src/test/run-pass/issue-23338-ensure-param-drop-order.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // ignore-pretty : (#23623) problems when  ending with // comments
  12
  13 // This test is ensuring that parameters are indeed dropped after
  14 // temporaries in a fn body.
  15
  16 use std::cell::RefCell;
  17
  18 use self::d::D;
  19
  20 pub fn main() {
  21     let log = RefCell::new(vec![]);
  22     d::println("created empty log");
  23     test(&log);
  24
  25     assert_eq!(&log.borrow()[..],
  26                [
  27                    //                                    created empty log
  28                    //    +-- Make D(da_0, 0)
  29                    //    | +-- Make D(de_1, 1)
  30                    //    | |                             calling foo
  31                    //    | |                             entered foo
  32                    //    | | +-- Make D(de_2, 2)
  33                    //    | | | +-- Make D(da_1, 3)
  34                    //    | | | | +-- Make D(de_3, 4)
  35                    //    | | | | | +-- Make D(de_4, 5)
  36                    3, // | | | +-- Drop D(da_1, 3)
  37                    //    | | |   | |
  38                    4, // | | |   +-- Drop D(de_3, 4)
  39                    //    | | |     |
  40                    //    | | |     |                     eval tail of foo
  41                    //    | | | +-- Make D(de_5, 6)
  42                    //    | | | | +-- Make D(de_6, 7)
  43                    6, // | | | +-- Drop D(de_5, 6)
  44                    //    | | |   | |
  45                    5, // | | |   | +-- Drop D(de_4, 5)
  46                    //    | | |   |
  47                    2, // | | +-- Drop D(de_2, 2)
  48                    //    | |     |
  49                    1, // | +-- Drop D(de_1, 1)
  50                    //    |       |
  51                    0, // +-- Drop D(da_0, 0)
  52                    //            |
  53                    //            |                       result D(de_6, 7)
  54                    7 //          +-- Drop D(de_6, 7)
  55
  56                        ]);
  57 }
  58
  59 fn test<'a>(log: d::Log<'a>) {
  60     let da = D::new("da", 0, log);
  61     let de = D::new("de", 1, log);
  62     d::println("calling foo");
  63     let result = foo(da, de);
  64     d::println(&format!("result {}", result));
  65 }
  66
  67 fn foo<'a>(da0: D<'a>, de1: D<'a>) -> D<'a> {
  68     d::println("entered foo");
  69     let de2 = de1.incr();      // creates D(de_2, 2)
  70     let de4 = {
  71         let _da1 = da0.incr(); // creates D(da_1, 3)
  72         de2.incr().incr()      // creates D(de_3, 4) and D(de_4, 5)
  73     };
  74     d::println("eval tail of foo");
  75     de4.incr().incr()          // creates D(de_5, 6) and D(de_6, 7)
  76 }
  77
  78 // This module provides simultaneous printouts of the dynamic extents
  79 // of all of the D values, in addition to logging the order that each
  80 // is dropped.
  81
  82 const PREF_INDENT: u32 = 16;
  83
  84 pub mod d {
  85     #![allow(unused_parens)]
  86     use std::fmt;
  87     use std::mem;
  88     use std::cell::RefCell;
  89
  90     static mut counter: u32 = 0;
  91     static mut trails: u64 = 0;
  92
  93     pub type Log<'a> = &'a RefCell<Vec<u32>>;
  94
  95     pub fn current_width() -> u32 {
  96         unsafe { max_width() - trails.leading_zeros() }
  97     }
  98
  99     pub fn max_width() -> u32 {
 100         unsafe {
 101             (mem::size_of_val(&trails)*8) as u32
 102         }
 103     }
 104
 105     pub fn indent_println(my_trails: u32, s: &str) {
 106         let mut indent: String = String::new();
 107         for i in 0..my_trails {
 108             unsafe {
 109                 if trails & (1 << i) != 0 {
 110                     indent = indent + "| ";
 111                 } else {
 112                     indent = indent + "  ";
 113                 }
 114             }
 115         }
 116         println!("{}{}", indent, s);
 117     }
 118
 119     pub fn println(s: &str) {
 120         indent_println(super::PREF_INDENT, s);
 121     }
 122
 123     fn first_avail() -> u32 {
 124         unsafe {
 125             for i in 0..64 {
 126                 if trails & (1 << i) == 0 {
 127                     return i;
 128                 }
 129             }
 130         }
 131         panic!("exhausted trails");
 132     }
 133
 134     pub struct D<'a> {
 135         name: &'static str, i: u32, uid: u32, trail: u32, log: Log<'a>
 136     }
 137
 138     impl<'a> fmt::Display for D<'a> {
 139         fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result {
 140             write!(w, "D({}_{}, {})", self.name, self.i, self.uid)
 141         }
 142     }
 143
 144     impl<'a> D<'a> {
 145         pub fn new(name: &'static str, i: u32, log: Log<'a>) -> D<'a> {
 146             unsafe {
 147                 let trail = first_avail();
 148                 let ctr = counter;
 149                 counter += 1;
 150                 trails |= (1 << trail);
 151                 let ret = D {
 152                     name: name, i: i, log: log, uid: ctr, trail: trail
 153                 };
 154                 indent_println(trail, &format!("+-- Make {}", ret));
 155                 ret
 156             }
 157         }
 158         pub fn incr(&self) -> D<'a> {
 159             D::new(self.name, self.i + 1, self.log)
 160         }
 161     }
 162
 163     impl<'a> Drop for D<'a> {
 164         fn drop(&mut self) {
 165             unsafe { trails &= !(1 << self.trail); };
 166             self.log.borrow_mut().push(self.uid);
 167             indent_println(self.trail, &format!("+-- Drop {}", self));
 168             indent_println(::PREF_INDENT, "");
 169         }
 170     }
 171 }