12 files changed, 117 insertions, 103 deletions
diff --git a/Help/variable/CMAKE_LINK_DEPENDS_USE_LINKER.rst b/Help/variable/CMAKE_LINK_DEPENDS_USE_LINKER.rst
index e1b37a5..1867ad8 100644
--- a/Help/variable/CMAKE_LINK_DEPENDS_USE_LINKER.rst
+++ b/Help/variable/CMAKE_LINK_DEPENDS_USE_LINKER.rst
@@ -10,3 +10,11 @@ variable with value ``FALSE``, you can deactivate this feature.
 
 This feature is also deactivated if the :prop_tgt:`LINK_DEPENDS_NO_SHARED`
 target property is true.
+
+.. note::
+
+  CMake version |release| defaults this variable to ``FALSE`` because
+  GNU binutils linkers (``ld``, ``ld.bfd``, ``ld.gold``) generate spurious
+  dependencies on temporary files when LTO is enabled.  See `GNU bug 30568`_.
+
+.. _`GNU bug 30568`: https://sourceware.org/bugzilla/show_bug.cgi?id=30568
diff --git a/Modules/Compiler/GNU.cmake b/Modules/Compiler/GNU.cmake
index 251e05a..d01054b 100644
--- a/Modules/Compiler/GNU.cmake
+++ b/Modules/Compiler/GNU.cmake
@@ -53,6 +53,9 @@ macro(__compiler_gnu lang)
   endif()
 
   # define flags for linker depfile generation
+  set(CMAKE_${lang}_LINKER_DEPFILE_FLAGS "LINKER:--dependency-file,<DEP_FILE>")
+  set(CMAKE_${lang}_LINKER_DEPFILE_FORMAT gcc)
+
   if(NOT DEFINED CMAKE_${lang}_LINKER_DEPFILE_SUPPORTED)
     ## Ensure ninja tool is recent enough...
     if(CMAKE_GENERATOR MATCHES "^Ninja")
@@ -82,15 +85,19 @@ macro(__compiler_gnu lang)
       unset(_linker_capabilities)
     endif()
   endif()
-
   if (CMAKE_${lang}_LINKER_DEPFILE_SUPPORTED)
-    set(CMAKE_${lang}_LINKER_DEPFILE_FLAGS "LINKER:--dependency-file,<DEP_FILE>")
-    set(CMAKE_${lang}_LINKER_DEPFILE_FORMAT gcc)
     set(CMAKE_${lang}_LINK_DEPENDS_USE_LINKER TRUE)
   else()
     unset(CMAKE_${lang}_LINK_DEPENDS_USE_LINKER)
   endif()
 
+  # For now, due to GNU binutils ld bug when LTO is enabled (see GNU bug
+    # `30568 <https://sourceware.org/bugzilla/show_bug.cgi?id=30568>`_),
+  # deactivate this feature.
+  if (NOT DEFINED CMAKE_LINK_DEPENDS_USE_LINKER)
+    set(CMAKE_LINK_DEPENDS_USE_LINKER FALSE)
+  endif()
+
   # Initial configuration flags.
   string(APPEND CMAKE_${lang}_FLAGS_INIT " ")
   string(APPEND CMAKE_${lang}_FLAGS_DEBUG_INIT " -g")
diff --git a/Modules/Compiler/NVHPC-Fortran.cmake b/Modules/Compiler/NVHPC-Fortran.cmake
index 59755b3..ca5f1b2 100644
--- a/Modules/Compiler/NVHPC-Fortran.cmake
+++ b/Modules/Compiler/NVHPC-Fortran.cmake
@@ -1,3 +1,7 @@
 include(Compiler/PGI-Fortran)
 include(Compiler/NVHPC)
 __compiler_nvhpc(Fortran)
+if(CMAKE_Fortran_COMPILER_VERSION VERSION_LESS 21.7)
+  # Before NVHPC 21.7 nvfortran didn't support isystem
+  unset(CMAKE_INCLUDE_SYSTEM_FLAG_Fortran)
+endif()
diff --git a/Modules/FindCxxTest.cmake b/Modules/FindCxxTest.cmake
index 04f8b59..714927f 100644
--- a/Modules/FindCxxTest.cmake
+++ b/Modules/FindCxxTest.cmake
@@ -7,136 +7,119 @@ FindCxxTest
 
 Find CxxTest unit testing framework.
 
-Find the CxxTest suite and declare a helper macro for creating unit
-tests and integrating them with CTest.  For more details on CxxTest
-see https://cxxtest.com
+Find the `CxxTest`_ suite and declare a helper macro for creating
+unit tests and integrating them with CTest.
 
-INPUT Variables
+.. _`CxxTest`: https://github.com/CxxTest/cxxtest#readme
 
-::
+Input Variables
+^^^^^^^^^^^^^^^
 
-   CXXTEST_USE_PYTHON [deprecated since 1.3]
-       Only used in the case both Python & Perl
-       are detected on the system to control
-       which CxxTest code generator is used.
-       Valid only for CxxTest version 3.
+``CXXTEST_USE_PYTHON``
+  .. deprecated:: 1.3
 
+  Only used in the case both Python & Perl
+  are detected on the system to control
+  which CxxTest code generator is used.
+  Valid only for CxxTest version 3.
 
+  In older versions of this Find Module,
+  this variable controlled if the Python test
+  generator was used instead of the Perl one,
+  regardless of which scripting language the
+  user had installed.
 
-::
+``CXXTEST_TESTGEN_ARGS``
+  .. versionadded:: 2.8.3
 
-       NOTE: In older versions of this Find Module,
-       this variable controlled if the Python test
-       generator was used instead of the Perl one,
-       regardless of which scripting language the
-       user had installed.
+  Specify a list of options to pass to the CxxTest code
+  generator.  If not defined, ``--error-printer`` is passed.
 
+Result Variables
+^^^^^^^^^^^^^^^^
 
+``CXXTEST_FOUND``
+  True if the CxxTest framework was found
 
-::
+``CXXTEST_INCLUDE_DIRS``
+  Where to find the CxxTest include directory
 
-   CXXTEST_TESTGEN_ARGS (since CMake 2.8.3)
-       Specify a list of options to pass to the CxxTest code
-       generator.  If not defined, --error-printer is
-       passed.
+``CXXTEST_PERL_TESTGEN_EXECUTABLE``
+  The perl-based test generator
 
+``CXXTEST_PYTHON_TESTGEN_EXECUTABLE``
+  The python-based test generator
 
+``CXXTEST_TESTGEN_EXECUTABLE``
+  .. versionadded:: 2.8.3
 
-OUTPUT Variables
+  The test generator that is actually used (chosen using user preferences
+  and interpreters found in the system)
 
-::
+``CXXTEST_TESTGEN_INTERPRETER``
+  .. versionadded:: 2.8.3
 
-   CXXTEST_FOUND
-       True if the CxxTest framework was found
-   CXXTEST_INCLUDE_DIRS
-       Where to find the CxxTest include directory
-   CXXTEST_PERL_TESTGEN_EXECUTABLE
-       The perl-based test generator
-   CXXTEST_PYTHON_TESTGEN_EXECUTABLE
-       The python-based test generator
-   CXXTEST_TESTGEN_EXECUTABLE (since CMake 2.8.3)
-       The test generator that is actually used (chosen using user preferences
-       and interpreters found in the system)
-   CXXTEST_TESTGEN_INTERPRETER (since CMake 2.8.3)
-       The full path to the Perl or Python executable on the system, on
-       platforms where the script cannot be executed using its shebang line.
+  The full path to the Perl or Python executable on the system, on
+  platforms where the script cannot be executed using its shebang line.
 
 
+Module Commands
+^^^^^^^^^^^^^^^
 
-MACROS for optional use by CMake users:
+.. command:: cxxtest_add_test
 
-::
+  Create a CxxTest runner and adds it to the CTest testing suite::
 
-    CXXTEST_ADD_TEST(<test_name> <gen_source_file> <input_files_to_testgen...>)
-       Creates a CxxTest runner and adds it to the CTest testing suite
-       Parameters:
-           test_name               The name of the test
-           gen_source_file         The generated source filename to be
-                                   generated by CxxTest
-           input_files_to_testgen  The list of header files containing the
-                                   CxxTest::TestSuite's to be included in
-                                   this runner
+    CXXTEST_ADD_TEST(<test_name> <gen_source_file>
+                     <input_files_to_testgen>...)
 
+  Parameters:
 
+  ``test_name``
+    The name of the test
 
-::
+  ``gen_source_file``
+    The generated source filename to be generated by CxxTest
 
-       #==============
-       Example Usage:
+  ``input_files_to_testgen``
+    The list of header files containing the CxxTest::TestSuite's
+    to be included in this runner
 
+Example Usage
+^^^^^^^^^^^^^
 
+The following example, if CxxTest is found, will:
 
-::
+* Invoke the testgen executable to autogenerate foo_test.cc in the
+  binary tree from "foo_test.h" in the current source directory.
+* Create an executable and test called unittest_foo.
 
-           find_package(CxxTest)
-           if(CXXTEST_FOUND)
-               include_directories(${CXXTEST_INCLUDE_DIR})
-               enable_testing()
+.. code-block:: cmake
 
+  find_package(CxxTest)
+  if(CXXTEST_FOUND)
+    include_directories(${CXXTEST_INCLUDE_DIR})
+    enable_testing()
+    CXXTEST_ADD_TEST(unittest_foo foo_test.cc
+                     ${CMAKE_CURRENT_SOURCE_DIR}/foo_test.h)
+    target_link_libraries(unittest_foo foo) # as needed
+  endif()
 
+``foo_test.h`` contains:
 
-::
-
-               CXXTEST_ADD_TEST(unittest_foo foo_test.cc
-                                 ${CMAKE_CURRENT_SOURCE_DIR}/foo_test.h)
-               target_link_libraries(unittest_foo foo) # as needed
-           endif()
-
-
-
-::
-
-              This will (if CxxTest is found):
-              1. Invoke the testgen executable to autogenerate foo_test.cc in the
-                 binary tree from "foo_test.h" in the current source directory.
-              2. Create an executable and test called unittest_foo.
-
-
-
-::
-
-      #=============
-      Example foo_test.h:
-
-
-
-::
-
-          #include <cxxtest/TestSuite.h>
-
-
+.. code-block:: c++
 
-::
+  #include <cxxtest/TestSuite.h>
+  class MyTestSuite : public CxxTest::TestSuite
+  {
+  public:
+     void testAddition( void )
+     {
+        TS_ASSERT( 1 + 1 > 1 );
+        TS_ASSERT_EQUALS( 1 + 1, 2 );
+     }
+  };
 
-          class MyTestSuite : public CxxTest::TestSuite
-          {
-          public:
-             void testAddition( void )
-             {
-                TS_ASSERT( 1 + 1 > 1 );
-                TS_ASSERT_EQUALS( 1 + 1, 2 );
-             }
-          };
 #]=======================================================================]
 
 # Version 1.4 (11/18/10) (CMake 2.8.4)
diff --git a/Tests/RunCMake/BuildDepends/LinkDependsCheck.cmake b/Tests/RunCMake/BuildDepends/LinkDependsCheck.cmake
index a21096b..596e1eb 100644
--- a/Tests/RunCMake/BuildDepends/LinkDependsCheck.cmake
+++ b/Tests/RunCMake/BuildDepends/LinkDependsCheck.cmake
@@ -2,7 +2,8 @@
 enable_language(C)
 
 file(WRITE "${CMAKE_BINARY_DIR}/LinkDependsUseLinker.cmake"
-     "set(CMAKE_C_LINK_DEPENDS_USE_LINKER \"${CMAKE_C_LINK_DEPENDS_USE_LINKER}\")\n")
+     "set(CMAKE_LINK_DEPENDS_USE_LINKER ${CMAKE_LINK_DEPENDS_USE_LINKER})
+set(CMAKE_C_LINK_DEPENDS_USE_LINKER ${CMAKE_C_LINK_DEPENDS_USE_LINKER})\n")
 
 
 file(GENERATE  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/check-$<LOWER_CASE:$<CONFIG>>.cmake"
diff --git a/Tests/RunCMake/BuildDepends/RunCMakeTest.cmake b/Tests/RunCMake/BuildDepends/RunCMakeTest.cmake
index dfa4f49..fada37a 100644
--- a/Tests/RunCMake/BuildDepends/RunCMakeTest.cmake
+++ b/Tests/RunCMake/BuildDepends/RunCMakeTest.cmake
@@ -199,12 +199,12 @@ endif()
 run_BuildDepends(CustomCommandUnityBuild)
 unset(run_BuildDepends_skip_step_2)
 
-#if (RunCMake_GENERATOR MATCHES "Make|Ninja" AND CMAKE_C_LINK_DEPENDS_USE_LINKER)
 if (RunCMake_GENERATOR MATCHES "Make|Ninja")
   set(run_BuildDepends_skip_step_2 1)
   run_BuildDepends(LinkDependsCheck)
   include("${RunCMake_BINARY_DIR}/LinkDependsCheck-build/LinkDependsUseLinker.cmake")
-  if (CMAKE_C_LINK_DEPENDS_USE_LINKER)
+  if ((NOT DEFINED CMAKE_LINK_DEPENDS_USE_LINKER OR CMAKE_LINK_DEPENDS_USE_LINKER)
+      AND CMAKE_C_LINK_DEPENDS_USE_LINKER)
     run_BuildDepends(LinkDependsExternalLibrary)
     unset(run_BuildDepends_skip_step_2)
     run_BuildDepends(LinkDepends)
diff --git a/Tests/RunCMake/CMakeLists.txt b/Tests/RunCMake/CMakeLists.txt
index f089a96..63b7568 100644
--- a/Tests/RunCMake/CMakeLists.txt
+++ b/Tests/RunCMake/CMakeLists.txt
@@ -452,7 +452,7 @@ add_RunCMake_test(add_custom_target)
 add_RunCMake_test(add_dependencies)
 add_RunCMake_test(add_executable)
 add_RunCMake_test(add_library)
-add_RunCMake_test(add_subdirectory)
+add_RunCMake_test(add_subdirectory -DCMAKE_Fortran_COMPILER=${CMAKE_Fortran_COMPILER})
 add_RunCMake_test(add_test)
 add_RunCMake_test(build_command)
 add_executable(exit_code exit_code.c)
diff --git a/Tests/RunCMake/add_subdirectory/RunCMakeTest.cmake b/Tests/RunCMake/add_subdirectory/RunCMakeTest.cmake
index ddf45af..3c70d07 100644
--- a/Tests/RunCMake/add_subdirectory/RunCMakeTest.cmake
+++ b/Tests/RunCMake/add_subdirectory/RunCMakeTest.cmake
@@ -3,7 +3,9 @@ include(RunCMake)
 run_cmake(DoesNotExist)
 run_cmake(Missing)
 run_cmake(Function)
+set(RunCMake_TEST_OPTIONS -DCMAKE_Fortran_COMPILER=${CMAKE_Fortran_COMPILER})
 run_cmake(System)
+unset(RunCMake_TEST_OPTIONS)
 
 macro(run_cmake_install case)
   set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/${case}-build)
diff --git a/Tests/RunCMake/add_subdirectory/System.cmake b/Tests/RunCMake/add_subdirectory/System.cmake
index 45d7d9a..1048a7a 100644
--- a/Tests/RunCMake/add_subdirectory/System.cmake
+++ b/Tests/RunCMake/add_subdirectory/System.cmake
@@ -1,4 +1,7 @@
 enable_language(CXX)
+if(CMAKE_Fortran_COMPILER)
+  enable_language(Fortran)
+endif()
 
 add_subdirectory(System SYSTEM)
 
diff --git a/Tests/RunCMake/add_subdirectory/System/CMakeLists.txt b/Tests/RunCMake/add_subdirectory/System/CMakeLists.txt
index ef74e80..8653b6f 100644
--- a/Tests/RunCMake/add_subdirectory/System/CMakeLists.txt
+++ b/Tests/RunCMake/add_subdirectory/System/CMakeLists.txt
@@ -4,6 +4,11 @@ add_subdirectory(SubSub1 SYSTEM)
 add_subdirectory(SubSub2)
 
 add_library(bar STATIC bar.cpp)
+if(CMAKE_Fortran_COMPILER)
+  target_sources(bar PRIVATE zap.f)
+endif()
+# Verify CMAKE_INCLUDE_SYSTEM_FLAG_<LANG> works
+target_link_libraries(bar PRIVATE subsub1bar)
 
 add_library(foo STATIC foo.cpp)
 set_target_properties(foo PROPERTIES SYSTEM OFF)
diff --git a/Tests/RunCMake/add_subdirectory/System/SubSub1/CMakeLists.txt b/Tests/RunCMake/add_subdirectory/System/SubSub1/CMakeLists.txt
index 291339b..24105b0 100644
--- a/Tests/RunCMake/add_subdirectory/System/SubSub1/CMakeLists.txt
+++ b/Tests/RunCMake/add_subdirectory/System/SubSub1/CMakeLists.txt
@@ -1,4 +1,5 @@
 add_library(subsub1bar STATIC bar.cpp)
+target_include_directories(subsub1bar PUBLIC ${CMAKE_CURRENT_BINARY_DIR})
 
 add_library(subsub1foo STATIC foo.cpp)
 set_target_properties(subsub1foo PROPERTIES SYSTEM OFF)
diff --git a/Tests/RunCMake/add_subdirectory/System/zap.f b/Tests/RunCMake/add_subdirectory/System/zap.f
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/Tests/RunCMake/add_subdirectory/System/zap.f