cmTarget: add support for C++ module fileset types

C++ modules have two variants which are of importance to CMake:

  - `CXX_MODULES`: interface modules (those using `export module M;`,
    `export module M:part;`, or `module M:internal_part;`)
  - `CXX_MODULE_HEADER_UNITS`: importable header units

Creating C++ modules or partitions are *not* supported in any other
source listing. This is because the source files must be installed (so
their scope matters), but not part of usage requirements (what it means
for a module source to be injected into a consumer is not clear at this
moment). Due to the way `FILE_SET` works with scopes, they are a perfect
fit as long as `INTERFACE` is not allowed (which it is not).

1 files changed, 13 insertions, 2 deletions

diff --git a/Tests/RunCMake/try_compile/CxxStandard-stderr.txt b/Tests/RunCMake/try_compile/CxxStandard-stderr.txt
index ec7245fdd4..cee1b4451f 100644
--- a/Tests/RunCMake/try_compile/CxxStandard-stderr.txt
+++ b/Tests/RunCMake/try_compile/CxxStandard-stderr.txt
@@ -1,6 +1,17 @@
-^CMake Error at .*/Tests/RunCMake/try_compile/CxxStandard-build/CMakeFiles/CMakeTmp/CMakeLists.txt:[0-9]+ \(add_executable\):
+^(CMake Error in .*/Tests/RunCMake/try_compile/CxxStandard-build/CMakeFiles/CMakeTmp/CMakeLists.txt:
+  The CXX_STANDARD property on target "cmTC_[0-9a-f]*" contained an invalid
+  value: "3".
+
+
+)?CMake Error at .*/Tests/RunCMake/try_compile/CxxStandard-build/CMakeFiles/CMakeTmp/CMakeLists.txt:[0-9]+ \(add_executable\):
   CXX_STANDARD is set to invalid value '3'
-+
+
+(
+CMake Error in .*/Tests/RunCMake/try_compile/CxxStandard-build/CMakeFiles/CMakeTmp/CMakeLists.txt:
+  The CXX_STANDARD property on target "cmTC_[0-9a-f]*" contained an invalid
+  value: "3".
+
+)?
 CMake Error at CxxStandard.cmake:[0-9]+ \(try_compile\):
   Failed to generate test project build system.
 Call Stack \(most recent call first\):