Tests/RunCMake/CXXModules: add module-using examples

This includes a number of examples that should work for various levels
of support in a compiler.

There are a number of tests which are gated on various features in the
compilers. To enable the tests, set `CMake_TEST_MODULE_COMPILATION` to a
comma-separated (to avoid `;`-escaping problems) to the list of features
which are supported:

  - `named`: Named modules are supported.
  - `shared`: Shared libraries with module usage at the API boundary are
    supported.
  - `partitions`: Named module partitions are supported.
  - `internal_partitions`: Named module internal partitions are
    supported.

Additionally, a `CMake_TEST_MODULE_COMPILATION_RULES` file must be
passed which contains the rules for how to build modules using the
provided compiler. It will be included in the tests to provide these
rules. To verify that the file provided works as intended, it must set
`CMake_TEST_CXXModules_UUID` to a specific version to indicate that it
is an expected file.

26 files changed, 340 insertions, 1 deletions

diff --git a/Tests/RunCMake/CMakeLists.txt b/Tests/RunCMake/CMakeLists.txt
index 3d2654c..bbf8ddc 100644
--- a/Tests/RunCMake/CMakeLists.txt
+++ b/Tests/RunCMake/CMakeLists.txt
@@ -565,7 +565,7 @@ endif()
 add_RunCMake_test(DependencyGraph -DCMAKE_Fortran_COMPILER=${CMAKE_Fortran_COMPILER})
 
 # Add C++ Module tests.
-add_RunCMake_test(CXXModules)
+add_RunCMake_test(CXXModules -DCMake_TEST_MODULE_COMPILATION=${CMake_TEST_MODULE_COMPILATION} -DCMake_TEST_MODULE_COMPILATION_RULES=${CMake_TEST_MODULE_COMPILATION_RULES})
 
 # ctresalloc links against CMakeLib and CTestLib, which means it can't be built
 # if CMake_TEST_EXTERNAL_CMAKE is activated (the compiler might be different.)
diff --git a/Tests/RunCMake/CXXModules/RunCMakeTest.cmake b/Tests/RunCMake/CXXModules/RunCMakeTest.cmake
index 00c1a8b..68fdcae 100644
--- a/Tests/RunCMake/CXXModules/RunCMakeTest.cmake
+++ b/Tests/RunCMake/CXXModules/RunCMakeTest.cmake
@@ -65,3 +65,56 @@ foreach (fileset_type IN LISTS fileset_types)
   # list.
   run_cmake("NotCXXSource${fileset_type}")
 endforeach ()
+
+# Actual compilation tests.
+if (NOT CMake_TEST_MODULE_COMPILATION)
+  return ()
+endif ()
+
+function (run_cxx_module_test directory)
+  set(test_name "${directory}")
+  if (NOT ARGN STREQUAL "")
+    list(POP_FRONT ARGN test_name)
+  endif ()
+
+  set(RunCMake_TEST_SOURCE_DIR "${CMAKE_CURRENT_LIST_DIR}/examples/${directory}")
+  set(RunCMake_TEST_BINARY_DIR "${RunCMake_BINARY_DIR}/examples/${test_name}-build")
+
+  if (RunCMake_GENERATOR_IS_MULTI_CONFIG)
+    set(RunCMake_TEST_OPTIONS -DCMAKE_CONFIGURATION_TYPES=Debug)
+  else ()
+    set(RunCMake_TEST_OPTIONS -DCMAKE_BUILD_TYPE=Debug)
+  endif ()
+
+  set(RunCMake_TEST_OPTIONS
+    "-DCMake_TEST_MODULE_COMPILATION_RULES=${CMake_TEST_MODULE_COMPILATION_RULES}"
+    ${ARGN})
+  run_cmake("examples/${test_name}")
+  set(RunCMake_TEST_NO_CLEAN 1)
+  run_cmake_command("${test_name}-build" "${CMAKE_COMMAND}" --build . --config Debug)
+  run_cmake_command("${test_name}-test" "${CMAKE_CTEST_COMMAND}" -C Debug)
+endfunction ()
+
+string(REPLACE "," ";" CMake_TEST_MODULE_COMPILATION "${CMake_TEST_MODULE_COMPILATION}")
+
+# Tests which use named modules.
+if ("named" IN_LIST CMake_TEST_MODULE_COMPILATION)
+  run_cxx_module_test(simple)
+  run_cxx_module_test(library library-static -DBUILD_SHARED_LIBS=OFF)
+  run_cxx_module_test(generated)
+endif ()
+
+# Tests which use named modules in shared libraries.
+if ("shared" IN_LIST CMake_TEST_MODULE_COMPILATION)
+  run_cxx_module_test(library library-shared -DBUILD_SHARED_LIBS=ON)
+endif ()
+
+# Tests which use partitions.
+if ("partitions" IN_LIST CMake_TEST_MODULE_COMPILATION)
+  run_cxx_module_test(partitions)
+endif ()
+
+# Tests which use internal partitions.
+if ("internal_partitions" IN_LIST CMake_TEST_MODULE_COMPILATION)
+  run_cxx_module_test(internal-partitions)
+endif ()
diff --git a/Tests/RunCMake/CXXModules/examples/cxx-modules-rules.cmake b/Tests/RunCMake/CXXModules/examples/cxx-modules-rules.cmake
new file mode 100644
index 0000000..91ad208
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/cxx-modules-rules.cmake
@@ -0,0 +1,18 @@
+set(CMAKE_EXPERIMENTAL_CXX_MODULE_CMAKE_API "17be90bd-a850-44e0-be50-448de847d652")
+
+if (NOT EXISTS "${CMake_TEST_MODULE_COMPILATION_RULES}")
+  message(FATAL_ERROR
+    "The `CMake_TEST_MODULE_COMPILATION_RULES` file must be specified "
+    "for these tests to operate.")
+endif ()
+
+include("${CMake_TEST_MODULE_COMPILATION_RULES}")
+
+if (NOT CMake_TEST_CXXModules_UUID STREQUAL "a246741c-d067-4019-a8fb-3d16b0c9d1d3")
+  message(FATAL_ERROR
+    "The compilation rule file needs updated for changes in the test "
+    "suite. Please see the history for what needs to be updated.")
+endif ()
+
+include(CTest)
+enable_testing()
diff --git a/Tests/RunCMake/CXXModules/examples/generated-stderr.txt b/Tests/RunCMake/CXXModules/examples/generated-stderr.txt
new file mode 100644
index 0000000..b9bbf34
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/generated-stderr.txt
@@ -0,0 +1,9 @@
+CMake Warning \(dev\) at CMakeLists.txt:12 \(target_sources\):
+  CMake's C\+\+ module support is experimental.  It is meant only for
+  experimentation and feedback to CMake developers.
+This warning is for project developers.  Use -Wno-dev to suppress it.
+
+CMake Warning \(dev\):
+  C\+\+20 modules support via CMAKE_EXPERIMENTAL_CXX_MODULE_DYNDEP is
+  experimental.  It is meant only for compiler developers to try.
+This warning is for project developers.  Use -Wno-dev to suppress it.
diff --git a/Tests/RunCMake/CXXModules/examples/generated/CMakeLists.txt b/Tests/RunCMake/CXXModules/examples/generated/CMakeLists.txt
new file mode 100644
index 0000000..73f7ff7
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/generated/CMakeLists.txt
@@ -0,0 +1,23 @@
+cmake_minimum_required(VERSION 3.24)
+project(cxx_modules_generated CXX)
+
+include("${CMAKE_SOURCE_DIR}/../cxx-modules-rules.cmake")
+
+configure_file(
+  "${CMAKE_CURRENT_SOURCE_DIR}/importable.cxx.in"
+  "${CMAKE_CURRENT_BINARY_DIR}/importable.cxx"
+  COPYONLY)
+
+add_executable(generated)
+target_sources(generated
+  PRIVATE
+    main.cxx
+  PRIVATE
+    FILE_SET CXX_MODULES
+      BASE_DIRS
+        "${CMAKE_CURRENT_BINARY_DIR}"
+      FILES
+        "${CMAKE_CURRENT_BINARY_DIR}/importable.cxx")
+target_compile_features(generated PUBLIC cxx_std_20)
+
+add_test(NAME generated COMMAND generated)
diff --git a/Tests/RunCMake/CXXModules/examples/generated/importable.cxx.in b/Tests/RunCMake/CXXModules/examples/generated/importable.cxx.in
new file mode 100644
index 0000000..a9287d7
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/generated/importable.cxx.in
@@ -0,0 +1,5 @@
+export module importable;
+
+export int from_import() {
+  return 0;
+}
diff --git a/Tests/RunCMake/CXXModules/examples/generated/main.cxx b/Tests/RunCMake/CXXModules/examples/generated/main.cxx
new file mode 100644
index 0000000..feb38d2
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/generated/main.cxx
@@ -0,0 +1,6 @@
+import importable;
+
+int main(int argc, char* argv[])
+{
+  return from_import();
+}
diff --git a/Tests/RunCMake/CXXModules/examples/internal-partitions-stderr.txt b/Tests/RunCMake/CXXModules/examples/internal-partitions-stderr.txt
new file mode 100644
index 0000000..4652aec
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/internal-partitions-stderr.txt
@@ -0,0 +1,9 @@
+CMake Warning \(dev\) at CMakeLists.txt:10 \(target_sources\):
+  CMake's C\+\+ module support is experimental.  It is meant only for
+  experimentation and feedback to CMake developers.
+This warning is for project developers.  Use -Wno-dev to suppress it.
+
+CMake Warning \(dev\):
+  C\+\+20 modules support via CMAKE_EXPERIMENTAL_CXX_MODULE_DYNDEP is
+  experimental.  It is meant only for compiler developers to try.
+This warning is for project developers.  Use -Wno-dev to suppress it.
diff --git a/Tests/RunCMake/CXXModules/examples/internal-partitions/CMakeLists.txt b/Tests/RunCMake/CXXModules/examples/internal-partitions/CMakeLists.txt
new file mode 100644
index 0000000..f5e9d94
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/internal-partitions/CMakeLists.txt
@@ -0,0 +1,31 @@
+cmake_minimum_required(VERSION 3.24)
+project(cxx_modules_internal_partitions CXX)
+
+include("${CMAKE_SOURCE_DIR}/../cxx-modules-rules.cmake")
+
+include(GenerateExportHeader)
+
+add_library(internal-partitions)
+generate_export_header(internal-partitions)
+target_sources(internal-partitions
+  PUBLIC
+    FILE_SET HEADERS
+      BASE_DIRS
+        "${CMAKE_CURRENT_BINARY_DIR}"
+      FILES
+        "${CMAKE_CURRENT_BINARY_DIR}/internal-partitions_export.h"
+    FILE_SET CXX_MODULES
+      BASE_DIRS
+        "${CMAKE_CURRENT_SOURCE_DIR}"
+      FILES
+        importable.cxx
+        partition.cxx)
+target_compile_features(internal-partitions PUBLIC cxx_std_20)
+
+add_executable(exe)
+target_link_libraries(exe PRIVATE internal-partitions)
+target_sources(exe
+  PRIVATE
+    main.cxx)
+
+add_test(NAME exe COMMAND exe)
diff --git a/Tests/RunCMake/CXXModules/examples/internal-partitions/importable.cxx b/Tests/RunCMake/CXXModules/examples/internal-partitions/importable.cxx
new file mode 100644
index 0000000..8be521b
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/internal-partitions/importable.cxx
@@ -0,0 +1,9 @@
+export module importable;
+import importable : internal_partition;
+
+#include "internal-partitions_export.h"
+
+export INTERNAL_PARTITIONS_EXPORT int from_import()
+{
+  return from_partition();
+}
diff --git a/Tests/RunCMake/CXXModules/examples/internal-partitions/main.cxx b/Tests/RunCMake/CXXModules/examples/internal-partitions/main.cxx
new file mode 100644
index 0000000..feb38d2
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/internal-partitions/main.cxx
@@ -0,0 +1,6 @@
+import importable;
+
+int main(int argc, char* argv[])
+{
+  return from_import();
+}
diff --git a/Tests/RunCMake/CXXModules/examples/internal-partitions/partition.cxx b/Tests/RunCMake/CXXModules/examples/internal-partitions/partition.cxx
new file mode 100644
index 0000000..b15f53c
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/internal-partitions/partition.cxx
@@ -0,0 +1,6 @@
+module importable : internal_partition;
+
+int from_partition()
+{
+  return 0;
+}
diff --git a/Tests/RunCMake/CXXModules/examples/library-shared-stderr.txt b/Tests/RunCMake/CXXModules/examples/library-shared-stderr.txt
new file mode 100644
index 0000000..4652aec
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/library-shared-stderr.txt
@@ -0,0 +1,9 @@
+CMake Warning \(dev\) at CMakeLists.txt:10 \(target_sources\):
+  CMake's C\+\+ module support is experimental.  It is meant only for
+  experimentation and feedback to CMake developers.
+This warning is for project developers.  Use -Wno-dev to suppress it.
+
+CMake Warning \(dev\):
+  C\+\+20 modules support via CMAKE_EXPERIMENTAL_CXX_MODULE_DYNDEP is
+  experimental.  It is meant only for compiler developers to try.
+This warning is for project developers.  Use -Wno-dev to suppress it.
diff --git a/Tests/RunCMake/CXXModules/examples/library-static-stderr.txt b/Tests/RunCMake/CXXModules/examples/library-static-stderr.txt
new file mode 100644
index 0000000..4652aec
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/library-static-stderr.txt
@@ -0,0 +1,9 @@
+CMake Warning \(dev\) at CMakeLists.txt:10 \(target_sources\):
+  CMake's C\+\+ module support is experimental.  It is meant only for
+  experimentation and feedback to CMake developers.
+This warning is for project developers.  Use -Wno-dev to suppress it.
+
+CMake Warning \(dev\):
+  C\+\+20 modules support via CMAKE_EXPERIMENTAL_CXX_MODULE_DYNDEP is
+  experimental.  It is meant only for compiler developers to try.
+This warning is for project developers.  Use -Wno-dev to suppress it.
diff --git a/Tests/RunCMake/CXXModules/examples/library/CMakeLists.txt b/Tests/RunCMake/CXXModules/examples/library/CMakeLists.txt
new file mode 100644
index 0000000..27fd94f
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/library/CMakeLists.txt
@@ -0,0 +1,30 @@
+cmake_minimum_required(VERSION 3.24)
+project(cxx_modules_library CXX)
+
+include("${CMAKE_SOURCE_DIR}/../cxx-modules-rules.cmake")
+
+include(GenerateExportHeader)
+
+add_library(library)
+generate_export_header(library)
+target_sources(library
+  PUBLIC
+    FILE_SET HEADERS
+      BASE_DIRS
+        "${CMAKE_CURRENT_BINARY_DIR}"
+      FILES
+        "${CMAKE_CURRENT_BINARY_DIR}/library_export.h"
+    FILE_SET CXX_MODULES
+      BASE_DIRS
+        "${CMAKE_CURRENT_SOURCE_DIR}"
+      FILES
+        importable.cxx)
+target_compile_features(library PUBLIC cxx_std_20)
+
+add_executable(exe)
+target_link_libraries(exe PRIVATE library)
+target_sources(exe
+  PRIVATE
+    main.cxx)
+
+add_test(NAME exe COMMAND exe)
diff --git a/Tests/RunCMake/CXXModules/examples/library/importable.cxx b/Tests/RunCMake/CXXModules/examples/library/importable.cxx
new file mode 100644
index 0000000..72ed0df
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/library/importable.cxx
@@ -0,0 +1,8 @@
+export module importable;
+
+#include "library_export.h"
+
+export LIBRARY_EXPORT int from_import()
+{
+  return 0;
+}
diff --git a/Tests/RunCMake/CXXModules/examples/library/main.cxx b/Tests/RunCMake/CXXModules/examples/library/main.cxx
new file mode 100644
index 0000000..feb38d2
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/library/main.cxx
@@ -0,0 +1,6 @@
+import importable;
+
+int main(int argc, char* argv[])
+{
+  return from_import();
+}
diff --git a/Tests/RunCMake/CXXModules/examples/partitions-stderr.txt b/Tests/RunCMake/CXXModules/examples/partitions-stderr.txt
new file mode 100644
index 0000000..4652aec
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/partitions-stderr.txt
@@ -0,0 +1,9 @@
+CMake Warning \(dev\) at CMakeLists.txt:10 \(target_sources\):
+  CMake's C\+\+ module support is experimental.  It is meant only for
+  experimentation and feedback to CMake developers.
+This warning is for project developers.  Use -Wno-dev to suppress it.
+
+CMake Warning \(dev\):
+  C\+\+20 modules support via CMAKE_EXPERIMENTAL_CXX_MODULE_DYNDEP is
+  experimental.  It is meant only for compiler developers to try.
+This warning is for project developers.  Use -Wno-dev to suppress it.
diff --git a/Tests/RunCMake/CXXModules/examples/partitions/CMakeLists.txt b/Tests/RunCMake/CXXModules/examples/partitions/CMakeLists.txt
new file mode 100644
index 0000000..3a7b0d4
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/partitions/CMakeLists.txt
@@ -0,0 +1,31 @@
+cmake_minimum_required(VERSION 3.24)
+project(cxx_modules_partitions CXX)
+
+include("${CMAKE_SOURCE_DIR}/../cxx-modules-rules.cmake")
+
+include(GenerateExportHeader)
+
+add_library(partitions)
+generate_export_header(partitions)
+target_sources(partitions
+  PUBLIC
+    FILE_SET HEADERS
+      BASE_DIRS
+        "${CMAKE_CURRENT_BINARY_DIR}"
+      FILES
+        "${CMAKE_CURRENT_BINARY_DIR}/partitions_export.h"
+    FILE_SET CXX_MODULES
+      BASE_DIRS
+        "${CMAKE_CURRENT_SOURCE_DIR}"
+      FILES
+        importable.cxx
+        partition.cxx)
+target_compile_features(partitions PUBLIC cxx_std_20)
+
+add_executable(exe)
+target_link_libraries(exe PRIVATE partitions)
+target_sources(exe
+  PRIVATE
+    main.cxx)
+
+add_test(NAME exe COMMAND exe)
diff --git a/Tests/RunCMake/CXXModules/examples/partitions/importable.cxx b/Tests/RunCMake/CXXModules/examples/partitions/importable.cxx
new file mode 100644
index 0000000..1e81aaf
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/partitions/importable.cxx
@@ -0,0 +1,9 @@
+export module importable;
+export import importable : partition;
+
+#include "partitions_export.h"
+
+export PARTITIONS_EXPORT int from_import()
+{
+  return from_partition();
+}
diff --git a/Tests/RunCMake/CXXModules/examples/partitions/main.cxx b/Tests/RunCMake/CXXModules/examples/partitions/main.cxx
new file mode 100644
index 0000000..c5b78c9
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/partitions/main.cxx
@@ -0,0 +1,6 @@
+import importable;
+
+int main(int argc, char* argv[])
+{
+  return from_import() + from_partition();
+}
diff --git a/Tests/RunCMake/CXXModules/examples/partitions/partition.cxx b/Tests/RunCMake/CXXModules/examples/partitions/partition.cxx
new file mode 100644
index 0000000..a47a4fd
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/partitions/partition.cxx
@@ -0,0 +1,8 @@
+export module importable : partition;
+
+#include "partitions_export.h"
+
+export PARTITIONS_EXPORT int from_partition()
+{
+  return 0;
+}
diff --git a/Tests/RunCMake/CXXModules/examples/simple-stderr.txt b/Tests/RunCMake/CXXModules/examples/simple-stderr.txt
new file mode 100644
index 0000000..5e4392a
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/simple-stderr.txt
@@ -0,0 +1,9 @@
+CMake Warning \(dev\) at CMakeLists.txt:7 \(target_sources\):
+  CMake's C\+\+ module support is experimental.  It is meant only for
+  experimentation and feedback to CMake developers.
+This warning is for project developers.  Use -Wno-dev to suppress it.
+
+CMake Warning \(dev\):
+  C\+\+20 modules support via CMAKE_EXPERIMENTAL_CXX_MODULE_DYNDEP is
+  experimental.  It is meant only for compiler developers to try.
+This warning is for project developers.  Use -Wno-dev to suppress it.
diff --git a/Tests/RunCMake/CXXModules/examples/simple/CMakeLists.txt b/Tests/RunCMake/CXXModules/examples/simple/CMakeLists.txt
new file mode 100644
index 0000000..442e425
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/simple/CMakeLists.txt
@@ -0,0 +1,18 @@
+cmake_minimum_required(VERSION 3.24)
+project(cxx_modules_simple CXX)
+
+include("${CMAKE_SOURCE_DIR}/../cxx-modules-rules.cmake")
+
+add_executable(simple)
+target_sources(simple
+  PRIVATE
+    main.cxx
+  PRIVATE
+    FILE_SET CXX_MODULES
+      BASE_DIRS
+        "${CMAKE_CURRENT_SOURCE_DIR}"
+      FILES
+        importable.cxx)
+target_compile_features(simple PUBLIC cxx_std_20)
+
+add_test(NAME simple COMMAND simple)
diff --git a/Tests/RunCMake/CXXModules/examples/simple/importable.cxx b/Tests/RunCMake/CXXModules/examples/simple/importable.cxx
new file mode 100644
index 0000000..607680a
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/simple/importable.cxx
@@ -0,0 +1,6 @@
+export module importable;
+
+export int from_import()
+{
+  return 0;
+}
diff --git a/Tests/RunCMake/CXXModules/examples/simple/main.cxx b/Tests/RunCMake/CXXModules/examples/simple/main.cxx
new file mode 100644
index 0000000..feb38d2
--- /dev/null
+++ b/Tests/RunCMake/CXXModules/examples/simple/main.cxx
@@ -0,0 +1,6 @@
+import importable;
+
+int main(int argc, char* argv[])
+{
+  return from_import();
+}