Fix compiler warnings with MacOS Clang 14.0.3 (#6467)

* Disabled unused but set variable warnings in CMakeLists.txt
* Updated changelog
* Fix warnings in existing files
* Remove global no-unused-but-set warnings and add back for parser files
* Disable the unused-but-set warning on the 3rd party Catch library
* Updates from review and added append_source_file_compile_options function
* Updates from review - beefed up append compile options function
* Some simplification of append compile options function
* check compile flag variable is global

CHANGELOG.md

@@ -16,7 +16,7 @@
 -----------
 
 ### Internals
-* None.
+* Fix compiler warnings with MacOS Clang 14.0.3 ([PR #6467](https://github.com/realm/realm-core/pull/6467))
 
 ----------------------------------------------
 

CMakeLists.txt

@@ -1,4 +1,5 @@
 cmake_minimum_required(VERSION 3.15)
+message(STATUS "CMake version: ${CMAKE_VERSION}")
 
 set(CMAKE_BUILD_TYPE Debug CACHE STRING "")
 project(RealmCore)
@@ -43,20 +44,53 @@ elseif(APPLE)
     set(CMAKE_VISIBILITY_INLINES_HIDDEN 1)
 endif()
 
-function(add_cxx_flag_if_supported flag)
+# Sets/clears the {FLAG} variable if the compiler flag is supported or not
+# The compiler flag check is only performed once and the value is cached as the out variable name
+function(check_if_cxx_compiler_flag_supported flag out_var)
     if(flag MATCHES "^-Wno-")
         # Compilers ignore unknown -Wno-foo flags, so look for -Wfoo instead.
         string(REPLACE "-Wno-" "-W" check_flag ${flag})
     else()
         set(check_flag ${flag})
     endif()
 
-    check_cxx_compiler_flag(${check_flag} HAVE${check_flag})
-    if(HAVE${check_flag})
+    check_cxx_compiler_flag(${check_flag} ${out_var})
+endfunction()
+
+function(add_cxx_flag_if_supported flag)
+    check_if_cxx_compiler_flag_supported(${flag} HAVE${flag})
+    if(HAVE${flag})
         add_compile_options($<$<COMPILE_LANGUAGE:CXX>:${flag}>)
     endif()
 endfunction()
 
+# Usage: append_source_file_compile_options(FILES <file1>[ <file2>...] FLAGS <flag1>[ <flag2>...])
+function(append_source_file_compile_options)
+    set(options)
+    set(args)
+    set(list_args FILES FLAGS)
+    cmake_parse_arguments(append_options "${options}" "${args}" "${list_args}" ${ARGN})
+    if (NOT append_options_FILES)
+        message(FATAL_ERROR "Missing FILES argument for append_source_file_compile_options")
+    endif()
+    if (NOT append_options_FLAGS)
+        message(FATAL_ERROR "Missing FLAGS argument for append_source_file_compile_options")
+    endif()
+    foreach(FLAG_ IN LISTS append_options_FLAGS)
+        check_if_cxx_compiler_flag_supported(${FLAG_} HAVE${FLAG_})
+        if (HAVE${FLAG_})
+            foreach(SRC_ IN LISTS append_options_FILES)
+                get_source_file_property(OLD_OPTS ${SRC_} COMPILE_OPTIONS)
+                if (NOT OLD_OPTS)
+                    set_source_files_properties(${SRC_} PROPERTIES COMPILE_OPTIONS "${FLAG_}")
+                elseif(NOT "${FLAG_}" IN_LIST OLD_OPTS)
+                    set_source_files_properties(${SRC_} PROPERTIES COMPILE_OPTIONS "${OLD_OPTS};${FLAG_}")
+                endif()
+            endforeach()
+        endif()
+    endforeach()
+endfunction()
+
 function(use_faster_linker)
     # If a linker has already been set, don't override.
     if ("${CMAKE_EXE_LINKER_FLAGS}" MATCHES "-fuse-ld=")
@@ -300,7 +334,7 @@ elseif(APPLE AND NOT CMAKE_SYSTEM_NAME STREQUAL "Darwin")
 endif()
 set(CATCH_CONFIG_ENABLE_ALL_STRINGMAKERS ON CACHE BOOL "Enable Catch2's optional standard library stringmakers")
 
-add_subdirectory(external/catch EXCLUDE_FROM_ALL)
+add_subdirectory(external EXCLUDE_FROM_ALL)
 
 # Cmake does not let us easily set the deployment target per-target, but Catch2
 # can use modern features because we only run tests on recent OS versions.

external/CMakeLists.txt

@@ -0,0 +1,4 @@
+cmake_minimum_required(VERSION 3.15)
+
+add_cxx_flag_if_supported(-Wno-unused-but-set-variable)
+add_subdirectory(catch)

src/realm/parser/CMakeLists.txt

@@ -33,6 +33,9 @@ endif()
 set(REALM_PARSER_SOURCES
     driver.cpp
     keypath_mapping.cpp
+) # REALM_PARSER_SOURCES
+
+set(REALM_PARSER_GENERATED
     generated/query_flex.cpp
     generated/query_bison.cpp
 ) # REALM_PARSER_SOURCES
@@ -56,13 +59,17 @@ set(REALM_PARSER_EXTRAS
     query_flex.ll
 )
 
+# Add custom warning flags for generated parser files if the flag is supported
+append_source_file_compile_options(FILES ${REALM_PARSER_GENERATED} FLAGS -Wno-unused-but-set-variable)
+
+# Append additional compile options to the generated/query_flex.cpp file
 if(MSVC)
-    set_source_files_properties(generated/query_flex.cpp PROPERTIES COMPILE_OPTIONS "/wd4018")
+    append_source_file_compile_options(FILES generated/query_flex.cpp FLAGS /wd4018)
 else()
-    set_source_files_properties(generated/query_flex.cpp PROPERTIES COMPILE_OPTIONS "-Wno-unreachable-code;-Wno-sign-compare")
+    append_source_file_compile_options(FILES generated/query_flex.cpp FLAGS -Wno-unreachable-code -Wno-sign-compare)
 endif()
 
-add_library(QueryParser STATIC ${REALM_PARSER_SOURCES} ${REALM_PARSER_HEADERS} ${REALM_PARSER_EXTRAS})
+add_library(QueryParser STATIC ${REALM_PARSER_SOURCES} ${REALM_PARSER_GENERATED} ${REALM_PARSER_HEADERS} ${REALM_PARSER_EXTRAS})
 add_library(realm-parser ALIAS QueryParser)
 add_library(Realm::QueryParser ALIAS QueryParser)
 target_link_libraries(QueryParser PUBLIC Storage)

test/CMakeLists.txt

@@ -122,7 +122,7 @@ set(CORE_TESTS ${CORE_TEST_SOURCES} ${LARGE_TEST_SOURCES} ${FUZZY_TEST_SOURCES})
 # FIXME: Benchmarks
 
 if (MSVC)
-    set_source_files_properties(test_query.cpp test_query_big.cpp PROPERTIES COMPILE_FLAGS /bigobj)
+    append_source_file_compile_options(FILES test_query.cpp test_query_big.cpp FLAGS /bigobj)
 endif()
 
 # Resources required for running the tests

test/test_lang_bind_helper.cpp

@@ -3986,7 +3986,7 @@ struct HandoverControl {
         while (m_handover != nullptr)
             m_changed.wait(lg);
         // std::cout << " -- put " << h << std::endl;
-        m_handover = move(h);
+        m_handover = std::move(h);
         m_changed.notify_all();
     }
     void get(std::unique_ptr<T>& h)
@@ -3996,7 +3996,7 @@ struct HandoverControl {
         while (m_handover == nullptr)
             m_changed.wait(lg);
         // std::cout << " -- get " << m_handover << std::endl;
-        h = move(m_handover);
+        h = std::move(m_handover);
         m_handover = nullptr;
         m_changed.notify_all();
     }
@@ -4005,7 +4005,7 @@ struct HandoverControl {
         LockGuard lg(m_lock);
         if (m_handover == nullptr)
             return false;
-        h = move(m_handover);
+        h = std::move(m_handover);
         m_handover = nullptr;
         m_changed.notify_all();
         return true;

test/test_query.cpp

@@ -2904,7 +2904,6 @@ TEST_IF(Query_StrIndex3, TEST_DURATION > 0)
 
         std::vector<ObjKey> vec;
 
-        size_t n = 0;
 #if defined REALM_DEBUG || REALM_ANDROID
         for (int i = 0; i < 4; i++) {
 #else
@@ -2924,7 +2923,6 @@ TEST_IF(Query_StrIndex3, TEST_DURATION > 0)
                         ObjKey key =
                             ttt.create_object().set_all(0, longstrings ? "AAAAAAAAAAAAAAAAAAAAAAAA" : "AA").get_key();
                         if (!longstrings) {
-                            n++;
                             vec.push_back(key);
                         }
                     }

test/test_shared.cpp

@@ -1841,13 +1841,10 @@ TEST(Shared_StringIndexBug3)
     }
 
     Random random(random_int<unsigned long>()); // Seed from slow global generator
-    size_t transactions = 0;
     std::vector<ObjKey> keys;
     for (size_t n = 0; n < 100; ++n) {
         const uint64_t action = random.draw_int_mod(1000);
 
-        transactions++;
-
         if (action <= 500) {
             // delete random user
             auto tr = db->start_write();