<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/133861>133861</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Misconfigured `LLVM_INSTALL_PREFIX` in LLVM Ubuntu nightly packages
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            cmake,
            packaging,
            build-problem
      </td>
    </tr>

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

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

<pre>
    To reproduce:
```bash
wget -O- https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
sudo add-apt-repository "deb http://apt.llvm.org/noble/ llvm-toolchain-noble main"
sudo apt-get update
sudo apt-get install llvm-21-dev
```
```cmake
cmake_minimum_required(VERSION 3.20)
enable_testing()

set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

set(CMAKE_FIND_PACKAGE_SORT_ORDER NATURAL)
set(CMAKE_FIND_PACKAGE_SORT_DIRECTION DEC)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

project(test)

find_package(LLVM REQUIRED CONFIG)
message(STATUS "Found LLVM ${LLVM_PACKAGE_VERSION}")
message(STATUS "Using LLVMConfig.cmake in: ${LLVM_DIR}")
include(AddLLVM)
```

CMake complaints:
```
-- The C compiler identification is GNU 13.3.0
-- The CXX compiler identification is GNU 13.3.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Performing Test HAVE_FFI_CALL
-- Performing Test HAVE_FFI_CALL - Success
-- Found FFI: /usr/lib/x86_64-linux-gnu/libffi.so
-- Could NOT find LibEdit (missing: LibEdit_INCLUDE_DIRS LibEdit_LIBRARIES) 
-- Found ZLIB: /usr/lib/x86_64-linux-gnu/libz.so (found version "1.3")
-- Found zstd: /usr/lib/x86_64-linux-gnu/libzstd.so
-- Found LibXml2: /usr/lib/x86_64-linux-gnu/libxml2.so (found version "2.9.14")
-- Could NOT find CURL (missing: CURL_LIBRARY CURL_INCLUDE_DIR) 
CMake Error at /usr/lib/llvm-21/cmake/LLVMConfig.cmake:3[7](https://github.com/dtcxzyw/conservative-clang/actions/runs/14184080393/job/39736102940#step:4:8)9 (include):
  include could not find requested file:

 /usr/lib/lib/cmake/llvm/LLVMExports.cmake
Call Stack (most recent call first):
  CMakeLists.txt:15 (find_package)


CMake Error at /usr/lib/llvm-21/cmake/LLVMConfig.cmake:40[9](https://github.com/dtcxzyw/conservative-clang/actions/runs/14184080393/job/39736102940#step:4:10) (include):
  include could not find requested file:

 /usr/lib/lib/cmake/llvm/LLVM-Config.cmake
Call Stack (most recent call first):
  CMakeLists.txt:15 (find_package)


-- Found LLVM 21.0.0
-- Using LLVMConfig.cmake in: /usr/lib/llvm-21/cmake
```

It happened two weeks ago.
first bad version: llvm-21-dev amd64 1:21~++20250318081715+7d7b58bc5d2b-1~exp1~20250318201846.794
last good version: llvm-21-dev amd64 1:21~++20250317083346+6b47bba44087-1~exp1~20250317083526.791

</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJzEV0tzoz4S_zTyRQUlxNMHHzCGWerv2FnbmfLuxSWQsPU3IBaJPOYwn31LQDyOJ5nJbu2jKhVw8-t3t7pFpOTHmrEZcOfAXUxIp06inVGVP397eZpkgr7MdgK2rGkF7XIG7BCgEHho-MuIPAEUPh2ZgsbagCelGqkxOAE4IY0yy_KxMkV7BDjRr4asSSNPQpnH5mie2QsEfgRlRwUkjTI0gVAKDYDCgUipoT-0rBGSK9G-QIAxZVmv6iNNtchKBnACe5VKiDI_EV4bPR1WhNcA44uKRhna_q6hRLFbKq-lImU5SMKWQdnjdQCu3_OKnDV__zxUvOZVVx1a9o-Ot4wCHHyNN9t0vYK2iRHAU4BCVpOsZAfFpOL1EeBgIGsjmAI4iO7CP-JDvL9fb3aHaH13ny5j_bwLV4stXK_ehSfpanG4D6M_wi_xYas515tFvIGrcPewCZcDz68ZFukmjnba1kUcvask2u8P2124WoSbBbT8n4VeAw6b-K8P6SZeXEy-Rcb7XbzSwdnCdZJcNDat-JPlGqpDdCEXvKaHhuRncmQAB8vl1zt4URGtV0n6ZcBWTMoBs92Fu4etLp5EdDWFPQ_ADvDn-vXi_pgj4C90iXwo5EHy-tgLiURd8KPZJx3yGtjhtdhFurkWxeu87KgWFVKqAaNL1-WEwuhOy8pF1ZSE10reNB1AoWHA3YnBqAfxkrWQU1YrXvCcKC5qyCX8snqAlm3a5jXDfv-vsCyYYrmuzGtN4TyFvC7EJyDQgFTUbEBGJ5afYSFa-CTa81uOIWpJJ1uAk0y3Z5Ln0IDyzJuG0Q9VwYIR1bVM_h7xxpYr4HVEPnTtPdDvnLviec89gOcAz3_h4w_-j718B_PGrHvWFqKtNHbHpIJ_Cb_GhyRJD1G4XH4CAg247fKcyVH10DtJkr7xqOQZwMlz4B08xyh53T0bx7obPhQFN-UY0Eh0JYWr9Q7qBoZLnsWUKwhwUHGpG0pLHamHdBUtHxax7qDthbhM55twk8ZbgKfw2qS_L9P5p236ZkqhtRY96yNrpa5_gLFl2pdWvYj-JhX9vGip6MXf8aTh2b4q8adFPFcl_shAbE5Ny7m28Sam0cNmeRNQTRoD97fhx1VoxzgOJ07ctqKFRN3aOc4-XbX9iMPJ7cEH7NAG7twH7gLg4O0WcOTq1GVmLiqAk3Gx0KJELVn7SBR_ZEZeEj3-EpLro0gCnLRd_7AcK3BQgOypDXDyp9Dm2FPf9iyEpw4C2JaK6T3AAXaop-dUe385ZqfD0QnhSIF5H65aqCFcejgzqRiFBS9flxv0U6KG_6_O63CMMYifG9Eqab6O_kivCltF8nOfBCEVbFnOagVz_aXg7TDFRqv6sC-5VNJUzwrYoeX2aX8z3saZ95_JkoOAO5_-f9Nkob7q_odpMt5E4b-dph-dr3cMbJnodZ7-Zmv4ZTp_2hJSBU-kaVjNKFRPAj4xdpaQHIXZb0itVDAjl9NDa7jaYSGpqOdAC9ghtr4Pswgj7CLbClBg-ZYL8NynfuYGWe5SnBnWd_bcWN9fQRhZgeOZ_tQBKCyJVPAoxL-hzUeBbTsewHMvc_wsI46DAv9Gmwa5WGuzAAondGbTqT0lEzazfMd2Atfx_MlpRgLqe8WU-jm2WMYw9d2CZa5Hc5LlRe5N-KwX6CALubaFfBN5me2znBT21LU83wcOYhXh5eUyMeFSdmxm2XbgWZOSZKyU_V0J47HOMMARwHiog36JHylZx0tqNK2-c1Sa6i4m7ayPStYdJXBQ2ZfURZXiqmSzOy7zvji6llEIPNTvkelquwuXy8P9Jk7SPfAQ5PVQXw9ZV6sO1vx4UuULHOtRTrq2nP2iw8fu6M25bNlJ723f0IPDjzP8zwAAAP__i8dSXA">