Create a check target to run clang-tidy

This help to run clang-tidy while build
Note: this only check example tree and needs
run-clang-tidy python script from llvm distro!

CMakeLists.txt

@@ -8,6 +8,7 @@ cmake_minimum_required(VERSION 3.2)
 #---------------------------------------------------------------------------------------
 include(cmake/utils.cmake)
 include(cmake/ide.cmake)
+include(cmake/clang-tidy.cmake)
 
 spdlog_extract_version()
 
@@ -180,8 +181,7 @@ if(SPDLOG_WCHAR_SUPPORT)
  endif()
 
  if(SPDLOG_NO_EXCEPTIONS)
-	target_compile_definitions(spdlog PUBLIC SPDLOG_NO_EXCEPTIONS)	
-
+	target_compile_definitions(spdlog PUBLIC SPDLOG_NO_EXCEPTIONS)
 	target_compile_definitions(spdlog_header_only INTERFACE SPDLOG_NO_EXCEPTIONS)
 
     if(NOT MSVC)

cmake/clang-tidy.cmake

@@ -0,0 +1,35 @@
+option(ENABLE_CLANG_TIDY "Add run-clang-tidy automatically to builds" OFF)
+find_program(CLANG_TIDY_EXE
+        NAMES run-clang-tidy.py run-clang-tidy run-clang-tidy-7
+        DOC "Path to clang-tidy executable")
+if(CLANG_TIDY_EXE)
+    message(STATUS "clang-tidy found: ${CLANG_TIDY_EXE}")
+    set(DCMAKE_EXPORT_COMPILE_COMMANDS ON)
+    set(CLANG_TIDY_CMD ${CLANG_TIDY_EXE})
+    message(STATUS "cmake source dir: ${CMAKE_SOURCE_DIR}")
+
+    if(ENABLE_CLANG_TIDY)
+        # NOTE: the project config file .clang-tidy is not found if the
+        # binary tree is not part of the source tree! CK
+        set(CMAKE_CXX_CLANG_TIDY ${CLANG_TIDY_CMD} CACHE STRING "" FORCE)
+    else()
+        set(CMAKE_CXX_CLANG_TIDY "" CACHE STRING "" FORCE) # delete it
+    endif()
+
+    if(NOT TARGET check)
+        add_custom_target(check)
+        message(STATUS "check target added")
+        set_target_properties(check PROPERTIES EXCLUDE_FROM_ALL TRUE)
+    endif()
+
+    add_custom_command(TARGET check PRE_BUILD
+        # -p BUILD_PATH Path used to read a compile command database (compile_commands.json).
+        # NOTE: we use defaults checks from .clang-tidy and examples only!
+        COMMAND ${CLANG_TIDY_EXE} -p ${CMAKE_BINARY_DIR} example
+        WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"   # location of compile_commands.json
+        COMMENT "Running check on targets at ${CMAKE_SOURCE_DIR} ..."
+        VERBATIM
+    )
+else()
+    message(AUTHOR_WARNING "run-clang-tidy not found!")
+endif()