disablewarnings is not handled correctly in visual studio with clang-cl

[luxploit]

What seems to be the problem?
When using toolset "clang", which will use clang-cl under VS, Premake incorrectly generates the arguments for disablewarnings. It generates with -Wno-[number] instead of /wd[number], which are only supported in clang-cl for clang specific options via the /clang: flag (eg. /clang:-Wno-c99-designator).

Seems to been introduced in this PR here: #2529

What did you expect to happen?
It should have generated: /wd28251 /wd4996 /wd4800 for the input disablewarnings { "28251", "4996", "4800" }, but instead generates -Wno-28251 -Wno-4996 -Wno-4800

Currently the workaround involves issuing the correct option via buildoptions like so:

filter "toolset:clang"
	buildoptions { "/wd28251", "/wd4996", "/wd4800" }
filter {}

Minimal example:

premake5.lua

workspace "test"
configurations { "Debug" }
platforms { "x64" }

filter "configurations:Debug"
	defines { "_DEBUG" }
	symbols "On"
filter {}

enablepch "Off"
multiprocessorcompile "On"

disablewarnings { "28251", "4996", "4800" }

project "testapp1"
	location "src"
	kind "ConsoleApp"
	toolset "clang"
	files { "src/**.hpp", "src/**.cpp" }

main.cpp

#include <stdio.h>

int main() {
   printf("hallo :)");
   return 0;
}

Tested with:

• Visual Studio 2026 (vs2026)
• Visual Studio 2022 (vs2022)

What version of Premake are you using?

PS C:\Users\Laura> premake5 --version
premake5 (Premake Build Script Generator) 5.0.0-beta8

[Jarod42]

My test case is https://github.com/Jarod42/premake-sample-projects/blob/master/projects/disablewarnings/premake5.lua, i.e.

filter "toolset:msc*"
	disablewarnings {
		"4035", -- '%function': no return value
		"4716", -- '%function': must return a value			
	}
filter "toolset:not msc*"
	disablewarnings {
		"return-type"
	}
filter {}

disablewarnings has to be protected by filtering as toolsets use different values.
Filtering on action is also possible though.
Unsure how to indicate to vs action if warning is in visual format (number) or gcc format (text) cleanly.
We can indeed use the fact that we have number vs text, but it looks like a hack...

[luxploit]

since clang only supports the named warnings only via the /clang flag in clang-cl, maybe check if it's a VS action and if the toolset is clang and the warning is an integer use /wd, else use /clang:-Wno- ? msvc doesn't support named warnings so it should be a decently okay solution.

[Jarod42]

Currently the workaround involves issuing the correct option via buildoptions like so:

filter "toolset:clang"
	buildoptions { "/wd28251", "/wd4996", "/wd4800" }
filter {}

I tried to use /wd4035 /wd4716 with visual studio with clang, but it got simply ignored (i.e. warning is still emit).
So the workaround seems to not work.

Filtering by toolset works and is not a workaround.