Help/dev: Adopt C++ subset rules in coding guide

Move the C++ subset rules from the `cmake-developer(7)` into our
dedicated coding guide since they do not need to be in user-facing
documentation.

Help/dev/source.rst

@@ -19,3 +19,24 @@ format only a subset of files, such as those that are locally modified.
 .. _`clang-format`: http://clang.llvm.org/docs/ClangFormat.html
 .. _`.clang-format`: ../../.clang-format
 .. _`Utilities/Scripts/clang-format.bash`: ../../Utilities/Scripts/clang-format.bash
+
+C++ Subset Permitted
+====================
+
+CMake supports compiling as C++98 in addition to C++11 and C++14.
+In order to support building on older toolchains some constructs
+need to be handled with care:
+
+* Use ``CM_AUTO_PTR`` instead of ``std::auto_ptr``.
+
+  The ``std::auto_ptr`` template is deprecated in C++11.  We want to use it
+  so we can build on C++98 compilers but we do not want to turn off compiler
+  warnings about deprecated interfaces in general.  Use the ``CM_AUTO_PTR``
+  macro instead.
+
+* Use ``size_t`` instead of ``std::size_t``.
+
+  Various implementations have differing implementation of ``size_t``.
+  When assigning the result of ``.size()`` on a container for example,
+  the result should be assigned to ``size_t`` not to ``std::size_t``,
+  ``unsigned int`` or similar types.

Help/manual/cmake-developer.7.rst

@@ -13,30 +13,6 @@ Introduction
 This manual is intended for reference by developers modifying the CMake
 source tree itself, and by those authoring externally-maintained modules.
 
-
-Permitted C++ Subset
-====================
-
-CMake is required to build with ancient C++ compilers and standard library
-implementations.  Some common C++ constructs may not be used in CMake in order
-to build with such toolchains.
-
-std::auto_ptr
--------------
-
-The ``std::auto_ptr`` template is deprecated in C++11.  We want to use it
-so we can build on C++98 compilers but we do not want to turn off compiler
-warnings about deprecated interfaces in general.  Use the ``CM_AUTO_PTR``
-macro instead.
-
-size_t
-------
-
-Various implementations have differing implementation of ``size_t``.  When
-assigning the result of ``.size()`` on a container for example, the result
-should be assigned to ``size_t`` not to ``std::size_t``, ``unsigned int`` or
-similar types.
-
 Adding Compile Features
 =======================