libstdc++: Setup internal FTM for mdspan.

Uses the FTM infrastructure to create an internal feature testing macro
for partial availability of mdspan; which is then used to hide the
contents of the header mdspan when compiling against a standard prior to
C++23.

libstdc++-v3/ChangeLog:

	* include/bits/version.def: Add internal feature testing macro
	__glibcxx_mdspan.
	* include/bits/version.h: Regenerate.

Signed-off-by: Luc Grosheintz <luc.grosheintz@gmail.com>

diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def
index 282667eabda61f01a80888b749ce81a0148769c1..f4d3de88bb2ba48e829920edb467704279195560 100644 (file)
--- a/libstdc++-v3/include/bits/version.def
+++ b/libstdc++-v3/include/bits/version.def
@@ -999,6 +999,15 @@ ftms = {
   };
 };
 
+ftms = {
+  name = mdspan;
+  no_stdname = true; // FIXME: remove
+  values = {
+    v = 1; // FIXME: 202207
+    cxxmin = 23;
+  };
+};
+
 ftms = {
   name = ssize;
   values = {

diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h
index bb7c0479c7235db0a810526ef43a1e7cb240a923..d5d75cef2de14b5a58f5d844f62d9b21833816dc 100644 (file)
--- a/libstdc++-v3/include/bits/version.h
+++ b/libstdc++-v3/include/bits/version.h
@@ -1114,6 +1114,15 @@
 #endif /* !defined(__cpp_lib_span) && defined(__glibcxx_want_span) */
 #undef __glibcxx_want_span
 
+#if !defined(__cpp_lib_mdspan)
+# if (__cplusplus >= 202100L)
+#  define __glibcxx_mdspan 1L
+#  if defined(__glibcxx_want_all) || defined(__glibcxx_want_mdspan)
+#  endif
+# endif
+#endif /* !defined(__cpp_lib_mdspan) && defined(__glibcxx_want_mdspan) */
+#undef __glibcxx_want_mdspan
+
 #if !defined(__cpp_lib_ssize)
 # if (__cplusplus >= 202002L)
 #  define __glibcxx_ssize 201902L