Fix RE::Init for Android and NetBSD.

This is a somewhat recent change for Android (I'm not clear on whether it's a recent change for NetBSD, or if Android was just very behind on its implementation), so while this worked fine as recently as API 32 devices, REG_GNU is required for API 34 (API 33 untested).

A test actually caught this, but #4334 "fixed" the test rather than the implementation. This CL also reverts the test change so it can catch the failure.

PiperOrigin-RevId: 571126374
Change-Id: I420dfcedea58f2c8b605f699515d744006c0a9d9

googletest/src/gtest-port.cc

@@ -697,13 +697,24 @@ bool RE::PartialMatch(const char* str, const RE& re) {
 void RE::Init(const char* regex) {
   pattern_ = regex;
 
+  // NetBSD (and Android, which takes its regex implemntation from NetBSD) does
+  // not include the GNU regex extensions (such as Perl style character classes
+  // like \w) in REG_EXTENDED. REG_EXTENDED is only specified to include the
+  // [[:alpha:]] style character classes. Enable REG_GNU wherever it is defined
+  // so users can use those extensions.
+#if defined(REG_GNU)
+  constexpr int reg_flags = REG_EXTENDED | REG_GNU;
+#else
+  constexpr int reg_flags = REG_EXTENDED;
+#endif
+
   // Reserves enough bytes to hold the regular expression used for a
   // full match.
   const size_t full_regex_len = strlen(regex) + 10;
   char* const full_pattern = new char[full_regex_len];
 
   snprintf(full_pattern, full_regex_len, "^(%s)$", regex);
-  is_valid_ = regcomp(&full_regex_, full_pattern, REG_EXTENDED) == 0;
+  is_valid_ = regcomp(&full_regex_, full_pattern, reg_flags) == 0;
   // We want to call regcomp(&partial_regex_, ...) even if the
   // previous expression returns false.  Otherwise partial_regex_ may
   // not be properly initialized can may cause trouble when it's
@@ -714,7 +725,7 @@ void RE::Init(const char* regex) {
   // regex.  We change it to an equivalent form "()" to be safe.
   if (is_valid_) {
     const char* const partial_regex = (*regex == '\0') ? "()" : regex;
-    is_valid_ = regcomp(&partial_regex_, partial_regex, REG_EXTENDED) == 0;
+    is_valid_ = regcomp(&partial_regex_, partial_regex, reg_flags) == 0;
   }
   EXPECT_TRUE(is_valid_)
       << "Regular expression \"" << regex

googletest/test/googletest-port-test.cc

@@ -418,8 +418,8 @@ TYPED_TEST(RETest, ImplicitConstructorWorks) {
   const RE simple(TypeParam("hello"));
   EXPECT_STREQ("hello", simple.pattern());
 
-  const RE normal(TypeParam(".*([[:alnum:]_]+)"));
-  EXPECT_STREQ(".*([[:alnum:]_]+)", normal.pattern());
+  const RE normal(TypeParam(".*(\\w+)"));
+  EXPECT_STREQ(".*(\\w+)", normal.pattern());
 }
 
 // Tests that RE's constructors reject invalid regular expressions.