<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/144501>144501</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Suspicious change to `libc++-20-dev` dependency on `libc++*`
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            packaging,
            platform:linux
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
            sylvestre
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          firewave
      </td>
    </tr>
</table>

<pre>
    Starting today I was seeing this installing the packages from `apt.llvm.org`

```
The following packages were automatically installed and are no longer required:
  libc++1-20 libc++abi1-20 libunwind-20
Use 'sudo apt autoremove' to remove them.
The following NEW packages will be installed:
  libc++1 libc++abi1 libunwind
The following packages will be upgraded:
  clang-20 clang-21 clang-tidy-20 clang-tidy-21 clang-tools-20 clang-tools-21 clangd-20 libc++-20-dev libc++abi-20-dev
  libclang-20-dev libclang-21-dev libclang-common-20-dev libclang-common-21-dev libclang-cpp20 libclang-cpp21
  libclang-rt-20-dev libclang-rt-21-dev libclang1-20 libclang1-21 liblldb-20 libllvm20 libllvm21 libunwind-20-dev
  lld-20 lldb-20 llvm-20 llvm-20-dev llvm-20-linker-tools llvm-20-runtime llvm-20-tools llvm-21 llvm-21-dev
  llvm-21-linker-tools llvm-21-runtime llvm-21-tools python3-lldb-20
```

The current system shows the following dependencies

```
$ apt-cache rdepends libc++1-20 libc++abi1-20 libunwind-20
libc++1-20
Reverse Depends:
 libc++-20-dev
libc++abi1-20
Reverse Depends:
  libc++1-20
 libc++abi-20-dev
libunwind-20
Reverse Depends:
  libc++1-20
 libunwind-20-dev
  libc++abi1-20
```

```
$ apt-cache show libc++-20-dev
Package: libc++-20-dev
Source: llvm-toolchain-20
Version: 1:20.1.7~++20250616065743+6146a88f6049-1~exp1~20250616065852.130
Architecture: amd64
Maintainer: LLVM Packaging Team <pkg-llvm-team@lists.alioth.debian.org>
Installed-Size: 20397
Depends: libc++1 (= 1:20.1.7~++20250616065743+6146a88f6049-1~exp1~20250616065852.130), libc++abi-20-dev (= 1:20.1.7~++20250616065743+6146a88f6049-1~exp1~20250616065852.130), libunwind-20-dev
```

Looks like the version was accidentally dropped from the dependency for the newer package:

```
$ apt-cache depends libc++-20-dev
libc++-20-dev
  Depends: libc++1
  Depends: libc++abi-20-dev
  Depends: libunwind-20-dev
```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJy0Vl-P4yYQ_zTkBSXC-E-SBz9kd2-lk_aqqnu9PhOY2HQxuICTSx_2s1fYxImT7Ekn9SRL9gzjmd_M_AZgzslKA5Qof0CUuqPag_MWEKUof5qxztfGljtp4cD2MNsacSxfPbNe6gp7I9gRf8YH5rAD6FW1dFhq55lSgwy4ZfyNVeDwzpoGo4Kw1i-U2jcLYytUEEQ24SlIfMjmaw14Z5Qyh-Bj_P8AFjDrvGmYl5wpdTyFAoGZFphZwNpgZXQFFlv4p5MWBEqDf4yV3HJEHxB9SOaUXIhsK0-aTh-kFnMaUPzpACO6dJ0wmLW-j2yhMXtAdIm9wYMQcmwWN6h_-_TXBXKpFN7CGe4dTFeAzmh-UJDotmsry8TZK1dMVyGj-JHEDy_F8awepHHNGOUuFgcxroppweaUzAXsp4ijckwrYhgNI5SpzE3TGH1jdlJfW7dtxDGKyTSe9Te-gmrqZ2x_FPpaKyW2UR-4efGVTIhxzlENVTn9p_bNxXsIGL-V1G9gh5qOSttpLxsY5cvV5PS-iDbId1wlV66SuNoefW10Oo8Ir2Yssop31oL22B2dhwa72hxcP7VnugloQQvQXIK7nVVEszAdc854DdgOxu6nh21qj8jmD9iDdYCfBoeR2jccnPwafX_4N76J8hGFr9D9jLs7TLkD8KoVH1c0dORu2r8PuwBK71fl1XSWD6uBFYESvGZSD-G_gXXS6LCcoHRDySJZLN8HH5TQnBRJQYp8maWIPhRJVrDValeQbD1P3uF7m7xfGK1yukjS4HVjeS09cN_ZPjJrRJEhsvnCpPZMarBB-_Ly7Qse0Ad6fQXWYJQ-tm_VfIAKrEEZUdJ5t2BKGl8vBGwl0_2BkX5CZPP5tJHOX-W_fSxK0vUSkc25RZPNFdEVSp_-v2TpGtHHu-z5daGumXXFoRdj3sLgvfVHEt4PLe5PZ8a5FKB9f2YKa9oWxHAcB8txwI94Z2yv0nAAezpoBrr_kKW3Y39vPi-H4n6fPl66OmGmNh9WZibKVKzTNZtBmSxzkuTLvEhndblORAE0pWuaQU4JZ9tMAOFZxgues4zMZBlbsUxITrN0sVxTWqxWdFvQfJWvCpQRaJhU41VmJp3roEyyLCfJTLEtKBfvVe2J7eFeRR-DRjG_M7ZB6UZJ3X2PFy5b9iOw7So3jsDo30uvoHztXCu5NJ3DvGa6gnAVQQW5LXNBLltr9NQK0VCmWWdVWXvf9psafUb0uZK-7rYLbhpEn0Pw-Jq31vwN3CP63GfqEH2Oye5L-l8AAAD__3--JBg">