find_file() not resolving relative paths correctly (?)

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4

Ok, I’ve reproduced this in a simpler form. The issue looks to be that find_file() resolves relative path components before it resolves symlinks, which is inconsistent with normal Linux path resolution. See the following CMake 3.18.4 output which searches using find_file() with both direct and symlink path; then cat just to prove normal Linux shell works.

I’m unable to upload a tar of the sample, but it’s easy enough to re-create. First the CMakeLists.txt:

cmake_minimum_required(VERSION 3.13)
project(FindPathSymlink LANGUAGES)

set(CMAKE_FIND_DEBUG_MODE TRUE)
find_file(var_direct file.so PATHS "${CMAKE_SOURCE_DIR}/usr/local/lib64" NO_DEFAULT_PATH)
find_file(var_symlink file.so PATHS "${CMAKE_SOURCE_DIR}/usr/7.3.0/../lib64/file.so" NO_DEFAULT_PATH)
execute_process(COMMAND cat ${CMAKE_SOURCE_DIR}/usr/7.3.0/../lib64/file.so
    OUTPUT_VARIABLE var_cat)

message(STATUS "find_file(usr/local/lib64): ${var_direct}")
message(STATUS "find_file(usr/7.3.0/../lib64): ${var_symlink}")
message(STATUS "cat 'usr/7.3.0/../lib64/file.so': ${var_cat}")

Then create the following directory / file layout:

mkdir -p usr/local/lib64
echo "Found you!" > usr/local/lib64/file.so 
mkdir -p usr/local/7.3.0
cd usr/
ln -s local/7.3.0 7.3.0

You should end up with the following layout:

$ find . -ls
  3571714      4 drwxr-xr-x   3 couchbase couchbase     4096 Oct 12 09:11 .
  3571715      4 drwxr-xr-x   3 couchbase couchbase     4096 Oct 12 09:03 ./usr
  3553162      0 lrwxrwxrwx   1 couchbase couchbase       11 Oct 12 09:03 ./usr/7.3.0 -> local/7.3.0
  3571716      4 drwxr-xr-x   4 couchbase couchbase     4096 Oct 12 09:02 ./usr/local
  3571717      4 drwxr-xr-x   2 couchbase couchbase     4096 Oct 12 09:01 ./usr/local/lib64
  3553107      4 -rw-r--r--   1 couchbase couchbase       11 Oct 12 09:09 ./usr/local/lib64/file.so
  3571718      4 drwxr-xr-x   2 couchbase couchbase     4096 Oct 12 09:02 ./usr/local/7.3.0
  3553900      4 -rw-r--r--   1 couchbase couchbase      589 Oct 12 09:09 ./CMakeLists.txt

Running this gives:

CMake Debug Log at CMakeLists.txt:5 (find_file):
  find_file called with the following settings:

    VAR: var_direct
    NAMES: "file.so"
    Documentation: Path to a file.
    Framework
      Only Search Frameworks: 0
      Search Frameworks Last: 0
      Search Frameworks First: 0
    AppBundle
      Only Search AppBundle: 0
      Search AppBundle Last: 0
      Search AppBundle First: 0
    NO_DEFAULT_PATH Enabled

  find_file considered the following locations:

  The item was found at

    /home/couchbase/find_file_symlinks2/usr/local/lib64/file.so



CMake Debug Log at CMakeLists.txt:6 (find_file):
  find_file called with the following settings:

    VAR: var_symlink
    NAMES: "file.so"
    Documentation: Path to a file.
    Framework
      Only Search Frameworks: 0
      Search Frameworks Last: 0
      Search Frameworks First: 0
    AppBundle
      Only Search AppBundle: 0
      Search AppBundle Last: 0
      Search AppBundle First: 0
    NO_DEFAULT_PATH Enabled

  find_file considered the following locations:

    /home/couchbase/find_file_symlinks2/usr/lib64/file.so/file.so

  The item was not found.



-- find_file(usr/local/lib64): /home/couchbase/find_file_symlinks2/usr/local/lib64/file.so
-- find_file(usr/7.3.0/../lib64): var_symlink-NOTFOUND
-- cat 'usr/7.3.0/../lib64/file.so': Found you!

-- Configuring done
-- Generating done
-- Build files have been written to: /home/couchbase/find_file_symlinks2/build