compile_flags plugin is too selective when filtering flags

[MinekPo1]

Xmake Version

v2.9.3+HEAD.a5da06f

Operating System Version and Architecture

GNU/Linux 6.8.0-35-generic Ubuntu+KDE Plasma

Describe Bug

the compile_flags plugin is too selective when filtering through flags resulting in important flags being excluded

Expected Behavior

All flags which control C or C++ (gcc's list, clang's documentation including flags but not in a nice list like gcc unfortunately, msvc's list) are included in the compile_flags.txt file.

Actual Behavior

Only flags beginning with -I, /I, -isystem or -D are included.

Project Configuration

add_cxxflags("-std=c++23")

Additional Information and Error Logs

N/A

[waruqi]

? I don't know what you mean. and what is your problem?

[MinekPo1]

Oh sorry, I didn't realize that it was unclear!

I've provided files to reproduce the issue here, but in short, the -std=c++23 flag is not written to compile_flags.txt as I feel it should be, which causes tools using the file to report issues which don't come up when building with xmake.

As another example, see msvc's /await flag, which if omitted can cause tooling using compile_flags.txt to possibly not be aware that using corutines is okay and raise syntax errors (not sure if any tooling that exists would use that flag and use compile_flags.txt tbh but oh well).

[SirLynix]

It looks like it's on purpose:

xmake/xmake/plugins/project/clang/compile_flags.lua

Lines 32 to 41 in 5d982b9

	-- get compile arguments
	local arguments = compiler.compflags(sourcefile, {target = target})
	for i, flag in ipairs(arguments) do
	-- only export the -I*/-D* flags
	if flag == "-I" or flag == "/I" or flag == "-isystem" then
	table.insert(flags, flag .. arguments[i + 1])
	elseif flag:find('^-[ID]') or flag:find("-isystem", 1, true) then
	table.insert(flags, flag)
	end
	end

I didn't know about compile_flags, what's the difference with compile_commands?

[waruqi]

The implementation of compile_flags is very old and many rule scripts are not implemented. As a result, some flags are missing.

We need some time to do some refactoring to improve it.