Force inline fast_fail to improve MSVC codegen

Author: tcbrindle

include/flux/core/assert.hpp

@@ -35,7 +35,8 @@ namespace detail {
 struct runtime_error_fn {
 private:
     [[noreturn]]
-    static inline void fail_fast()
+    FLUX_ALWAYS_INLINE
+    static void fail_fast()
     {
 #if FLUX_HAS_BUILTIN_TRAP
         __builtin_trap();
@@ -67,8 +68,9 @@ struct runtime_error_fn {
 
 public:
     [[noreturn]]
-    inline void operator()(char const* msg,
-                           std::source_location loc = std::source_location::current()) const
+    FLUX_ALWAYS_INLINE
+    void operator()(char const* msg,
+                    std::source_location loc = std::source_location::current()) const
     {
         if constexpr (config::on_error == error_policy::fail_fast) {
             fail_fast();
@@ -125,8 +127,7 @@ struct indexed_bounds_check_fn {
                 }
             }
 #endif
-            assert_fn{}(idx >= T{0}, "index cannot be negative", loc);
-            assert_fn{}(idx < limit, "out-of-bounds sequence access", loc);
+            assert_fn{}(idx >= T{0} && idx < limit, "out-of-bounds sequence access", loc);
         }
     }
 };

include/flux/macros.hpp

@@ -23,10 +23,12 @@
 
 #define FLUX_DECLVAL(...)  ((static_cast<__VA_ARGS__(*)()noexcept>(nullptr))())
 
-#ifdef __GNUC__
-#define FLUX_ALWAYS_INLINE [[gnu::always_inline]]
+#if defined(__GNUC__)
+#  define FLUX_ALWAYS_INLINE [[gnu::always_inline]] inline
+#elif defined(_MSC_VER)
+#  define FLUX_ALWAYS_INLINE __forceinline
 #else
-#define FLUX_ALWAYS_INLINE
+#  define FLUX_ALWAYS_INLINE inline
 #endif
 
 #define FLUX_NO_UNIQUE_ADDRESS [[no_unique_address]]