Disable warnings when built as subdirectory

Fixes #165.

Author: foonathan

CMakeLists.txt

@@ -5,25 +5,31 @@
 cmake_minimum_required(VERSION 3.11)
 project(cppast VERSION 0.1.0)
 
+if(CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
+    set(is_top_level_project TRUE)
+else()
+    set(is_top_level_project FALSE)
+endif()
+
 # options
 option(CPPAST_BUILD_TEST "whether or not to build the tests" OFF)
 option(CPPAST_BUILD_EXAMPLE "whether or not to build the examples" OFF)
 option(CPPAST_BUILD_TOOL "whether or not to build the tool" OFF)
 
-if(${CPPAST_BUILD_TEST} OR (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR))
+if(${CPPAST_BUILD_TEST} OR ${is_top_level_project})
     set(build_test ON)
     set(CMAKE_EXPORT_COMPILE_COMMANDS ON) # for the self integration test
 else()
     set(build_test OFF)
 endif()
 
-if(${CPPAST_BUILD_EXAMPLE} OR (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR))
+if(${CPPAST_BUILD_EXAMPLE} OR ${is_top_level_project})
     set(build_example ON)
 else()
     set(build_example OFF)
 endif()
 
-if(${CPPAST_BUILD_TOOL} OR (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR))
+if(${CPPAST_BUILD_TOOL} OR ${is_top_level_project})
     set(build_tool ON)
 else()
     set(build_tool OFF)

src/CMakeLists.txt

@@ -113,15 +113,18 @@ target_compile_definitions(cppast PUBLIC
                                 CPPAST_VERSION_MINOR="${cppast_VERSION_MINOR}"
                                 CPPAST_VERSION_MAJOR="${cppast_VERSION_MAJOR}"
                                 CPPAST_VERSION_STRING="${cppast_VERSION}")
-target_compile_options(cppast PRIVATE
-                           # clang/GCC warnings
-                           $<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:GNU>>:
-                           -pedantic-errors -Werror -Wall -Wextra -Wconversion -Wsign-conversion>
-                           # disable noexcept type warning on GCC
-                           $<$<CXX_COMPILER_ID:GNU>: -Wno-noexcept-type>
-                           # MSVC warnings
-                           $<$<CXX_COMPILER_ID:MSVC>:
-                           /W3>)
+
+if(${is_top_level_project})
+    target_compile_options(cppast PRIVATE
+                               # clang/GCC warnings
+                               $<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:GNU>>:
+                               -pedantic-errors -Werror -Wall -Wextra -Wconversion -Wsign-conversion>
+                               # disable noexcept type warning on GCC
+                               $<$<CXX_COMPILER_ID:GNU>: -Wno-noexcept-type>
+                               # MSVC warnings
+                               $<$<CXX_COMPILER_ID:MSVC>:
+                               /W3>)
+endif()
 
 install(TARGETS cppast)
 install(DIRECTORY ../include/ DESTINATION include)