cmSourceFile: internally track CMake-managed source files

These source file types don't necessarily show up in the CMake code, but
are side effects of other behaviors in CMake. Support tracking them
specially so that heuristics are not required to figure out if a given
`cmSourceFile` is one of them.

Source/cmGeneratorTarget.cxx

@@ -3141,6 +3141,7 @@ std::string cmGeneratorTarget::GetPchFileObject(std::string const& config,
 
     auto* pchSf = this->Makefile->GetOrCreateSource(
       pchSource, false, cmSourceFileLocationKind::Known);
+    pchSf->SetSpecialSourceType(cmSourceFile::SpecialSourceType::PchSource);
     pchSf->ResolveFullPath();
     filename = cmStrCat(this->GetObjectDirectory(config), '/',
                         this->GetObjectName(pchSf));
@@ -3188,6 +3189,8 @@ std::string cmGeneratorTarget::GetPchFile(std::string const& config,
         auto pchSource = this->GetPchSource(config, language, arch);
         auto* pchSf = this->Makefile->GetOrCreateSource(
           pchSource, false, cmSourceFileLocationKind::Known);
+        pchSf->SetSpecialSourceType(
+          cmSourceFile::SpecialSourceType::PchSource);
         pchSf->ResolveFullPath();
         std::string cfgSubdir;
         if (this->GetGlobalGenerator()->IsMultiConfig()) {
@@ -5798,6 +5801,8 @@ std::string cmGeneratorTarget::GenerateHeaderSetVerificationFile(
     this->LocalGenerator->GetCurrentBinaryDirectory(), '/', this->GetName(),
     "_verify_interface_header_sets/", headerFilename, extension);
   auto* verificationSource = this->Makefile->GetOrCreateSource(filename);
+  source.SetSpecialSourceType(
+    cmSourceFile::SpecialSourceType::HeaderSetVerificationSource);
   verificationSource->SetProperty("LANGUAGE", language);
 
   cmSystemTools::MakeDirectory(cmSystemTools::GetFilenamePath(filename));

Source/cmGlobalXCodeGenerator.cxx

@@ -740,7 +740,9 @@ void cmGlobalXCodeGenerator::AddExtraTargets(
       this->CurrentMakefile->GetSafeDefinition("CMAKE_XCODE_XCCONFIG"),
       this->CurrentLocalGenerator, config);
     if (!xcconfig.empty()) {
-      allbuild->AddSource(xcconfig);
+      auto* xcconfig_sf = allbuild->AddSource(xcconfig);
+      xcconfig_sf->SetSpecialSourceType(
+        cmSourceFile::SpecialSourceType::XcodeXCConfigFile);
     }
   }
 
@@ -1161,6 +1163,8 @@ void cmGlobalXCodeGenerator::AddXCodeProjBuildRule(
     target->GetLocalGenerator()->GetCurrentSourceDirectory());
   cmSourceFile* srcCMakeLists = target->Makefile->GetOrCreateSource(
     listfile, false, cmSourceFileLocationKind::Known);
+  srcCMakeLists->SetSpecialSourceType(
+    cmSourceFile::SpecialSourceType::CMakeLists);
   if (!cm::contains(sources, srcCMakeLists)) {
     sources.push_back(srcCMakeLists);
   }
@@ -1538,6 +1542,7 @@ bool cmGlobalXCodeGenerator::CreateXCodeTarget(
     std::string plist = this->ComputeInfoPListLocation(gtgt);
     cmSourceFile* sf = gtgt->Makefile->GetOrCreateSource(
       plist, true, cmSourceFileLocationKind::Known);
+    sf->SetSpecialSourceType(cmSourceFile::SpecialSourceType::BundleInfoPlist);
     commonSourceFiles.push_back(sf);
   }
 
@@ -1811,6 +1816,8 @@ void cmGlobalXCodeGenerator::ForceLinkerLanguage(cmGeneratorTarget* gtgt)
     fout << '\n';
   }
   if (cmSourceFile* sf = mf->GetOrCreateSource(fname)) {
+    sf->SetSpecialSourceType(
+      cmSourceFile::SpecialSourceType::XcodeForceLinkerSource);
     sf->SetProperty("LANGUAGE", llang);
     sf->SetProperty("CXX_SCAN_FOR_MODULES", "0");
     gtgt->AddSource(fname);
@@ -4519,6 +4526,7 @@ bool cmGlobalXCodeGenerator::CreateGroups(
           gtgt->GetLocalGenerator()->GetCurrentSourceDirectory());
         cmSourceFile* sf = gtgt->Makefile->GetOrCreateSource(
           listfile, false, cmSourceFileLocationKind::Known);
+        sf->SetSpecialSourceType(cmSourceFile::SpecialSourceType::CMakeLists);
         addSourceToGroup(sf->ResolveFullPath());
       }
 
@@ -4527,6 +4535,8 @@ bool cmGlobalXCodeGenerator::CreateGroups(
         std::string plist = this->ComputeInfoPListLocation(gtgt.get());
         cmSourceFile* sf = gtgt->Makefile->GetOrCreateSource(
           plist, true, cmSourceFileLocationKind::Known);
+        sf->SetSpecialSourceType(
+          cmSourceFile::SpecialSourceType::BundleInfoPlist);
         addSourceToGroup(sf->ResolveFullPath());
       }
     }

Source/cmLocalGenerator.cxx

@@ -2786,6 +2786,8 @@ void cmLocalGenerator::AddPchDependencies(cmGeneratorTarget* target)
 
         auto* pch_sf = this->Makefile->GetOrCreateSource(
           pchSource, false, cmSourceFileLocationKind::Known);
+        pch_sf->SetSpecialSourceType(
+          cmSourceFile::SpecialSourceType::PchSource);
         // PCH sources should never be scanned as they cannot contain C++
         // module references.
         pch_sf->SetProperty("CXX_SCAN_FOR_MODULES", "0");
@@ -2881,6 +2883,8 @@ void cmLocalGenerator::AddPchDependencies(cmGeneratorTarget* target)
           // be grouped as "Precompile Header File"
           auto* pchHeader_sf = this->Makefile->GetOrCreateSource(
             pchHeader, false, cmSourceFileLocationKind::Known);
+          pchHeader_sf->SetSpecialSourceType(
+            cmSourceFile::SpecialSourceType::PchHeader);
           std::string err;
           pchHeader_sf->ResolveFullPath(&err);
           if (!err.empty()) {
@@ -2989,7 +2993,9 @@ void cmLocalGenerator::CopyPchCompilePdb(
     cmSourceFile* copy_rule = this->AddCustomCommandToOutput(std::move(cc));
     if (copy_rule) {
       copy_rule->SetProperty("CXX_SCAN_FOR_MODULES", "0");
-      target->AddSource(copy_rule->ResolveFullPath());
+      auto* pch_pdb_sf = target->AddSource(copy_rule->ResolveFullPath());
+      pch_pdb_sf->SetSpecialSourceType(
+        cmSourceFile::SpecialSourceType::PchPdbReuseSource);
     }
   }
 }
@@ -3338,6 +3344,8 @@ void cmLocalGenerator::AddUnityBuild(cmGeneratorTarget* target)
 
     for (UnitySource const& file : unity_files) {
       auto* unity = this->GetMakefile()->GetOrCreateSource(file.Path);
+      unity->SetSpecialSourceType(
+        cmSourceFile::SpecialSourceType::UnitySource);
       target->AddSource(file.Path, true);
       unity->SetProperty("SKIP_UNITY_BUILD_INCLUSION", "ON");
       unity->SetProperty("UNITY_SOURCE_FILE", file.Path);

Source/cmLocalXCodeGenerator.cxx

@@ -158,7 +158,8 @@ void cmLocalXCodeGenerator::AddXCConfigSources(cmGeneratorTarget* target)
       *xcconfig,
       this, config);
     if (!file.empty()) {
-      target->AddSource(file);
+      auto* xcconfig_sf = target->AddSource(file);
+      xcconfig_sf->SetSpecialSourceType(cmSourceFile::SpecialSourceType::XcodeXCConfigFile);
     }
   }
 }

Source/cmMakefile.cxx

@@ -3147,6 +3147,7 @@ void cmMakefile::AddTargetObject(std::string const& tgtName,
 {
   cmSourceFile* sf =
     this->GetOrCreateSource(objFile, true, cmSourceFileLocationKind::Known);
+  sf->SetSpecialSourceType(cmSourceFile::SpecialSourceType::Object);
   sf->SetObjectLibrary(tgtName);
   sf->SetProperty("EXTERNAL_OBJECT", "1");
   // TODO: Compute a language for this object based on the associated source

Source/cmQTWrapCPPCommand.cxx

@@ -43,6 +43,8 @@ bool cmQTWrapCPPCommand(std::vector<std::string> const& args,
       std::string newName =
         cmStrCat(mf.GetCurrentBinaryDirectory(), "/moc_", srcName, ".cxx");
       cmSourceFile* sf = mf.GetOrCreateSource(newName, true);
+      sf->SetSpecialSourceType(
+        cmSourceFile::SpecialSourceType::QtWrapCppSource);
       if (curr) {
         sf->SetProperty("ABSTRACT", curr->GetProperty("ABSTRACT"));
       }

Source/cmQtAutoGenInitializer.cxx

@@ -2105,6 +2105,8 @@ cmSourceFile* cmQtAutoGenInitializer::RegisterGeneratedSource(
   std::string const& filename)
 {
   cmSourceFile* gFile = this->Makefile->GetOrCreateSource(filename, true);
+  gFile->SetSpecialSourceType(
+    cmSourceFile::SpecialSourceType::QtAutogenSource);
   gFile->MarkAsGenerated();
   gFile->SetProperty("SKIP_AUTOGEN", "1");
   gFile->SetProperty("SKIP_LINTING", "ON");

Source/cmSourceFile.cxx

@@ -29,6 +29,11 @@ cmSourceFile::cmSourceFile(cmMakefile* mf, std::string const& name,
   }
 }
 
+void cmSourceFile::SetSpecialSourceType(cmSourceFile::SpecialSourceType type)
+{
+  this->SpecialSource = type;
+}
+
 std::string const& cmSourceFile::GetExtension() const
 {
   return this->Extension;

Source/cmSourceFile.h

@@ -40,6 +40,34 @@ public:
   cmCustomCommand* GetCustomCommand() const;
   void SetCustomCommand(std::unique_ptr<cmCustomCommand> cc);
 
+  enum class SpecialSourceType
+  {
+    // Sources for user-provided sources.
+    User,
+    // Source files for object files.
+    Object,
+    // Sources representing `CMakeLists.txt` files.
+    CMakeLists,
+    // Xcode `Info.plist` files for bundle targets.
+    BundleInfoPlist,
+    // Xcode source to force a link to occur with an appropriate language.
+    XcodeForceLinkerSource,
+    // Xcode `
+    XcodeXCConfigFile,
+    // Header set verification files.
+    HeaderSetVerificationSource,
+    // PCH files.
+    PchHeader,
+    PchSource,
+    PchPdbReuseSource,
+    // Unity sources.
+    UnitySource,
+    // Qt support sources.
+    QtWrapCppSource,
+    QtAutogenSource,
+  };
+  void SetSpecialSourceType(SpecialSourceType type);
+
   //! Set/Get a property of this source file
   void SetProperty(std::string const& prop, cmValue value);
   void RemoveProperty(std::string const& prop)
@@ -166,6 +194,7 @@ private:
   std::vector<BT<std::string>> IncludeDirectories;
   bool FindFullPathFailed = false;
   bool IsGenerated = false;
+  SpecialSourceType SpecialSource = SpecialSourceType::User;
 
   bool FindFullPath(std::string* error, std::string* cmp0115Warning);
   void CheckExtension();