Fix sign conversion warnings in qt_sinks.h (#3487)

Add static_cast to fix compiler warnings when building with
-Werror=sign-conversion and -Werror=shorten-64-to-32:

1. Cast msg.color_range_start/end to qsizetype when passing to
   QString::fromUtf8(), since QString expects signed qsizetype but
   the message fields are size_t (unsigned).

2. Cast msg.level to size_t when indexing into colors_ array, since
   level_enum is a signed int but array indexing expects size_t.

These casts are safe because:
- qsizetype is guaranteed to be the same size as size_t per Qt docs
- color_range values come from valid string positions
- level values are from a small enum range

Fixes #3321

CMakeLists.txt

@@ -19,7 +19,11 @@ include(GNUInstallDirs)
 # Set default build to release
 # ---------------------------------------------------------------------------------------
 if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
+    # Set CMAKE_BUILD_TYPE only if this project is top-level
+    if((DEFINED PROJECT_IS_TOP_LEVEL AND PROJECT_IS_TOP_LEVEL)
+        OR (NOT DEFINED PROJECT_IS_TOP_LEVEL AND CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR))
         set(CMAKE_BUILD_TYPE "Release" CACHE STRING "Choose Release or Debug" FORCE)
+    endif()
 endif()
 
 # ---------------------------------------------------------------------------------------

include/spdlog/details/os-inl.h

@@ -489,7 +489,7 @@ SPDLOG_INLINE void utf8_to_wstrbuf(string_view_t str, wmemory_buf_t &target) {
         result_size =
             ::MultiByteToWideChar(CP_UTF8, 0, str.data(), str_size, target.data(), result_size);
         if (result_size > 0) {
-            assert(result_size == target.size());
+            assert(result_size == static_cast<int>(target.size()));
             return;
         }
     }

include/spdlog/sinks/ansicolor_sink.h

@@ -78,8 +78,10 @@ public:
     const string_view_t red_bold = "\033[31m\033[1m";
     const string_view_t bold_on_red = "\033[1m\033[41m";
 
-private:
+protected:
     FILE *target_file_;
+
+private:
     mutex_t &mutex_;
     bool should_do_colors_;
     std::unique_ptr<spdlog::formatter> formatter_;

include/spdlog/sinks/qt_sinks.h

@@ -160,8 +160,8 @@ protected:
             payload = QString::fromUtf8(str.data(), static_cast<int>(str.size()));
             // convert color ranges from byte index to character index.
             if (msg.color_range_start < msg.color_range_end) {
-                color_range_start = QString::fromUtf8(str.data(), msg.color_range_start).size();
-                color_range_end = QString::fromUtf8(str.data(), msg.color_range_end).size();
+                color_range_start = QString::fromUtf8(str.data(), static_cast<qsizetype>(msg.color_range_start)).size();
+                color_range_end = QString::fromUtf8(str.data(), static_cast<qsizetype>(msg.color_range_end)).size();
             }
         } else {
             payload = QString::fromLatin1(str.data(), static_cast<int>(str.size()));
@@ -171,7 +171,7 @@ protected:
                              qt_text_edit_,          // text edit to append to
                              std::move(payload),     // text to append
                              default_color_,         // default color
-                             colors_.at(msg.level),  // color to apply
+                             colors_.at(static_cast<size_t>(msg.level)),  // color to apply
                              color_range_start,      // color range start
                              color_range_end};       // color range end