Allow using only types in `TEMPLATE_TEST_CASE_SIG`. (#2995)

Right now `TEMPLATE_TEST_CASE_SIG` fails to compile when the signature contains only types:

```
TEMPLATE_TEST_CASE_SIG(
  "TemplateTestSig: compiles with two type parameters",
  "[template][onlytypes]",
  ((typename U, typename V), U, V), (int,int)) {}
```

The trick is to resolve the ambiguity between the two overloads of
`get_wrapper` (`TypeList` and `Nttp`) by making one match more strongly.
We also need to allow `reg_test` to register more than one type.

Add unit tests.

Fixes #2680

---------

Co-authored-by: Martin Hořeňovský <martin.horenovsky@gmail.com>

20 files changed, 182 insertions, 32 deletions

diff --git a/src/catch2/internal/catch_preprocessor.hpp b/src/catch2/internal/catch_preprocessor.hpp
index 08e844d2..1fc8fb8c 100644
--- a/src/catch2/internal/catch_preprocessor.hpp
+++ b/src/catch2/internal/catch_preprocessor.hpp
@@ -16,6 +16,15 @@
 #endif
 
 
+namespace Catch {
+    namespace Detail {
+        template <int N>
+        struct priority_tag : priority_tag<N - 1> {};
+        template <>
+        struct priority_tag<0> {};
+    }
+}
+
 #define CATCH_RECURSION_LEVEL0(...) __VA_ARGS__
 #define CATCH_RECURSION_LEVEL1(...) CATCH_RECURSION_LEVEL0(CATCH_RECURSION_LEVEL0(CATCH_RECURSION_LEVEL0(__VA_ARGS__)))
 #define CATCH_RECURSION_LEVEL2(...) CATCH_RECURSION_LEVEL1(CATCH_RECURSION_LEVEL1(CATCH_RECURSION_LEVEL1(__VA_ARGS__)))
@@ -75,10 +84,10 @@
 #define INTERNAL_CATCH_MAKE_NAMESPACE(name) INTERNAL_CATCH_MAKE_NAMESPACE2(name)
 
 #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
-#define INTERNAL_CATCH_MAKE_TYPE_LIST2(...) decltype(get_wrapper<INTERNAL_CATCH_REMOVE_PARENS_GEN(__VA_ARGS__)>())
+#define INTERNAL_CATCH_MAKE_TYPE_LIST2(...) decltype(get_wrapper<INTERNAL_CATCH_REMOVE_PARENS_GEN(__VA_ARGS__)>(Catch::Detail::priority_tag<1>{}))
 #define INTERNAL_CATCH_MAKE_TYPE_LIST(...) INTERNAL_CATCH_MAKE_TYPE_LIST2(INTERNAL_CATCH_REMOVE_PARENS(__VA_ARGS__))
 #else
-#define INTERNAL_CATCH_MAKE_TYPE_LIST2(...) INTERNAL_CATCH_EXPAND_VARGS(decltype(get_wrapper<INTERNAL_CATCH_REMOVE_PARENS_GEN(__VA_ARGS__)>()))
+#define INTERNAL_CATCH_MAKE_TYPE_LIST2(...) INTERNAL_CATCH_EXPAND_VARGS(decltype(get_wrapper<INTERNAL_CATCH_REMOVE_PARENS_GEN(__VA_ARGS__)>(Catch::Detail::priority_tag<1>{})))
 #define INTERNAL_CATCH_MAKE_TYPE_LIST(...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_MAKE_TYPE_LIST2(INTERNAL_CATCH_REMOVE_PARENS(__VA_ARGS__)))
 #endif
 
@@ -101,11 +110,11 @@
 
 #define INTERNAL_CATCH_TYPE_GEN\
     template<typename...> struct TypeList {};\
-    template<typename...Ts>\
-    constexpr auto get_wrapper() noexcept -> TypeList<Ts...> { return {}; }\
+    template<typename... Ts>\
+    constexpr auto get_wrapper(Catch::Detail::priority_tag<1>) noexcept -> TypeList<Ts...> { return {}; }\
     template<template<typename...> class...> struct TemplateTypeList{};\
     template<template<typename...> class...Cs>\
-    constexpr auto get_wrapper() noexcept -> TemplateTypeList<Cs...> { return {}; }\
+    constexpr auto get_wrapper(Catch::Detail::priority_tag<1>) noexcept -> TemplateTypeList<Cs...> { return {}; }\
     template<typename...>\
     struct append;\
     template<typename...>\
@@ -135,10 +144,10 @@
 #define INTERNAL_CATCH_NTTP_1(signature, ...)\
     template<INTERNAL_CATCH_REMOVE_PARENS(signature)> struct Nttp{};\
     template<INTERNAL_CATCH_REMOVE_PARENS(signature)>\
-    constexpr auto get_wrapper() noexcept -> Nttp<__VA_ARGS__> { return {}; } \
+    constexpr auto get_wrapper(Catch::Detail::priority_tag<0>) noexcept -> Nttp<__VA_ARGS__> { return {}; } \
     template<template<INTERNAL_CATCH_REMOVE_PARENS(signature)> class...> struct NttpTemplateTypeList{};\
     template<template<INTERNAL_CATCH_REMOVE_PARENS(signature)> class...Cs>\
-    constexpr auto get_wrapper() noexcept -> NttpTemplateTypeList<Cs...> { return {}; } \
+    constexpr auto get_wrapper(Catch::Detail::priority_tag<0>) noexcept -> NttpTemplateTypeList<Cs...> { return {}; } \
     \
     template< template<INTERNAL_CATCH_REMOVE_PARENS(signature)> class Container, template<INTERNAL_CATCH_REMOVE_PARENS(signature)> class List, INTERNAL_CATCH_REMOVE_PARENS(signature)>\
     struct rewrap<NttpTemplateTypeList<Container>, List<__VA_ARGS__>> { using type = TypeList<Container<__VA_ARGS__>>; };\
@@ -163,13 +172,14 @@
     template<INTERNAL_CATCH_REMOVE_PARENS(signature)>\
     static void TestName()
 
-#define INTERNAL_CATCH_NTTP_REGISTER0(TestFunc, signature)\
-    template<typename Type>\
-    void reg_test(TypeList<Type>, Catch::NameAndTags nameAndTags)\
+#define INTERNAL_CATCH_TYPES_REGISTER(TestFunc)\
+    template<typename... Ts>\
+    void reg_test(TypeList<Ts...>, Catch::NameAndTags nameAndTags)\
     {\
-        Catch::AutoReg( Catch::makeTestInvoker(&TestFunc<Type>), CATCH_INTERNAL_LINEINFO, Catch::StringRef(), nameAndTags);\
+        Catch::AutoReg( Catch::makeTestInvoker(&TestFunc<Ts...>), CATCH_INTERNAL_LINEINFO, Catch::StringRef(), nameAndTags);\
     }
 
+#define INTERNAL_CATCH_NTTP_REGISTER0(TestFunc, signature, ...)
 #define INTERNAL_CATCH_NTTP_REGISTER(TestFunc, signature, ...)\
     template<INTERNAL_CATCH_REMOVE_PARENS(signature)>\
     void reg_test(Nttp<__VA_ARGS__>, Catch::NameAndTags nameAndTags)\
@@ -218,7 +228,7 @@
 #define INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD(TestName, ...) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD1, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD0)(TestName, __VA_ARGS__)
 #define INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD(TestName, ClassName, ...) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD1, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD0)(TestName, ClassName, __VA_ARGS__)
 #define INTERNAL_CATCH_NTTP_REG_METHOD_GEN(TestName, ...) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD0, INTERNAL_CATCH_NTTP_REGISTER_METHOD0)(TestName, __VA_ARGS__)
-#define INTERNAL_CATCH_NTTP_REG_GEN(TestFunc, ...) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER0, INTERNAL_CATCH_NTTP_REGISTER0)(TestFunc, __VA_ARGS__)
+#define INTERNAL_CATCH_NTTP_REG_GEN(TestFunc, ...) INTERNAL_CATCH_TYPES_REGISTER(TestFunc) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER0, INTERNAL_CATCH_NTTP_REGISTER0)(TestFunc, __VA_ARGS__)
 #define INTERNAL_CATCH_DEFINE_SIG_TEST(TestName, ...) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X,INTERNAL_CATCH_DEFINE_SIG_TEST_X,INTERNAL_CATCH_DEFINE_SIG_TEST1, INTERNAL_CATCH_DEFINE_SIG_TEST0)(TestName, __VA_ARGS__)
 #define INTERNAL_CATCH_DECLARE_SIG_TEST(TestName, ...) INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DECLARE_SIG_TEST_X,INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X,INTERNAL_CATCH_DECLARE_SIG_TEST_X,INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST1, INTERNAL_CATCH_DECLARE_SIG_TEST0)(TestName, __VA_ARGS__)
 #define INTERNAL_CATCH_REMOVE_PARENS_GEN(...) INTERNAL_CATCH_VA_NARGS_IMPL(__VA_ARGS__, INTERNAL_CATCH_REMOVE_PARENS_11_ARG,INTERNAL_CATCH_REMOVE_PARENS_10_ARG,INTERNAL_CATCH_REMOVE_PARENS_9_ARG,INTERNAL_CATCH_REMOVE_PARENS_8_ARG,INTERNAL_CATCH_REMOVE_PARENS_7_ARG,INTERNAL_CATCH_REMOVE_PARENS_6_ARG,INTERNAL_CATCH_REMOVE_PARENS_5_ARG,INTERNAL_CATCH_REMOVE_PARENS_4_ARG,INTERNAL_CATCH_REMOVE_PARENS_3_ARG,INTERNAL_CATCH_REMOVE_PARENS_2_ARG,INTERNAL_CATCH_REMOVE_PARENS_1_ARG)(__VA_ARGS__)
@@ -228,7 +238,7 @@
 #define INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD(TestName, ...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD1, INTERNAL_CATCH_DEFINE_SIG_TEST_METHOD0)(TestName, __VA_ARGS__))
 #define INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD(TestName, ClassName, ...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X,INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD_X, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD1, INTERNAL_CATCH_DECLARE_SIG_TEST_METHOD0)(TestName, ClassName, __VA_ARGS__))
 #define INTERNAL_CATCH_NTTP_REG_METHOD_GEN(TestName, ...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD, INTERNAL_CATCH_NTTP_REGISTER_METHOD0, INTERNAL_CATCH_NTTP_REGISTER_METHOD0)(TestName, __VA_ARGS__))
-#define INTERNAL_CATCH_NTTP_REG_GEN(TestFunc, ...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER0, INTERNAL_CATCH_NTTP_REGISTER0)(TestFunc, __VA_ARGS__))
+#define INTERNAL_CATCH_NTTP_REG_GEN(TestFunc, ...) INTERNAL_CATCH_TYPES_REGISTER(TestFunc) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER, INTERNAL_CATCH_NTTP_REGISTER0, INTERNAL_CATCH_NTTP_REGISTER0)(TestFunc, __VA_ARGS__))
 #define INTERNAL_CATCH_DEFINE_SIG_TEST(TestName, ...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X,INTERNAL_CATCH_DEFINE_SIG_TEST_X,INTERNAL_CATCH_DEFINE_SIG_TEST1, INTERNAL_CATCH_DEFINE_SIG_TEST0)(TestName, __VA_ARGS__))
 #define INTERNAL_CATCH_DECLARE_SIG_TEST(TestName, ...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL( "dummy", __VA_ARGS__, INTERNAL_CATCH_DECLARE_SIG_TEST_X,INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DEFINE_SIG_TEST_X,INTERNAL_CATCH_DECLARE_SIG_TEST_X,INTERNAL_CATCH_DECLARE_SIG_TEST_X, INTERNAL_CATCH_DECLARE_SIG_TEST1, INTERNAL_CATCH_DECLARE_SIG_TEST0)(TestName, __VA_ARGS__))
 #define INTERNAL_CATCH_REMOVE_PARENS_GEN(...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL(__VA_ARGS__, INTERNAL_CATCH_REMOVE_PARENS_11_ARG,INTERNAL_CATCH_REMOVE_PARENS_10_ARG,INTERNAL_CATCH_REMOVE_PARENS_9_ARG,INTERNAL_CATCH_REMOVE_PARENS_8_ARG,INTERNAL_CATCH_REMOVE_PARENS_7_ARG,INTERNAL_CATCH_REMOVE_PARENS_6_ARG,INTERNAL_CATCH_REMOVE_PARENS_5_ARG,INTERNAL_CATCH_REMOVE_PARENS_4_ARG,INTERNAL_CATCH_REMOVE_PARENS_3_ARG,INTERNAL_CATCH_REMOVE_PARENS_2_ARG,INTERNAL_CATCH_REMOVE_PARENS_1_ARG)(__VA_ARGS__))
diff --git a/src/catch2/internal/catch_template_test_registry.hpp b/src/catch2/internal/catch_template_test_registry.hpp
index 0ea354bc..7ba64ace 100644
--- a/src/catch2/internal/catch_template_test_registry.hpp
+++ b/src/catch2/internal/catch_template_test_registry.hpp
@@ -139,7 +139,7 @@
                 }                                                     \
             };                                                        \
             static int INTERNAL_CATCH_UNIQUE_NAME( globalRegistrar ) = [](){ \
-                using TestInit = typename create<TestName, decltype(get_wrapper<INTERNAL_CATCH_REMOVE_PARENS(TmplTypes)>()), TypeList<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(INTERNAL_CATCH_REMOVE_PARENS(TypesList))>>::type; \
+                using TestInit = typename create<TestName, decltype(get_wrapper<INTERNAL_CATCH_REMOVE_PARENS(TmplTypes)>(Catch::Detail::priority_tag<1>{})), TypeList<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(INTERNAL_CATCH_REMOVE_PARENS(TypesList))>>::type; \
                 TestInit t;                                           \
                 t.reg_tests();                                        \
                 return 0;                                             \
@@ -271,7 +271,7 @@
                 }\
             };\
             static int INTERNAL_CATCH_UNIQUE_NAME( globalRegistrar ) = [](){\
-                using TestInit = typename create<TestNameClass, decltype(get_wrapper<INTERNAL_CATCH_REMOVE_PARENS(TmplTypes)>()), TypeList<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(INTERNAL_CATCH_REMOVE_PARENS(TypesList))>>::type;\
+                using TestInit = typename create<TestNameClass, decltype(get_wrapper<INTERNAL_CATCH_REMOVE_PARENS(TmplTypes)>(Catch::Detail::priority_tag<1>{})), TypeList<INTERNAL_CATCH_MAKE_TYPE_LISTS_FROM_TYPES(INTERNAL_CATCH_REMOVE_PARENS(TypesList))>>::type;\
                 TestInit t;\
                 t.reg_tests();\
                 return 0;\
diff --git a/tests/SelfTest/Baselines/automake.sw.approved.txt b/tests/SelfTest/Baselines/automake.sw.approved.txt
index 1f5a08a3..bff15522 100644
--- a/tests/SelfTest/Baselines/automake.sw.approved.txt
+++ b/tests/SelfTest/Baselines/automake.sw.approved.txt
@@ -262,6 +262,10 @@ Message from section two
 :test-result: PASS TemplateTest: vectors can be sized and resized - int
 :test-result: PASS TemplateTest: vectors can be sized and resized - std::string
 :test-result: PASS TemplateTest: vectors can be sized and resized - std::tuple<int,float>
+:test-result: FAIL TemplateTestSig: compiles with a single int parameter - 1
+:test-result: FAIL TemplateTestSig: compiles with a single int parameter - 3
+:test-result: FAIL TemplateTestSig: compiles with a single int parameter - 6
+:test-result: FAIL TemplateTestSig: compiles with two type parameters - int,int
 :test-result: PASS TemplateTestSig: vectors can be sized and resized - (std::tuple<int, float>), 6
 :test-result: PASS TemplateTestSig: vectors can be sized and resized - float,4
 :test-result: PASS TemplateTestSig: vectors can be sized and resized - int,5
diff --git a/tests/SelfTest/Baselines/automake.sw.multi.approved.txt b/tests/SelfTest/Baselines/automake.sw.multi.approved.txt
index 0bbe9d52..b30e5491 100644
--- a/tests/SelfTest/Baselines/automake.sw.multi.approved.txt
+++ b/tests/SelfTest/Baselines/automake.sw.multi.approved.txt
@@ -255,6 +255,10 @@
 :test-result: PASS TemplateTest: vectors can be sized and resized - int
 :test-result: PASS TemplateTest: vectors can be sized and resized - std::string
 :test-result: PASS TemplateTest: vectors can be sized and resized - std::tuple<int,float>
+:test-result: FAIL TemplateTestSig: compiles with a single int parameter - 1
+:test-result: FAIL TemplateTestSig: compiles with a single int parameter - 3
+:test-result: FAIL TemplateTestSig: compiles with a single int parameter - 6
+:test-result: FAIL TemplateTestSig: compiles with two type parameters - int,int
 :test-result: PASS TemplateTestSig: vectors can be sized and resized - (std::tuple<int, float>), 6
 :test-result: PASS TemplateTestSig: vectors can be sized and resized - float,4
 :test-result: PASS TemplateTestSig: vectors can be sized and resized - int,5
diff --git a/tests/SelfTest/Baselines/compact.sw.approved.txt b/tests/SelfTest/Baselines/compact.sw.approved.txt
index b7f48cbc..50f09b1b 100644
--- a/tests/SelfTest/Baselines/compact.sw.approved.txt
+++ b/tests/SelfTest/Baselines/compact.sw.approved.txt
@@ -2854,7 +2854,7 @@ InternalBenchmark.tests.cpp:<line number>: passed: med == 18. for: 18.0 == 18.0
 InternalBenchmark.tests.cpp:<line number>: passed: q3 == 23. for: 23.0 == 23.0
 Misc.tests.cpp:<line number>: passed:
 Misc.tests.cpp:<line number>: passed:
-test cases:  419 |  313 passed |  86 failed | 6 skipped | 14 failed as expected
-assertions: 2269 | 2087 passed | 147 failed | 35 failed as expected
+test cases:  423 |  313 passed |  90 failed | 6 skipped | 14 failed as expected
+assertions: 2273 | 2087 passed | 151 failed | 35 failed as expected
 
 
diff --git a/tests/SelfTest/Baselines/compact.sw.multi.approved.txt b/tests/SelfTest/Baselines/compact.sw.multi.approved.txt
index 9e3e5372..7e5535ba 100644
--- a/tests/SelfTest/Baselines/compact.sw.multi.approved.txt
+++ b/tests/SelfTest/Baselines/compact.sw.multi.approved.txt
@@ -2843,7 +2843,7 @@ InternalBenchmark.tests.cpp:<line number>: passed: med == 18. for: 18.0 == 18.0
 InternalBenchmark.tests.cpp:<line number>: passed: q3 == 23. for: 23.0 == 23.0
 Misc.tests.cpp:<line number>: passed:
 Misc.tests.cpp:<line number>: passed:
-test cases:  419 |  313 passed |  86 failed | 6 skipped | 14 failed as expected
-assertions: 2269 | 2087 passed | 147 failed | 35 failed as expected
+test cases:  423 |  313 passed |  90 failed | 6 skipped | 14 failed as expected
+assertions: 2273 | 2087 passed | 151 failed | 35 failed as expected
 
 
diff --git a/tests/SelfTest/Baselines/console.std.approved.txt b/tests/SelfTest/Baselines/console.std.approved.txt
index 495264b4..92d44a87 100644
--- a/tests/SelfTest/Baselines/console.std.approved.txt
+++ b/tests/SelfTest/Baselines/console.std.approved.txt
@@ -1610,6 +1610,6 @@ due to unexpected exception with message:
   Why would you throw a std::string?
 
 ===============================================================================
-test cases:  419 |  327 passed |  71 failed | 7 skipped | 14 failed as expected
+test cases:  423 |  331 passed |  71 failed | 7 skipped | 14 failed as expected
 assertions: 2252 | 2087 passed | 130 failed | 35 failed as expected
 
diff --git a/tests/SelfTest/Baselines/console.sw.approved.txt b/tests/SelfTest/Baselines/console.sw.approved.txt
index 7e7f4bd2..9e4e0e16 100644
--- a/tests/SelfTest/Baselines/console.sw.approved.txt
+++ b/tests/SelfTest/Baselines/console.sw.approved.txt
@@ -12527,6 +12527,42 @@ with expansion:
   5 >= 5
 
 -------------------------------------------------------------------------------
+TemplateTestSig: compiles with a single int parameter - 1
+-------------------------------------------------------------------------------
+Misc.tests.cpp:<line number>
+...............................................................................
+
+
+No assertions in test case 'TemplateTestSig: compiles with a single int parameter - 1'
+
+-------------------------------------------------------------------------------
+TemplateTestSig: compiles with a single int parameter - 3
+-------------------------------------------------------------------------------
+Misc.tests.cpp:<line number>
+...............................................................................
+
+
+No assertions in test case 'TemplateTestSig: compiles with a single int parameter - 3'
+
+-------------------------------------------------------------------------------
+TemplateTestSig: compiles with a single int parameter - 6
+-------------------------------------------------------------------------------
+Misc.tests.cpp:<line number>
+...............................................................................
+
+
+No assertions in test case 'TemplateTestSig: compiles with a single int parameter - 6'
+
+-------------------------------------------------------------------------------
+TemplateTestSig: compiles with two type parameters - int,int
+-------------------------------------------------------------------------------
+Misc.tests.cpp:<line number>
+...............................................................................
+
+
+No assertions in test case 'TemplateTestSig: compiles with two type parameters - int,int'
+
+-------------------------------------------------------------------------------
 TemplateTestSig: vectors can be sized and resized - (std::tuple<int, float>), 6
 -------------------------------------------------------------------------------
 Misc.tests.cpp:<line number>
@@ -19012,6 +19048,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  419 |  313 passed |  86 failed | 6 skipped | 14 failed as expected
-assertions: 2269 | 2087 passed | 147 failed | 35 failed as expected
+test cases:  423 |  313 passed |  90 failed | 6 skipped | 14 failed as expected
+assertions: 2273 | 2087 passed | 151 failed | 35 failed as expected
 
diff --git a/tests/SelfTest/Baselines/console.sw.multi.approved.txt b/tests/SelfTest/Baselines/console.sw.multi.approved.txt
index 7971092f..84205756 100644
--- a/tests/SelfTest/Baselines/console.sw.multi.approved.txt
+++ b/tests/SelfTest/Baselines/console.sw.multi.approved.txt
@@ -12520,6 +12520,42 @@ with expansion:
   5 >= 5
 
 -------------------------------------------------------------------------------
+TemplateTestSig: compiles with a single int parameter - 1
+-------------------------------------------------------------------------------
+Misc.tests.cpp:<line number>
+...............................................................................
+
+
+No assertions in test case 'TemplateTestSig: compiles with a single int parameter - 1'
+
+-------------------------------------------------------------------------------
+TemplateTestSig: compiles with a single int parameter - 3
+-------------------------------------------------------------------------------
+Misc.tests.cpp:<line number>
+...............................................................................
+
+
+No assertions in test case 'TemplateTestSig: compiles with a single int parameter - 3'
+
+-------------------------------------------------------------------------------
+TemplateTestSig: compiles with a single int parameter - 6
+-------------------------------------------------------------------------------
+Misc.tests.cpp:<line number>
+...............................................................................
+
+
+No assertions in test case 'TemplateTestSig: compiles with a single int parameter - 6'
+
+-------------------------------------------------------------------------------
+TemplateTestSig: compiles with two type parameters - int,int
+-------------------------------------------------------------------------------
+Misc.tests.cpp:<line number>
+...............................................................................
+
+
+No assertions in test case 'TemplateTestSig: compiles with two type parameters - int,int'
+
+-------------------------------------------------------------------------------
 TemplateTestSig: vectors can be sized and resized - (std::tuple<int, float>), 6
 -------------------------------------------------------------------------------
 Misc.tests.cpp:<line number>
@@ -19001,6 +19037,6 @@ Misc.tests.cpp:<line number>
 Misc.tests.cpp:<line number>: PASSED:
 
 ===============================================================================
-test cases:  419 |  313 passed |  86 failed | 6 skipped | 14 failed as expected
-assertions: 2269 | 2087 passed | 147 failed | 35 failed as expected
+test cases:  423 |  313 passed |  90 failed | 6 skipped | 14 failed as expected
+assertions: 2273 | 2087 passed | 151 failed | 35 failed as expected
 
diff --git a/tests/SelfTest/Baselines/junit.sw.approved.txt b/tests/SelfTest/Baselines/junit.sw.approved.txt
index 8c8fe477..a7bcc914 100644
--- a/tests/SelfTest/Baselines/junit.sw.approved.txt
+++ b/tests/SelfTest/Baselines/junit.sw.approved.txt
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <testsuitesloose text artifact
 >
-  <testsuite name="<exe-name>" errors="17" failures="130" skipped="12" tests="2281" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="134" skipped="12" tests="2285" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="random-seed" value="1"/>
       <property name="filters" value="&quot;*&quot; ~[!nonportable] ~[!benchmark] ~[approvals]"/>
@@ -1475,6 +1475,10 @@ at Misc.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="TemplateTest: vectors can be sized and resized - std::tuple&lt;int,float>/resizing smaller changes size but not capacity/We can use the 'swap trick' to reset the capacity" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="TemplateTest: vectors can be sized and resized - std::tuple&lt;int,float>/reserving bigger changes capacity but not size" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="TemplateTest: vectors can be sized and resized - std::tuple&lt;int,float>/reserving smaller does not change size or capacity" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="TemplateTestSig: compiles with a single int parameter - 1" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="TemplateTestSig: compiles with a single int parameter - 3" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="TemplateTestSig: compiles with a single int parameter - 6" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="TemplateTestSig: compiles with two type parameters - int,int" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="TemplateTestSig: vectors can be sized and resized - (std::tuple&lt;int, float>), 6" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="TemplateTestSig: vectors can be sized and resized - (std::tuple&lt;int, float>), 6/resizing bigger changes size and capacity" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="TemplateTestSig: vectors can be sized and resized - (std::tuple&lt;int, float>), 6/resizing smaller changes size but not capacity" time="{duration}" status="run"/>
diff --git a/tests/SelfTest/Baselines/junit.sw.multi.approved.txt b/tests/SelfTest/Baselines/junit.sw.multi.approved.txt
index 1f5b820f..20ae2abf 100644
--- a/tests/SelfTest/Baselines/junit.sw.multi.approved.txt
+++ b/tests/SelfTest/Baselines/junit.sw.multi.approved.txt
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <testsuites>
-  <testsuite name="<exe-name>" errors="17" failures="130" skipped="12" tests="2281" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
+  <testsuite name="<exe-name>" errors="17" failures="134" skipped="12" tests="2285" hostname="tbd" time="{duration}" timestamp="{iso8601-timestamp}">
     <properties>
       <property name="random-seed" value="1"/>
       <property name="filters" value="&quot;*&quot; ~[!nonportable] ~[!benchmark] ~[approvals]"/>
@@ -1474,6 +1474,10 @@ at Misc.tests.cpp:<line number>
     <testcase classname="<exe-name>.global" name="TemplateTest: vectors can be sized and resized - std::tuple&lt;int,float>/resizing smaller changes size but not capacity/We can use the 'swap trick' to reset the capacity" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="TemplateTest: vectors can be sized and resized - std::tuple&lt;int,float>/reserving bigger changes capacity but not size" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="TemplateTest: vectors can be sized and resized - std::tuple&lt;int,float>/reserving smaller does not change size or capacity" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="TemplateTestSig: compiles with a single int parameter - 1" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="TemplateTestSig: compiles with a single int parameter - 3" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="TemplateTestSig: compiles with a single int parameter - 6" time="{duration}" status="run"/>
+    <testcase classname="<exe-name>.global" name="TemplateTestSig: compiles with two type parameters - int,int" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="TemplateTestSig: vectors can be sized and resized - (std::tuple&lt;int, float>), 6" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="TemplateTestSig: vectors can be sized and resized - (std::tuple&lt;int, float>), 6/resizing bigger changes size and capacity" time="{duration}" status="run"/>
     <testcase classname="<exe-name>.global" name="TemplateTestSig: vectors can be sized and resized - (std::tuple&lt;int, float>), 6/resizing smaller changes size but not capacity" time="{duration}" status="run"/>
diff --git a/tests/SelfTest/Baselines/sonarqube.sw.approved.txt b/tests/SelfTest/Baselines/sonarqube.sw.approved.txt
index 8b303074..915c5a9b 100644
--- a/tests/SelfTest/Baselines/sonarqube.sw.approved.txt
+++ b/tests/SelfTest/Baselines/sonarqube.sw.approved.txt
@@ -1893,6 +1893,10 @@ at Misc.tests.cpp:<line number>
     <testCase name="TemplateTest: vectors can be sized and resized - std::tuple&lt;int,float>/resizing smaller changes size but not capacity/We can use the 'swap trick' to reset the capacity" duration="{duration}"/>
     <testCase name="TemplateTest: vectors can be sized and resized - std::tuple&lt;int,float>/reserving bigger changes capacity but not size" duration="{duration}"/>
     <testCase name="TemplateTest: vectors can be sized and resized - std::tuple&lt;int,float>/reserving smaller does not change size or capacity" duration="{duration}"/>
+    <testCase name="TemplateTestSig: compiles with a single int parameter - 1" duration="{duration}"/>
+    <testCase name="TemplateTestSig: compiles with a single int parameter - 3" duration="{duration}"/>
+    <testCase name="TemplateTestSig: compiles with a single int parameter - 6" duration="{duration}"/>
+    <testCase name="TemplateTestSig: compiles with two type parameters - int,int" duration="{duration}"/>
     <testCase name="TemplateTestSig: vectors can be sized and resized - (std::tuple&lt;int, float>), 6" duration="{duration}"/>
     <testCase name="TemplateTestSig: vectors can be sized and resized - (std::tuple&lt;int, float>), 6/resizing bigger changes size and capacity" duration="{duration}"/>
     <testCase name="TemplateTestSig: vectors can be sized and resized - (std::tuple&lt;int, float>), 6/resizing smaller changes size but not capacity" duration="{duration}"/>
diff --git a/tests/SelfTest/Baselines/sonarqube.sw.multi.approved.txt b/tests/SelfTest/Baselines/sonarqube.sw.multi.approved.txt
index 4de52352..cc890873 100644
--- a/tests/SelfTest/Baselines/sonarqube.sw.multi.approved.txt
+++ b/tests/SelfTest/Baselines/sonarqube.sw.multi.approved.txt
@@ -1892,6 +1892,10 @@ at Misc.tests.cpp:<line number>
     <testCase name="TemplateTest: vectors can be sized and resized - std::tuple&lt;int,float>/resizing smaller changes size but not capacity/We can use the 'swap trick' to reset the capacity" duration="{duration}"/>
     <testCase name="TemplateTest: vectors can be sized and resized - std::tuple&lt;int,float>/reserving bigger changes capacity but not size" duration="{duration}"/>
     <testCase name="TemplateTest: vectors can be sized and resized - std::tuple&lt;int,float>/reserving smaller does not change size or capacity" duration="{duration}"/>
+    <testCase name="TemplateTestSig: compiles with a single int parameter - 1" duration="{duration}"/>
+    <testCase name="TemplateTestSig: compiles with a sing