| 25 Nov 2025 |
 samasaur | i would be pretty surprised if it was something in nix-darwin | 02:20:11 |
| samasaur | perhaps it's a different thing you're using? buildEnv has some use cases in package definitions as well | 02:20:38 |
 megmug | Download shell.nix | 10:44:01 |
| megmug | Hello there, is it expected on a semi recent nixpkgs unstable commit, to have system libraries like iostream unavaillable on MacOS? I've been struggling getting a Linux project to build with a basic nix-shell that tries to use the clangStdenv | 10:44:24 |
| megmug | I'm thinking I'm probably doing something wrong but I can't find a lot of info on the web | 10:45:06 |
| megmug | I'm trying to compile a simple module like this, and I just can't get it to find iostream | 10:48:00 |
| megmug | Download cli.cppm | 10:48:10 |
 K900 | I don't think we really have C++ modules working | 10:55:30 |
| K900 | On any of the compilers | 10:55:37 |
| K900 | It needs some cc-wrapper fixing but nothing uses them or can agree on how to use them | 10:55:53 |
| K900 | So no one did the work | 10:56:13 |
| megmug | Ok, so it's probably an interaction with the modules? Without modules, it should work? | 10:56:38 |
| K900 | Yes | 10:56:58 |
| megmug | That would help since the project is early anyways, can go back to headers still | 10:57:01 |
| megmug | Thank you! | 10:57:16 |
| megmug | It's interesting though that it already works on linux | 10:57:26 |
| megmug | Also, it didn't fail immediately - the same module using stdio.h + printf works on macos | 10:58:55 |
 Randy Eckenrode | C++ modules support is fixed on staging. | 11:32:05 |
| Randy Eckenrode | https://github.com/NixOS/nixpkgs/pull/462747 | 11:32:44 |
| Randy Eckenrode | A change was made to fix clang foo.cpp that broke clang-scan-deps, which CMake uses for module support. | 11:33:50 |
| Randy Eckenrode | It had to be ported to the clang-tools wrapper, which would have gone to master if not for the large number of Linux rebuilds it caused. | 11:34:43 |
| megmug | Aha - could this possibly affect non-module projects as well then? Because I am still getting errors despite removing all the modules. clang-scan-deps fails to find some stuff (on macos). | 11:37:28 |
| Randy Eckenrode | If it uses clang-scan-deps, it will be broken. | 11:39:02 |
| Randy Eckenrode | Also clangd. | 11:39:10 |
| Randy Eckenrode | You may be able to work around it by setting env.NIX_CFLAGS_COMPILE to -isystem ${stdenv.cc.libcxx}. | 11:42:42 |
| Randy Eckenrode | * You may be able to work around it by setting env.NIX_CFLAGS_COMPILE to -isystem ${stdenv.cc.libcxx}/include/c++/v1. | 11:43:01 |
| Randy Eckenrode | (Path from memory, so may be off.) | 11:43:14 |
| megmug | Hm, or just build the nix-shell on a different version maybe? Is the change already on master branch? Or can i go back far enough to get a version that didn't have the problem? | 11:44:38 |
| Randy Eckenrode | It’s on staging. It won’t make it to master until mid-December probably. | 11:47:04 |
| Randy Eckenrode | If you use staging, you’ll have to do a stdenv bootstrap and build everything from source. | 11:47:43 |
