4 files changed, 40 insertions, 0 deletions
diff --git a/Source/Checks/cm_cxx_attribute_fallthrough.cxx b/Source/Checks/cm_cxx_attribute_fallthrough.cxx
new file mode 100644
index 0000000..df43625
--- /dev/null
+++ b/Source/Checks/cm_cxx_attribute_fallthrough.cxx
@@ -0,0 +1,11 @@
+int main(int argc, char* argv[])
+{
+  int i = 3;
+  switch (argc) {
+    case 1:
+      i = 0;
+      __attribute__((fallthrough));
+    default:
+      return i;
+  }
+}
diff --git a/Source/Checks/cm_cxx_fallthrough.cxx b/Source/Checks/cm_cxx_fallthrough.cxx
new file mode 100644
index 0000000..7b35a5f
--- /dev/null
+++ b/Source/Checks/cm_cxx_fallthrough.cxx
@@ -0,0 +1,11 @@
+int main(int argc, char* argv[])
+{
+  int i = 3;
+  switch (argc) {
+    case 1:
+      i = 0;
+      [[fallthrough]];
+    default:
+      return i;
+  }
+}
diff --git a/Source/Checks/cm_cxx_features.cmake b/Source/Checks/cm_cxx_features.cmake
index 76c823c..c3835c3 100644
--- a/Source/Checks/cm_cxx_features.cmake
+++ b/Source/Checks/cm_cxx_features.cmake
@@ -38,6 +38,13 @@ endfunction()
 
 cm_check_cxx_feature(auto_ptr)
 cm_check_cxx_feature(eq_delete)
+cm_check_cxx_feature(fallthrough)
+if(NOT CMake_HAVE_CXX_FALLTHROUGH)
+  cm_check_cxx_feature(gnu_fallthrough)
+  if(NOT CMake_HAVE_CXX_GNU_FALLTHROUGH)
+    cm_check_cxx_feature(attribute_fallthrough)
+  endif()
+endif()
 cm_check_cxx_feature(make_unique)
 if(CMake_HAVE_CXX_MAKE_UNIQUE)
   set(CMake_HAVE_CXX_UNIQUE_PTR 1)
diff --git a/Source/Checks/cm_cxx_gnu_fallthrough.cxx b/Source/Checks/cm_cxx_gnu_fallthrough.cxx
new file mode 100644
index 0000000..6021094
--- /dev/null
+++ b/Source/Checks/cm_cxx_gnu_fallthrough.cxx
@@ -0,0 +1,11 @@
+int main(int argc, char* argv[])
+{
+  int i = 3;
+  switch (argc) {
+    case 1:
+      i = 0;
+      [[gnu::fallthrough]];
+    default:
+      return i;
+  }
+}