dynalib: fixes C++ variant of DYNALIB_FN_EXPORT() with recent GCC ver…

…sions
particle-iot · Dec 10, 2019 · e68fab4 · e68fab4
1 parent edf805c
commit e68fab4
Showing 1 changed file with 8 additions and 3 deletions.
diff --git a/dynalib/inc/dynalib.h b/dynalib/inc/dynalib.h
@@ -57,14 +57,19 @@
 
 #include <type_traits>
 
+// XXX: casting is not allowed in constexpr functions (at least since C++14).
+// We were previously casting to const void* in dynalib_checked_cast(), which resulted in
+// dynalib tables being placed into .bss section with certain GCC versions.
+// Miraculously, everything works correctly if the cast is outside of the constexpr function.
+
 template<typename T1, typename T2>
-constexpr const void* dynalib_checked_cast(T2 *p) {
+constexpr T2* dynalib_checked_cast(T2 *p) {
     static_assert(std::is_same<T1, T2>::value, "Signature of the dynamically exported function has changed");
-    return (const void*)p;
+    return p;
 }
 
 #define DYNALIB_FN_EXPORT(index, tablename, name, type) \
-    dynalib_checked_cast<type>(name),
+    reinterpret_cast<const void*>(dynalib_checked_cast<type>(name)),
 
 #define DYNALIB_STATIC_ASSERT(cond, msg) \
     static_assert(cond, msg)