build: cmake: add compatibility target of dev-headers

our CI builds "dev-headers" as a gating check. but the target names
generated by CMake's Ninja Multi-Config generator does not follow
this naming convention. we could have headers:Dev, but still, it's
different from what we are using, before completely switching to
CMake, let's keep this backward compatibility by adding a target
with the same name.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

CMakeLists.txt

@@ -126,6 +126,15 @@ option(Scylla_CHECK_HEADERS
   "Add check-headers target for checking the self-containness of headers")
 if(Scylla_CHECK_HEADERS)
     add_custom_target(check-headers)
+    # compatibility target used by CI, which builds "dev-headers" for building
+    # "headers" of the "dev" mode. but we don't have such an alias. what we
+    # have is check-headers:Dev, and we don't want to build check-headers
+    # for all "CMAKE_DEFAULT_CONFIGS". so, before we , let's add an target
+    # which only build build check-headers for Dev, and skip it otherwise.
+    add_custom_target(dev-headers
+        COMMAND ${CMAKE_COMMAND}
+          "$<IF:$<CONFIG:Dev>,--build;${CMAKE_BINARY_DIR};--config;$<CONFIG>;--target;check-headers,-E;echo;skipping;dev-headers;in;$<CONFIG>>"
+        COMMAND_EXPAND_LISTS)
 endif()
 
 include(check_headers)

configure.py

@@ -2426,6 +2426,7 @@ def configure_using_cmake(args):
         'CMAKE_CXX_FLAGS': args.user_cflags,
         'CMAKE_EXE_LINKER_FLAGS': semicolon_separated(args.user_ldflags),
         'CMAKE_EXPORT_COMPILE_COMMANDS': 'ON',
+        'Scylla_CHECK_HEADERS': 'ON',
     }
     if args.date_stamp:
         settings['Scylla_DATE_STAMP'] = args.date_stamp