BUG: Do not automatically set HEADER_FILE_ONLY

Long ago the native build system generators needed HEADER_FILE_ONLY to
be set on header files to stop them from building.  The modern
generators correctly handle headers without the help of this property.
This removes automatic setting of the property so that it can be used
reliably as an indicator of project author intention.  It fixes VS IDE
project files to show header files normally instead of excluded (broken
by the fix for issue #7845).

Source/cmCPluginAPI.cxx

@@ -706,10 +706,6 @@ void CCONV cmSourceFileSetName(void *arg, const char* name, const char* dir,
     headerExts.push_back(headerExtensions[i]);
     }
 
-  // Implement the old SetName method code here.
-  sf->Properties.SetProperty("HEADER_FILE_ONLY", "1",
-                             cmProperty::SOURCE_FILE);
-
   // Save the original name given.
   sf->SourceName = name;
 
@@ -742,13 +738,6 @@ void CCONV cmSourceFileSetName(void *arg, const char* name, const char* dir,
         }
       }
 
-    // See if the file is a header file
-    if(std::find( headerExts.begin(), headerExts.end(),
-                  sf->SourceExtension ) == headerExts.end())
-      {
-      sf->Properties.SetProperty("HEADER_FILE_ONLY", "0",
-                                 cmProperty::SOURCE_FILE);
-      }
     sf->FullPath = hname;
     return;
     }
@@ -763,8 +752,6 @@ void CCONV cmSourceFileSetName(void *arg, const char* name, const char* dir,
     if(cmSystemTools::FileExists(hname.c_str()))
       {
       sf->SourceExtension = *ext;
-      sf->Properties.SetProperty("HEADER_FILE_ONLY", "0",
-                                 cmProperty::SOURCE_FILE);
       sf->FullPath = hname;
       return;
       }
@@ -814,9 +801,11 @@ void CCONV cmSourceFileSetName2(void *arg, const char* name, const char* dir,
     }
 
   // Implement the old SetName method code here.
-  sf->Properties.SetProperty("HEADER_FILE_ONLY",
-                             headerFileOnly? "1" : "0",
-                             cmProperty::SOURCE_FILE);
+  if(headerFileOnly)
+    {
+    sf->Properties.SetProperty("HEADER_FILE_ONLY", "1",
+                               cmProperty::SOURCE_FILE);
+    }
   sf->SourceName = name;
   std::string fname = sf->SourceName;
   if(ext && strlen(ext))

Source/cmGlobalXCodeGenerator.cxx

@@ -732,7 +732,7 @@ cmGlobalXCodeGenerator::CreateXCodeTargets(cmLocalGenerator* gen,
         {
         externalObjFiles.push_back(xsf);
         }
-      else if((*i)->GetPropertyAsBool("HEADER_FILE_ONLY") ||
+      else if(this->IsHeaderFile(*i) ||
         (tsFlags.Type == cmTarget::SourceFileTypePrivateHeader) ||
         (tsFlags.Type == cmTarget::SourceFileTypePublicHeader))
         {
@@ -742,7 +742,7 @@ cmGlobalXCodeGenerator::CreateXCodeTargets(cmLocalGenerator* gen,
         {
         resourceFiles.push_back(xsf);
         }
-      else
+      else if(!(*i)->GetPropertyAsBool("HEADER_FILE_ONLY"))
         {
         // Include this file in the build if it has a known language
         // and has not been listed as an ignored extension for this
@@ -911,6 +911,15 @@ cmGlobalXCodeGenerator::CreateXCodeTargets(cmLocalGenerator* gen,
     }
 }
 
+//----------------------------------------------------------------------------
+bool cmGlobalXCodeGenerator::IsHeaderFile(cmSourceFile* sf)
+{
+  const std::vector<std::string>& hdrExts =
+    this->CurrentMakefile->GetHeaderExtensions();
+  return (std::find(hdrExts.begin(), hdrExts.end(), sf->GetExtension()) !=
+          hdrExts.end());
+}
+
 //----------------------------------------------------------------------------
 cmXCodeObject*
 cmGlobalXCodeGenerator::CreateBuildPhase(const char* name,

Source/cmGlobalXCodeGenerator.h

@@ -159,6 +159,7 @@ private:
                                        cmTarget& cmtarget);
   void CreateXCodeTargets(cmLocalGenerator* gen, 
                           std::vector<cmXCodeObject*>&);
+  bool IsHeaderFile(cmSourceFile*);
   void AddDependTarget(cmXCodeObject* target,
                        cmXCodeObject* dependTarget);
   void CreateXCodeDependHackTarget(std::vector<cmXCodeObject*>& targets);

Source/cmSourceFile.cxx

@@ -246,25 +246,6 @@ void cmSourceFile::CheckExtension()
     this->SetProperty("EXTERNAL_OBJECT", "1");
     }
 
-  // Look for header files.
-  cmMakefile* mf = this->Location.GetMakefile();
-  const std::vector<std::string>& hdrExts = mf->GetHeaderExtensions();
-  if(std::find(hdrExts.begin(), hdrExts.end(), this->Extension) ==
-     hdrExts.end())
-    {
-    // This is not a known header file extension.  Mark it as not a
-    // header unless the user has already explicitly set the property.
-    if(!this->GetProperty("HEADER_FILE_ONLY"))
-      {
-      this->SetProperty("HEADER_FILE_ONLY", "0");
-      }
-    }
-  else
-    {
-    // This is a known header file extension.  The source cannot be compiled.
-    this->SetProperty("HEADER_FILE_ONLY", "1");
-    }
-
   // Try to identify the source file language from the extension.
   if(this->Language.empty())
     {