Make string matchers work with std::wstring_view

This reapplies the change that was rolled back, with the change that it removes the convertibility requirement to string_view, because that excluded some desirable explicit conversions (like absl::Cord). Note that this is now the same criterion previously used by testing::internal::StringLike.

Fixes: #4912
PiperOrigin-RevId: 959205696
Change-Id: I002cb1224f5a2701bdf8e68ea4d91776b9c38593

googlemock/include/gmock/gmock-matchers.h

@@ -4982,116 +4982,68 @@ internal::ResultOfMatcher<Callable, InnerMatcher> ResultOf(
 
 // Matches a string equal to str.
 template <typename T = std::string>
-PolymorphicMatcher<internal::StrEqualityMatcher<std::string>> StrEq(
-    const internal::StringLike<T>& str) {
+PolymorphicMatcher<internal::StrEqualityMatcher<internal::StringType<T>>> StrEq(
+    const T& str) {
   return MakePolymorphicMatcher(
-      internal::StrEqualityMatcher<std::string>(std::string(str), true, true));
+      internal::StrEqualityMatcher<internal::StringType<T>>(
+          internal::StringType<T>(str), true, true));
 }
 
 // Matches a string not equal to str.
 template <typename T = std::string>
-PolymorphicMatcher<internal::StrEqualityMatcher<std::string>> StrNe(
-    const internal::StringLike<T>& str) {
+PolymorphicMatcher<internal::StrEqualityMatcher<internal::StringType<T>>> StrNe(
+    const T& str) {
   return MakePolymorphicMatcher(
-      internal::StrEqualityMatcher<std::string>(std::string(str), false, true));
+      internal::StrEqualityMatcher<internal::StringType<T>>(
+          internal::StringType<T>(str), false, true));
 }
 
 // Matches a string equal to str, ignoring case.
 template <typename T = std::string>
-PolymorphicMatcher<internal::StrEqualityMatcher<std::string>> StrCaseEq(
-    const internal::StringLike<T>& str) {
+PolymorphicMatcher<internal::StrEqualityMatcher<internal::StringType<T>>>
+StrCaseEq(const T& str) {
   return MakePolymorphicMatcher(
-      internal::StrEqualityMatcher<std::string>(std::string(str), true, false));
+      internal::StrEqualityMatcher<internal::StringType<T>>(
+          internal::StringType<T>(str), true, false));
 }
 
 // Matches a string not equal to str, ignoring case.
 template <typename T = std::string>
-PolymorphicMatcher<internal::StrEqualityMatcher<std::string>> StrCaseNe(
-    const internal::StringLike<T>& str) {
-  return MakePolymorphicMatcher(internal::StrEqualityMatcher<std::string>(
-      std::string(str), false, false));
+PolymorphicMatcher<internal::StrEqualityMatcher<internal::StringType<T>>>
+StrCaseNe(const T& str) {
+  return MakePolymorphicMatcher(
+      internal::StrEqualityMatcher<internal::StringType<T>>(
+          internal::StringType<T>(str), false, false));
 }
 
 // Creates a matcher that matches any string, std::string, or C string
 // that contains the given substring.
 template <typename T = std::string>
-PolymorphicMatcher<internal::HasSubstrMatcher<std::string>> HasSubstr(
-    const internal::StringLike<T>& substring) {
+PolymorphicMatcher<internal::HasSubstrMatcher<internal::StringType<T>>>
+HasSubstr(const T& substring) {
   return MakePolymorphicMatcher(
-      internal::HasSubstrMatcher<std::string>(std::string(substring)));
+      internal::HasSubstrMatcher<internal::StringType<T>>(
+          internal::StringType<T>(substring)));
 }
 
 // Matches a string that starts with 'prefix' (case-sensitive).
 template <typename T = std::string>
-PolymorphicMatcher<internal::StartsWithMatcher<std::string>> StartsWith(
-    const internal::StringLike<T>& prefix) {
+PolymorphicMatcher<internal::StartsWithMatcher<internal::StringType<T>>>
+StartsWith(const T& prefix) {
   return MakePolymorphicMatcher(
-      internal::StartsWithMatcher<std::string>(std::string(prefix)));
+      internal::StartsWithMatcher<internal::StringType<T>>(
+          internal::StringType<T>(prefix)));
 }
 
 // Matches a string that ends with 'suffix' (case-sensitive).
 template <typename T = std::string>
-PolymorphicMatcher<internal::EndsWithMatcher<std::string>> EndsWith(
-    const internal::StringLike<T>& suffix) {
+PolymorphicMatcher<internal::EndsWithMatcher<internal::StringType<T>>> EndsWith(
+    const T& suffix) {
   return MakePolymorphicMatcher(
-      internal::EndsWithMatcher<std::string>(std::string(suffix)));
+      internal::EndsWithMatcher<internal::StringType<T>>(
+          internal::StringType<T>(suffix)));
 }
 
-#if GTEST_HAS_STD_WSTRING
-// Wide string matchers.
-
-// Matches a string equal to str.
-inline PolymorphicMatcher<internal::StrEqualityMatcher<std::wstring>> StrEq(
-    const std::wstring& str) {
-  return MakePolymorphicMatcher(
-      internal::StrEqualityMatcher<std::wstring>(str, true, true));
-}
-
-// Matches a string not equal to str.
-inline PolymorphicMatcher<internal::StrEqualityMatcher<std::wstring>> StrNe(
-    const std::wstring& str) {
-  return MakePolymorphicMatcher(
-      internal::StrEqualityMatcher<std::wstring>(str, false, true));
-}
-
-// Matches a string equal to str, ignoring case.
-inline PolymorphicMatcher<internal::StrEqualityMatcher<std::wstring>> StrCaseEq(
-    const std::wstring& str) {
-  return MakePolymorphicMatcher(
-      internal::StrEqualityMatcher<std::wstring>(str, true, false));
-}
-
-// Matches a string not equal to str, ignoring case.
-inline PolymorphicMatcher<internal::StrEqualityMatcher<std::wstring>> StrCaseNe(
-    const std::wstring& str) {
-  return MakePolymorphicMatcher(
-      internal::StrEqualityMatcher<std::wstring>(str, false, false));
-}
-
-// Creates a matcher that matches any ::wstring, std::wstring, or C wide string
-// that contains the given substring.
-inline PolymorphicMatcher<internal::HasSubstrMatcher<std::wstring>> HasSubstr(
-    const std::wstring& substring) {
-  return MakePolymorphicMatcher(
-      internal::HasSubstrMatcher<std::wstring>(substring));
-}
-
-// Matches a string that starts with 'prefix' (case-sensitive).
-inline PolymorphicMatcher<internal::StartsWithMatcher<std::wstring>> StartsWith(
-    const std::wstring& prefix) {
-  return MakePolymorphicMatcher(
-      internal::StartsWithMatcher<std::wstring>(prefix));
-}
-
-// Matches a string that ends with 'suffix' (case-sensitive).
-inline PolymorphicMatcher<internal::EndsWithMatcher<std::wstring>> EndsWith(
-    const std::wstring& suffix) {
-  return MakePolymorphicMatcher(
-      internal::EndsWithMatcher<std::wstring>(suffix));
-}
-
-#endif  // GTEST_HAS_STD_WSTRING
-
 // Creates a polymorphic matcher that matches a 2-tuple where the
 // first field == the second field.
 inline internal::Eq2Matcher Eq() { return internal::Eq2Matcher(); }

googlemock/test/gmock-matchers-comparisons_test.cc

@@ -42,6 +42,10 @@
 #include "test/gmock-matchers_test.h"
 #include "gtest/gtest.h"
 
+#if GTEST_INTERNAL_HAS_STRING_VIEW
+#include <string_view>
+#endif
+
 // Silence warning C4244: 'initializing': conversion from 'int' to 'short',
 // possible loss of data and C4100, unreferenced local parameter
 GTEST_DISABLE_MSC_WARNINGS_PUSH_(4244 4100)
@@ -1254,22 +1258,29 @@ TEST(RefTest, ExplainsResult) {
 // Tests string comparison matchers.
 
 template <typename T = std::string>
-std::string FromStringLike(internal::StringLike<T> str) {
-  return std::string(str);
+internal::StringType<T> ToString(T str) {
+  return internal::StringType<T>(str);
 }
 
-TEST(StringLike, TestConversions) {
-  EXPECT_EQ("foo", FromStringLike("foo"));
-  EXPECT_EQ("foo", FromStringLike(std::string("foo")));
+TEST(StringType, TestConversions) {
+  EXPECT_EQ("foo", ToString("foo"));
+  EXPECT_EQ("foo", ToString(std::string("foo")));
+
+#if GTEST_HAS_STD_WSTRING
+  EXPECT_EQ(L"foo", ToString(L"foo"));
+  EXPECT_EQ(L"foo", ToString(std::wstring(L"foo")));
+#endif
+
 #if GTEST_INTERNAL_HAS_STRING_VIEW
-  EXPECT_EQ("foo", FromStringLike(internal::StringView("foo")));
+  EXPECT_EQ("foo", ToString(internal::StringView("foo")));
+  EXPECT_EQ(L"foo", ToString(std::wstring_view(L"foo")));
 #endif  // GTEST_INTERNAL_HAS_STRING_VIEW
 
   // Non deducible types.
-  EXPECT_EQ("", FromStringLike({}));
-  EXPECT_EQ("foo", FromStringLike({'f', 'o', 'o'}));
+  EXPECT_EQ("", ToString({}));
+  EXPECT_EQ("foo", ToString({'f', 'o', 'o'}));
   const char buf[] = "foo";
-  EXPECT_EQ("foo", FromStringLike({buf, buf + 3}));
+  EXPECT_EQ("foo", ToString({buf, buf + 3}));
 }
 
 TEST(StrEqTest, MatchesEqualString) {

googletest/include/gtest/gtest-matchers.h

@@ -45,6 +45,7 @@
 #include <memory>
 #include <ostream>
 #include <string>
+#include <string_view>
 #include <type_traits>
 
 #include "gtest/gtest-printers.h"
@@ -812,9 +813,26 @@ class [[nodiscard]] ImplicitCastEqMatcher {
   StoredRhs stored_rhs_;
 };
 
-template <typename T,
-          typename = std::enable_if_t<std::is_constructible_v<std::string, T>>>
-using StringLike = T;
+// Dummy function (never defined) whose return type evaluates to std::string if
+// the given type is a string-like type that can be converted to std::string,
+// either directly or through an intermediate std::string_view.
+template <class T>
+extern std::enable_if_t<std::is_constructible_v<std::string, T>, std::string>
+ResolveAsString(const void* /* preferred */);
+
+#if GTEST_HAS_STD_WSTRING
+// Same as above, but for std::wstring. In cases where both conversions are
+// possible, this overload takes lower priority.
+template <class T>
+extern std::enable_if_t<std::is_constructible_v<std::wstring, T>, std::wstring>
+ResolveAsString(... /* fallback */);
+#endif
+
+// Evaluates to the std::basic_string type that the given string-like type can
+// be converted to. Prefers std::string over std::wstring if both are possible.
+// Fails in a SFINAE-friendly way if no conversion was viable.
+template <typename T>
+using StringType = decltype(ResolveAsString<T>(nullptr));
 
 // Implements polymorphic matchers MatchesRegex(regex) and
 // ContainsRegex(regex), which can be used as a Matcher<T> as long as
@@ -877,9 +895,10 @@ inline PolymorphicMatcher<internal::MatchesRegexMatcher> MatchesRegex(
   return MakePolymorphicMatcher(internal::MatchesRegexMatcher(regex, true));
 }
 template <typename T = std::string>
-PolymorphicMatcher<internal::MatchesRegexMatcher> MatchesRegex(
-    const internal::StringLike<T>& regex) {
-  return MatchesRegex(new internal::RE(std::string(regex)));
+std::enable_if_t<std::is_constructible_v<internal::RE, internal::StringType<T>>,
+                 PolymorphicMatcher<internal::MatchesRegexMatcher>>
+MatchesRegex(const T& regex) {
+  return MatchesRegex(new internal::RE(internal::StringType<T>(regex)));
 }
 
 // Matches a string that contains regular expression 'regex'.
@@ -889,9 +908,10 @@ inline PolymorphicMatcher<internal::MatchesRegexMatcher> ContainsRegex(
   return MakePolymorphicMatcher(internal::MatchesRegexMatcher(regex, false));
 }
 template <typename T = std::string>
-PolymorphicMatcher<internal::MatchesRegexMatcher> ContainsRegex(
-    const internal::StringLike<T>& regex) {
-  return ContainsRegex(new internal::RE(std::string(regex)));
+std::enable_if_t<std::is_constructible_v<internal::RE, internal::StringType<T>>,
+                 PolymorphicMatcher<internal::MatchesRegexMatcher>>
+ContainsRegex(const T& regex) {
+  return ContainsRegex(new internal::RE(internal::StringType<T>(regex)));
 }
 
 // Creates a polymorphic matcher that matches anything equal to x.