From d8f5af7b6422854432a07f4381f9ed9c0d861110 Mon Sep 17 00:00:00 2001
From: Krystian Kuzniarek <krystian.kuzniarek@gmail.com>
Date: Sun, 18 Aug 2019 13:35:28 +0200
Subject: [PATCH] improve error messages upon failed static assertions

---
 googlemock/include/gmock/gmock-matchers.h     | 24 +++++++++----------
 .../gmock/internal/gmock-internal-utils.h     |  9 ++++---
 2 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/googlemock/include/gmock/gmock-matchers.h b/googlemock/include/gmock/gmock-matchers.h
index 5fe38205e3..dfbd37562e 100644
--- a/googlemock/include/gmock/gmock-matchers.h
+++ b/googlemock/include/gmock/gmock-matchers.h
@@ -2072,15 +2072,15 @@ class ContainerEqMatcher {
   typedef typename View::type StlContainer;
   typedef typename View::const_reference StlContainerReference;
 
+  static_assert(!std::is_const<Container>::value,
+                "Container type must not be const");
+  static_assert(!std::is_reference<Container>::value,
+                "Container type must not be a reference");
+
   // We make a copy of expected in case the elements in it are modified
   // after this matcher is created.
   explicit ContainerEqMatcher(const Container& expected)
-      : expected_(View::Copy(expected)) {
-    // Makes sure the user doesn't instantiate this class template
-    // with a const or reference type.
-    (void)testing::StaticAssertTypeEq<Container,
-        GTEST_REMOVE_REFERENCE_AND_CONST_(Container)>();
-  }
+      : expected_(View::Copy(expected)) {}
 
   void DescribeTo(::std::ostream* os) const {
     *os << "equals ";
@@ -2247,15 +2247,15 @@ class PointwiseMatcher {
   typedef typename RhsView::type RhsStlContainer;
   typedef typename RhsStlContainer::value_type RhsValue;
 
+  static_assert(!std::is_const<RhsContainer>::value,
+                "RhsContainer type must not be const");
+  static_assert(!std::is_reference<RhsContainer>::value,
+                "RhsContainer type must not be a reference");
+
   // Like ContainerEq, we make a copy of rhs in case the elements in
   // it are modified after this matcher is created.
   PointwiseMatcher(const TupleMatcher& tuple_matcher, const RhsContainer& rhs)
-      : tuple_matcher_(tuple_matcher), rhs_(RhsView::Copy(rhs)) {
-    // Makes sure the user doesn't instantiate this class template
-    // with a const or reference type.
-    (void)testing::StaticAssertTypeEq<RhsContainer,
-        GTEST_REMOVE_REFERENCE_AND_CONST_(RhsContainer)>();
-  }
+      : tuple_matcher_(tuple_matcher), rhs_(RhsView::Copy(rhs)) {}
 
   template <typename LhsContainer>
   operator Matcher<LhsContainer>() const {
diff --git a/googlemock/include/gmock/internal/gmock-internal-utils.h b/googlemock/include/gmock/internal/gmock-internal-utils.h
index c49e28e2f5..5841b4b829 100644
--- a/googlemock/include/gmock/internal/gmock-internal-utils.h
+++ b/googlemock/include/gmock/internal/gmock-internal-utils.h
@@ -401,9 +401,8 @@ class StlContainerView {
   typedef const type& const_reference;
 
   static const_reference ConstReference(const RawContainer& container) {
-    // Ensures that RawContainer is not a const type.
-    testing::StaticAssertTypeEq<
-        RawContainer, typename std::remove_const<RawContainer>::type>();
+    static_assert(!std::is_const<RawContainer>::value,
+                  "RawContainer type must not be const");
     return container;
   }
   static type Copy(const RawContainer& container) { return container; }
@@ -423,8 +422,8 @@ class StlContainerView<Element[N]> {
   typedef const type const_reference;
 
   static const_reference ConstReference(const Element (&array)[N]) {
-    // Ensures that Element is not a const type.
-    testing::StaticAssertTypeEq<Element, RawElement>();
+    static_assert(std::is_same<Element, RawElement>::value,
+                  "Element type must not be const");
     return type(array, N, RelationToSourceReference());
   }
   static type Copy(const Element (&array)[N]) {