CPack add easy possibility to warn about CPACK_SET_DESTDIR

CPackNSIS will only warn but sooner or later it should error out

Source/CPack/cmCPackGenerator.cxx

@@ -66,6 +66,27 @@ int cmCPackGenerator::PrepareNames()
   cmCPackLogger(cmCPackLog::LOG_DEBUG,
     "Create temp directory." << std::endl);
 
+  // checks CPACK_SET_DESTDIR support
+  if (IsOn("CPACK_SET_DESTDIR"))
+    {
+      if (SETDESTDIR_UNSUPPORTED==SupportsSetDestdir())
+        {
+          cmCPackLogger(cmCPackLog::LOG_ERROR,
+                        "CPACK_SET_DESTDIR is set to ON but the '"
+                        << Name << "' generator does NOT support it."
+                        << std::endl);
+          return 0;
+        }
+      else if (SETDESTDIR_SHOULD_NOT_BE_USED==SupportsSetDestdir())
+        {
+          cmCPackLogger(cmCPackLog::LOG_WARNING,
+                        "CPACK_SET_DESTDIR is set to ON but it is "
+                        << "usually a bad idea to do that with '"
+                        << Name << "' generator. Use at your own risk."
+                        << std::endl);
+        }
+  }
+
   std::string tempDirectory = this->GetOption("CPACK_PACKAGE_DIRECTORY");
   tempDirectory += "/_CPack_Packages/";
   const char* toplevelTag = this->GetOption("CPACK_TOPLEVEL_TAG");
@@ -953,6 +974,8 @@ int cmCPackGenerator::DoPackage()
   cmCPackLogger(cmCPackLog::LOG_OUTPUT,
     "Create package using " << this->Name.c_str() << std::endl);
 
+  // Prepare CPack internal name and check
+  // values for many CPACK_xxx vars
   if ( !this->PrepareNames() )
     {
     return 0;
@@ -1430,6 +1453,13 @@ std::string cmCPackGenerator::GetComponentPackageFileName(
   return initialPackageFileName + suffix;
 }
 
+//----------------------------------------------------------------------
+enum cmCPackGenerator::CPackSetDestdirSupport
+cmCPackGenerator::SupportsSetDestdir() const
+{
+  return cmCPackGenerator::SETDESTDIR_SUPPORTED;
+}
+
 //----------------------------------------------------------------------
 bool cmCPackGenerator::SupportsComponentInstallation() const
 {

Source/CPack/cmCPackGenerator.h

@@ -189,6 +189,29 @@ protected:
   virtual int InstallProjectViaInstallCMakeProjects(
     bool setDestDir, const char* tempInstallDirectory);
 
+  /**
+   * The various level of support of
+   * CPACK_SET_DESTDIR used by the generator.
+   */
+  enum CPackSetDestdirSupport {
+    /* the generator works with or without it */
+    SETDESTDIR_SUPPORTED,
+    /* the generator works best if automatically handled */
+    SETDESTDIR_INTERNALLY_SUPPORTED,
+    /* no official support, use at your own risk */
+    SETDESTDIR_SHOULD_NOT_BE_USED,
+    /* officially NOT supported */
+    SETDESTDIR_UNSUPPORTED
+  };
+
+  /**
+   * Does the CPack generator support CPACK_SET_DESTDIR?
+   * The default legacy value is 'true' generator
+   * have to override it in order change this.
+   * @return CPackSetDestdirSupport
+   */
+  virtual enum CPackSetDestdirSupport SupportsSetDestdir() const;
+
   /**
    * Does the CPack generator support component installation?.
    * Some Generators requires the user to set

Source/CPack/cmCPackNSISGenerator.cxx

@@ -64,6 +64,7 @@ int cmCPackNSISGenerator::PackageFiles()
       << std::endl);
     return false;
     }
+
   std::string nsisFileName = this->GetOption("CPACK_TOPLEVEL_DIRECTORY");
   std::string tmpFile = nsisFileName;
   tmpFile += "/NSISOutput.log";
@@ -630,6 +631,13 @@ bool cmCPackNSISGenerator::GetListOfSubdirectories(const char* topdir,
   return true;
 }
 
+//----------------------------------------------------------------------
+enum cmCPackGenerator::CPackSetDestdirSupport
+cmCPackNSISGenerator::SupportsSetDestdir() const
+{
+  return cmCPackGenerator::SETDESTDIR_SHOULD_NOT_BE_USED;
+}
+
 //----------------------------------------------------------------------
 bool cmCPackNSISGenerator::SupportsComponentInstallation() const
 {

Source/CPack/cmCPackNSISGenerator.h

@@ -44,6 +44,7 @@ protected:
   bool GetListOfSubdirectories(const char* dir,
     std::vector<std::string>& dirs);
 
+  enum cmCPackGenerator::CPackSetDestdirSupport SupportsSetDestdir() const;
   virtual bool SupportsComponentInstallation() const;
 
   /// Produce a string that contains the NSIS code to describe a