Test the reflection path of type_name on gcc 16, with coherent flags

.github/workflows/ci_tests.yml

@@ -46,7 +46,8 @@ jobs:
                       "tests": [
                         "Debug.Default", "Release.Default", "Release.TSan",
                         "Release.MaxSan", "Debug.Werror",
-                        "Debug.Coverage", "Debug.-DBEMAN_EXPECTED_USE_MODULES=On"
+                        "Debug.Coverage", "Debug.-DBEMAN_EXPECTED_USE_MODULES=On",
+                        "Debug.-DCMAKE_CXX_FLAGS=-freflection"
                       ]
                     }
                   ]

CMakePresets.json

@@ -51,6 +51,28 @@
         "CMAKE_TOOLCHAIN_FILE": "${sourceDir}/infra/cmake/gnu-toolchain.cmake"
       }
     },
+    {
+      "name": "gcc-16-debug",
+      "displayName": "GCC 16 Debug Build (C++26, reflection)",
+      "inherits": [
+        "_root-config"
+      ],
+      "cacheVariables": {
+        "CMAKE_BUILD_TYPE": "Debug",
+        "CMAKE_TOOLCHAIN_FILE": "${sourceDir}/cmake/gcc-16-toolchain.cmake"
+      }
+    },
+    {
+      "name": "gcc-16-release",
+      "displayName": "GCC 16 Release Build (C++26, reflection)",
+      "inherits": [
+        "_root-config",
+        "_release-base"
+      ],
+      "cacheVariables": {
+        "CMAKE_TOOLCHAIN_FILE": "${sourceDir}/cmake/gcc-16-toolchain.cmake"
+      }
+    },
     {
       "name": "llvm-debug",
       "displayName": "Clang Debug Build",
@@ -172,6 +194,20 @@
         "_root-build"
       ]
     },
+    {
+      "name": "gcc-16-debug",
+      "configurePreset": "gcc-16-debug",
+      "inherits": [
+        "_root-build"
+      ]
+    },
+    {
+      "name": "gcc-16-release",
+      "configurePreset": "gcc-16-release",
+      "inherits": [
+        "_root-build"
+      ]
+    },
     {
       "name": "llvm-debug",
       "configurePreset": "llvm-debug",
@@ -237,6 +273,16 @@
       "inherits": "_test_base",
       "configurePreset": "gcc-release"
     },
+    {
+      "name": "gcc-16-debug",
+      "inherits": "_test_base",
+      "configurePreset": "gcc-16-debug"
+    },
+    {
+      "name": "gcc-16-release",
+      "inherits": "_test_base",
+      "configurePreset": "gcc-16-release"
+    },
     {
       "name": "llvm-debug",
       "inherits": "_test_base",
@@ -303,6 +349,40 @@
         }
       ]
     },
+    {
+      "name": "gcc-16-debug",
+      "steps": [
+        {
+          "type": "configure",
+          "name": "gcc-16-debug"
+        },
+        {
+          "type": "build",
+          "name": "gcc-16-debug"
+        },
+        {
+          "type": "test",
+          "name": "gcc-16-debug"
+        }
+      ]
+    },
+    {
+      "name": "gcc-16-release",
+      "steps": [
+        {
+          "type": "configure",
+          "name": "gcc-16-release"
+        },
+        {
+          "type": "build",
+          "name": "gcc-16-release"
+        },
+        {
+          "type": "test",
+          "name": "gcc-16-release"
+        }
+      ]
+    },
     {
       "name": "llvm-debug",
       "steps": [

tests/beman/expected/CMakeLists.txt

@@ -41,6 +41,7 @@ set(beman_expected_beman_only_tests
     expected_review_corrections.test.cpp
     expected_smf_regressions.test.cpp
     header_idempotence.test.cpp
+    type_name.test.cpp
 )
 
 include(Catch)

tests/beman/expected/type_name.test.cpp

@@ -0,0 +1,26 @@
+// tests/beman/expected/type_name.test.cpp                            -*-C++-*-
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// Beman-only: a compiler with reflection gets the reflection implementation of
+// testing/type_name.hpp.
+//
+// The selection needs both the compiler's __cpp_impl_reflection and the
+// library's __cpp_lib_reflection, and falling back is silent: every other test
+// still passes using the fallback. So whenever the compiler has reflection,
+// check that it was used. A build that forces an implementation with
+// BEMAN_EXPECTED_TESTING_TYPE_NAME_USE_REFLECTION has made its own choice, and
+// is not second-guessed.
+
+#if defined(BEMAN_EXPECTED_TESTING_TYPE_NAME_USE_REFLECTION)
+    #define BEMAN_EXPECTED_TESTING_TYPE_NAME_FORCED
+#endif
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <beman/expected/testing/type_name.hpp>
+
+#if defined(__cpp_impl_reflection) && !defined(BEMAN_EXPECTED_TESTING_TYPE_NAME_FORCED)
+TEST_CASE("type_name: a compiler with reflection gets the reflection implementation", "[type_name]") {
+    CHECK(BEMAN_EXPECTED_TESTING_TYPE_NAME_USE_REFLECTION == 1);
+}
+#endif