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, 4 insertions, 0 deletions

diff --git a/Source/cmTarget.h b/Source/cmTarget.h
index 5ed018e..94d6688 100644
--- a/Source/cmTarget.h
+++ b/Source/cmTarget.h
@@ -275,8 +275,12 @@ public:
   cmBTStringRange GetLinkInterfaceDirectExcludeEntries() const;
 
   cmBTStringRange GetHeaderSetsEntries() const;
+  cmBTStringRange GetCxxModuleSetsEntries() const;
+  cmBTStringRange GetCxxModuleHeaderSetsEntries() const;
 
   cmBTStringRange GetInterfaceHeaderSetsEntries() const;
+  cmBTStringRange GetInterfaceCxxModuleSetsEntries() const;
+  cmBTStringRange GetInterfaceCxxModuleHeaderSetsEntries() const;
 
   std::string ImportedGetFullPath(const std::string& config,
                                   cmStateEnums::ArtifactType artifact) const;