[cmake] Do not enable compiler warnings globally but instead through an interface target

CMakeLists.txt

@@ -17,13 +17,23 @@ set(BUILD_SHARED_LIBS OFF)
 # Export the list of compile-commands into compile_commands.json
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-# Enable compiler warnings for the whole project
+# Global compiler options
 add_compile_options(
-		-Wall
-		-Wextra
-		$<$<CONFIG:Debug>:-Og>
-		$<$<CONFIG:Debug>:-ggdb3>
-		)
+  $<$<CONFIG:Debug>:-Og>
+  $<$<CONFIG:Debug>:-ggdb3>
+)
+
+# Create an Interface target for compiler warnings
+add_library(project_warnings INTERFACE)
+install(TARGETS project_warnings EXPORT app4triqs-targets)
+target_compile_options(project_warnings
+  INTERFACE
+    -Wall
+    -Wextra
+    -Wshadow
+    -Wpedantic
+    -Wno-sign-compare
+)
 
 # Load Dependencies
 find_package(TRIQS 2.2 REQUIRED)

c++/app4triqs/CMakeLists.txt

@@ -2,7 +2,7 @@ file(GLOB_RECURSE sources *.cpp)
 add_library(app4triqs_c ${sources})
 
 # Link against dependencies
-target_link_libraries(app4triqs_c PUBLIC triqs)
+target_link_libraries(app4triqs_c PUBLIC triqs PRIVATE project_warnings)
 
 # Configure compilation
 target_compile_options(app4triqs_c PUBLIC -fPIC)

test/c++/CMakeLists.txt

@@ -10,7 +10,7 @@ set(all_tests toto)
 foreach(test ${all_tests})
   get_filename_component(test_name ${test} NAME_WE)
   add_executable(${test_name} ${test})
-  target_link_libraries(${test_name} app4triqs_c triqs::gtest)
+  target_link_libraries(${test_name} app4triqs_c triqs::gtest project_warnings)
   add_test(${test_name} ${test_name})
   # Run clang-tidy if found
   if(CLANG_TIDY_EXECUTABLE)