本文简要介绍rust语言中 Function std::ptr::drop_in_place 的用法。 用法 pub unsafe fn drop_in_place<T>(to_drop: *mut T) where T: ?Sized, 执行指向值的析构函数(如果有)。 这在语义上等同于调用 ptr::read 并丢弃结果,但具有以下优点: 这是必需的使用drop_in_place删除未调整大小的类型(例如...
虚表header 中的drop_in_place是一个函数指针,其指向的函数能够原地 drop 当前胖指针所引用的对象。size和align两个域分别给出对象的大小和内存对齐,这两个域共同构成一个std::alloc::Layout结构,可用于释放当前胖指针所引用的对象所占据的内存。虚表 header 的存在使得 trait object 总是能被销毁和释放。例如当销...
41,(%rax)jmp.LBB18_7.LBB18_5:.Ltmp15:leaq48(%rsp),%rdicallq_ZN4core3ptr49drop_in_place$LT$alloc..boxed..Box$LT$i32$GT$$GT$17hac96f08cecbb6861E.Ltmp16:jmp.LBB18_12.LBB18_6:movl20(%rsp),%eaxmovq8(%rsp),%rcxmovq%rcx,56(%rsp)movl%eax,64(%rsp)jmp.LBB18_5.LBB18_7:....
intrinsics::drop_in_place<T: ?Sized>(to_drop: * mut T) 在某些情况下,可能会将变量设置成不允许编译器自动调用变量的drop函数, 此时若是仍需要对变量调用drop,则在代码中显式调用此函数以出发对T类型的drop调用。 intrinsics::forget<T: ?Sized> (_:T) 代码中调用这个函数后,编译器不对forget的变量自...
fndrop(&mut self){unsafe{self.inner().dec_strong();// 强引用计数减 1ifself.inner().strong()==0{// destroy the contained objectptr::drop_in_place(Self::get_mut_unchecked(self));// remove the implicit "strong weak" pointer now that we've// destroyed the contents.self.inner().dec...
pub(super)fndrop_remaining(&mutself){ unsafe{ ptr::drop_in_place(self.as_mut_slice()); } self.ptr=self.end; } SpecFromIter<T, I> for Vec<T>callsVec::IntoIter::drop_remaining().drop_remaining()callsdrop_in_place()before overwriting the pointer. As a result, dropped elements are ...
std::ptr::drop_in_place(p); std::alloc::dealloc(p * , Layout::new::<M>()); } my_speed: <M> = ::new(M{id:.to_owned()}); my_speed_ptr: * M = & *my_speed; } 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. ...
// SAFETY: The value stored in inner is valid. unsafe { core::ptr::drop_in_place(inner) }; // SAFETY: The pointer was initialised from the result of a call to `alloc`. unsafe { dealloc(self.ptr.cast().as_ptr(), layout) }; ...
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Code #![feature(inline_const, const_type_id)] use std::alloc::Layout; use std::any::TypeId; use std::mem::transmute; use std::ptr::drop_in_place; pub struct VTable { layout: Layout, type_id: TypeId, drop_in_place: unsafe fn(*mut ()), } i...