CI: Add -Og for debug builds, for better ABI checking

CMakeLists.txt

@@ -194,7 +194,7 @@ include( CMakeColors )
 set( CMAKE_CXX_STANDARD 17 )
 set( CMAKE_CXX_STANDARD_REQUIRED ON )
 set( CMAKE_CXX_FLAGS                "${CMAKE_CXX_FLAGS} -Wall -Werror=return-type" )
-set( CMAKE_CXX_FLAGS_DEBUG          "-g ${CMAKE_CXX_FLAGS_DEBUG}" )
+set( CMAKE_CXX_FLAGS_DEBUG          "-Og -g ${CMAKE_CXX_FLAGS_DEBUG}" )
 set( CMAKE_CXX_FLAGS_MINSIZEREL     "-Os -DNDEBUG" )
 set( CMAKE_CXX_FLAGS_RELEASE        "-O3 -DNDEBUG" )
 set( CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g" )
@@ -202,7 +202,7 @@ set( CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g" )
 set( CMAKE_C_STANDARD 99 )
 set( CMAKE_C_STANDARD_REQUIRED ON )
 set( CMAKE_C_FLAGS                  "${CMAKE_C_FLAGS} -Wall" )
-set( CMAKE_C_FLAGS_DEBUG            "-g" )
+set( CMAKE_C_FLAGS_DEBUG            "-Og -g" )
 set( CMAKE_C_FLAGS_MINSIZEREL       "-Os -DNDEBUG" )
 set( CMAKE_C_FLAGS_RELEASE          "-O4 -DNDEBUG" )
 set( CMAKE_C_FLAGS_RELWITHDEBINFO   "-O2 -g" )
@@ -230,6 +230,10 @@ if( CMAKE_CXX_COMPILER_ID MATCHES "Clang" )
         string( APPEND CMAKE_CXX_FLAGS " ${CLANG_WARNINGS}" )
     endforeach()
 
+    # The dwarf-debugging flags are slightly different, too
+    string( APPEND CMAKE_CXX_FLAGS_DEBUG " -gdwarf" )
+    string( APPEND CMAKE_C_FLAGS_DEBUG " -gdwarf" )
+
     # Third-party code where we don't care so much about compiler warnings
     # (because it's uncomfortable to patch) get different flags; use
     #       mark_thirdparty_code( <file> [<file>...] )