rustc: error while loading shared libraries: libz.so.1: cannot open shared object file: No such file or directory

### Solution to issue cannot be found in the documentation.

- [x] I checked the documentation.

### Issue

`rust` fails to compile the `libc` crate

> `Compiling libc v0.2.180`
> `[libc 0.2.180] thread 'main' (1096078) panicked at $BUILD_PREFIX/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/libc-0.2.180/build.rs:211:5:`
> `[libc 0.2.180] failed to run rustc: $BUILD_PREFIX/bin/rustc: error while loading shared libraries: libz.so.1: cannot open shared object file: No such file or directory`

## workaround

```sh
export LD_LIBRARY_PATH="$BUILD_PREFIX/lib:$LD_LIBRARY_PATH"

# cargo auditable install ...
```

## reproduce

```
cd $(mktemp -d)
git clone https://github.com/milahu/conda-recipes --branch debug-rqbit
cd conda-recipes
git checkout 2e86822ba1f2130ae22fdb9ab3b006618d4dedbb
rattler-build build -r recipes/rqbit/recipe.bad.yaml \
  --variant-config recipes/rqbit/variant_config.yaml
```

### recipes

- [recipe.bad.yaml](https://github.com/milahu/conda-recipes/raw/debug-rqbit/recipes/rqbit/recipe.bad.yaml)
- [recipe.yaml](https://github.com/milahu/conda-recipes/raw/debug-rqbit/recipes/rqbit/recipe.yaml) - with the workaround

### build logs

- [recipe.bad.yaml.build.log](https://github.com/milahu/conda-recipes/raw/debug-rqbit/recipes/rqbit/recipe.bad.yaml.build.log)
- [recipe.yaml.build.log](https://github.com/milahu/conda-recipes/raw/debug-rqbit/recipes/rqbit/recipe.yaml.build.log) - with the workaround

### docs

- [ChatGPT-Conda-Build-Fix.md](https://github.com/milahu/conda-recipes/blob/debug-rqbit/recipes/rqbit/ChatGPT-Conda-Build-Fix.md)

<details>
<summary>
bug report by chatGPT
</summary>

<blockquote>

## 🐛 Rust toolchain fails in sanitized Cargo build environment due to missing `libz.so.1`

### Summary

The conda-forge Rust toolchain (`rustc`) fails to run inside sanitized Cargo build-script environments because `libz.so.1` is not found, even though:

* `rustc` works when run directly
* `libz.so.1` is present in the conda prefix
* `rustc` has valid RPATH (`$ORIGIN/../lib`)
* `ldd rustc` resolves `libz.so.1` correctly

The failure only occurs when Cargo runs build scripts with a restricted `LD_LIBRARY_PATH`.

---

### Error

During compilation (e.g. `libc v0.2.180` build script):

```
error: failed to run custom build command for `libc v0.2.180`
Caused by:
  failed to run rustc: libz.so.1: cannot open shared object file: No such file or directory
```

---

### Reproduction context

This happens in:

* conda-forge rust-feedstock toolchain
* rattler-build environments (and any Cargo build-script sandbox with sanitized env)
* Linux x86_64

---

### Key observation

In failing cases, Cargo sets a restricted environment:

```
LD_LIBRARY_PATH=/etc/sane-libs:...
```

This removes the conda prefix library path, so:

* `$BUILD_PREFIX/lib` is not visible
* RPATH alone is not sufficient for `libz.so.1` resolution in this context

Manually restoring it fixes the issue:

```bash
export LD_LIBRARY_PATH="$BUILD_PREFIX/lib:$LD_LIBRARY_PATH"
```

---

### Evidence

`rustc` links against `libz.so.1`:

```
ldd $(which rustc) | grep libz
libz.so.1 => .../lib/libz.so.1
```

But fails in Cargo build scripts due to missing runtime search path.

---

### Expected behavior

Rust toolchain binaries packaged by conda-forge should run in fully sanitized build environments without requiring `LD_LIBRARY_PATH` overrides, assuming:

* RPATH is correctly set
* all shared dependencies are properly discoverable at runtime

---

### Question

Is this expected behavior for the current Rust feedstock packaging (i.e. requiring `LD_LIBRARY_PATH` in sanitized environments), or does this indicate an incomplete runtime dependency/RPATH setup (specifically around `libz.so.1`)?

</blockquote>

</details>

## related

similar issues

i tried to apply the workarounds from there, but nothing works

- #71 
- #76 



### Installed packages

```shell
# packages in environment at /home/user/src/milahu/conda-recipes/.mamba/envs/conda-build:
#
# Name                    Version                   Build  Channel
_openmp_mutex             4.5                      20_gnu    conda-forge
anyio                     3.7.1              pyhd8ed1ab_0    conda-forge
archspec                  0.2.5              pyhd8ed1ab_0    conda-forge
attrs                     26.1.0             pyhcf101f3_0    conda-forge
backports.zstd            1.5.0           py312h90b7ffd_0    conda-forge
beautifulsoup4            4.14.3             pyha770c72_0    conda-forge
boa                       0.17.0             pyhd8ed1ab_3    conda-forge
boltons                   25.0.0             pyhd8ed1ab_0    conda-forge
brotli-python             1.2.0           py312hdb49522_1    conda-forge
bzip2                     1.0.8                hda65f42_9    conda-forge
c-ares                    1.34.6               hb03c661_0    conda-forge
ca-certificates           2026.5.14            h06a4308_0  
certifi                   2026.5.20       py312h06a4308_0  
cffi                      2.0.0           py312h460c074_1    conda-forge
chardet                   7.4.3              pyhcf101f3_0    conda-forge
charset-normalizer        3.4.7              pyhd8ed1ab_0    conda-forge
click                     8.4.0              pyhc90fa1f_0    conda-forge
conda                     24.11.3         py312h06a4308_0  
conda-build               24.5.1          py312h7900ff3_0    conda-forge
conda-index               0.7.0              pyhd8ed1ab_0    conda-forge
conda-libmamba-solver     24.9.0             pyhd8ed1ab_0    conda-forge
conda-package-handling    2.4.0              pyh7900ff3_2    conda-forge
conda-package-streaming   0.12.0             pyhd8ed1ab_0    conda-forge
distro                    1.9.0              pyhd8ed1ab_1    conda-forge
exceptiongroup            1.3.1              pyhd8ed1ab_0    conda-forge
filelock                  3.29.0             pyhd8ed1ab_0    conda-forge
fmt                       11.1.4               h07f6e7f_1    conda-forge
frozendict                2.4.7           py312h4c3975b_0    conda-forge
h2                        4.3.0              pyhcf101f3_0    conda-forge
hpack                     4.1.0              pyhd8ed1ab_0    conda-forge
hyperframe                6.1.0              pyhd8ed1ab_0    conda-forge
icu                       78.3                 h33c6efd_0    conda-forge
idna                      3.13               pyhcf101f3_0    conda-forge
jinja2                    3.1.6              pyhcf101f3_1    conda-forge
joblib                    1.5.3              pyhd8ed1ab_0    conda-forge
json5                     0.14.0             pyhd8ed1ab_0    conda-forge
jsonpatch                 1.33               pyhd8ed1ab_1    conda-forge
jsonpointer               3.1.1              pyhcf101f3_0    conda-forge
jsonschema                4.26.0             pyhcf101f3_0    conda-forge
jsonschema-specifications 2025.9.1           pyhcf101f3_0    conda-forge
keyutils                  1.6.3                hb9d3cd8_0    conda-forge
krb5                      1.22.2               ha1258a1_0    conda-forge
ld_impl_linux-64          2.45.1          default_hbd61a6d_102    conda-forge
libarchive                3.8.7           gpl_hc2c16d8_101    conda-forge
libcurl                   8.20.0               hcf29cc6_0    conda-forge
libedit                   3.1.20250104    pl5321h7949ede_0    conda-forge
libev                     4.33                 hd590300_2    conda-forge
libexpat                  2.8.0                hecca717_0    conda-forge
libffi                    3.5.2                h3435931_0    conda-forge
libgcc                    15.2.0              he0feb66_19    conda-forge
libgcc-ng                 15.2.0              h69a702a_19    conda-forge
libgomp                   15.2.0              he0feb66_19    conda-forge
libiconv                  1.18                 h3b78370_2    conda-forge
liblief                   0.14.1               h5888daf_2    conda-forge
liblzma                   5.8.3                hb03c661_0    conda-forge
libmamba                  1.5.12               h44b872a_2    conda-forge
libmambapy                1.5.12          py312h2549379_2    conda-forge
libnghttp2                1.68.1               h877daf1_0    conda-forge
libnsl                    2.0.1                hb9d3cd8_1    conda-forge
libsolv                   0.7.37               h9463b59_0    conda-forge
libsqlite                 3.53.1               hf4e2dac_0    conda-forge
libssh2                   1.11.1               hf672d98_0    conda-forge
libstdcxx                 15.2.0              h934c35e_19    conda-forge
libstdcxx-ng              15.2.0              hdf11a46_19    conda-forge
libuuid                   2.42.1               h5347b49_0    conda-forge
libxcrypt                 4.4.36               hd590300_1    conda-forge
libxml2                   2.15.3               h49c6c72_0    conda-forge
libxml2-16                2.15.3               hca6bf5a_0    conda-forge
libzlib                   1.3.2                h25fd6f3_2    conda-forge
lz4-c                     1.10.0               h5888daf_1    conda-forge
lzo                       2.10              h280c20c_1002    conda-forge
markdown-it-py            4.2.0              pyhd8ed1ab_0    conda-forge
markupsafe                3.0.3           py312h8a5da7c_1    conda-forge
mdurl                     0.1.2              pyhd8ed1ab_1    conda-forge
menuinst                  2.4.2           py312h7900ff3_0    conda-forge
msgpack-python            1.1.2           py312hd9148b4_1    conda-forge
ncurses                   6.6                  hdb14827_0    conda-forge
openssl                   3.6.2                h35e630c_0    conda-forge
packaging                 26.2               pyhc364b38_0    conda-forge
patch                     2.8               hb03c661_1002    conda-forge
patchelf                  0.17.2               h58526e2_0    conda-forge
pip                       26.1.1             pyh8b19718_0    conda-forge
pkginfo                   1.12.1.2           pyhd8ed1ab_0    conda-forge
platformdirs              4.9.6              pyhcf101f3_0    conda-forge
pluggy                    1.6.0              pyhf9edf01_1    conda-forge
prompt-toolkit            3.0.52             pyha770c72_0    conda-forge
prompt_toolkit            3.0.52               hd8ed1ab_0    conda-forge
psutil                    7.2.2           py312h5253ce2_0    conda-forge
py-lief                   0.14.1          py312h2ec8cdc_2    conda-forge
pybind11-abi              4                    hd8ed1ab_3    conda-forge
pycosat                   0.6.6           py312h4c3975b_3    conda-forge
pycparser                 2.22               pyh29332c3_1    conda-forge
pygments                  2.20.0             pyhd8ed1ab_0    conda-forge
pysocks                   1.7.1              pyha55dd90_7    conda-forge
python                    3.12.13         hd63d673_0_cpython    conda-forge
python-libarchive-c       5.3                pyhe01879c_1    conda-forge
python_abi                3.12                    8_cp312    conda-forge
pytz                      2026.2             pyhcf101f3_0    conda-forge
pyyaml                    6.0.3           py312h8a5da7c_1    conda-forge
rattler-build             0.55.1               h300ab14_0  
readline                  8.3                  h853b02a_0    conda-forge
referencing               0.37.0             pyhcf101f3_0    conda-forge
reproc                    14.2.7.post0         hb03c661_1    conda-forge
reproc-cpp                14.2.7.post0         hecca717_1    conda-forge
requests                  2.34.2             pyhcf101f3_0    conda-forge
rich                      15.0.0             pyhcf101f3_0    conda-forge
ripgrep                   15.1.0               hdab8a38_0    conda-forge
rpds-py                   0.30.0          py312h868fb18_0    conda-forge
ruamel.yaml               0.18.17         py312h5253ce2_2    conda-forge
ruamel.yaml.clib          0.2.15          py312h5253ce2_1    conda-forge
setuptools                82.0.1             pyh332efcf_0    conda-forge
sniffio                   1.3.1              pyhd8ed1ab_2    conda-forge
soupsieve                 2.8.3              pyhd8ed1ab_0    conda-forge
tk                        8.6.13          noxft_ha0e22de_103    conda-forge
tqdm                      4.67.3             pyh8f84b5b_0    conda-forge
truststore                0.10.4             pyhcf101f3_0    conda-forge
typing-extensions         4.15.0               h396c80c_0    conda-forge
typing_extensions         4.15.0             pyhcf101f3_0    conda-forge
tzdata                    2025c                hc9c84f9_1    conda-forge
urllib3                   2.7.0              pyhd8ed1ab_0    conda-forge
watchgod                  0.8.2              pyhd8ed1ab_1    conda-forge
wcwidth                   0.7.0              pyhd8ed1ab_0    conda-forge
wheel                     0.47.0             pyhd8ed1ab_0    conda-forge
yaml                      0.2.5                h280c20c_3    conda-forge
yaml-cpp                  0.8.0                h59595ed_0    conda-forge
zstandard                 0.25.0          py312h5253ce2_1    conda-forge
zstd                      1.5.7                hb78ec9c_6    conda-forge
```

### Environment info

```shell
active environment : base
    active env location : /home/user/src/milahu/conda-recipes/.mamba/envs/conda-build
            shell level : 1
       user config file : /home/user/.condarc
 populated config files : /home/user/.condarc
          conda version : 24.11.3
    conda-build version : 24.5.1
         python version : 3.12.13.final.0
                 solver : libmamba (default)
       virtual packages : __archspec=1=zen3
                          __conda=24.11.3=0
                          __cuda=13.2=0
                          __glibc=2.42=0
                          __linux=6.18.25=0
                          __unix=0=0
       base environment : /home/user/src/milahu/conda-recipes/.mamba/envs/conda-build  (writable)
      conda av data dir : /home/user/src/milahu/conda-recipes/.mamba/envs/conda-build/etc/conda
  conda av metadata url : None
           channel URLs : https://repo.anaconda.com/pkgs/main/linux-64
                          https://repo.anaconda.com/pkgs/main/noarch
                          https://repo.anaconda.com/pkgs/r/linux-64
                          https://repo.anaconda.com/pkgs/r/noarch
          package cache : /home/user/src/milahu/conda-recipes/.mamba/envs/conda-build/pkgs
                          /home/user/.conda/pkgs
       envs directories : /home/user/src/milahu/conda-recipes/.mamba/envs/conda-build/envs
                          /home/user/.conda/envs
               platform : linux-64
             user-agent : conda/24.11.3 requests/2.34.2 CPython/3.12.13 Linux/6.18.25 nixos/26.05 glibc/2.42 solver/libmamba conda-libmamba-solver/24.9.0 libmambapy/1.5.12
                UID:GID : 1000:100
             netrc file : None
           offline mode : False
```

Navigation Menu

Uh oh!

Uh oh!

rustc: error while loading shared libraries: libz.so.1: cannot open shared object file: No such file or directory #290

Solution to issue cannot be found in the documentation.

Issue

workaround

reproduce

recipes

build logs

docs

🐛 Rust toolchain fails in sanitized Cargo build environment due to missing `libz.so.1`

Summary

Error

Reproduction context

Key observation

Evidence

Expected behavior

Question

related

Installed packages

Environment info

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Uh oh!

Uh oh!

rustc: error while loading shared libraries: libz.so.1: cannot open shared object file: No such file or directory #290

Description

Solution to issue cannot be found in the documentation.

Issue

workaround

reproduce

recipes

build logs

docs

🐛 Rust toolchain fails in sanitized Cargo build environment due to missing libz.so.1

Summary

Error

Reproduction context

Key observation

Evidence

Expected behavior

Question

related

Installed packages

Environment info

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions

🐛 Rust toolchain fails in sanitized Cargo build environment due to missing `libz.so.1`