commit f4486389b87b1758caffe4621ed45754e698fa47
author Rian Quinn <rianquinn@gmail.com> Fri Oct 28 00:45:54 2016 -0600
committer Neil MacIntosh <neilmac@microsoft.com> Thu Oct 27 23:45:54 2016 -0700
tree 58c9c3b6c5838d9f02a7b31cc0401cc006e48e52
parent 6cffe0d14cbc0540e16939aaffbee3451fa0a131

Fix overflow found by GCC in basic_zstring_span::as_string_span().

This patch fixes an overflow that was identified with
strict overflow warnings enabled, and optimizations
turned on

Signed-off-by: “Rian <“rianquinn@gmail.com”>

gsl/string_span

diff --git a/gsl/string_span b/gsl/string_span
index fb943dc..703bc01 100644
--- a/gsl/string_span
+++ b/gsl/string_span
@@ -554,7 +554,8 @@
 
     constexpr string_span_type as_string_span() const noexcept
     {
-        return span_.first(span_.size() - 1);
+        auto sz = span_.size();
+        return span_.first(sz <= 0 ? 0 : sz - 1);
     }
 
     constexpr string_span_type ensure_z() const noexcept { return gsl::ensure_z(span_); }