Eclipse unable to recognize stdatomic and related symbols

[sunnynarula]

Describe the bug
Eclipse fails to recognize paths and symbols associated with stdatomic, atomic keywords etc

To Reproduce
Steps to reproduce the behavior:

1. Create a c project, "C Managed Build"
2. Select Executable/Empty Project/Linux GCC
3. For project name give name Test
4. Go to project properties and under C/C++ Build/Settings, under GCC C Compiler/Dialect Select language standard ISO C11( -std=c11)
5. Create a source file Test.c with the following contents:
   struct TestStruct {
   _Atomic int testName;
   };

int main() {
return 0;
}

6. Build the project and verify it compiles without error
   Build Finished. 0 errors, 0 warnings.
7. Note the error:Even though gcc gives back no errors eclipse shows error under the _Atomic keyword with text "Syntax error"

Expected behavior
Eclipse should not be showing this error

Screenshots

Version Information (please complete the following information):

• OS and OS Version/extra details: Ubuntu 24.04.1 LTS updated based on latest available updated as of today 22 Nov 2024 with gcc version 13.2.0
• Eclipse Version from Help -> About : Eclipse IDE for C/C++ Developers (includes Incubating components)
  Version: 2024-06 (4.32.0)
  Build id: 20240606-1231
• CDT Version from Help -> About -> Installation Details -> Features tab : Eclipse CDT Eclipse C/C++ Development Tools 11.6.0.202406041555 org.eclipse.cdt

Additional context
The problem goes beyond this and possibly spans to using newer C11 features like stdatomic , since I am unaware of how CDT is designed, I am unable to understand how to get around it. I have only reported issue for features I have gotten around to using on my current project. For now I am turning off/ignoring the errors, but I am worried this will turn of analysis where the errors are genuine in the source. I tried to resolve the issues by trying to add indexing path entries etc but none of the solutions available on the internet work.

[gr1mpatr0n]

Unfortunately C11 atomics support in IDEs and LSPs seems to be a pretty widespread problem (I just opened an equivalent issue under JetBrains' CLion for example). It's almost certainly a clangd issue, assuming you're using that, and even if you do manage to get it working, if you're using anything other than clang's stdatomic.h, you will end up with warnings as GCC passes a copy of the atomic pointer argument which clang doesn't do (see llvm/llvm-project#60572).

I don't even want to know how much chaos trying to use MSVC would cause...

IMO this is a problem with using clangd as a catch-all LSP - it really only cares about clang/LLVM.

[gr1mpatr0n]

As an aside though, you should probably just be using atomic_int which will be typedef'd to _Atomic int. Not saying it will fix your problem, but it will at least defer it to the libc layer.