Fix C++26 invalid enum operation

[CrackedMatter]

ImGui version: 1.91.1

ImGui fails to compile on C++26 (Clang) with the following error:

imgui_widgets.cpp:5199:62: error: invalid bitwise operation between different enumeration types ('ImGuiItemFlagsPrivate_' and 'ImGuiItemFlags_')
 5199 |         g.NextItemData.ItemFlags |= ImGuiItemFlags_Inputable | ImGuiItemFlags_NoTabStop;
      |                                     ~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~

Adding a cast fixes the error.

Related to #7383.

[ocornut]

Thank you. I ought to add this test to my local build scripts.

[ocornut]

FYI I tried the command-line from #7383 (comment) and even with this couldn't trigger the warning.

# clang-cl -v
clang version 17.0.3
Target: x86_64-pc-windows-msvc
Thread model: posix
InstalledDir: C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\Llvm\x64\bin

So even though I have a local build file it doesn't repro this. I assume it might need Clang 19 but that's not avail from VS yet

[nicolasnoble]

Clang-18 is available on Ubuntu 24.04, and I can see clang-19 on debian sid. It might be a good idea to bump and/or add ubuntu 24.04 to the CI, since it's the new LTS, but this wouldn't pick up clang-19 there, and I'm not sure trying to use Debian testing or unstable would be a good idea.

[ocornut]

I upgraded to Ubuntu 24.04 now but it seems GCC there supports up to C++20.
I added a C++20 build to Linux GCC and MacOS Clang, and a C++26 to Linux Clang.

[CrackedMatter]

$ ./clang -v
Android (12027248, +pgo, +bolt, +lto, +mlgo, based on r522817) clang version 18.0.1 (https://android.googlesource.com/toolchain/llvm-project d8003a456d14a3deb8054cdaa529ffbf02d9b262)
Target: x86_64-unknown-linux-gnu
Thread model: posix