cxxmodules: add properties to control scanning

The `CXX_SCAN_FOR_MODULES` property may be used to control scanning for
targets and for source files rather than assuming "C++20 always needs to
be scanned".

1 files changed, 12 insertions, 1 deletions

diff --git a/Source/cmNinjaTargetGenerator.h b/Source/cmNinjaTargetGenerator.h
index bb75fb3..d09f04b 100644
--- a/Source/cmNinjaTargetGenerator.h
+++ b/Source/cmNinjaTargetGenerator.h
@@ -19,6 +19,7 @@
 #include "cmOSXBundleGenerator.h"
 
 class cmCustomCommand;
+class cmFileSet;
 class cmGeneratedFileStream;
 class cmGeneratorTarget;
 class cmLocalNinjaGenerator;
@@ -67,8 +68,14 @@ protected:
   cmFileSet const* GetFileSetForSource(std::string const& config,
                                        cmSourceFile const* sf);
 
+  enum class WithScanning
+  {
+    No,
+    Yes,
+  };
   std::string LanguageCompilerRule(const std::string& lang,
-                                   const std::string& config) const;
+                                   const std::string& config,
+                                   WithScanning withScanning) const;
   std::string LanguagePreprocessAndScanRule(std::string const& lang,
                                             const std::string& config) const;
   std::string LanguageScanRule(std::string const& lang,
@@ -76,6 +83,8 @@ protected:
   std::string LanguageDyndepRule(std::string const& lang,
                                  const std::string& config) const;
   bool NeedDyndep(std::string const& lang, std::string const& config) const;
+  bool NeedDyndepForSource(std::string const& lang, std::string const& config,
+                           cmSourceFile const* sf);
   bool NeedExplicitPreprocessing(std::string const& lang) const;
   bool CompileWithDefines(std::string const& lang) const;
   bool NeedCxxModuleSupport(std::string const& lang,
@@ -154,6 +163,8 @@ protected:
                           const std::string& config);
   void WriteCompileRule(const std::string& language,
                         const std::string& config);
+  void WriteCompileRule(const std::string& language, const std::string& config,
+                        WithScanning withScanning);
   void WriteObjectBuildStatements(const std::string& config,
                                   const std::string& fileConfig,
                                   bool firstForConfig);