Merge topic 'compiler-features'

7647f6af Add CM_OVERRIDE to some functions
5286110d cxx features: add check for override
09aa2c94 Use <unordered_set> where available
ea5477e4 Make C++ feature checks extensible

5 files changed, 65 insertions, 25 deletions

diff --git a/Source/Checks/cm_cxx11_unordered_map.cmake b/Source/Checks/cm_cxx11_unordered_map.cmake
deleted file mode 100644
index 80fe391..0000000
--- a/Source/Checks/cm_cxx11_unordered_map.cmake
+++ /dev/null
@@ -1,25 +0,0 @@
-
-if(CMAKE_CXX_STANDARD AND NOT DEFINED CMake_HAVE_CXX11_UNORDERED_MAP)
-  message(STATUS "Checking if compiler supports C++11 unordered_map")
-  try_compile(CMake_HAVE_CXX11_UNORDERED_MAP
-    ${CMAKE_CURRENT_BINARY_DIR}
-    ${CMAKE_CURRENT_LIST_DIR}/cm_cxx11_unordered_map.cpp
-    CMAKE_FLAGS -DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD}
-    OUTPUT_VARIABLE OUTPUT
-    )
-  if(CMake_HAVE_CXX11_UNORDERED_MAP)
-    message(STATUS "Checking if compiler supports C++11 unordered_map - yes")
-    file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
-      "Determining if compiler supports C++11 unordered_map passed with the following output:\n"
-      "${OUTPUT}\n"
-      "\n"
-      )
-  else()
-    message(STATUS "Checking if compiler supports C++11 unordered_map - no")
-    file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
-      "Determining if compiler supports C++11 unordered_map failed with the following output:\n"
-      "${OUTPUT}\n"
-      "\n"
-      )
-  endif()
-endif()
diff --git a/Source/Checks/cm_cxx_features.cmake b/Source/Checks/cm_cxx_features.cmake
new file mode 100644
index 0000000..18dbaf8
--- /dev/null
+++ b/Source/Checks/cm_cxx_features.cmake
@@ -0,0 +1,38 @@
+
+function(cm_check_cxx_feature name)
+  string(TOUPPER ${name} FEATURE)
+  if(NOT DEFINED CMake_HAVE_CXX_${FEATURE})
+    message(STATUS "Checking if compiler supports C++ ${name}")
+    try_compile(CMake_HAVE_CXX_${FEATURE}
+      ${CMAKE_CURRENT_BINARY_DIR}
+      ${CMAKE_CURRENT_LIST_DIR}/cm_cxx_${name}.cxx
+      CMAKE_FLAGS -DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD}
+      OUTPUT_VARIABLE OUTPUT
+      )
+    # If using the feature causes warnings, treat it as broken/unavailable.
+    if(OUTPUT MATCHES "warning")
+      set(CMake_HAVE_CXX_${FEATURE} OFF CACHE INTERNAL "TRY_COMPILE" FORCE)
+    endif()
+    if(CMake_HAVE_CXX_${FEATURE})
+      message(STATUS "Checking if compiler supports C++ ${name} - yes")
+      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
+        "Determining if compiler supports C++ ${name} passed with the following output:\n"
+        "${OUTPUT}\n"
+        "\n"
+        )
+    else()
+      message(STATUS "Checking if compiler supports C++ ${name} - no")
+      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
+        "Determining if compiler supports C++ ${name} failed with the following output:\n"
+        "${OUTPUT}\n"
+        "\n"
+        )
+    endif()
+  endif()
+endfunction()
+
+if(CMAKE_CXX_STANDARD)
+  cm_check_cxx_feature(override)
+  cm_check_cxx_feature(unordered_map)
+  cm_check_cxx_feature(unordered_set)
+endif()
diff --git a/Source/Checks/cm_cxx_override.cxx b/Source/Checks/cm_cxx_override.cxx
new file mode 100644
index 0000000..9395a0a
--- /dev/null
+++ b/Source/Checks/cm_cxx_override.cxx
@@ -0,0 +1,20 @@
+struct Foo
+{
+  virtual int test() const = 0;
+};
+
+struct Bar : Foo
+{
+  int test() const override { return 0; }
+};
+
+int test(Foo const& foo)
+{
+  return foo.test();
+}
+
+int main()
+{
+  Bar const bar;
+  return test(bar);
+}
diff --git a/Source/Checks/cm_cxx11_unordered_map.cpp b/Source/Checks/cm_cxx_unordered_map.cxx
index be3de25..be3de25 100644
--- a/Source/Checks/cm_cxx11_unordered_map.cpp
+++ b/Source/Checks/cm_cxx_unordered_map.cxx
diff --git a/Source/Checks/cm_cxx_unordered_set.cxx b/Source/Checks/cm_cxx_unordered_set.cxx
new file mode 100644
index 0000000..de4bb77
--- /dev/null
+++ b/Source/Checks/cm_cxx_unordered_set.cxx
@@ -0,0 +1,7 @@
+#include <unordered_set>
+int main()
+{
+  std::unordered_set<int> set;
+  set.insert(0);
+  return 0;
+}