GCC 14: No match for operator= for Givaro::ZRing<Givaro::Integer>

[musicinmybrain]

When compiling givaro with GCC 14.0.1 (as now packaged in Fedora Rawhide, the development version of Fedora Linux), I see the following regression:

givaro/givaro/givaro/random-integer.h: In member function 'Givaro::RandomIntegerIterator<_Unsigned, _Exact_Size>& Givaro::RandomIntegerIterator<_Unsigned, _Exact_Size>::operator=(const Givaro::RandomIntegerIterator<_Unsigned, _Exact_Size>&)':
givaro/givaro/givaro/random-integer.h:90:54: error: no match for 'operator=' (operand types are 'Givaro::RandomIntegerIterator<_Unsigned, _Exact_Size>::Integer_Domain' {aka 'Givaro::ZRing<Givaro::Integer>'} and 'const Givaro::RandomIntegerIterator<_Unsigned, _Exact_Size>::Integer_Domain' {aka 'const Givaro::ZRing<Givaro::Integer>'})
   90 |                 const_cast<Integer_Domain&>(_ring)=R._ring;
      |                                                      ^~~~~

I initially observed this with givaro 4.2.0, but I can also reproduce it with current master, a6b3708.

I would be happy to offer a PR, but I haven’t figured out what the correct fix is.

[jgdumas]

Hello, thank you for the report.
I can reproduce this indeed with g++-14.
It is not clear to me yet why this is happening, I'll investigate ...

In the meantime, a simple patch is just to remove the line !
(the line is there for (future) genericity, but for all current usage it just assigns an empty object to another empty object !)

[musicinmybrain]

Thanks! The following workaround does appear to be effective:

From 20caba1b549fe46b483f120f8eec6ec4e9f4572d Mon Sep 17 00:00:00 2001
From: "Benjamin A. Beasley" <code@musicinmybrain.net>
Date: Thu, 25 Jan 2024 08:29:17 -0500
Subject: [PATCH] Temporary GCC 14 workaround
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Fixes https://github.com/linbox-team/givaro/issues/226 “GCC 14: No match
for operator= for Givaro::ZRing<Givaro::Integer>”

Recommended in
https://github.com/linbox-team/givaro/issues/226#issuecomment-1908853755
---
 src/kernel/integer/random-integer.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/kernel/integer/random-integer.h b/src/kernel/integer/random-integer.h
index f9361d33..ea189a36 100644
--- a/src/kernel/integer/random-integer.h
+++ b/src/kernel/integer/random-integer.h
@@ -87,7 +87,6 @@ namespace Givaro
             if (this != &R) {
                 _bits = R._bits;
                 _integer = R._integer;
-                const_cast<Integer_Domain&>(_ring)=R._ring;
             }
             return *this;
         }
-- 
2.43.0

[jgdumas]

OK. The reference to a singleton element should not be copied.
Patch is thus now within commit b0cf33e.
And givaro compiles completely with g++-14 for me

[musicinmybrain]

Thanks!