Enable LIBOQS_DIR as cache entry and environment variable.

[ghost]

Fix #273

liboqs_DIR is a CMake cache entry to hint CMake about the location of liboqs
CMake package.

However, being able to use LIBOQS_DIR (full capitalized) would be more
convenient.

This PR adds the ability to use either liboqs_DIR as a cache entry, liboqs_DIR
as an environment variable, LIBOQS_DIR as a cache entry and LIBOQS_DIR
as an env variable.

Tests were also added to make sure that these variables are well taken
by CMake during the configuration stage.

[baentsch]

Thanks very much for all this work, particularly the new CI test for this "chose any capitalization" feature -- I'm just not sure why it's "green": When looking at it, it seems to have failed, e.g. open "Test oqsprovider" twisty at https://github.com/open-quantum-safe/oqs-provider/actions/runs/6430477110/job/17461513594 (?)

[ghost]

I'm testing cases where liboqs_DIR and LIBOQS_DIR mismatch (we don't want people to think that the bad value was taken because in fact they forgot to unsete LIBOQS_DIR for instance).
This is why we see some error strings here.

About

git config --global --add safe.directory /__w/oqs-provider/oqs-provider

I think it's due to the fact that I'm using REALPATH, which resolves symlinks.
I've switched to ABSOLUTE (which does not), let's see what happens!

[baentsch]

let's see what happens!

Not the right thing :-/ Besides, why doesn't this get reported as a CI error? And: Would an actual build and test not be prudent?

[ajbozarth]

I've tried running this with multiple build commands and none of them work, even the one that did previously.

Usually I put the liboqs_DIR env var before the cmake command, but I also tried putting it inline as well (though this has never worked for me even on main).

Here's the four commands and tried and the error (red text) associated with each of them

1. liboqs_DIR=$WORKSPACE/oqs cmake -DCMAKE_INSTALL_PREFIX=$WORKSPACE/oqs-provider -DOPENSSL_ROOT_DIR=$WORKSPACE -DCMAKE_BUILD_TYPE=Release -S . -B _build (this is the one that works on main)

CMake Error at CMakeLists.txt:101 (message):
  `libos_DIR` environment variable does not match the value previously set
  ('/Users/ajbozarth/workspace/quantum/openssl_build/oqs' !=
  '/Users/ajbozarth/workspace/quantum/oqs-provider').

2. cmake -Dliboqs_DIR=$WORKSPACE/oqs -DCMAKE_INSTALL_PREFIX=$WORKSPACE/oqs-provider -DOPENSSL_ROOT_DIR=$WORKSPACE -DCMAKE_BUILD_TYPE=Release -S . -B _build

CMake Error at CMakeLists.txt:87 (message):
  `liboqs_DIR` cache entry and `LIBOQS_DIR` environment variable mismatch
  ('/Users/ajbozarth/workspace/quantum/openssl_build/oqs' !=
  '/Users/ajbozarth/workspace/quantum/oqs-provider').

3. LIBOQS_DIR=$WORKSPACE/oqs cmake -DCMAKE_INSTALL_PREFIX=$WORKSPACE/oqs-provider -DOPENSSL_ROOT_DIR=$WORKSPACE -DCMAKE_BUILD_TYPE=Release -S . -B _build (note that this error is the one that I see when run options 2, 3 and 4 on main)

CMake Error at CMakeLists.txt:111 (find_package):
  By not providing "Findliboqs.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "liboqs", but
  CMake did not find one.

  Could not find a package configuration file provided by "liboqs" with any
  of the following names:

    liboqsConfig.cmake
    liboqs-config.cmake

  Add the installation prefix of "liboqs" to CMAKE_PREFIX_PATH or set
  "liboqs_DIR" to a directory containing one of the above files.  If "liboqs"
  provides a separate development package or SDK, be sure it has been
  installed.

4. cmake -DLIBOQS_DIR=$WORKSPACE/oqs -DCMAKE_INSTALL_PREFIX=$WORKSPACE/oqs-provider -DOPENSSL_ROOT_DIR=$WORKSPACE -DCMAKE_BUILD_TYPE=Release -S . -B _build

CMake Error at CMakeLists.txt:90 (message):
  `LIBOQS_DIR` cache entry and `LIBOQS_DIR` environment variable mismatch
  ('/Users/ajbozarth/workspace/quantum/openssl_build/oqs' != '').

[baentsch]

even the one that did previously.

Well, previously we were using cmake as intended. Now we try to do something going against its conventions. Apologies to @thb-sb to have suggested you "quickly" do this PR.

[ghost]

even the one that did previously.

Well, previously we were using cmake as intended. Now we try to do something going against its conventions. Apologies to @thb-sb to have suggested you "quickly" do this PR.

No problem.

Indeed we're trying to go against CMake conventions here. We may better keep the current variable as it follows CMake rules.

Another "solution": if LIBOQS_DIR is set, we could display a warning to redirect developers to liboqs_DIR.

Note that liboqs_DIR should be used as a CMake cache entry

[baentsch]

We may better keep the current variable as it follows CMake rules.

Fully agree. Do you want to update this PR (maybe just add a documentation clarification instead of the new code) or just close it?

[ghost]

We may better keep the current variable as it follows CMake rules.

Fully agree. Do you want to update this PR (maybe just add a documentation clarification instead of the new code) or just close it?

I'll close this one since I've cross-referenced it with the issue.

Thank you!