Build: Use interface targets for inheriting flags and definitions

* Remove the usage of global flags and definitions
  set through the CMAKE_CXX_FLAGS variable.
* Use cmake target compile features for setting the
  CXX standard automatically.
* Make C++14 globally available in the project
* Closes #21033

(cherry picked from commit e60c1f84a7e13577a82046b02b214f9466d20a7c)

1 files changed, 62 insertions, 0 deletions

diff --git a/cmake/macros/ConfigureBaseTargets.cmake b/cmake/macros/ConfigureBaseTargets.cmake
new file mode 100644
index 00000000000..ca3773b8f01
--- /dev/null
+++ b/cmake/macros/ConfigureBaseTargets.cmake
@@ -0,0 +1,62 @@
+# Copyright (C) 2008-2017 TrinityCore <http://www.trinitycore.org/>
+#
+# This file is free software; as a special exception the author gives
+# unlimited permission to copy and/or distribute it, with or without
+# modifications, as long as this notice is preserved.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY, to the extent permitted by law; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+# An interface library to make the target com available to other targets
+add_library(trinity-compile-option-interface INTERFACE)
+
+# An interface library to make the target features available to other targets
+add_library(trinity-feature-interface INTERFACE)
+
+target_compile_features(trinity-feature-interface
+  INTERFACE
+    cxx_alias_templates
+    cxx_auto_type
+    cxx_constexpr
+    cxx_decltype
+    cxx_decltype_auto
+    cxx_final
+    cxx_lambdas
+    cxx_generic_lambdas
+    cxx_variadic_templates
+    cxx_defaulted_functions
+    cxx_nullptr
+    cxx_trailing_return_types
+    cxx_return_type_deduction)
+
+# An interface library to make the warnings level available to other targets
+# This interface taget is set-up through the platform specific script
+add_library(trinity-warning-interface INTERFACE)
+
+# An interface amalgamation which provides the flags and definitions
+# used by the dependency targets.
+add_library(trinity-dependency-interface INTERFACE)
+target_link_libraries(trinity-dependency-interface
+  INTERFACE
+    trinity-compile-option-interface
+    trinity-feature-interface)
+
+if(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+  target_compile_options(trinity-dependency-interface
+    INTERFACE
+      /W0)
+else()
+  target_compile_options(trinity-dependency-interface
+    INTERFACE
+      -w)
+endif()
+
+# An interface amalgamation which provides the flags and definitions
+# used by the core targets.
+add_library(trinity-core-interface INTERFACE)
+target_link_libraries(trinity-core-interface
+  INTERFACE
+    trinity-compile-option-interface
+    trinity-feature-interface
+    trinity-warning-interface)