From 16bf12d1e838263d753f082caeb7dc4222997ce2 Mon Sep 17 00:00:00 2001
From: Ben Boeckel <ben.boeckel@kitware.com>
Date: Tue, 5 Mar 2024 13:43:29 -0500
Subject: Tests/CXXModules; add tests for `CXX_MODULE_STD` behavior

---
 Tests/RunCMake/CXXModules/Inspect.cmake                    |  6 ++++++
 Tests/RunCMake/CXXModules/NoCXX23TargetNotRequired.cmake   | 11 +++++++++++
 Tests/RunCMake/CXXModules/NoCXX23TargetRequired-result.txt |  1 +
 Tests/RunCMake/CXXModules/NoCXX23TargetRequired-stderr.txt |  4 ++++
 Tests/RunCMake/CXXModules/NoCXX23TargetRequired.cmake      | 11 +++++++++++
 Tests/RunCMake/CXXModules/NoCXX23TargetUnset.cmake         | 13 +++++++++++++
 Tests/RunCMake/CXXModules/RunCMakeTest.cmake               |  7 +++++++
 7 files changed, 53 insertions(+)
 create mode 100644 Tests/RunCMake/CXXModules/NoCXX23TargetNotRequired.cmake
 create mode 100644 Tests/RunCMake/CXXModules/NoCXX23TargetRequired-result.txt
 create mode 100644 Tests/RunCMake/CXXModules/NoCXX23TargetRequired-stderr.txt
 create mode 100644 Tests/RunCMake/CXXModules/NoCXX23TargetRequired.cmake
 create mode 100644 Tests/RunCMake/CXXModules/NoCXX23TargetUnset.cmake

diff --git a/Tests/RunCMake/CXXModules/Inspect.cmake b/Tests/RunCMake/CXXModules/Inspect.cmake
index 612b01b..1597bd8 100644
--- a/Tests/RunCMake/CXXModules/Inspect.cmake
+++ b/Tests/RunCMake/CXXModules/Inspect.cmake
@@ -15,11 +15,17 @@ if (CMAKE_CXX_FLAGS MATCHES "-std=")
   set(forced_cxx_standard 1)
 endif ()
 
+set(have_cxx23_import_std 0)
+if (TARGET "__CMAKE::CXX23")
+  set(have_cxx23_import_std 1)
+endif ()
+
 # Forward information about the C++ compile features.
 string(APPEND info "\
 set(CMAKE_CXX_COMPILE_FEATURES \"${CMAKE_CXX_COMPILE_FEATURES}\")
 set(CMAKE_MAKE_PROGRAM \"${CMAKE_MAKE_PROGRAM}\")
 set(forced_cxx_standard \"${forced_cxx_standard}\")
+set(have_cxx23_import_std \"${have_cxx23_import_std}\")
 set(CMAKE_CXX_COMPILER_VERSION \"${CMAKE_CXX_COMPILER_VERSION}\")
 set(CMAKE_CXX_OUTPUT_EXTENSION \"${CMAKE_CXX_OUTPUT_EXTENSION}\")
 set(CXXModules_default_build_type \"${CMAKE_BUILD_TYPE}\")
diff --git a/Tests/RunCMake/CXXModules/NoCXX23TargetNotRequired.cmake b/Tests/RunCMake/CXXModules/NoCXX23TargetNotRequired.cmake
new file mode 100644
index 0000000..2d9bffa
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/NoCXX23TargetNotRequired.cmake
@@ -0,0 +1,11 @@
+enable_language(CXX)
+set(CMAKE_CXX_SCANDEP_SOURCE "echo")
+
+set(CMAKE_CXX_MODULE_STD 0)
+
+add_library(nocxx23target)
+target_sources(nocxx23target
+  PRIVATE
+    FILE_SET fs TYPE CXX_MODULES FILES
+      sources/module.cxx)
+target_compile_features(nocxx23target PRIVATE cxx_std_23)
diff --git a/Tests/RunCMake/CXXModules/NoCXX23TargetRequired-result.txt b/Tests/RunCMake/CXXModules/NoCXX23TargetRequired-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/NoCXX23TargetRequired-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/CXXModules/NoCXX23TargetRequired-stderr.txt b/Tests/RunCMake/CXXModules/NoCXX23TargetRequired-stderr.txt
new file mode 100644
index 0000000..56468d0
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/NoCXX23TargetRequired-stderr.txt
@@ -0,0 +1,4 @@
+CMake Error in CMakeLists.txt:
+  The "CXX_MODULE_STD" property on the target "nocxx23target" requires that
+  the "__CMAKE::CXX23" target exist, but it was not provided by the
+  toolchain.
diff --git a/Tests/RunCMake/CXXModules/NoCXX23TargetRequired.cmake b/Tests/RunCMake/CXXModules/NoCXX23TargetRequired.cmake
new file mode 100644
index 0000000..fac05e2
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/NoCXX23TargetRequired.cmake
@@ -0,0 +1,11 @@
+enable_language(CXX)
+set(CMAKE_CXX_SCANDEP_SOURCE "echo")
+
+set(CMAKE_CXX_MODULE_STD 1)
+
+add_library(nocxx23target)
+target_sources(nocxx23target
+  PRIVATE
+    FILE_SET fs TYPE CXX_MODULES FILES
+      sources/module.cxx)
+target_compile_features(nocxx23target PRIVATE cxx_std_23)
diff --git a/Tests/RunCMake/CXXModules/NoCXX23TargetUnset.cmake b/Tests/RunCMake/CXXModules/NoCXX23TargetUnset.cmake
new file mode 100644
index 0000000..8f6a656
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/NoCXX23TargetUnset.cmake
@@ -0,0 +1,13 @@
+enable_language(CXX)
+set(CMAKE_CXX_SCANDEP_SOURCE "echo")
+
+# TODO(cxxmodules): Add instances of this test which test the policy
+# of the property's unset behavior.
+# set(CMAKE_CXX_MODULE_STD …)
+
+add_library(nocxx23target)
+target_sources(nocxx23target
+  PRIVATE
+    FILE_SET fs TYPE CXX_MODULES FILES
+      sources/module.cxx)
+target_compile_features(nocxx23target PRIVATE cxx_std_23)
diff --git a/Tests/RunCMake/CXXModules/RunCMakeTest.cmake b/Tests/RunCMake/CXXModules/RunCMakeTest.cmake
index 297860b..2fd4c46 100644
--- a/Tests/RunCMake/CXXModules/RunCMakeTest.cmake
+++ b/Tests/RunCMake/CXXModules/RunCMakeTest.cmake
@@ -90,6 +90,13 @@ if ("cxx_std_23" IN_LIST CMAKE_CXX_COMPILE_FEATURES)
   run_cmake(CXXImportStdInvalidGenex)
 endif ()
 
+if ("cxx_std_23" IN_LIST CMAKE_CXX_COMPILE_FEATURES AND
+    NOT have_cxx23_import_std)
+  run_cmake(NoCXX23TargetUnset)
+  run_cmake(NoCXX23TargetNotRequired)
+  run_cmake(NoCXX23TargetRequired)
+endif ()
+
 run_cmake(InstallBMI)
 run_cmake(InstallBMIGenericArgs)
 run_cmake(InstallBMIIgnore)
-- 
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