cmstd: Modernize CMake system headers

Provide a standardized way to handle the C++ "standard" headers
customized to be used with current CMake C++ standard constraints.
Offer under directory `cm` headers which can be used as direct
replacements of the standard ones.  For example:

    #include <cm/string_view>

can be used safely for CMake development in place of the `<string_view>`
standard header.

Fixes: #19491

8 files changed, 15 insertions, 8 deletions

diff --git a/Source/CPack/WiX/cmCPackWIXGenerator.cxx b/Source/CPack/WiX/cmCPackWIXGenerator.cxx
index f784832..683f275 100644
--- a/Source/CPack/WiX/cmCPackWIXGenerator.cxx
+++ b/Source/CPack/WiX/cmCPackWIXGenerator.cxx
@@ -11,8 +11,9 @@
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
 #include "cmUuid.h"
-#include "cm_string_view.hxx"
+
 #include <algorithm>
+#include <cm/string_view>
 
 #include "cmWIXDirectoriesSourceWriter.h"
 #include "cmWIXFeaturesSourceWriter.h"
diff --git a/Source/CPack/WiX/cmWIXFilesSourceWriter.cxx b/Source/CPack/WiX/cmWIXFilesSourceWriter.cxx
index dd3caf9..7705d83 100644
--- a/Source/CPack/WiX/cmWIXFilesSourceWriter.cxx
+++ b/Source/CPack/WiX/cmWIXFilesSourceWriter.cxx
@@ -9,10 +9,10 @@
 #include "cmSystemTools.h"
 #include "cmUuid.h"
 
-#include "cm_sys_stat.h"
-
 #include "cmCMakeToWixPath.h"
 
+#include "cm_sys_stat.h"
+
 cmWIXFilesSourceWriter::cmWIXFilesSourceWriter(cmCPackLog* logger,
                                                std::string const& filename,
                                                GuidType componentGuidType)
diff --git a/Source/CPack/cmCPackDebGenerator.cxx b/Source/CPack/cmCPackDebGenerator.cxx
index 0e64b5a..4f299f7 100644
--- a/Source/CPack/cmCPackDebGenerator.cxx
+++ b/Source/CPack/cmCPackDebGenerator.cxx
@@ -10,9 +10,11 @@
 #include "cmGeneratedFileStream.h"
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
-#include "cm_sys_stat.h"
 
 #include "cmsys/Glob.hxx"
+
+#include "cm_sys_stat.h"
+
 #include <cstring>
 #include <map>
 #include <ostream>
diff --git a/Source/CPack/cmCPackExternalGenerator.cxx b/Source/CPack/cmCPackExternalGenerator.cxx
index 5dc6ace..05e5c21 100644
--- a/Source/CPack/cmCPackExternalGenerator.cxx
+++ b/Source/CPack/cmCPackExternalGenerator.cxx
@@ -17,7 +17,7 @@
 #include <utility>
 #include <vector>
 
-#include "cm_memory.hxx"
+#include <cm/memory>
 
 int cmCPackExternalGenerator::InitializeInternal()
 {
diff --git a/Source/CPack/cmCPackExternalGenerator.h b/Source/CPack/cmCPackExternalGenerator.h
index 176d6a9..b77e45b 100644
--- a/Source/CPack/cmCPackExternalGenerator.h
+++ b/Source/CPack/cmCPackExternalGenerator.h
@@ -4,6 +4,7 @@
 #define cmCPackExternalGenerator_h
 
 #include "cmCPackGenerator.h"
+
 #include "cm_sys_stat.h"
 
 #include <memory>
diff --git a/Source/CPack/cmCPackGenerator.h b/Source/CPack/cmCPackGenerator.h
index fc00b09..33026c1 100644
--- a/Source/CPack/cmCPackGenerator.h
+++ b/Source/CPack/cmCPackGenerator.h
@@ -10,9 +10,10 @@
 #include <string>
 #include <vector>
 
+#include "cm_sys_stat.h"
+
 #include "cmCPackComponentGroup.h"
 #include "cmSystemTools.h"
-#include "cm_sys_stat.h"
 
 class cmCPackLog;
 class cmGlobalGenerator;
diff --git a/Source/CPack/cmCPackOSXX11Generator.cxx b/Source/CPack/cmCPackOSXX11Generator.cxx
index 992299a..cd65694 100644
--- a/Source/CPack/cmCPackOSXX11Generator.cxx
+++ b/Source/CPack/cmCPackOSXX11Generator.cxx
@@ -4,13 +4,14 @@
 
 #include <sstream>
 
+#include "cm_sys_stat.h"
+
 #include "cmCPackGenerator.h"
 #include "cmCPackLog.h"
 #include "cmDuration.h"
 #include "cmGeneratedFileStream.h"
 #include "cmStringAlgorithms.h"
 #include "cmSystemTools.h"
-#include "cm_sys_stat.h"
 
 cmCPackOSXX11Generator::cmCPackOSXX11Generator() = default;
 
diff --git a/Source/CPack/cmCPackSTGZGenerator.cxx b/Source/CPack/cmCPackSTGZGenerator.cxx
index eb48c37..eb1e24c 100644
--- a/Source/CPack/cmCPackSTGZGenerator.cxx
+++ b/Source/CPack/cmCPackSTGZGenerator.cxx
@@ -8,11 +8,12 @@
 #include <string>
 #include <vector>
 
+#include "cm_sys_stat.h"
+
 #include "cmArchiveWrite.h"
 #include "cmCPackGenerator.h"
 #include "cmCPackLog.h"
 #include "cmSystemTools.h"
-#include "cm_sys_stat.h"
 
 cmCPackSTGZGenerator::cmCPackSTGZGenerator()
   : cmCPackArchiveGenerator(cmArchiveWrite::CompressGZip, "paxr", ".sh")