-Wtemplate-id-cdtor compilation warnings with GCC 14

[akien-mga]

Tested versions

• Reproducible in 4.3.dev (86bf835)
• Likely affects earlier branches too so the fix should be cherry-picked

System information

Fedora Linux 40 (KDE Plasma) - Wayland - Vulkan (Forward+) - dedicated AMD Radeon RX 7600M XT (RADV NAVI33) () - AMD Ryzen 7 7840HS w/ Radeon 780M Graphics (16 Threads)

Issue description

I just upgraded to Fedora 40 which provides GCC 14.0.1 (RC version).

This version started raising a new type of warning:

warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]

We don't compile with C++20 yet (@Repiteo is working on supporting it in #89660), but it seems like GCC made this a warning for earlier versions of the standard anyway.

Here are the affected files from a Linux editor dev build:

./core/templates/safe_refcount.h:149:49: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
  149 |         _ALWAYS_INLINE_ explicit SafeNumeric<T>(T p_value = static_cast<T>(0)) {
      |                                                 ^
./core/templates/safe_refcount.h:149:49: note: remove the '< >'

./core/templates/ring_buffer.h:214:22: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
  214 |         RingBuffer<T>(int p_power = 0) {
      |                      ^
./core/templates/ring_buffer.h:214:22: note: remove the '< >'
./core/templates/ring_buffer.h:217:9: warning: template-id not allowed for destructor in C++20 [-Wtemplate-id-cdtor]
  217 |         ~RingBuffer<T>() {}
      |         ^
./core/templates/ring_buffer.h:217:9: note: remove the '< >'

thirdparty/clipper2/include/clipper2/clipper.core.h:183:22: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
  183 |     explicit Point<T>(const Point<T2>& p) { Init(p.x, p.y); }
      |                      ^
thirdparty/clipper2/include/clipper2/clipper.core.h:183:22: note: remove the '< >'

Workaround for affected users:

• Either build with werror=no
• Or add cxxflags="-Wno-error=template-id-cdtor" to your scons command

Steps to reproduce

• scons dev_build=yes dev_mode=yes

Minimal reproduction project (MRP)

n/a