This barfed with
error: [json.exception.type_error.302] type must be string, but is array
on `nix build github:malt3/bazel-env#bazel-env` because it has a `exportReferencesGraph` with a value like `["string",...["string"]]`.
This breaks gdb pretty-printers inserted into .debug_gdb_scripts section,
because it implies --compress-debug-sections=zlib, -Wa,--compress-debug-sections.
This is very unfortunate, because then gdb can't use pretty printers for
Boost.Unordered (which are very useful, since boost::unoredred_flat_map is
impossible to debug). This seems perfectly fine to disable in the dev-shell for
the time being.
See [1-3] for further references.
With this change I'm able to use boost's pretty-printers out-of-the box:
```
p *importResolutionCache
$2 = boost::concurrent_flat_map with 1 elements = {[{accessor = {p = std::shared_ptr<nix::SourceAccessor> (use count 5, weak count 1) = {
get() = 0x555555d830a8}}, path = {static root = {static root = <same as static member of an already seen type>, path = "/"},
path = "/derivation-internal.nix"}}] = {accessor = {p = std::shared_ptr<nix::SourceAccessor> (use count 5, weak count 1) = {
get() = 0x555555d830a8}}, path = {static root = {static root = <same as static member of an already seen type>, path = "/"},
path = "/derivation-internal.nix"}}}
```
When combined with a simple `add-auto-load-safe-path ~/code` in .gdbinit
[1]: https://gerrit.lix.systems/c/lix/+/3880
[2]: https://git.lix.systems/lix-project/lix/issues/1003
[3]: https://sourceware.org/pipermail/gdb-patches/2025-October/221398.html
Firstly, this is now available on darwin where the default in llvm 19.
Secondly, this leads to very weird segfaults when building with newer nixpkgs for some reason.
(It's UB after all).
This appears when building with the following:
mesonComponentOverrides = finalAttrs: prevAttrs: {
mesonBuildType = "debugoptimized";
dontStrip = true;
doCheck = false;
separateDebugInfo = false;
preConfigure = (prevAttrs.preConfigure or "") + ''
case "$mesonBuildType" in
release|minsize|debugoptimized) appendToVar mesonFlags "-Db_lto=true" ;;
*) appendToVar mesonFlags "-Db_lto=false" ;;
esac
'';
};
And with the following nixpkgs input:
nix build ".#nix-cli" -L --override-input nixpkgs "https://releases.nixos.org/nixos/unstable/nixos-25.11pre870157.7df7ff7d8e00/nixexprs.tar.xz"
Stacktrace:
#0 0x00000000006afdc0 in ?? ()
#1 0x00007ffff71cebb6 in _Unwind_ForcedUnwind_Phase2 () from /nix/store/41ym1jm1b7j3rhglk82gwg9jml26z1km-gcc-14.3.0-lib/lib/libgcc_s.so.1
#2 0x00007ffff71cf5b5 in _Unwind_Resume () from /nix/store/41ym1jm1b7j3rhglk82gwg9jml26z1km-gcc-14.3.0-lib/lib/libgcc_s.so.1
#3 0x00007ffff7eac7d8 in std::basic_ios<char, std::char_traits<char> >::~basic_ios (this=<optimized out>, this=<optimized out>)
at /nix/store/82kmz7r96navanrc2fgckh2bamiqrgsw-gcc-14.3.0/include/c++/14.3.0/bits/basic_ios.h:286
#4 std::__cxx11::basic_ostringstream<char, std::char_traits<char>, std::allocator<char> >::basic_ostringstream (this=<optimized out>, this=<optimized out>)
at /nix/store/82kmz7r96navanrc2fgckh2bamiqrgsw-gcc-14.3.0/include/c++/14.3.0/sstream:806
#5 nix::SimpleLogger::logEI (this=<optimized out>, ei=...) at ../logging.cc:121
#6 0x00007ffff7515794 in nix::Logger::logEI (this=0x675450, lvl=nix::lvlError, ei=...) at /nix/store/bkshji3nnxmrmgwa4n2kaxadajkwvn65-nix-util-2.32.0pre-dev/include/nix/util/logging.hh:144
#7 nix::handleExceptions (programName=..., fun=...) at ../shared.cc:336
#8 0x000000000047b76b in main (argc=<optimized out>, argv=<optimized out>) at /nix/store/82kmz7r96navanrc2fgckh2bamiqrgsw-gcc-14.3.0/include/c++/14.3.0/bits/new_allocator.h:88
