src/tools/clippy/tests/ui/seek_to_start_instead_of_rewind.fixed

   1 // run-rustfix
   2 #![allow(unused)]
   3 #![warn(clippy::seek_to_start_instead_of_rewind)]
   4
   5 use std::fs::OpenOptions;
   6 use std::io::{Read, Seek, SeekFrom, Write};
   7
   8 struct StructWithSeekMethod {}
   9
  10 impl StructWithSeekMethod {
  11     fn seek(&mut self, from: SeekFrom) {}
  12 }
  13
  14 trait MySeekTrait {
  15     fn seek(&mut self, from: SeekFrom) {}
  16 }
  17
  18 struct StructWithSeekTrait {}
  19 impl MySeekTrait for StructWithSeekTrait {}
  20
  21 // This should NOT trigger clippy warning because
  22 // StructWithSeekMethod does not implement std::io::Seek;
  23 fn seek_to_start_false_method(t: &mut StructWithSeekMethod) {
  24     t.seek(SeekFrom::Start(0));
  25 }
  26
  27 // This should NOT trigger clippy warning because
  28 // StructWithSeekMethod does not implement std::io::Seek;
  29 fn seek_to_start_method_owned_false(mut t: StructWithSeekMethod) {
  30     t.seek(SeekFrom::Start(0));
  31 }
  32
  33 // This should NOT trigger clippy warning because
  34 // StructWithSeekMethod does not implement std::io::Seek;
  35 fn seek_to_start_false_trait(t: &mut StructWithSeekTrait) {
  36     t.seek(SeekFrom::Start(0));
  37 }
  38
  39 // This should NOT trigger clippy warning because
  40 // StructWithSeekMethod does not implement std::io::Seek;
  41 fn seek_to_start_false_trait_owned(mut t: StructWithSeekTrait) {
  42     t.seek(SeekFrom::Start(0));
  43 }
  44
  45 // This should NOT trigger clippy warning because
  46 // StructWithSeekMethod does not implement std::io::Seek;
  47 fn seek_to_start_false_trait_bound<T: MySeekTrait>(t: &mut T) {
  48     t.seek(SeekFrom::Start(0));
  49 }
  50
  51 // This should trigger clippy warning
  52 fn seek_to_start<T: Seek>(t: &mut T) {
  53     t.rewind();
  54 }
  55
  56 // This should trigger clippy warning
  57 fn owned_seek_to_start<T: Seek>(mut t: T) {
  58     t.rewind();
  59 }
  60
  61 // This should NOT trigger clippy warning because
  62 // it does not seek to start
  63 fn seek_to_5<T: Seek>(t: &mut T) {
  64     t.seek(SeekFrom::Start(5));
  65 }
  66
  67 // This should NOT trigger clippy warning because
  68 // it does not seek to start
  69 fn seek_to_end<T: Seek>(t: &mut T) {
  70     t.seek(SeekFrom::End(0));
  71 }
  72
  73 // This should NOT trigger clippy warning because
  74 // expr is used here
  75 fn seek_to_start_in_let<T: Seek>(t: &mut T) {
  76     let a = t.seek(SeekFrom::Start(0)).unwrap();
  77 }
  78
  79 fn main() {
  80     let mut f = OpenOptions::new()
  81         .write(true)
  82         .read(true)
  83         .create(true)
  84         .open("foo.txt")
  85         .unwrap();
  86
  87     let mut my_struct_trait = StructWithSeekTrait {};
  88     seek_to_start_false_trait_bound(&mut my_struct_trait);
  89
  90     let hello = "Hello!\n";
  91     write!(f, "{hello}").unwrap();
  92     seek_to_5(&mut f);
  93     seek_to_end(&mut f);
  94     seek_to_start(&mut f);
  95
  96     let mut buf = String::new();
  97     f.read_to_string(&mut buf).unwrap();
  98
  99     assert_eq!(&buf, hello);
 100 }
 101
 102 #[clippy::msrv = "1.54"]
 103 fn msrv_1_54() {
 104     let mut f = OpenOptions::new()
 105         .write(true)
 106         .read(true)
 107         .create(true)
 108         .open("foo.txt")
 109         .unwrap();
 110
 111     let hello = "Hello!\n";
 112     write!(f, "{hello}").unwrap();
 113
 114     f.seek(SeekFrom::Start(0));
 115
 116     let mut buf = String::new();
 117     f.read_to_string(&mut buf).unwrap();
 118
 119     assert_eq!(&buf, hello);
 120 }
 121
 122 #[clippy::msrv = "1.55"]
 123 fn msrv_1_55() {
 124     let mut f = OpenOptions::new()
 125         .write(true)
 126         .read(true)
 127         .create(true)
 128         .open("foo.txt")
 129         .unwrap();
 130
 131     let hello = "Hello!\n";
 132     write!(f, "{hello}").unwrap();
 133
 134     f.rewind();
 135
 136     let mut buf = String::new();
 137     f.read_to_string(&mut buf).unwrap();
 138
 139     assert_eq!(&buf, hello);
 140 }