Fix variant test for libstdc++ version 9 (#1515)

By using non-trivially copyable types, we force libstdc++-9's variant to
properly enter the valueless-by-exception state for our stringification
test.

Related to #1511

1 files changed, 22 insertions, 11 deletions

diff --git a/projects/SelfTest/UsageTests/ToStringVariant.tests.cpp b/projects/SelfTest/UsageTests/ToStringVariant.tests.cpp
index 62f923f0..86475bd8 100644
--- a/projects/SelfTest/UsageTests/ToStringVariant.tests.cpp
+++ b/projects/SelfTest/UsageTests/ToStringVariant.tests.cpp
@@ -6,6 +6,18 @@
 #include <string>
 #include <variant>
 
+// We need 2 types with non-trivial copies/moves
+struct MyType1 {
+    MyType1() = default;
+    MyType1(MyType1 const&) { throw 1; }
+    MyType1& operator=(MyType1 const&) { throw 3; }
+};
+struct MyType2 {
+    MyType2() = default;
+    MyType2(MyType2 const&) { throw 2; }
+    MyType2& operator=(MyType2 const&) { throw 4; }
+};
+
 TEST_CASE( "variant<std::monostate>", "[toString][variant][approvals]")
 {
     using type = std::variant<std::monostate>;
@@ -26,19 +38,18 @@ TEST_CASE( "variant<float, int>", "[toString][variant][approvals]")
     using type = std::variant<float, int>;
     CHECK( "0.5f" == ::Catch::Detail::stringify(type{0.5f}) );
     CHECK( "0" == ::Catch::Detail::stringify(type{0}) );
+}
 
-    SECTION("valueless by exception") {
-        struct sample {
-            operator int() const { throw 42; }
-        };
+TEST_CASE( "variant -- valueless-by-exception", "[toString][variant][approvals]" ) {
+    using type = std::variant<MyType1, MyType2>;
 
-        type value{1.5f};
-        REQUIRE_THROWS_AS( value.emplace<int>(sample{}), int );
-        REQUIRE( value.valueless_by_exception() );
-        CHECK( "{valueless variant}" == ::Catch::Detail::stringify(value) );
-    }
+    type value;
+    REQUIRE_THROWS_AS(value.emplace<MyType2>(MyType2{}), int);
+    REQUIRE(value.valueless_by_exception());
+    CHECK("{valueless variant}" == ::Catch::Detail::stringify(value));
 }
 
+
 TEST_CASE( "variant<string, int>", "[toString][variant][approvals]")
 {
     using type = std::variant<std::string, int>;
@@ -48,7 +59,7 @@ TEST_CASE( "variant<string, int>", "[toString][variant][approvals]")
 
 TEST_CASE( "variant<variant<float, int>, string>", "[toString][variant][approvals]")
 {
-    using inner = std::variant<float, int>;
+    using inner = std::variant<MyType1, float, int>;
     using type = std::variant<inner, std::string>;
     CHECK( "0.5f" == ::Catch::Detail::stringify(type{0.5f}) );
     CHECK( "0" == ::Catch::Detail::stringify(type{0}) );
@@ -63,7 +74,7 @@ TEST_CASE( "variant<variant<float, int>, string>", "[toString][variant][approval
         REQUIRE( std::holds_alternative<inner>(value) );
         REQUIRE( std::holds_alternative<float>(std::get<inner>(value)) );
 
-        REQUIRE_THROWS_AS( std::get<0>(value).emplace<int>(sample{}), int );
+        REQUIRE_THROWS_AS( std::get<0>(value).emplace<MyType1>(MyType1{}), int );
 
         // outer variant is still valid and contains inner
         REQUIRE( std::holds_alternative<inner>(value) );