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* gcc-wwwdocs branch master updated. 9b8a31d640d1c508be86637b6d82fcabf4d31590
@ 2023-03-19  7:46 Thomas Kテカnig
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From: Thomas Kテカnig @ 2023-03-19  7:46 UTC (permalink / raw)
  To: gcc-cvs-wwwdocs

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- Log -----------------------------------------------------------------
commit 9b8a31d640d1c508be86637b6d82fcabf4d31590
Author: Thomas Koenig <tkoenig@gcc.gnu.org>
Date:   Sun Mar 19 08:43:15 2023 +0100

    Fix "doesn't"; add chapter on integer overflow for Fortran.
    
    Removed stuff.

diff --git a/htdocs/gcc-13/porting_to.html b/htdocs/gcc-13/porting_to.html
index 0ee58802..db0bf2fa 100644
--- a/htdocs/gcc-13/porting_to.html
+++ b/htdocs/gcc-13/porting_to.html
@@ -203,11 +203,27 @@ class Alloc
 <p>
 Since C++20, there is no <code>rebind</code> member in
 <code>std::allocator</code>, so deriving your own allocator types from
-<code>std::allocator</code> is simpler and doesn't require the derived
+<code>std::allocator</code> is simpler and does not require the derived
 allocator to provide its own <code>rebind</code>.
 For compatibility with previous C++ standards, the member should still be
 provided. The converting constructor is still required even in C++20.
 </p>
 
+<h2 id="fortran">Fortran language issues</h2>
+<h3 id="overflow">Behavior on integer overflow</h3>
+<p>
+GCC 13 includes new optimizations which may change behavior on
+integer overflow.  Traditional code, like linear congruential
+pseudo-random number generators in old programs and relying on a
+specific, non-standard behavior may now generate unexpected results.
+The option <code>-fsanitize=undefined</code> can be used to detect
+such code at runtime.
+</p>
+<p>
+It is recommended to use the intrinsic subroutine
+<code>RANDOM_NUMBER</code> for random number generators
+or, if the old behavior is desired, to use the <code>-fwrapv</code>
+option.  Note that this option can impact performance.
+</p>
 </body>
 </html>

-----------------------------------------------------------------------

Summary of changes:
 htdocs/gcc-13/porting_to.html | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)


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