Remove unsafe lifetime transmute in vt::Stream (#178)

A lending iterator ties the item lifetime to the borrow of `self`,
so writing the lifetimes that way Just Works.

src/input.rs

@@ -302,16 +302,15 @@ impl Parser {
 }
 
 /// An iterator that parses VT sequences into input events.
-///
-/// Can't implement [`Iterator`], because this is a "lending iterator".
 pub struct Stream<'parser, 'vt, 'input> {
     parser: &'parser mut Parser,
     stream: vt::Stream<'vt, 'input>,
 }
 
-impl<'input> Stream<'_, '_, 'input> {
-    #[allow(clippy::should_implement_trait)]
-    pub fn next(&mut self) -> Option<Input<'input>> {
+impl<'input> Iterator for Stream<'_, '_, 'input> {
+    type Item = Input<'input>;
+
+    fn next(&mut self) -> Option<Input<'input>> {
         loop {
             if self.parser.bracketed_paste {
                 return self.handle_bracketed_paste();
@@ -489,7 +488,9 @@ impl<'input> Stream<'_, '_, 'input> {
             }
         }
     }
+}
 
+impl<'input> Stream<'_, '_, 'input> {
     /// Once we encounter the start of a bracketed paste
     /// we seek to the end of the paste in this function.
     ///

src/vt.rs

@@ -3,7 +3,7 @@
 
 //! Our VT parser.
 
-use std::{mem, time};
+use std::time;
 
 use crate::simd::memchr2;
 
@@ -114,7 +114,7 @@ pub struct Stream<'parser, 'input> {
     off: usize,
 }
 
-impl<'parser, 'input> Stream<'parser, 'input> {
+impl<'input> Stream<'_, 'input> {
     /// Returns the input that is being parsed.
     pub fn input(&self) -> &'input str {
         self.input
@@ -136,11 +136,12 @@ impl<'parser, 'input> Stream<'parser, 'input> {
     }
 
     /// Parses the next VT sequence from the previously given input.
-    #[allow(clippy::should_implement_trait)]
-    pub fn next(&mut self) -> Option<Token<'parser, 'input>> {
-        // I don't know how to tell Rust that `self.parser` and its lifetime
-        // `'parser` outlives `self`, and at this point I don't care.
-        let parser = unsafe { mem::transmute::<_, &'parser mut Parser>(&mut *self.parser) };
+    #[allow(
+        clippy::should_implement_trait,
+        reason = "can't implement Iterator because this is a lending iterator"
+    )]
+    pub fn next(&mut self) -> Option<Token<'_, 'input>> {
+        let parser = &mut *self.parser;
         let input = self.input;
         let bytes = input.as_bytes();
 
@@ -242,7 +243,7 @@ impl<'parser, 'input> Stream<'parser, 'input> {
                                 if parser.csi.param_count != 0 || parser.csi.params[0] != 0 {
                                     parser.csi.param_count += 1;
                                 }
-                                return Some(Token::Csi(&parser.csi as &'parser Csi));
+                                return Some(Token::Csi(&parser.csi));
                             }
                             b';' => parser.csi.param_count += 1,
                             b'<'..=b'?' => parser.csi.private_byte = c as char,