From 499442d7ef9242ce1bb329d69ea13ee6d340421c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Ho=C5=99e=C5=88ovsk=C3=BD?=
 <martin.horenovsky@gmail.com>
Date: Sun, 23 Aug 2026 15:05:36 +0200
Subject: [PATCH] Further reduce stamped out types for each templated test case

This provides further speed-ups for TUs with many test cases templated
over the same set of types. For especially test-heavy (but still
realistic) TUs, the speed up is up to 20%.
---
 src/catch2/internal/catch_preprocessor.hpp    | 57 ++++++++++++++-----
 .../internal/catch_template_test_registry.hpp |  2 +
 2 files changed, 44 insertions(+), 15 deletions(-)

diff --git a/src/catch2/internal/catch_preprocessor.hpp b/src/catch2/internal/catch_preprocessor.hpp
index c112905d..b7336c47 100644
--- a/src/catch2/internal/catch_preprocessor.hpp
+++ b/src/catch2/internal/catch_preprocessor.hpp
@@ -51,6 +51,23 @@ namespace Catch {
         struct convert;
         template <template <typename...> class Final, template <typename...> class List, typename... Ts>
         struct convert<Final, List<Ts...>> { using type = typename append<Final<>, TypeList<Ts>...>::type; };
+
+        // These are helpers for the PRODUCT templated test cases.
+        // Note that the _SIG macros (for NTTPs) also use specializations
+        // of these, but they have to use their own instances due to needing
+        // per-sig specializations and we have to keep these in their own
+        // unnamed namespace.
+        template <typename...>
+        struct rewrap;
+        template <template <typename...> class Container, template <typename...> class List, typename... elems>
+        struct rewrap<TemplateTypeList<Container>, List<elems...>> { using type = TypeList<Container<elems...>>; };
+        template <template <typename...> class Container, template <typename...> class List, class... Elems, typename... Elements>
+        struct rewrap<TemplateTypeList<Container>, List<Elems...>, Elements...> { using type = typename append<TypeList<Container<Elems...>>, typename rewrap<TemplateTypeList<Container>, Elements...>::type>::type; };
+
+        template <template <typename...> class, typename...>
+        struct create;
+        template <template <typename...> class Final, template <typename...> class... Containers, typename... Types>
+        struct create<Final, TemplateTypeList<Containers...>, TypeList<Types...>> { using type = typename append<Final<>, typename rewrap<TemplateTypeList<Containers>, Types...>::type...>::type; };
     }
 }
 
@@ -146,27 +163,33 @@ namespace Catch {
     using Catch::Detail::TemplateTypeList;             \
     using Catch::Detail::get_template_wrapper;         \
     using Catch::Detail::append;                       \
-    using Catch::Detail::convert;                      \
-    template<typename...>                              \
-    struct rewrap;                                     \
-    template<template<typename...> class, typename...> \
-    struct create;                                     \
-                                                       \
-    template< template<typename...> class Container, template<typename...> class List, typename...elems>\
-    struct rewrap<TemplateTypeList<Container>, List<elems...>> { using type = TypeList<Container<elems...>>; };\
-    template< template<typename...> class Container, template<typename...> class List, class...Elems, typename...Elements>\
-    struct rewrap<TemplateTypeList<Container>, List<Elems...>, Elements...> { using type = typename append<TypeList<Container<Elems...>>, typename rewrap<TemplateTypeList<Container>, Elements...>::type>::type; };\
-    \
-    template<template <typename...> class Final, template< typename...> class...Containers, typename...Types>\
-    struct create<Final, TemplateTypeList<Containers...>, TypeList<Types...>> { using type = typename append<Final<>, typename rewrap<TemplateTypeList<Containers>, Types...>::type...>::type; };
+    using Catch::Detail::convert;
 
-#define INTERNAL_CATCH_NTTP_1(signature, ...)\
+// This stamps out the per test case specializations of wrapper handlers
+// for _SIG (NTTP) macros inside their own namespace, so they can add
+// their required specializations
+#define INTERNAL_CATCH_NTTP_1( signature, ... ) \
     template<INTERNAL_CATCH_REMOVE_PARENS(signature)> struct Nttp{};\
     template<INTERNAL_CATCH_REMOVE_PARENS(signature)>\
     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 C, template<INTERNAL_CATCH_REMOVE_PARENS(signature)> class...Cs>\
-    constexpr auto get_template_wrapper(Catch::Detail::priority_tag<0>) noexcept -> NttpTemplateTypeList<C, Cs...> { return {}; } \
+    constexpr auto get_template_wrapper(Catch::Detail::priority_tag<0>) noexcept -> NttpTemplateTypeList<C, Cs...> { return {}; }
+
+// This stamps out the per test case specializations of type-product
+// machinery for the NTTP product macros.
+#define INTERNAL_CATCH_NTTP_REWRAP_1( signature, ... ) \
+    template<typename...>                              \
+    struct rewrap;                                     \
+    template<template<typename...> class, typename...> \
+    struct create;                                     \
+    \
+    template< template<typename...> class Container, template<typename...> class List, typename...elems>\
+    struct rewrap<TemplateTypeList<Container>, List<elems...>> { using type = TypeList<Container<elems...>>; };\
+    template< template<typename...> class Container, template<typename...> class List, class...Elems, typename...Elements>\
+    struct rewrap<TemplateTypeList<Container>, List<Elems...>, Elements...> { using type = typename append<TypeList<Container<Elems...>>, typename rewrap<TemplateTypeList<Container>, Elements...>::type>::type; };\
+    template<template <typename...> class Final, template< typename...> class...Containers, typename...Types>\
+    struct create<Final, TemplateTypeList<Containers...>, TypeList<Types...>> { using type = typename append<Final<>, typename rewrap<TemplateTypeList<Containers>, Types...>::type...>::type; };\
     \
     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__>>; };\
@@ -243,7 +266,9 @@ namespace Catch {
 
 #ifndef CATCH_CONFIG_TRADITIONAL_MSVC_PREPROCESSOR
 #define INTERNAL_CATCH_NTTP_0
+#define INTERNAL_CATCH_NTTP_0_REWRAP using Catch::Detail::rewrap; using Catch::Detail::create;
 #define INTERNAL_CATCH_NTTP_GEN(...) INTERNAL_CATCH_VA_NARGS_IMPL(__VA_ARGS__, INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_1( __VA_ARGS__),INTERNAL_CATCH_NTTP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_0)
+#define INTERNAL_CATCH_NTTP_REWRAP_GEN(...) INTERNAL_CATCH_VA_NARGS_IMPL(__VA_ARGS__, INTERNAL_CATCH_NTTP_REWRAP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_REWRAP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_REWRAP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_REWRAP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_REWRAP_1(__VA_ARGS__), INTERNAL_CATCH_NTTP_REWRAP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_REWRAP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_REWRAP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_REWRAP_1( __VA_ARGS__),INTERNAL_CATCH_NTTP_REWRAP_1( __VA_ARGS__), INTERNAL_CATCH_NTTP_0_REWRAP)
 #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__)
@@ -253,7 +278,9 @@ namespace Catch {
 #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__)
 #else
 #define INTERNAL_CATCH_NTTP_0(signature)
+#define INTERNAL_CATCH_NTTP_0_REWRAP(signature) using Catch::Detail::rewrap; using Catch::Detail::create;
 #define INTERNAL_CATCH_NTTP_GEN(...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL(__VA_ARGS__, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_1,INTERNAL_CATCH_NTTP_1, INTERNAL_CATCH_NTTP_0)( __VA_ARGS__))
+#define INTERNAL_CATCH_NTTP_REWRAP_GEN(...) INTERNAL_CATCH_EXPAND_VARGS(INTERNAL_CATCH_VA_NARGS_IMPL(__VA_ARGS__, INTERNAL_CATCH_NTTP_REWRAP_1, INTERNAL_CATCH_NTTP_REWRAP_1, INTERNAL_CATCH_NTTP_REWRAP_1, INTERNAL_CATCH_NTTP_REWRAP_1, INTERNAL_CATCH_NTTP_REWRAP_1, INTERNAL_CATCH_NTTP_REWRAP_1, INTERNAL_CATCH_NTTP_REWRAP_1, INTERNAL_CATCH_NTTP_REWRAP_1, INTERNAL_CATCH_NTTP_REWRAP_1,INTERNAL_CATCH_NTTP_REWRAP_1, INTERNAL_CATCH_NTTP_0_REWRAP)( __VA_ARGS__))
 #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__))
diff --git a/src/catch2/internal/catch_template_test_registry.hpp b/src/catch2/internal/catch_template_test_registry.hpp
index 8c441724..ed25251a 100644
--- a/src/catch2/internal/catch_template_test_registry.hpp
+++ b/src/catch2/internal/catch_template_test_registry.hpp
@@ -127,6 +127,7 @@
         namespace INTERNAL_CATCH_MAKE_NAMESPACE(TestName) {                                     \
             INTERNAL_CATCH_TYPE_GEN                                                  \
             INTERNAL_CATCH_NTTP_GEN(INTERNAL_CATCH_REMOVE_PARENS(Signature))         \
+            INTERNAL_CATCH_NTTP_REWRAP_GEN(INTERNAL_CATCH_REMOVE_PARENS(Signature))  \
             template<typename... Types>                               \
             struct TestName {                                         \
                 void reg_tests() {                                          \
@@ -259,6 +260,7 @@
     namespace INTERNAL_CATCH_MAKE_NAMESPACE(TestNameClass) {\
         INTERNAL_CATCH_TYPE_GEN                  \
         INTERNAL_CATCH_NTTP_GEN(INTERNAL_CATCH_REMOVE_PARENS(Signature))\
+        INTERNAL_CATCH_NTTP_REWRAP_GEN(INTERNAL_CATCH_REMOVE_PARENS(Signature))\
         template<typename...Types>\
         struct TestNameClass{\
             void reg_tests(){\