CMake: Make libint2 Fortran interface explicit

.github/workflows/cmake.yml

@@ -97,8 +97,9 @@ jobs:
     - name: Install prerequisite MacOS packages
       if: ${{ steps.skip_check.outputs.should_skip != 'true' && matrix.os == 'macos-15' }}
       run: |
-        brew install ninja gcc@11 gmp boost eigen@3 bison ccache automake python
-        echo "FC=/opt/homebrew/Cellar/gcc@11/11.5.0/bin/gfortran-11" >> $GITHUB_ENV
+        brew untap aws/tap || true
+        brew install ninja gcc gmp boost eigen@3 bison ccache automake python
+        echo "FC=$(brew --prefix gcc)/bin/gfortran" >> $GITHUB_ENV
         /opt/homebrew/bin/pip3 install --break-system-packages pytest numpy scipy scikit-image
         /opt/homebrew/bin/pip3 show pytest numpy scipy scikit-image
 
@@ -217,6 +218,7 @@ jobs:
             libargs: >
               -D BUILD_SHARED_LIBS=ON
               -D LIBINT2_ENABLE_FORTRAN=ON
+              -D CMAKE_EXE_LINKER_FLAGS="-Wl,-rpath-link,${CONDA_PREFIX}/lib"
             testargs: ""
 
           - runs-on: windows-latest
@@ -324,7 +326,6 @@ jobs:
           -B build \
           -G Ninja \
           -D CMAKE_INSTALL_PREFIX="${{github.workspace}}/installed" \
-          -D CMAKE_CXX_COMPILER=${CXX} \
           -D LIBINT2_REQUIRE_CXX_API_COMPILED=ON \
           -D LIBINT2_ENABLE_PYTHON=ON \
           -D CMAKE_PREFIX_PATH="${CONDA_PREFIX}" \

CMakeLists.txt

@@ -82,7 +82,8 @@ set(pnv libint2) # projectnameversion
 #     build libint-library-export target before library build targets appear
 #   - (4) unpack the export tarball and build the library and install into \<build\>/library-install-stage/
 #   - duration depends on number of integrals requested; runs in parallel
-#   - consumes language-interface and the CMAKE_INSTALL_[DATA|INCLUDE|LIB]DIR paths options
+#   - consumes language-interface, the CMAKE_INSTALL_[DATA|INCLUDE|LIB]DIR paths
+#     options, and LIBINT2_INSTALL_FMODDIR
 #   - the default build target includes this final library build
 #   - (5) optionally testable
 #   - (6) install into CMAKE_INSTALL_PREFIX

INSTALL.md

@@ -51,7 +51,7 @@ The Libint build is structured into three parts:
     or dependency (FetchContent or ExternalProject)
   - (4) unpack the export tarball and build the library and install into \<build\>/library-install-stage/
   - duration depends on number of integrals requested; runs in parallel
-  - consumes language-interface and the CMAKE_INSTALL_[DATA|INCLUDE|LIB]DIR paths options
+  - consumes language-interface, the CMAKE_INSTALL_[DATA|INCLUDE|LIB]DIR paths options, and LIBINT2_INSTALL_FMODDIR
   - the default build target includes this final library build
   - (5) optionally testable
   - (6) install into CMAKE_INSTALL_PREFIX
@@ -329,6 +329,7 @@ Note that options, docs, and CMake components are focused on the C++ interface,
 
 ### Install Paths (L) (TARBALL)
 
+* `LIBINT2_INSTALL_FMODDIR` - L - For `LIBINT2_ENABLE_FORTRAN=ON`, the directory below `CMAKE_INSTALL_PREFIX` into which `libint_f.mod` is installed and which the `Libint2::fortran` target adds to its interface. Distribution packages that keep Fortran modules in a compiler-specific location (e.g. `lib64/gfortran/modules`) can set it at configure time rather than relocating the module after install. [Default=`CMAKE_INSTALL_INCLUDEDIR`]
 * `LIBINT2_PREFIX_PYTHON_INSTALL` - L - For `LIBINT2_ENABLE_PYTHON=ON`, whether to install the Python module in the Linux manner to `CMAKE_INSTALL_PREFIX` or to not install it. Note: not a path; the installation sub-path below `CMAKE_INSTALL_PREFIX` is determined by querying `Python_EXECUTABLE`. For alternate installation in the Python manner to `Python_EXECUTABLE`'s site-packages, see target libint2-python-wheel. [Default=OFF]
 
 
@@ -383,13 +384,13 @@ Note that options, docs, and CMake components are focused on the C++ interface,
 | `Libint2::int2`        | `C`                  | yes              | always                                | impossible                                                                                                             | `int-{static,shared}`                | `libint2`     |
 | `Libint2::cxx`         | `CXX_ho`             | yes              | `LIBINT2_REQUIRE_CXX_API=ON`          | `LIBINT2_REQUIRE_CXX_API=OFF` & withhold Eigen3 & `LIBINT2_REQUIRE_CXX_API_COMPILED=OFF` & `LIBINT2_ENABLE_PYTHON=OFF` | `int-cxx-headeronly-{static,shared}` | `libint2_cxx` |
 | `Libint2::int2-cxx`    | `CXX`                | yes              | `LIBINT2_REQUIRE_CXX_API_COMPILED=ON` | `LIBINT2_REQUIRE_CXX_API_COMPILED=OFF`                                                                                 | `int-cxx-{static,shared}`   |               |
-| Fortran local[^19]     | (NYI)                | no               | `LIBINT2_ENABLE_FORTRAN=ON`           | `LIBINT2_ENABLE_FORTRAN=OFF`                                                                                           | `libint_f`                           |               |
+| `Libint2::fortran`     | `fortran`            | no               | `LIBINT2_ENABLE_FORTRAN=ON`           | `LIBINT2_ENABLE_FORTRAN=OFF`                                                                                           | `int_f`, `libint_f`[^19]             |               |
 
 [^15]: Targets for library consumer use. These are available after `find_package(Libint2)` or `add_subdirectory()`.
 [^16]: Ensure target found in installation after `find_package(Libint2 COMPONENTS ...)`.
 [^17]: Targets in export/CMakeLists.txt.export . Names subject to change. Use namespaced target names in any consuming code.
 [^18]: Deprecated legacy aliases. Update any uses to namespaced target.
-[^19]: The `libint_f` internal target defines the Fortran interface to Libint2. One must also link to `Libint2::int2` or `Libint2::cxx`. At present, it is not exported, and a namespaced target is not defined.
+[^19]: `libint_f` compiles the Fortran module; `int_f` archives it and carries the usage requirements, so linking `Libint2::fortran` alone brings in the Fortran module directory, the generated Fortran headers, and the Libint2 C library. Set `LIBINT2_INSTALL_FMODDIR` to control where `libint_f.mod` is installed.
 
 
 -----------------------------------------------------------------------------

cmake/libint2-config.cmake.in

@@ -26,6 +26,7 @@
 #   eri_HH_dD       - search for library including 2-body integrals with 2 centers
 #   eri_hh_dD       - ditto
 #   g12_hhhh_dD     - search for library including F12 integrals with Gaussian factors
+#   fortran         - search for library including the fortran interface target
 #
 #                    cart       shell_set   used_by
 #                    --------   ---------   -------
@@ -93,30 +94,17 @@ foreach(_eri @Libint2_CONFIG_COMPONENTS@)  # Libint2_CONFIG_COMPONENTS
     set(${L2}_${_eri}_FOUND 1)
 endforeach()
 
-check_required_components(${L2})
+# N.B. check_required_components() is deferred to the end of this file so that
+# the language components can be resolved from the imported targets below
+# rather than from configure-time options
 
 # Import library targets
-if(NOT TARGET ${L2}::int-shared AND NOT TARGET ${L2}::int-static)
+if(NOT TARGET ${L2}::int2)
   include("${CMAKE_CURRENT_LIST_DIR}/${pnv}-targets.cmake")
 endif()
 
-# Create convenience aliases matching the build-tree names
-if (TARGET ${L2}::int-shared)
-    if (NOT TARGET ${L2}::int2)
-        add_library(${L2}::int2 ALIAS ${L2}::int-shared)
-    endif()
-elseif (TARGET ${L2}::int-static)
-    if (NOT TARGET ${L2}::int2)
-        add_library(${L2}::int2 ALIAS ${L2}::int-static)
-    endif()
+if (TARGET ${L2}::fortran)
+    set(${L2}_fortran_FOUND 1)
 endif()
 
-if (TARGET ${L2}::int-cxx-headeronly-shared)
-    if (NOT TARGET ${L2}::cxx)
-        add_library(${L2}::cxx ALIAS ${L2}::int-cxx-headeronly-shared)
-    endif()
-elseif (TARGET ${L2}::int-cxx-headeronly-static)
-    if (NOT TARGET ${L2}::cxx)
-        add_library(${L2}::cxx ALIAS ${L2}::int-cxx-headeronly-static)
-    endif()
-endif()
+check_required_components(${L2})