Alternative symlink-creating mode for file(INSTALL ...)

An new environment variable 'CMAKE_INSTALL_MODE' is introduced,
which can be used to ask CMake to create symbolic links
instead of copying files during a file(INSTALL ...).

The operation is at the file level only, directory trees are
still created using actual directories, not links.

Signed-off-by: Felix Lelchuk <felix.lelchuk@gmx.de>

1 files changed, 76 insertions, 0 deletions

diff --git a/Tests/InstallMode/Subproject.cmake b/Tests/InstallMode/Subproject.cmake
new file mode 100644
index 0000000..e4354d6
--- /dev/null
+++ b/Tests/InstallMode/Subproject.cmake
@@ -0,0 +1,76 @@
+include(ExternalProject)
+
+# add_subproject(<name> [NO_INSTALL] [DIR <dirname>] [DEPENDS [subpro_dep ...]])
+function(add_subproject _name)
+  cmake_parse_arguments(_arg "NO_INSTALL" "DIR" "DEPENDS" ${ARGN})
+
+  if(_arg_UNPARSED_ARGUMENTS)
+    message(FATAL_ERROR "There are unparsed arguments")
+  endif()
+
+  set(_maybe_NO_INSTALL)
+  if(_arg_NO_INSTALL)
+    set(_maybe_NO_INSTALL "INSTALL_COMMAND")
+  else()
+    # This is a trick to get a valid call.
+    # Since we set UPDATE_COMMAND to ""
+    # explicitly below, this won't harm.
+    set(_maybe_NO_INSTALL "UPDATE_COMMAND")
+  endif()
+
+  if(CMAKE_GENERATOR MATCHES "Ninja Multi-Config")
+    # Replace list separator before passing on to ExternalProject_Add
+    string(REPLACE ";" "|" _CONFIGURATION_TYPES "${CMAKE_CONFIGURATION_TYPES}")
+    string(REPLACE ";" "|" _CROSS_CONFIGS "${CMAKE_CROSS_CONFIGS}")
+    string(REPLACE ";" "|" _DEFAULT_CONFIGS "${CMAKE_DEFAULT_CONFIGS}")
+
+    set(_maybe_NINJA_MULTICONFIG_ARGS
+      "-DCMAKE_CONFIGURATION_TYPES:STRINGS=${_CONFIGURATION_TYPES}"
+      "-DCMAKE_CROSS_CONFIGS:STRINGS=${_CROSS_CONFIGS}"
+      "-DCMAKE_DEFAULT_BUILD_TYPE:STRING=${CMAKE_DEFAULT_BUILD_TYPE}"
+      "-DCMAKE_DEFAULT_CONFIGS:STRINGS=${_DEFAULT_CONFIGS}"
+    )
+  endif()
+
+  ExternalProject_Add("${_name}"
+    DOWNLOAD_COMMAND      ""
+    UPDATE_COMMAND        ""
+    ${_maybe_NO_INSTALL}  ""
+
+    BUILD_ALWAYS          ON
+
+    LOG_DOWNLOAD          OFF
+    LOG_UPDATE            OFF
+    LOG_PATCH             OFF
+    LOG_CONFIGURE         OFF
+    LOG_BUILD             OFF
+    LOG_INSTALL           OFF
+
+    SOURCE_DIR            "${PROJECT_SOURCE_DIR}/${_arg_DIR}"
+
+    # Private build directory per subproject
+    BINARY_DIR            "${PROJECT_BINARY_DIR}/subproject/${_arg_DIR}"
+
+    # Common install directory, populated immediately
+    # during build (during build - not install - of superproject)
+    INSTALL_DIR           "${CMAKE_INSTALL_PREFIX}"
+
+    DEPENDS
+      ${_arg_DEPENDS}
+
+    LIST_SEPARATOR "|"
+    CMAKE_ARGS
+      "-DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>"
+
+      # We can rely on ExternalProject to pick the right
+      # generator (and architecture/toolset where applicable),
+      # however, we need to explicitly inherit other parent
+      # project's build settings.
+      "-DCMAKE_BUILD_TYPE:STRING=${CMAKE_BUILD_TYPE}"
+      ${_maybe_NINJA_MULTICONFIG_ARGS}
+
+      # Subproject progress reports clutter up the output, disable
+      "-DCMAKE_TARGET_MESSAGES:BOOL=OFF"
+      "-DCMAKE_RULE_MESSAGES:BOOL=OFF"
+  )
+endfunction()