Modernize: Use #pragma once in all header files

#pragma once is a widely supported compiler pragma, even though it is
not part of the C++ standard. Many of the issues keeping #pragma once
from being standardized (distributed filesystems, build farms, hard
links, etc.) do not apply to CMake - it is easy to build CMake on a
single machine. CMake also does not install any header files which can
be consumed by other projects (though cmCPluginAPI.h has been
deliberately omitted from this conversion in case anyone is still using
it.) Finally, #pragma once has been required to build CMake since at
least August 2017 (7f29bbe6 enabled server mode unconditionally, which
had been using #pragma once since September 2016 (b13d3e0d)). The fact
that we now require C++11 filters out old compilers, and it is unlikely
that there is a compiler which supports C++11 but does not support
#pragma once.

Source/CPack/IFW/cmCPackIFWCommon.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackIFWCommon_h
-#define cmCPackIFWCommon_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -77,5 +76,3 @@ protected:
                              cmCPackLog_msg.str().c_str());                   \
     }                                                                         \
   } while (false)
-
-#endif // cmCPackIFWCommon_h

Source/CPack/IFW/cmCPackIFWGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackIFWGenerator_h
-#define cmCPackIFWGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -152,5 +151,3 @@ private:
   std::vector<std::string> PkgsDirsVector;
   std::vector<std::string> RepoDirsVector;
 };
-
-#endif

Source/CPack/IFW/cmCPackIFWInstaller.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackIFWInstaller_h
-#define cmCPackIFWInstaller_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -132,5 +131,3 @@ protected:
   void printSkippedOptionWarning(const std::string& optionName,
                                  const std::string& optionValue);
 };
-
-#endif // cmCPackIFWInstaller_h

Source/CPack/IFW/cmCPackIFWPackage.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackIFWPackage_h
-#define cmCPackIFWPackage_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -149,5 +148,3 @@ public:
   // Patch to package directory
   std::string Directory;
 };
-
-#endif // cmCPackIFWPackage_h

Source/CPack/IFW/cmCPackIFWRepository.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackIFWRepository_h
-#define cmCPackIFWRepository_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -84,5 +83,3 @@ public:
   RepositoriesVector RepositoryUpdate;
   std::string Directory;
 };
-
-#endif // cmCPackIFWRepository_h

Source/CPack/WiX/cmCMakeToWixPath.h

@@ -1,12 +1,9 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCMakeToWixPath_h
-#define cmCMakeToWixPath_h
+#pragma once
 
 #include "cmConfigure.h" //IWYU pragma: keep
 
 #include <string>
 
 std::string CMakeToWixPath(const std::string& cygpath);
-
-#endif // cmCMakeToWixPath_h

Source/CPack/WiX/cmCPackWIXGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackWIXGenerator_h
-#define cmCPackWIXGenerator_h
+#pragma once
 
 #include <map>
 #include <memory>
@@ -171,5 +170,3 @@ private:
 
   cmWIXSourceWriter::GuidType ComponentGuidType;
 };
-
-#endif

Source/CPack/WiX/cmWIXAccessControlList.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmWIXAccessControlList_h
-#define cmWIXAccessControlList_h
+#pragma once
 
 #include "cmCPackLog.h"
 #include "cmInstalledFile.h"
@@ -29,5 +28,3 @@ private:
   cmInstalledFile const& InstalledFile;
   cmWIXSourceWriter& SourceWriter;
 };
-
-#endif

Source/CPack/WiX/cmWIXDirectoriesSourceWriter.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmWIXDirectoriesSourceWriter_h
-#define cmWIXDirectoriesSourceWriter_h
+#pragma once
 
 #include <string>
 
@@ -29,5 +28,3 @@ public:
 
   void EndInstallationPrefixDirectory(size_t size);
 };
-
-#endif

Source/CPack/WiX/cmWIXFeaturesSourceWriter.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmWIXFeaturesSourceWriter_h
-#define cmWIXFeaturesSourceWriter_h
+#pragma once
 
 #include "cmCPackGenerator.h"
 #include "cmWIXPatch.h"
@@ -27,5 +26,3 @@ public:
 
   void EmitComponentRef(std::string const& id);
 };
-
-#endif

Source/CPack/WiX/cmWIXFilesSourceWriter.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmWIXFilesSourceWriter_h
-#define cmWIXFilesSourceWriter_h
+#pragma once
 
 #include "cmCPackGenerator.h"
 #include "cmWIXPatch.h"
@@ -37,5 +36,3 @@ public:
                                 std::string const& filePath, cmWIXPatch& patch,
                                 cmInstalledFile const* installedFile);
 };
-
-#endif

Source/CPack/WiX/cmWIXPatch.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmWIXPatch_h
-#define cmWIXPatch_h
+#pragma once
 
 #include <string>
 
@@ -33,5 +32,3 @@ private:
 
   cmWIXPatchParser::fragment_map_t Fragments;
 };
-
-#endif

Source/CPack/WiX/cmWIXPatchParser.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackWIXPatchParser_h
-#define cmCPackWIXPatchParser_h
+#pragma once
 
 #include <map>
 #include <memory>
@@ -91,5 +90,3 @@ private:
 
   std::vector<cmWIXPatchElement*> ElementStack;
 };
-
-#endif

Source/CPack/WiX/cmWIXRichTextFormatWriter.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmWIXRichTextFormatWriter_h
-#define cmWIXRichTextFormatWriter_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -42,5 +41,3 @@ private:
 
   cmsys::ofstream File;
 };
-
-#endif

Source/CPack/WiX/cmWIXShortcut.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmWIXShortcut_h
-#define cmWIXShortcut_h
+#pragma once
 
 #include <map>
 #include <set>
@@ -56,5 +55,3 @@ private:
   shortcut_type_map_t Shortcuts;
   shortcut_id_map_t EmptyIdMap;
 };
-
-#endif

Source/CPack/WiX/cmWIXSourceWriter.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmWIXSourceWriter_h
-#define cmWIXSourceWriter_h
+#pragma once
 
 #include <string>
 #include <vector>
@@ -76,5 +75,3 @@ private:
 
   GuidType ComponentGuidType;
 };
-
-#endif

Source/CPack/cmCPackArchiveGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackArchiveGenerator_h
-#define cmCPackArchiveGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -93,5 +92,3 @@ private:
   std::string ArchiveFormat;
   std::string OutputExtension;
 };
-
-#endif

Source/CPack/cmCPackBundleGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackBundleGenerator_h
-#define cmCPackBundleGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -33,5 +32,3 @@ protected:
 
   std::string InstallPrefix;
 };
-
-#endif

Source/CPack/cmCPackComponentGroup.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackComponentGroup_h
-#define cmCPackComponentGroup_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -167,5 +166,3 @@ public:
   /// The list of components.
   std::vector<cmCPackComponent*> Components;
 };
-
-#endif

Source/CPack/cmCPackCygwinBinaryGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackCygwinBinaryGenerator_h
-#define cmCPackCygwinBinaryGenerator_h
+#pragma once
 
 #include "cmCPackArchiveGenerator.h"
 
@@ -25,5 +24,3 @@ protected:
   virtual const char* GetOutputExtension();
   std::string OutputExtension;
 };
-
-#endif

Source/CPack/cmCPackCygwinSourceGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackCygwinSourceGenerator_h
-#define cmCPackCygwinSourceGenerator_h
+#pragma once
 
 #include "cmCPackArchiveGenerator.h"
 
@@ -27,5 +26,3 @@ protected:
   std::string InstallPrefix;
   std::string OutputExtension;
 };
-
-#endif

Source/CPack/cmCPackDebGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackDebGenerator_h
-#define cmCPackDebGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -69,5 +68,3 @@ private:
 
   std::vector<std::string> packageFiles;
 };
-
-#endif

Source/CPack/cmCPackDragNDropGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackDragNDropGenerator_h
-#define cmCPackDragNDropGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -81,5 +80,3 @@ private:
   bool BreakLongLine(const std::string& line, std::vector<std::string>& lines,
                      std::string* error);
 };
-
-#endif

Source/CPack/cmCPackExternalGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackExternalGenerator_h
-#define cmCPackExternalGenerator_h
+#pragma once
 
 #include <memory>
 #include <string>
@@ -86,5 +85,3 @@ private:
 
   std::unique_ptr<cmCPackExternalVersionGenerator> Generator;
 };
-
-#endif

Source/CPack/cmCPackFreeBSDGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackFreeBSDGenerator_h
-#define cmCPackFreeBSDGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -33,5 +32,3 @@ protected:
   std::string var_lookup(const char* var_name);
   void write_manifest_fields(cmGeneratedFileStream&);
 };
-
-#endif

Source/CPack/cmCPackGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackGenerator_h
-#define cmCPackGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -339,5 +338,3 @@ protected:
     this->Logger->Log(logType, __FILE__, __LINE__,                            \
                       cmCPackLog_msg.str().c_str());                          \
   } while (false)
-
-#endif

Source/CPack/cmCPackGeneratorFactory.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackGeneratorFactory_h
-#define cmCPackGeneratorFactory_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -44,5 +43,3 @@ private:
   DescriptionsMap GeneratorDescriptions;
   cmCPackLog* Logger;
 };
-
-#endif

Source/CPack/cmCPackLog.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackLog_h
-#define cmCPackLog_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -139,5 +138,3 @@ inline std::ostream& operator<<(std::ostream& os, const cmCPackLogWrite& c)
   os.flush();
   return os;
 }
-
-#endif

Source/CPack/cmCPackNSISGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackNSISGenerator_h
-#define cmCPackNSISGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -85,5 +84,3 @@ protected:
 
   bool Nsis64;
 };
-
-#endif

Source/CPack/cmCPackNuGetGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackNuGetGenerator_h
-#define cmCPackNuGetGenerator_h
+#pragma once
 
 #include "cmCPackGenerator.h"
 
@@ -33,5 +32,3 @@ protected:
    */
   void AddGeneratedPackageNames();
 };
-
-#endif

Source/CPack/cmCPackOSXX11Generator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackOSXX11Generator_h
-#define cmCPackOSXX11Generator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -38,5 +37,3 @@ protected:
                              bool copyOnly = false);
   std::string InstallPrefix;
 };
-
-#endif

Source/CPack/cmCPackPKGGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackPKGGenerator_h
-#define cmCPackPKGGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -94,5 +93,3 @@ protected:
   // The PostFlight component when creating a metapackage
   cmCPackComponent PostFlightComponent;
 };
-
-#endif

Source/CPack/cmCPackPackageMakerGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackPackageMakerGenerator_h
-#define cmCPackPackageMakerGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -49,5 +48,3 @@ protected:
   double PackageMakerVersion;
   unsigned int PackageCompatibilityVersion;
 };
-
-#endif

Source/CPack/cmCPackProductBuildGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackProductBuildGenerator_h
-#define cmCPackProductBuildGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -49,5 +48,3 @@ protected:
   const char* GetComponentScript(const char* script,
                                  const char* script_component);
 };
-
-#endif

Source/CPack/cmCPackRPMGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackRPMGenerator_h
-#define cmCPackRPMGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -68,5 +67,3 @@ protected:
 
   void AddGeneratedPackageNames();
 };
-
-#endif

Source/CPack/cmCPackSTGZGenerator.h

@@ -1,7 +1,6 @@
 /* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
    file Copyright.txt or https://cmake.org/licensing for details.  */
-#ifndef cmCPackSTGZGenerator_h
-#define cmCPackSTGZGenerator_h
+#pragma once
 
 #include "cmConfigure.h" // IWYU pragma: keep
 
@@ -30,5 +29,3 @@ protected:
   int InitializeInternal() override;
   int GenerateHeader(std::ostream* os) override;
 };
-
-#endif