Address review: fix all compiler warnings across GCC, Clang, and MSVC

Requested by @lefticus in PR #687 review.

Fix warnings-as-errors failures on all three compiler families:

- GCC Release: replace strncpy with memcpy in mystrdup (stringop-truncation)
- GCC ASAN+UBSAN Release: add bounds check in Operator() before indexing
  m_operators array — the recursive call could exceed the array size of 12,
  which is an actual out-of-bounds bug, not just a warning
- GCC: downgrade maybe-uninitialized to warning (false positive in libstdc++
  std::regex under sanitizers + optimizations)
- AppleClang: add default cases to all switch statements on Common_Types in
  boxed_number.hpp (Wswitch-default)
- AppleClang: mark Dispatch_Engine move ctor/assignment as deleted since
  shared_mutex is non-movable (Wdefaulted-function-deleted)
- AppleClang on macOS: suppress Wpoison-system-directories for /usr/local/include
- MSVC Release: suppress C4702 (unreachable code) around if-constexpr in
  proxy_functions_detail.hpp
- Fix unused variable warnings in emscripten_eval_test.cpp when asserts are
  disabled in Release mode

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

CMakeLists.txt

@@ -180,11 +180,11 @@ else()
   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)
   else()
-    add_definitions(-Wnoexcept)
+    add_definitions(-Wnoexcept -Wno-error=maybe-uninitialized)
   endif()
 
   if(APPLE)
-    add_definitions(-Wno-sign-compare)
+    add_definitions(-Wno-sign-compare -Wno-poison-system-directories)
   endif()
 endif()
 

include/chaiscript/dispatchkit/boxed_number.hpp

@@ -272,6 +272,8 @@ namespace chaiscript {
           return callable(*static_cast<const float *>(bv.get_const_ptr()));
         case Common_Types::t_long_double:
           return callable(*static_cast<const long double *>(bv.get_const_ptr()));
+        default:
+          throw chaiscript::detail::exception::bad_any_cast();
       }
       throw chaiscript::detail::exception::bad_any_cast();
     }
@@ -479,6 +481,8 @@ namespace chaiscript {
         case Common_Types::t_long_double:
           check_type<long double, Target>();
           return get_as_aux<Target, long double>(bv);
+        default:
+          throw chaiscript::detail::exception::bad_any_cast();
       }
 
       throw chaiscript::detail::exception::bad_any_cast();
@@ -509,6 +513,8 @@ namespace chaiscript {
           return get_as_aux<Target, float>(bv);
         case Common_Types::t_long_double:
           return get_as_aux<Target, long double>(bv);
+        default:
+          throw chaiscript::detail::exception::bad_any_cast();
       }
 
       throw chaiscript::detail::exception::bad_any_cast();
@@ -538,6 +544,8 @@ namespace chaiscript {
           return to_string_aux<float>(bv);
         case Common_Types::t_long_double:
           return to_string_aux<long double>(bv);
+        default:
+          throw chaiscript::detail::exception::bad_any_cast();
       }
 
       throw chaiscript::detail::exception::bad_any_cast();

include/chaiscript/dispatchkit/dispatchkit.hpp

@@ -377,8 +377,8 @@ namespace chaiscript {
 
       Dispatch_Engine(const Dispatch_Engine &) = delete;
       Dispatch_Engine &operator=(const Dispatch_Engine &) = delete;
-      Dispatch_Engine(Dispatch_Engine &&) = default;
-      Dispatch_Engine &operator=(Dispatch_Engine &&) = default;
+      Dispatch_Engine(Dispatch_Engine &&) = delete;
+      Dispatch_Engine &operator=(Dispatch_Engine &&) = delete;
 
 #ifndef CHAISCRIPT_NO_THREADS
       /// Track an async thread so it can be joined during destruction

include/chaiscript/dispatchkit/proxy_functions_detail.hpp

@@ -92,6 +92,10 @@ namespace chaiscript {
       /// The function attempts to unbox each parameter to the expected type.
       /// if any unboxing fails the execution of the function fails and
       /// the bad_boxed_cast is passed up to the caller.
+#ifdef CHAISCRIPT_MSVC
+#pragma warning(push)
+#pragma warning(disable : 4702)
+#endif
       template<typename Callable, typename Ret, typename... Params>
       Boxed_Value
       call_func(Ret (*sig)(Params...), const Callable &f, const chaiscript::Function_Params &params, const Type_Conversions_State &t_conversions) {
@@ -102,6 +106,9 @@ namespace chaiscript {
           return Handle_Return<Ret>::handle(call_func(sig, std::index_sequence_for<Params...>{}, f, params, t_conversions));
         }
       }
+#ifdef CHAISCRIPT_MSVC
+#pragma warning(pop)
+#endif
 
     } // namespace detail
   } // namespace dispatch

include/chaiscript/language/chaiscript_parser.hpp

@@ -2570,6 +2570,10 @@ namespace chaiscript {
         bool retval = false;
         const auto prev_stack_top = m_match_stack.size();
 
+        if (t_precedence >= m_operators.size()) {
+          return Value();
+        }
+
         if (m_operators[t_precedence] != Operator_Precedence::Prefix) {
           if (Operator(t_precedence + 1)) {
             retval = true;

src/main.cpp

@@ -34,7 +34,7 @@ char *mystrdup(const char *s) {
 #ifdef CHAISCRIPT_MSVC
   strcpy_s(d, len + 1, s); // Copy the characters
 #else
-  strncpy(d, s, len); // Copy the characters
+  memcpy(d, s, len);
 #endif
   d[len] = '\0';
   return d; // Return the new string

unittests/emscripten_eval_test.cpp

@@ -16,36 +16,34 @@
 #include <string>
 
 int main() {
-  // Test eval (void return) - same as Emscripten eval()
   chaiscript_eval("var x = 42");
 
-  // Test evalString - same as Emscripten evalString()
-  std::string s = chaiscript_eval_string("to_string(x)");
+  const std::string s = chaiscript_eval_string("to_string(x)");
   assert(s == "42");
+  static_cast<void>(s);
 
-  // Test evalInt - same as Emscripten evalInt()
-  int i = chaiscript_eval_int("1 + 2");
+  const int i = chaiscript_eval_int("1 + 2");
   assert(i == 3);
+  static_cast<void>(i);
 
-  // Test evalBool - same as Emscripten evalBool()
   bool b = chaiscript_eval_bool("true");
   assert(b == true);
-
   b = chaiscript_eval_bool("false");
   assert(b == false);
+  static_cast<void>(b);
 
-  // Test evalFloat - same as Emscripten evalFloat()
-  float f = chaiscript_eval_float("1.5f");
+  const float f = chaiscript_eval_float("1.5f");
   assert(std::abs(f - 1.5f) < 0.001f);
+  static_cast<void>(f);
 
-  // Test evalDouble - same as Emscripten evalDouble()
-  double d = chaiscript_eval_double("3.14");
+  const double d = chaiscript_eval_double("3.14");
   assert(std::abs(d - 3.14) < 0.001);
+  static_cast<void>(d);
 
-  // Test a more complex expression
   chaiscript_eval("def square(n) { return n * n; }");
-  int sq = chaiscript_eval_int("square(7)");
+  const int sq = chaiscript_eval_int("square(7)");
   assert(sq == 49);
+  static_cast<void>(sq);
 
   return 0;
 }