Add support for exporting package info vars into <Package>Config.cmake files (#516)

[bartlettroscoe]

Addresses #516

This provides a mechanism for packages to provide information about how they were configured to downstream CMake projects.

Any cache vars set with tribits_add_option_and_define() are exported automatically but TriBITS packages can call tribits_pkg_export_cache_var(<cacheVarName>) to export any cache vars.

See updated documentation for details.

[bartlettroscoe]

Hello @KyleFromKitware, can you do a quick review? If not, I can merge and we can set this up for a post-merge review when you have the time.

[bartlettroscoe]

So asserting these exported cache vars has exposed one error in Trilinos CMakeLists.txt files that will need to be fixed in the Pliris package. Details are shown below

Testing against Trilinos and identification of defect with Pliris_ENABLE_DREAL: (click to expand)

NOTE: I tested this with the Trilinos clang-10.0.0 PR build for Trilinos 'develop' version:

$ cd Trilinos/

$ gitdist-status --dist-repos=.,TriBITS
-----------------------------------------------------------------------------------------------------
| ID | Repo Dir        | Branch                   | Tracking Branch                     | C | M | ? |
|----|-----------------|--------------------------|-------------------------------------|---|---|---|
|  0 | Trilinos (Base) | develop                  | github/develop                      |   |   |   |
|  1 | TriBITS         | 516-export-pkg-info-vars | rab-github/516-export-pkg-info-vars |   |   |   |
-----------------------------------------------------------------------------------------------------

$ gitdist-repo-versions --dist-repos=.,TriBITS
*** Base Git Repo: Trilinos
f0ba7236d6c0e36c3e7f7fbe0cd66e9ec26798a2 [Mon Aug 22 15:14:05 2022 -0600] <[email protected]>
Merge Pull Request #10914 from trilinos/Trilinos/stk-snapshot
*** Git Repo: TriBITS
903b9a1cd298d87b52550dd6ef420f75e9e3502e [Tue Aug 23 08:42:45 2022 -0600] <[email protected]>
Assert exported cache and local vars have same value (#516)

I ran:

$ ssh crf450

$ cd ~/Trilinos.base/BUILDS/PR/clang-10.0.0/

$ cat load-env.sh
export TRILINOS_DIR=${HOME}/Trilinos.base/Trilinos
source ${TRILINOS_SRC}/packages/framework/GenConfig/gen-config.sh \
--cmake-fragment GenConfigSettings.cmake \
rhel7_sems-clang-10.0.0-openmpi-1.10.1-serial_release-debug_shared_no-kokkos-arch_no-asan_no-complex_no-fpic_mpi_no-pt_no-rdc_no-uvm_deprecated-on_no-package-enables \
--force -y \
"$@" \
${TRILINOS_DIR}

$ cat do-configure
rm -rf CMakeCache.txt CMakeFiles
cmake \
-G Ninja \
-C GenConfigSettings.cmake \
-D Trilinos_TRIBITS_DIR:STRING=TriBITS/tribits \
-D Trilinos_ENABLE_ALL_FORWARD_DEP_PACKAGES=OFF \
-D Trilinos_ENABLE_TESTS=ON \
"$@" \
${TRILINOS_DIR}

$ . load-env.sh

$ time ./do-configure -DTrilinos_ENABLE_ALL_PACKAGES=ON &> configure.out

real    0m41.081s
user    0m35.373s
sys     0m11.629s

$ tail configure.out 

Finished configuring Trilinos!

Total time to configure Trilinos: 0m38.652s
-- If publishing results using Trilinos, please cite us: https://trilinos.github.io/cite.html
-- Configuring incomplete, errors occurred!
See also "/ascldap/users/rabartl/Trilinos.base/BUILDS/PR/clang-10.0.0/CMakeFiles/CMakeOutput.log".
See also "/ascldap/users/rabartl/Trilinos.base/BUILDS/PR/clang-10.0.0/CMakeFiles/CMakeError.log".

This showed the errors:

$ grep -A 2 ERROR: configure.out 
  ERROR: The cache variable Pliris_ENABLE_DREAL with the cache var value
  'OFF' is not the same value as the local variable Pliris_ENABLE_DREAL with
  value 'ON'!
--
  ERROR: The cache variable Pliris_ENABLE_DREAL with the cache var value
  'OFF' is not the same value as the local variable Pliris_ENABLE_DREAL with
  value 'ON'!

And reconfiguring with:

$ cmake . &> configure.2.out

showed the same errors.

A search of that package shows:

$ cd packages/pliris/

$ find . -name CMakeLists.txt -exec grep -nH _ENABLE_DREAL {} \;
./CMakeLists.txt:23:TRIBITS_ADD_OPTION_AND_DEFINE(${PACKAGE_NAME}_ENABLE_DREAL
./CMakeLists.txt:41:   NOT ${PACKAGE_NAME}_ENABLE_DREAL)
./CMakeLists.txt:43:  SET(${PACKAGE_NAME}_ENABLE_DREAL ON)
./test/CMakeLists.txt:1:IF(Pliris_ENABLE_DREAL)
./src/CMakeLists.txt:118:  IF(Pliris_ENABLE_DREAL)
./src/CMakeLists.txt:170:ELSEIF(Pliris_ENABLE_DREAL)

and you can see the error on line 43 :-(

[rabartlett1972]

@KyleFromKitware signed off on the fix in #520 (comment).