Rust 2021 edition

Author: EbTech

.travis.yml

@@ -1,6 +1,6 @@
 language: rust
 rust:
-  - 1.51.0 # Version currently supported by Codeforces
+  #- 1.58.0 # Version currently supported by Codeforces
   - stable
   - beta
   - nightly
@@ -12,5 +12,4 @@ script:
 matrix:
   allow_failures:
     - rust: nightly
-    - rust: beta # clippy currently has a bug on beta
   fast_finish: true

Cargo.toml

@@ -1,8 +1,8 @@
 [package]
 name = "contest-algorithms"
-version = "0.3.0"
+version = "0.3.1-alpha.0"
 authors = ["Aram Ebtekar"]
-edition = "2018"
+edition = "2021"
 
 description = "Common algorithms and data structures for programming contests"
 repository = "https://github.com/EbTech/rust-algorithms"

src/graph/util.rs

@@ -91,7 +91,7 @@ impl<'a> Iterator for DfsIterator<'a> {
     fn next(&mut self) -> Option<Self::Item> {
         loop {
             let &u = self.stack.last()?;
-            while let Some((e, v)) = self.adj_iters[u].next() {
+            for (e, v) in self.adj_iters[u].by_ref() {
                 if !self.visited[v] {
                     self.visited[v] = true;
                     self.stack.push(v);

src/scanner.rs

@@ -35,7 +35,6 @@ impl<R: io::BufRead> Scanner<R> {
 }
 
 /// Same API as Scanner but nearly twice as fast, using horribly unsafe dark arts
-/// **REQUIRES** Rust 1.34 or higher
 pub struct UnsafeScanner<R> {
     reader: R,
     buf_str: Vec<u8>,
@@ -118,9 +117,8 @@ mod test {
 
     #[test]
     fn test_compile_stdio() {
-        let (stdin, stdout) = (io::stdin(), io::stdout());
-        let mut scan = Scanner::new(stdin.lock());
-        let mut out = io::BufWriter::new(stdout.lock());
+        let mut scan = Scanner::new(io::stdin().lock());
+        let mut out = io::BufWriter::new(io::stdout().lock());
 
         if false {
             solve(&mut scan, &mut out);

src/string_proc.rs

@@ -142,6 +142,7 @@ impl<C: std::hash::Hash + Eq> MultiMatcher<C> {
     /// If there are duplicate patterns, all but one copy will be ignored.
     pub fn new(patterns: impl IntoIterator<Item = impl IntoIterator<Item = C>>) -> Self {
         let mut trie = Trie::default();
+        #[allow(clippy::needless_collect)] // It's not needless: it affects trie.links.len()
         let pat_nodes: Vec<usize> = patterns.into_iter().map(|pat| trie.insert(pat)).collect();
 
         let mut pat_id = vec![None; trie.links.len()];
@@ -155,7 +156,7 @@ impl<C: std::hash::Hash + Eq> MultiMatcher<C> {
 
         while let Some(node) = q.pop_front() {
             for (ch, &child) in &trie.links[node] {
-                let nx = Self::next(&trie, &fail, fail[node], &ch);
+                let nx = Self::next(&trie, &fail, fail[node], ch);
                 fail[child] = nx;
                 fast[child] = if pat_id[nx].is_some() { nx } else { fast[nx] };
                 q.push_back(child);
@@ -246,7 +247,7 @@ impl SuffixArray {
             let mut cur_rank = prev_rank.clone();
 
             let pos = (n - skip..n).chain(sfx.into_iter().filter_map(|p| p.checked_sub(skip)));
-            sfx = Self::counting_sort(pos, &prev_rank, max(n, 256));
+            sfx = Self::counting_sort(pos, prev_rank, max(n, 256));
 
             let mut prev = sfx[0];
             cur_rank[prev] = 0;