| 7 Nov 2025 |
 Mic92 | Sergei Zimmerman (xokdvium): https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/include/pstl/parallel_backend_tbb.h | 19:18:09 |
| Mic92 | yeah | 19:18:14 |
| Mic92 | Sergei Zimmerman (xokdvium): https://github.com/gcc-mirror/gcc/blob/d14d24b26126ec9c6c8ba5b2e573ed8e26347e6b/libstdc%2B%2B-v3/include/bits/c%2B%2Bconfig#L943 | 19:20:41 |
| Mic92 | we can either turn it off or we should make an explicit dependency | 19:20:56 |
 Sergei Zimmerman (xokdvium) | I guess we should just undef it yeah. We are not using parallel algorithms anywhere | 19:21:37 |
| Sergei Zimmerman (xokdvium) | ‘nix-meson-build-support/common` for this type of thing should suffice? | 19:22:37 |
| Mic92 | yeah that's what I am looking at | 19:25:01 |
| Mic92 | Still compiling but I think you were also stumbling over this? Eelco https://github.com/NixOS/nix/pull/14509 | 19:28:40 |
| Mic92 | Feels like worth a backport as well | 19:29:00 |
| Mic92 | Eelco: I wasn't able to reproduce your issue:
~/git/nix/build no-tbb
nix-util-env % gdb ./src/nix/nix
Reading symbols from ./src/nix/nix...
(gdb) bt
No stack.
(gdb) b main
rBreakpoint 1 at 0x965866: file ../src/nix/main.cc, line 563.
(gdb) r
Starting program: /home/joerg/git/nix/build/src/nix/nix
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/nix/store/g8zyryr9cr6540xsyg4avqkwgxpnwj2a-glibc-2.40-66/lib/libthread_db.so.1".
Breakpoint 1, main (argc=1, argv=0x7ffffffe9a98) at ../src/nix/main.cc:563
563 {
(gdb)
| 19:31:40 |
| Mic92 | * Eelco: I wasn't able to reproduce your issue:
~/git/nix/build no-tbb
nix-util-env % gdb ./src/nix/nix
Reading symbols from ./src/nix/nix...
(gdb) bt
No stack.
(gdb) b main
rBreakpoint 1 at 0x965866: file ../src/nix/main.cc, line 563.
(gdb) r
Starting program: /home/joerg/git/nix/build/src/nix/nix
\[Thread debugging using libthread\_db enabled\]
Using host libthread\_db library "/nix/store/g8zyryr9cr6540xsyg4avqkwgxpnwj2a-glibc-2.40-66/lib/libthread\_db.so.1".
Breakpoint 1, main (argc=1, argv=0x7ffffffe9a98) at ../src/nix/main.cc:563
563 {
(gdb)
| 19:31:50 |
| Mic92 | Sure you didn't build meson in release mode or something by accident? | 19:32:04 |
| Mic92 | This was with gcc now, didn't test clang etc | 19:33:51 |
 John Ericson | Mic92: I see the PR | 19:51:01 |
| John Ericson | so wow I thought that TBB thing had something to do with blake3 | 19:51:16 |
| John Ericson | but turns out it is unrelated? | 19:51:20 |
| John Ericson | is libstc++ doing some has_include trickier by anychance? | 19:51:35 |
| John Ericson | * is libstc++ doing some has_include trickier by any chance? | 19:51:37 |
| Mic92 | John Ericson: it was triggered by us adding blake3, seems like gcc has a trigger. | 19:51:37 |
| Mic92 | it does | 19:51:48 |
| Mic92 | https://github.com/gcc-mirror/gcc/blob/d14d24b26126ec9c6c8ba5b2e573ed8e26347e6b/libstdc%2B%2B-v3/include/bits/c%2B%2Bconfig#L943 | 19:51:54 |
| John Ericson | ah yeah | 19:53:55 |
| John Ericson | libstdc++-v3/include/bits/c++config:# define _GLIBCXX_USE_TBB_PAR_BACKEND __has_include(<tbb/tbb.h>) | 19:54:00 |
| John Ericson | I would mention that + the blake3 in the commit message | 19:54:16 |
| John Ericson | IMO it boils down to, we want tbb to act like an (optional) private dependency of blake3, but it is public and leaking out like this | 19:54:58 |
| Mic92 | added | 19:58:53 |
| Mic92 | * added https://github.com/NixOS/nix/pull/14509/files#diff-cad591cdc5170341a06019235c8734d55351bb1683223e0ddccabc1446452712R49 | 19:59:20 |
| John Ericson | approvd | 20:09:16 |
| Sergei Zimmerman (xokdvium) | Nixpkgs bump: https://github.com/NixOS/nixpkgs/pull/459549. If anybody wants to throw some non x86_64-linux compute on it that’d be great | 21:36:34 |
|  @emma:rory.gay left the room. | 22:40:57 |
