From 2b6b042a77446ff322cd7522ca068d9f2a21c1d1 Mon Sep 17 00:00:00 2001
From: Abseil Team <absl-team@google.com>
Date: Thu, 16 Jan 2025 12:50:32 -0800
Subject: [PATCH] Cast mutable lvalue references to const from
 testing::ResultOf

PiperOrigin-RevId: 716343482
Change-Id: I125bc4725886958d026c88f3902a8289e476598b
---
 googlemock/include/gmock/gmock-matchers.h | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/googlemock/include/gmock/gmock-matchers.h b/googlemock/include/gmock/gmock-matchers.h
index 18cbe160..e979544c 100644
--- a/googlemock/include/gmock/gmock-matchers.h
+++ b/googlemock/include/gmock/gmock-matchers.h
@@ -2281,6 +2281,9 @@ class ResultOfMatcher {
   class Impl : public MatcherInterface<T> {
     using ResultType = decltype(CallableTraits<Callable>::template Invoke<T>(
         std::declval<CallableStorageType>(), std::declval<T>()));
+    using InnerType = std::conditional_t<
+        std::is_lvalue_reference<ResultType>::value,
+        const typename std::remove_reference<ResultType>::type&, ResultType>;
 
    public:
     template <typename M>
@@ -2288,7 +2291,7 @@ class ResultOfMatcher {
          const CallableStorageType& callable, const M& matcher)
         : result_description_(result_description),
           callable_(callable),
-          matcher_(MatcherCast<ResultType>(matcher)) {}
+          matcher_(MatcherCast<InnerType>(matcher)) {}
 
     void DescribeTo(::std::ostream* os) const override {
       if (result_description_.empty()) {
@@ -2318,7 +2321,7 @@ class ResultOfMatcher {
       // takes a non-const reference as argument.
       // Also, specifying template argument explicitly is needed because T could
       // be a non-const reference (e.g. Matcher<Uncopyable&>).
-      ResultType result =
+      InnerType result =
           CallableTraits<Callable>::template Invoke<T>(callable_, obj);
       return MatchPrintAndExplain(result, matcher_, listener);
     }
@@ -2331,7 +2334,7 @@ class ResultOfMatcher {
     // use stateful callables with ResultOf(), which doesn't guarantee
     // how many times the callable will be invoked.
     mutable CallableStorageType callable_;
-    const Matcher<ResultType> matcher_;
+    const Matcher<InnerType> matcher_;
   };  // class Impl
 
   const std::string result_description_;