Auto merge of rust-lang#127481 - a1phyr:pattern_gat, r=<try>

Remove generic lifetime parameter of trait `Pattern`

Use a GAT for `Searcher` associated type because this trait is always implemented for every lifetime anyway.

cc rust-lang#27721

Author: bors

Diff for: library/alloc/src/str.rs

@@ -269,7 +269,7 @@ impl str {
                   without modifying the original"]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    pub fn replace<'a, P: Pattern<'a>>(&'a self, from: P, to: &str) -> String {
+    pub fn replace<P: Pattern>(&self, from: P, to: &str) -> String {
         let mut result = String::new();
         let mut last_end = 0;
         for (start, part) in self.match_indices(from) {
@@ -309,7 +309,7 @@ impl str {
     #[must_use = "this returns the replaced string as a new allocation, \
                   without modifying the original"]
     #[stable(feature = "str_replacen", since = "1.16.0")]
-    pub fn replacen<'a, P: Pattern<'a>>(&'a self, pat: P, to: &str, count: usize) -> String {
+    pub fn replacen<P: Pattern>(&self, pat: P, to: &str, count: usize) -> String {
         // Hope to reduce the times of re-allocation
         let mut result = String::with_capacity(32);
         let mut last_end = 0;

Diff for: library/alloc/src/string.rs

@@ -1497,10 +1497,7 @@ impl String {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[unstable(feature = "string_remove_matches", reason = "new API", issue = "72826")]
-    pub fn remove_matches<'a, P>(&'a mut self, pat: P)
-    where
-        P: for<'x> Pattern<'x>,
-    {
+    pub fn remove_matches<P: Pattern>(&mut self, pat: P) {
         use core::str::pattern::Searcher;
 
         let rejections = {
@@ -2285,35 +2282,41 @@ impl<'a> Extend<Cow<'a, str>> for String {
     reason = "API not fully fleshed out and ready to be stabilized",
     issue = "27721"
 )]
-impl<'a, 'b> Pattern<'a> for &'b String {
-    type Searcher = <&'b str as Pattern<'a>>::Searcher;
+impl<'b> Pattern for &'b String {
+    type Searcher<'a> = <&'b str as Pattern>::Searcher<'a>;
 
-    fn into_searcher(self, haystack: &'a str) -> <&'b str as Pattern<'a>>::Searcher {
+    fn into_searcher(self, haystack: &str) -> <&'b str as Pattern>::Searcher<'_> {
         self[..].into_searcher(haystack)
     }
 
     #[inline]
-    fn is_contained_in(self, haystack: &'a str) -> bool {
+    fn is_contained_in(self, haystack: &str) -> bool {
         self[..].is_contained_in(haystack)
     }
 
     #[inline]
-    fn is_prefix_of(self, haystack: &'a str) -> bool {
+    fn is_prefix_of(self, haystack: &str) -> bool {
         self[..].is_prefix_of(haystack)
     }
 
     #[inline]
-    fn strip_prefix_of(self, haystack: &'a str) -> Option<&'a str> {
+    fn strip_prefix_of(self, haystack: &str) -> Option<&str> {
         self[..].strip_prefix_of(haystack)
     }
 
     #[inline]
-    fn is_suffix_of(self, haystack: &'a str) -> bool {
+    fn is_suffix_of<'a>(self, haystack: &'a str) -> bool
+    where
+        Self::Searcher<'a>: core::str::pattern::ReverseSearcher<'a>,
+    {
         self[..].is_suffix_of(haystack)
     }
 
     #[inline]
-    fn strip_suffix_of(self, haystack: &'a str) -> Option<&'a str> {
+    fn strip_suffix_of<'a>(self, haystack: &'a str) -> Option<&str>
+    where
+        Self::Searcher<'a>: core::str::pattern::ReverseSearcher<'a>,
+    {
         self[..].strip_suffix_of(haystack)
     }
 }

Diff for: library/alloc/tests/str.rs

@@ -1927,12 +1927,10 @@ mod pattern {
         }
     }
 
-    fn cmp_search_to_vec<'a>(
-        rev: bool,
-        pat: impl Pattern<'a, Searcher: ReverseSearcher<'a>>,
-        haystack: &'a str,
-        right: Vec<SearchStep>,
-    ) {
+    fn cmp_search_to_vec<'a, P>(rev: bool, pat: P, haystack: &'a str, right: Vec<SearchStep>)
+    where
+        P: Pattern<Searcher<'a>: ReverseSearcher<'a>>,
+    {
         let mut searcher = pat.into_searcher(haystack);
         let mut v = vec![];
         loop {
@@ -2191,9 +2189,9 @@ generate_iterator_test! {
 fn different_str_pattern_forwarding_lifetimes() {
     use std::str::pattern::Pattern;
 
-    fn foo<'a, P>(p: P)
+    fn foo<P>(p: P)
     where
-        for<'b> &'b P: Pattern<'a>,
+        for<'b> &'b P: Pattern,
     {
         for _ in 0..3 {
             "asdf".find(&p);