Fix #518: Enable warnings as errors and fix all compiler warnings

Enable -Werror for GCC/Clang and /WX for MSVC to enforce warning-free
builds. Fix wchar_t-to-char narrowing conversion in chaiscript_windows.hpp
by using explicit static_cast. Replace deprecated std::wstring_convert in
chaiscript_parser.hpp with direct static_cast. Add noexcept to JSON default
constructor, and mark intentionally unused parameters with [[maybe_unused]].

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CMakeLists.txt

@@ -155,7 +155,7 @@ else()
 endif()
 
 if(MSVC)
-  add_definitions(/W4 /w14545 /w34242 /w34254 /w34287 /w44263 /w44265 /w44296 /w44311 /w44826 /we4289 /w14546 /w14547 /w14549 /w14555 /w14619 /w14905 /w14906 /w14928)
+  add_definitions(/W4 /WX /w14545 /w34242 /w34254 /w34287 /w44263 /w44265 /w44296 /w44311 /w44826 /we4289 /w14546 /w14547 /w14549 /w14555 /w14619 /w14905 /w14906 /w14928)
 
   if(MSVC_VERSION STREQUAL "1800")
     # VS2013 doesn't have magic statics
@@ -175,7 +175,7 @@ if(MSVC)
   # how to workaround or fix the error. So I'm disabling it globally.
   add_definitions(/wd4503)
 else()
-  add_definitions(-Wall -Wextra -Wconversion -Wshadow -Wnon-virtual-dtor -Wold-style-cast -Wcast-align -Wcast-qual -Wunused -Woverloaded-virtual -Wno-noexcept-type -Wpedantic -Werror=return-type)
+  add_definitions(-Wall -Wextra -Werror -Wconversion -Wshadow -Wnon-virtual-dtor -Wold-style-cast -Wcast-align -Wcast-qual -Wunused -Woverloaded-virtual -Wno-noexcept-type -Wpedantic)
 
   if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "AppleClang")
     add_definitions(-Weverything -Wno-c++98-compat-pedantic  -Wno-c++98-compat -Wno-documentation -Wno-switch-enum -Wno-weak-vtables -Wno-missing-prototypes -Wno-padded -Wno-missing-noreturn -Wno-exit-time-destructors -Wno-documentation-unknown-command -Wno-unused-template -Wno-undef -Wno-double-promotion)

include/chaiscript/dispatchkit/bootstrap.hpp

@@ -269,7 +269,7 @@ namespace chaiscript::bootstrap {
     /// \brief perform all common bootstrap functions for std::string, void and POD types
     /// \param[in,out] m Module to add bootstrapped functions to
     /// \param[in] t_no_io If true, skip registering print_string and println_string
-    static void bootstrap(Module &m, const bool t_no_io = false) {
+    static void bootstrap(Module &m, [[maybe_unused]] const bool t_no_io = false) {
       m.add(user_type<void>(), "void");
       m.add(user_type<bool>(), "bool");
       m.add(user_type<Boxed_Value>(), "Object");

include/chaiscript/language/chaiscript_engine.hpp

@@ -584,7 +584,7 @@ namespace chaiscript {
     /// (the symbol mentioned above), an exception is thrown.
     ///
     /// \throw chaiscript::exception::load_module_error In the event that no matching module can be found.
-    std::string load_module(const std::string &t_module_name) {
+    std::string load_module([[maybe_unused]] const std::string &t_module_name) {
 #ifdef CHAISCRIPT_NO_DYNLOAD
       throw chaiscript::exception::load_module_error("Loadable module support was disabled (CHAISCRIPT_NO_DYNLOAD)");
 #else

include/chaiscript/language/chaiscript_parser.hpp

@@ -26,11 +26,6 @@
 #include "chaiscript_optimizer.hpp"
 #include "chaiscript_tracer.hpp"
 
-#if defined(CHAISCRIPT_UTF16_UTF32)
-#include <codecvt>
-#include <locale>
-#endif
-
 #if defined(CHAISCRIPT_MSVC) && defined(max) && defined(min)
 #define CHAISCRIPT_PUSHED_MIN_MAX
 #pragma push_macro("max") // Why Microsoft? why? This is worse than bad
@@ -81,15 +76,7 @@ namespace chaiscript {
 
         static string_type str_from_ll(long long val) {
           using target_char_type = typename string_type::value_type;
-#if defined(CHAISCRIPT_UTF16_UTF32)
-          // prepare converter
-          std::wstring_convert<std::codecvt_utf8<target_char_type>, target_char_type> converter;
-          // convert
-          return converter.from_bytes(u8str_from_ll(val));
-#else
-          // no conversion available, just put value as character
-          return string_type(1, target_char_type(val)); // size, character
-#endif
+          return string_type(1, static_cast<target_char_type>(val));
         }
       };
 

include/chaiscript/language/chaiscript_windows.hpp

@@ -22,12 +22,22 @@ namespace chaiscript {
     struct Loadable_Module {
       template<typename T>
       static std::wstring to_wstring(const T &t_str) {
-        return std::wstring(t_str.begin(), t_str.end());
+        std::wstring result;
+        result.reserve(t_str.size());
+        for (const auto &ch : t_str) {
+          result.push_back(static_cast<wchar_t>(ch));
+        }
+        return result;
       }
 
       template<typename T>
       static std::string to_string(const T &t_str) {
-        return std::string(t_str.begin(), t_str.end());
+        std::string result;
+        result.reserve(t_str.size());
+        for (const auto &ch : t_str) {
+          result.push_back(static_cast<char>(ch));
+        }
+        return result;
       }
 
 #if defined(_UNICODE) || defined(UNICODE)

include/chaiscript/utility/json.hpp

@@ -47,7 +47,7 @@ namespace chaiscript::json {
       Internal(std::nullptr_t)
           : d(nullptr) {
       }
-      Internal()
+      Internal() noexcept
           : d(nullptr) {
       }
       Internal(Class c)
@@ -153,7 +153,7 @@ namespace chaiscript::json {
       typename Container::const_iterator end() const noexcept { return object ? object->end() : typename Container::const_iterator(); }
     };
 
-    JSON() = default;
+    JSON() noexcept = default;
     JSON(std::nullptr_t) {}
 
     explicit JSON(Class type)

unittests/compiled_tests.cpp

@@ -1970,3 +1970,11 @@ TEST_CASE("Exception from C++ [] operator is catchable in ChaiScript") {
     caught
   )") == true);
 }
+
+TEST_CASE("Unicode escape sequences produce correct values") {
+  chaiscript::ChaiScript_Basic chai(create_chaiscript_stdlib(), create_chaiscript_parser());
+
+  CHECK(chai.eval<std::string>(R"("\u0041")") == "A");
+  CHECK(chai.eval<std::string>(R"("\u004F")") == "O");
+  CHECK(chai.eval<std::string>(R"("\u0030")") == "0");
+}