From: Luc Grosheintz <luc.grosheintz@gmail.com>
Date: Mon, 8 Dec 2025 20:23:40 +0000 (+0100)
Subject: libstdc++: Silence warning in mdspan.
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=64d5e1eb97f198c9377c393d648c8db2617a80d0;p=thirdparty%2Fgcc.git

libstdc++: Silence warning in mdspan.

Splitting the tests for submdspan triggered a compiler warning. This
commit changes the implementation of __dynamic_extents. In particular,
how the span is created. Functionally, the two are equivalent.

libstdc++-v3/ChangeLog:

	* include/std/mdspan (_ExtentsStorage::_M_dynamic_extents):
	Create span from pointer + size, not begin and end iterators.

Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>
Signed-off-by: Luc Grosheintz <luc.grosheintz@gmail.com>
---

diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan
index 981fa1c601a..f0f6630b472 100644
--- a/libstdc++-v3/include/std/mdspan
+++ b/libstdc++-v3/include/std/mdspan
@@ -271,7 +271,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	requires (_Extents.size() > 0)
 	{
 	  return {_M_dyn_exts + _S_dynamic_index(__begin),
-		  _M_dyn_exts + _S_dynamic_index(__end)};
+		  _S_dynamic_index(__end) - _S_dynamic_index(__begin)};
 	}
 
       private: