http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59948
--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> --- (In reply to Marc Glisse from comment #0) > if (f != 0B) > // Shouldn't we know that f!=0? It is defined just above. This happens because the test in fold-const.c is: return !VAR_OR_FUNCTION_DECL_P (base) || !DECL_WEAK (base); and f is marked as weak. If I remove 'inline' or put 'static' then this code is folded to true. However, I can't easily do the same for _M_manager. The condition in fold-const.c probably needs to be weakened (no pun), as I strongly doubt it is legal to replace an inline f with 0. Note that cp/class.c contains this: /* ??? Probably should check DECL_WEAK here. */ if (t && DECL_P (t)) *nonnull = 1; which we may want to keep in sync. With f static, we get the shorter but still not so good: int m() () { struct function h; int _21; <bb 2>: MEM[(int (*<T58fa>) (int) *)&h] = f; h._M_invoker = _M_invoke; h.D.26465._M_manager = _M_manager; if (_M_manager == 0B) // Can't make it non-weak goto <bb 3>; else goto <bb 4>; <bb 3>: std::__throw_bad_function_call (); <bb 4>: _21 = f (1); // Did we notice the function is really f too late for inlining? std::_Function_base::_Base_manager<int (*)(int)>::_M_manager (&MEM[(struct _Function_base *)&h]._M_functor, &MEM[(struct _Function_base *)&h]._M_functor, 3); // Again, not inlined h ={v} {CLOBBER}; h ={v} {CLOBBER}; //Maybe we could remove one of the clobbers somewhere along the way? return _21; } If I change fold-const.c (the condition is probably wrong, I just wanted to move forward): - return !VAR_OR_FUNCTION_DECL_P (base) || !DECL_WEAK (base); + return !VAR_OR_FUNCTION_DECL_P (base) || !DECL_WEAK (base) || DECL_DECLARED_INLINE_P (base); It removes the test _M_manager == 0, but it still inlines neither f nor _M_manager.