128];
 	PCRE2_SIZE           erroffset;
 	int                  errnumber;

ext/pcre/tests/bug75539.phpt

@@ -1,5 +1,11 @@
 --TEST--
 Bug #75539 - Recursive call errors are not reported by preg_last_error()
+--SKIPIF--
+<?php
+if (10 == PCRE_VERSION_MAJOR && 37 == PCRE_VERSION_MINOR) {
+    die("skip ");
+}
+?>
 --FILE--
 <?php
 

ext/pcre/tests/bug81101.phpt

@@ -0,0 +1,30 @@
+--TEST--
+Bug #81101 - Invalid single character repetition issues in JIT
+--FILE--
+<?php
+
+$matches = [];
+$test = ' App\Domain\Repository\MetaData\SomethingRepositoryInterface';
+
+preg_match('/\\\\([^\\\\]+)\s*$/', $test, $matches);
+var_dump($matches);
+
+$test2 = ' App\Domain\Exception\NotFoundException';
+
+preg_match('/\\\\([^\\\\]+)\s*$/', $test2, $matches);
+var_dump($matches);
+
+?>
+--EXPECT--
+array(2) {
+  [0]=>
+  string(29) "\SomethingRepositoryInterface"
+  [1]=>
+  string(28) "SomethingRepositoryInterface"
+}
+array(2) {
+  [0]=>
+  string(18) "\NotFoundException"
+  [1]=>
+  string(17) "NotFoundException"
+}