From 9cc7be60d7004a45a1c87880f808144df9f58254 Mon Sep 17 00:00:00 2001
From: Sean Bryan <sean.bryan@anu.edu.au>
Date: Mon, 4 Mar 2024 17:07:20 +1100
Subject: [PATCH] Add support for specifying CMake targets

---
 CMakeLists.txt                                |  4 ++--
 build.bash                                    | 18 +++++++++++++++++-
 documentation/docs/user_guide/installation.md |  8 ++++----
 3 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f0f7c2c5b..b290aee93 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -145,7 +145,7 @@ add_executable(
 )
 target_compile_options(cable PRIVATE ${CABLE_Fortran_FLAGS})
 target_link_libraries(cable PRIVATE PkgConfig::NETCDF)
-install(TARGETS cable RUNTIME)
+install(TARGETS cable RUNTIME OPTIONAL)
 
 if(MPI_Fortran_FOUND)
     add_executable(
@@ -159,5 +159,5 @@ if(MPI_Fortran_FOUND)
     )
     target_compile_options(cable-mpi PRIVATE ${CABLE_Fortran_FLAGS})
     target_link_libraries(cable-mpi PRIVATE PkgConfig::NETCDF MPI::MPI_Fortran)
-    install(TARGETS cable-mpi RUNTIME)
+    install(TARGETS cable-mpi RUNTIME OPTIONAL)
 endif()
diff --git a/build.bash b/build.bash
index aaec757f2..ddab76698 100755
--- a/build.bash
+++ b/build.bash
@@ -1,6 +1,7 @@
 #!/bin/bash
 
 nproc_default=4
+targets_default=(all)
 
 script_name=$(basename "${0}")
 
@@ -17,6 +18,10 @@ Options:
                 Specify the compiler to use.
   -j <jobs>     Specify the number of parallel jobs in the compilation. By
                 default this value is set to $nproc_default.
+  -t <tgt>, --target <tgt>
+                Build the CMake target <tgt> instead of the default target
+                (${targets_default[*]}). This option may be used more than once
+                to specify multiple targets.
   -h, --help    Show this screen.
 
 Enabling debug mode:
@@ -29,6 +34,12 @@ Enabling verbose output from Makefile builds:
   To enable more verbose output from Makefile builds, specify the CMake option
   -DCMAKE_VERBOSE_MAKEFILE=ON when invoking $script_name.
 
+Enabling serial only or MPI only builds:
+
+  Serial only or MPI only builds can be done by specifying the --target
+  <executable> option when invoking $script_name where <executable> is the name
+  of either the serial or MPI executable.
+
 EOF
 }
 
@@ -48,6 +59,10 @@ while [ $# -gt 0 ]; do
             CMAKE_BUILD_PARALLEL_LEVEL=$2
             shift
             ;;
+        -t|--target)
+            targets+=("$2")
+            shift
+            ;;
         -h|--help)
             show_help
             exit
@@ -88,7 +103,8 @@ if hostname -f | grep gadi.nci.org.au > /dev/null; then
 fi
 
 export CMAKE_BUILD_PARALLEL_LEVEL="${CMAKE_BUILD_PARALLEL_LEVEL:=$nproc_default}"
+: "${targets:=${targets_default[*]}}"
 
 cmake -S . -B build "${cmake_args[@]}" &&\
-cmake --build build &&\
+cmake --build build --target "${targets[@]}" &&\
 cmake --install build --prefix .
diff --git a/documentation/docs/user_guide/installation.md b/documentation/docs/user_guide/installation.md
index 766556195..e6e389fbb 100644
--- a/documentation/docs/user_guide/installation.md
+++ b/documentation/docs/user_guide/installation.md
@@ -88,7 +88,7 @@ To execute the build, run:
 
     ./build.bash
 
-This loads the required build dependencies and invokes CMake. Both serial and parallel (MPI) applications are built with a single invocation of CMake. **Note** the MPI executable will only be built if CMake can find the location of the installed MPI libraries.
+This loads the required build dependencies and invokes CMake. Both serial and parallel (MPI) applications are built by default with a single invocation of CMake. **Note** the MPI executable will only be built if CMake can find the location of the installed MPI libraries.
 
 ### Cleaning the build
 
@@ -106,9 +106,9 @@ The release build is default. To enable debug mode, specify the CMake option `-D
 
 To enable more verbose output from Makefile builds, specify the CMake option `-DCMAKE_VERBOSE_MAKEFILE=ON` when invoking `build.bash`.
 
-### Parallel compilation
+### Enabling serial only or MPI only builds:
 
-By default, the compilation is done in parallel. The number of parallel jobs can be overwritten by setting the environment variable [`CMAKE_BUILD_PARALLEL_LEVEL`](https://cmake.org/cmake/help/latest/envvar/CMAKE_BUILD_PARALLEL_LEVEL.html).
+Serial only or MPI only builds can be done by specifying the `--target <executable>` option when invoking `build.bash` where `<executable>` is the name of either the serial or MPI executable.
 
 ???+ tip
     Run `./build.bash --help` for information on supported options.
@@ -120,4 +120,4 @@ By default, the compilation is done in parallel. The number of parallel jobs can
 [build.bash-hostname-check]: https://github.com/CABLE-LSM/CABLE/blob/main/build.bash#L45-L55
 [clean-build]: installation.md/#cleaning-the-build
 [build-system]: ../developer_guide/other_resources/build_system.md
-[hive-forum-cable]: https://forum.access-hive.org.au/c/land/cable/18
\ No newline at end of file
+[hive-forum-cable]: https://forum.access-hive.org.au/c/land/cable/18