Merge topic 'ExternalProject_independent-step-targets'

468fb734 Help: Add notes for topic 'ExternalProject_independent-step-targets'
67cfbf8e ExternalProject: Add unit tests
f598f1aa ExternalProject: Add ExternalProject_Add_StepDependencies function
4ae133e0 ExternalProject: Add independent step targets

8 files changed, 211 insertions, 16 deletions

diff --git a/Help/release/dev/ExternalProject_independent-step-targets.rst b/Help/release/dev/ExternalProject_independent-step-targets.rst
new file mode 100644
index 0000000000..02e8db8385
--- /dev/null
+++ b/Help/release/dev/ExternalProject_independent-step-targets.rst
@@ -0,0 +1,6 @@
+ExternalProject_independent-step-targets
+----------------------------------------
+
+* The :module:`ExternalProject` module learned options to create
+  independent external project step targets that do not depend
+  on the builtin steps.
diff --git a/Modules/ExternalProject.cmake b/Modules/ExternalProject.cmake
index 3d1ab34ae8..851343799a 100644
--- a/Modules/ExternalProject.cmake
+++ b/Modules/ExternalProject.cmake
@@ -166,6 +166,9 @@ Create custom targets to build projects in external trees
 
   ``STEP_TARGETS <step-target>...``
     Generate custom targets for these steps
+  ``INDEPENDENT_STEP_TARGETS <step-target>...``
+    Generate custom targets for these steps that do not depend on other
+    external projects even if a dependency is set
 
   The ``*_DIR`` options specify directories for the project, with default
   directories computed as follows.  If the ``PREFIX`` option is given to
@@ -260,18 +263,30 @@ not defined.  Behavior of shell operators like ``&&`` is not defined.
   The ``ExternalProject_Add_StepTargets`` function generates custom
   targets for the steps listed::
 
-    ExternalProject_Add_StepTargets(<name> [step1 [step2 [...]]])
-
-If ``STEP_TARGETS`` is set then ``ExternalProject_Add_StepTargets`` is
-automatically called at the end of matching calls to
-``ExternalProject_Add_Step``.  Pass ``STEP_TARGETS`` explicitly to
+    ExternalProject_Add_StepTargets(<name> [NO_DEPENDS] [step1 [step2 [...]]])
+
+If ``NO_DEPENDS`` is set, the target will not depend on the
+dependencies of the complete project. This is usually safe to use for
+the download, update, and patch steps that do not require that all the
+dependencies are updated and built.  Using ``NO_DEPENDS`` for other
+of the default steps might break parallel builds, so you should avoid,
+it.  For custom steps, you should consider whether or not the custom
+commands requires that the dependencies are configured, built and
+installed.
+
+If ``STEP_TARGETS`` or ``INDEPENDENT_STEP_TARGETS`` is set then
+``ExternalProject_Add_StepTargets`` is automatically called at the end
+of matching calls to ``ExternalProject_Add_Step``.  Pass
+``STEP_TARGETS`` or ``INDEPENDENT_STEP_TARGETS`` explicitly to
 individual ``ExternalProject_Add`` calls, or implicitly to all
-``ExternalProject_Add`` calls by setting the directory property
-``EP_STEP_TARGETS``.
+``ExternalProject_Add`` calls by setting the directory properties
+``EP_STEP_TARGETS`` and ``EP_INDEPENDENT_STEP_TARGETS``.  The
+``INDEPENDENT`` version of the argument and of the property will call
+``ExternalProject_Add_StepTargets`` with the ``NO_DEPENDS`` argument.
 
-If ``STEP_TARGETS`` is not set, clients may still manually call
-``ExternalProject_Add_StepTargets`` after calling
-``ExternalProject_Add`` or ``ExternalProject_Add_Step``.
+If ``STEP_TARGETS`` and ``INDEPENDENT_STEP_TARGETS`` are not set,
+clients may still manually call ``ExternalProject_Add_StepTargets``
+after calling ``ExternalProject_Add`` or ``ExternalProject_Add_Step``.
 
 This functionality is provided to make it easy to drive the steps
 independently of each other by specifying targets on build command
@@ -288,6 +303,19 @@ line prior to any ``ExternalProject_Add`` calls in your ``CMakeLists.txt``
 file::
 
  set_property(DIRECTORY PROPERTY EP_STEP_TARGETS configure build test)
+
+.. command:: ExternalProject_Add_StepDependencies
+
+  The ``ExternalProject_Add_StepDependencies`` function add some
+  dependencies for some external project step::
+
+    ExternalProject_Add_StepDependencies(<name> <step> [target1 [target2 [...]]])
+
+  This function takes care to set both target and file level
+  dependencies, and will ensure that parallel builds will not break.
+  It should be used instead of :command:`add_dependencies()` when adding
+  a dependency for some of the step targets generated by
+  ``ExternalProject``.
 #]=======================================================================]
 
 #=============================================================================
@@ -397,10 +425,19 @@ define_property(DIRECTORY PROPERTY "EP_STEP_TARGETS" INHERITED
   BRIEF_DOCS
   "List of ExternalProject steps that automatically get corresponding targets"
   FULL_DOCS
+  "These targets will be dependent on the main target dependencies"
   "See documentation of the ExternalProject_Add_StepTargets() function in the "
   "ExternalProject module."
   )
 
+define_property(DIRECTORY PROPERTY "EP_INDEPENDENT_STEP_TARGETS" INHERITED
+  BRIEF_DOCS
+  "List of ExternalProject steps that automatically get corresponding targets"
+  FULL_DOCS
+  "These targets will not be dependent on the main target dependencies"
+  "See documentation of the ExternalProject_Add_StepTargets() function in the "
+  "ExternalProject module."
+  )
 
 function(_ep_write_gitclone_script script_filename source_dir git_EXECUTABLE git_repository git_tag git_submodules src_name work_dir gitclone_infofile gitclone_stampfile)
   file(WRITE ${script_filename}
@@ -1283,19 +1320,28 @@ endfunction()
 
 function(ExternalProject_Add_StepTargets name)
   set(steps ${ARGN})
-
+  if("${ARGV1}" STREQUAL "NO_DEPENDS")
+    set(no_deps 1)
+    list(REMOVE_AT steps 0)
+  endif()
   foreach(step ${steps})
+    if(no_deps  AND  "${step}" MATCHES "^(configure|build|install|test)$")
+      message(AUTHOR_WARNING "Using NO_DEPENDS for \"${step}\" step  might break parallel builds")
+    endif()
     _ep_get_step_stampfile(${name} ${step} stamp_file)
     add_custom_target(${name}-${step}
       DEPENDS ${stamp_file})
+    set_property(TARGET ${name}-${step} PROPERTY _EP_IS_EXTERNAL_PROJECT_STEP 1)
     set_property(TARGET ${name}-${step} PROPERTY LABELS ${name})
     set_property(TARGET ${name}-${step} PROPERTY FOLDER "ExternalProjectTargets/${name}")
 
     # Depend on other external projects (target-level).
-    get_property(deps TARGET ${name} PROPERTY _EP_DEPENDS)
-    foreach(arg IN LISTS deps)
-      add_dependencies(${name}-${step} ${arg})
-    endforeach()
+    if(NOT no_deps)
+      get_property(deps TARGET ${name} PROPERTY _EP_DEPENDS)
+      foreach(arg IN LISTS deps)
+        add_dependencies(${name}-${step} ${arg})
+      endforeach()
+    endif()
   endforeach()
 endfunction()
 
@@ -1386,6 +1432,7 @@ function(ExternalProject_Add_Step name step)
     WORKING_DIRECTORY ${work_dir}
     VERBATIM
     )
+  set_property(TARGET ${name} APPEND PROPERTY _EP_STEPS ${step})
 
   # Add custom "step target"?
   get_property(step_targets TARGET ${name} PROPERTY _EP_STEP_TARGETS)
@@ -1398,6 +1445,60 @@ function(ExternalProject_Add_Step name step)
       break()
     endif()
   endforeach()
+
+  get_property(independent_step_targets TARGET ${name} PROPERTY _EP_INDEPENDENT_STEP_TARGETS)
+  if(NOT independent_step_targets)
+    get_property(independent_step_targets DIRECTORY PROPERTY EP_INDEPENDENT_STEP_TARGETS)
+  endif()
+  foreach(st ${independent_step_targets})
+    if("${st}" STREQUAL "${step}")
+      ExternalProject_Add_StepTargets(${name} NO_DEPENDS ${step})
+      break()
+    endif()
+  endforeach()
+endfunction()
+
+
+function(ExternalProject_Add_StepDependencies name step)
+  set(dependencies ${ARGN})
+
+  # Sanity checks on "name" and "step".
+  if(NOT TARGET ${name})
+    message(FATAL_ERROR "Cannot find target \"${name}\". Perhaps it has not yet been created using ExternalProject_Add.")
+  endif()
+
+  get_property(is_ep TARGET ${name} PROPERTY _EP_IS_EXTERNAL_PROJECT)
+  if(NOT is_ep)
+    message(FATAL_ERROR "Target \"${name}\" was not generated by ExternalProject_Add.")
+  endif()
+
+  get_property(steps TARGET ${name} PROPERTY _EP_STEPS)
+  list(FIND steps ${step} is_step)
+  if(NOT is_step)
+    message(FATAL_ERROR "External project \"${name}\" does not have a step \"${step}\".")
+  endif()
+
+  if(TARGET ${name}-${step})
+    get_property(is_ep_step TARGET ${name}-${step} PROPERTY _EP_IS_EXTERNAL_PROJECT_STEP)
+    if(NOT is_ep_step)
+      message(FATAL_ERROR "Target \"${name}\" was not generated by ExternalProject_Add_StepTargets.")
+    endif()
+  endif()
+
+  # Always add file-level dependency, but add target-level dependency
+  # only if the target exists for that step.
+  _ep_get_step_stampfile(${name} ${step} stamp_file)
+  foreach(dep ${dependencies})
+    add_custom_command(APPEND
+      OUTPUT ${stamp_file}
+      DEPENDS ${dep})
+    if(TARGET ${name}-${step})
+      foreach(dep ${dependencies})
+        add_dependencies(${name}-${step} ${dep})
+      endforeach()
+    endif()
+  endforeach()
+
 endfunction()
 
 
diff --git a/Tests/ExternalProjectUpdate/CMakeLists.txt b/Tests/ExternalProjectUpdate/CMakeLists.txt
index c33e90b51b..582b0a87dd 100644
--- a/Tests/ExternalProjectUpdate/CMakeLists.txt
+++ b/Tests/ExternalProjectUpdate/CMakeLists.txt
@@ -19,6 +19,7 @@ set(base "${CMAKE_BINARY_DIR}/CMakeExternals")
 set(binary_base "${base}/Build")
 set_property(DIRECTORY PROPERTY EP_BASE ${base})
 set_property(DIRECTORY PROPERTY EP_STEP_TARGETS configure build test)
+set_property(DIRECTORY PROPERTY EP_INDEPENDENT_STEP_TARGETS update)
 
 set(do_git_tests 0)
 
@@ -68,8 +69,8 @@ if(do_git_tests)
     CMAKE_GENERATOR "${CMAKE_GENERATOR}"
     CMAKE_ARGS -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>
     INSTALL_COMMAND ""
-    DEPENDS "SetupLocalGITRepository"
   )
+  ExternalProject_Add_StepDependencies(${proj} download SetupLocalGITRepository)
   set_property(TARGET ${proj} PROPERTY FOLDER "GIT")
 endif()
 
diff --git a/Tests/RunCMake/ExternalProject/Add_StepDependencies.cmake b/Tests/RunCMake/ExternalProject/Add_StepDependencies.cmake
new file mode 100644
index 0000000000..38683f12ed
--- /dev/null
+++ b/Tests/RunCMake/ExternalProject/Add_StepDependencies.cmake
@@ -0,0 +1,20 @@
+cmake_minimum_required(VERSION ${CMAKE_VERSION})
+
+include(ExternalProject)
+
+ExternalProject_Add(BAR URL https://cmake.org/bar.tar.gz)
+
+ExternalProject_Add(FOO URL https://cmake.org/foo.tar.gz STEP_TARGETS update)
+ExternalProject_Add_Step(FOO do_something COMMAND ${CMAKE_COMMAND} -E echo "Doing something")
+ExternalProject_Add_Step(FOO do_something_else COMMAND ${CMAKE_COMMAND} -E echo "Doing something else")
+ExternalProject_Add_StepTargets(FOO do_something)
+
+# download and do_something_else are not targets, but the file-level
+# dependency are set.
+ExternalProject_Add_StepDependencies(FOO download BAR)
+ExternalProject_Add_StepDependencies(FOO do_something_else BAR)
+
+# update and do_something are targets, therefore both file-level and
+# target-level dependencies are set.
+ExternalProject_Add_StepDependencies(FOO update BAR)
+ExternalProject_Add_StepDependencies(FOO do_something BAR)
diff --git a/Tests/RunCMake/ExternalProject/Add_StepDependencies_no_target.cmake b/Tests/RunCMake/ExternalProject/Add_StepDependencies_no_target.cmake
new file mode 100644
index 0000000000..264c3f04c7
--- /dev/null
+++ b/Tests/RunCMake/ExternalProject/Add_StepDependencies_no_target.cmake
@@ -0,0 +1,10 @@
+cmake_minimum_required(VERSION ${CMAKE_VERSION})
+
+include(ExternalProject)
+
+ExternalProject_Add(BAR URL https://cmake.org/bar.tar.gz)
+
+ExternalProject_Add(FOO URL https://cmake.org/foo.tar.gz STEP_TARGETS update)
+ExternalProject_Add_Step(FOO do_something COMMAND ${CMAKE_COMMAND} -E echo "Doing something")
+ExternalProject_Add_Step(FOO do_something_else COMMAND ${CMAKE_COMMAND} -E echo "Doing something else")
+ExternalProject_Add_StepTargets(FOO do_something)
diff --git a/Tests/RunCMake/ExternalProject/NO_DEPENDS-stderr.txt b/Tests/RunCMake/ExternalProject/NO_DEPENDS-stderr.txt
new file mode 100644
index 0000000000..4cb051dbb0
--- /dev/null
+++ b/Tests/RunCMake/ExternalProject/NO_DEPENDS-stderr.txt
@@ -0,0 +1,36 @@
+CMake Warning \(dev\) at .*/Modules/ExternalProject.cmake:[0-9]+. \(message\):
+  Using NO_DEPENDS for "configure" step might break parallel builds
+Call Stack \(most recent call first\):
+  .*/Modules/ExternalProject.cmake:[0-9]+ \(ExternalProject_Add_StepTargets\)
+  .*/Modules/ExternalProject.cmake:[0-9]+ \(ExternalProject_Add_Step\)
+  .*/Modules/ExternalProject.cmake:[0-9]+ \(_ep_add_configure_command\)
+  NO_DEPENDS.cmake:[0-9]+ \(ExternalProject_Add\)
+  CMakeLists.txt:[0-9]+ \(include\)
+This warning is for project developers.  Use -Wno-dev to suppress it.
+
+CMake Warning \(dev\) at .*/Modules/ExternalProject.cmake:[0-9]+. \(message\):
+  Using NO_DEPENDS for "build" step might break parallel builds
+Call Stack \(most recent call first\):
+  .*/Modules/ExternalProject.cmake:[0-9]+ \(ExternalProject_Add_StepTargets\)
+  .*/Modules/ExternalProject.cmake:[0-9]+ \(ExternalProject_Add_Step\)
+  .*/Modules/ExternalProject.cmake:[0-9]+ \(_ep_add_build_command\)
+  NO_DEPENDS.cmake:[0-9]+ \(ExternalProject_Add\)
+  CMakeLists.txt:[0-9]+ \(include\)
+This warning is for project developers.  Use -Wno-dev to suppress it.
+
+CMake Warning \(dev\) at .*/Modules/ExternalProject.cmake:[0-9]+. \(message\):
+  Using NO_DEPENDS for "install" step might break parallel builds
+Call Stack \(most recent call first\):
+  .*/Modules/ExternalProject.cmake:[0-9]+ \(ExternalProject_Add_StepTargets\)
+  .*/Modules/ExternalProject.cmake:[0-9]+ \(ExternalProject_Add_Step\)
+  .*/Modules/ExternalProject.cmake:[0-9]+ \(_ep_add_install_command\)
+  NO_DEPENDS.cmake:[0-9]+ \(ExternalProject_Add\)
+  CMakeLists.txt:[0-9]+ \(include\)
+This warning is for project developers.  Use -Wno-dev to suppress it.
+
+CMake Warning \(dev\) at .*/Modules/ExternalProject.cmake:[0-9]+. \(message\):
+  Using NO_DEPENDS for "test" step might break parallel builds
+Call Stack \(most recent call first\):
+  NO_DEPENDS.cmake:[0-9]+ \(ExternalProject_Add_StepTargets\)
+  CMakeLists.txt:[0-9]+ \(include\)
+This warning is for project developers.  Use -Wno-dev to suppress it.
diff --git a/Tests/RunCMake/ExternalProject/NO_DEPENDS.cmake b/Tests/RunCMake/ExternalProject/NO_DEPENDS.cmake
new file mode 100644
index 0000000000..57626d679c
--- /dev/null
+++ b/Tests/RunCMake/ExternalProject/NO_DEPENDS.cmake
@@ -0,0 +1,18 @@
+cmake_minimum_required(VERSION 2.8.12)
+
+include(ExternalProject RESULT_VARIABLE GOO)
+
+set_property(DIRECTORY PROPERTY EP_INDEPENDENT_STEP_TARGETS download patch update configure build)
+
+ExternalProject_Add(FOO
+                    URL https://example.org/foo.tar.gz)
+
+ExternalProject_Add(BAR
+                    URL https://example.org/bar.tar.gz
+                    TEST_COMMAND echo test
+                    INDEPENDENT_STEP_TARGETS install)
+# This one should not give a warning
+ExternalProject_Add_Step(BAR bar
+                         COMMAND echo bar)
+
+ExternalProject_Add_StepTargets(BAR NO_DEPENDS test bar)
diff --git a/Tests/RunCMake/ExternalProject/RunCMakeTest.cmake b/Tests/RunCMake/ExternalProject/RunCMakeTest.cmake
index 1614eccaf0..0f5dcefb75 100644
--- a/Tests/RunCMake/ExternalProject/RunCMakeTest.cmake
+++ b/Tests/RunCMake/ExternalProject/RunCMakeTest.cmake
@@ -3,3 +3,6 @@ include(RunCMake)
 run_cmake(CMAKE_CACHE_ARGS)
 run_cmake(CMAKE_CACHE_DEFAULT_ARGS)
 run_cmake(CMAKE_CACHE_mix)
+run_cmake(NO_DEPENDS)
+run_cmake(Add_StepDependencies)
+run_cmake(Add_StepDependencies_no_target)