Auto merge of #52646 - ljedrz:single_char_pattern, r=michaelwoerister

Change single char str patterns to chars

A `char` is faster.

src/librustc/dep_graph/debug.rs

@@ -40,7 +40,7 @@ pub fn accepts_all(&self) -> bool {
     /// Tests whether `node` meets the filter, returning true if so.
     pub fn test(&self, node: &DepNode) -> bool {
         let debug_str = format!("{:?}", node);
-        self.text.split("&")
+        self.text.split('&')
                  .map(|s| s.trim())
                  .all(|f| debug_str.contains(f))
     }

src/librustc/middle/stability.rs

@@ -165,7 +165,7 @@ fn annotate<F>(&mut self, id: NodeId, attrs: &[Attribute],
                         &attr::Stable {since: stab_since}) = (&stab.rustc_depr, &stab.level) {
                     // Explicit version of iter::order::lt to handle parse errors properly
                     for (dep_v, stab_v) in
-                            dep_since.as_str().split(".").zip(stab_since.as_str().split(".")) {
+                            dep_since.as_str().split('.').zip(stab_since.as_str().split('.')) {
                         if let (Ok(dep_v), Ok(stab_v)) = (dep_v.parse::<u64>(), stab_v.parse()) {
                             match dep_v.cmp(&stab_v) {
                                 Ordering::Less => {

src/librustc_mir/util/pretty.rs

@@ -117,8 +117,8 @@ pub fn dump_enabled<'a, 'gcx, 'tcx>(
         // see notes on #41697 below
         tcx.item_path_str(source.def_id)
     });
-    filters.split("|").any(|or_filter| {
-        or_filter.split("&").all(|and_filter| {
+    filters.split('|').any(|or_filter| {
+        or_filter.split('&').all(|and_filter| {
             and_filter == "all" || pass_name.contains(and_filter) || node_path.contains(and_filter)
         })
     })
@@ -388,7 +388,7 @@ struct ExtraComments<'cx, 'gcx: 'tcx, 'tcx: 'cx> {
 
 impl<'cx, 'gcx, 'tcx> ExtraComments<'cx, 'gcx, 'tcx> {
     fn push(&mut self, lines: &str) {
-        for line in lines.split("\n") {
+        for line in lines.split('\n') {
             self.comments.push(line.to_string());
         }
     }

src/librustc_target/abi/mod.rs

@@ -92,8 +92,8 @@ pub fn parse(target: &Target) -> Result<TargetDataLayout, String> {
 
         let mut dl = TargetDataLayout::default();
         let mut i128_align_src = 64;
-        for spec in target.data_layout.split("-") {
-            match &spec.split(":").collect::<Vec<_>>()[..] {
+        for spec in target.data_layout.split('-') {
+            match &spec.split(':').collect::<Vec<_>>()[..] {
                 &["e"] => dl.endian = Endian::Little,
                 &["E"] => dl.endian = Endian::Big,
                 &["a", ref a..] => dl.aggregate_align = align(a, "a")?,

src/libstd/sys/redox/net/mod.rs

@@ -41,12 +41,12 @@ fn next(&mut self) -> Option<Self::Item> {
 pub fn lookup_host(host: &str) -> Result<LookupHost> {
     let mut ip_string = String::new();
     File::open("/etc/net/ip")?.read_to_string(&mut ip_string)?;
-    let ip: Vec<u8> = ip_string.trim().split(".").map(|part| part.parse::<u8>()
+    let ip: Vec<u8> = ip_string.trim().split('.').map(|part| part.parse::<u8>()
                                .unwrap_or(0)).collect();
 
     let mut dns_string = String::new();
     File::open("/etc/net/dns")?.read_to_string(&mut dns_string)?;
-    let dns: Vec<u8> = dns_string.trim().split(".").map(|part| part.parse::<u8>()
+    let dns: Vec<u8> = dns_string.trim().split('.').map(|part| part.parse::<u8>()
                                  .unwrap_or(0)).collect();
 
     if ip.len() == 4 && dns.len() == 4 {

src/libstd/sys/unix/os.rs

@@ -564,7 +564,7 @@ fn gnu_get_libc_version() -> *const libc::c_char
 // ignoring any extra dot-separated parts. Otherwise return None.
 #[cfg(target_env = "gnu")]
 fn parse_glibc_version(version: &str) -> Option<(usize, usize)> {
-    let mut parsed_ints = version.split(".").map(str::parse::<usize>).fuse();
+    let mut parsed_ints = version.split('.').map(str::parse::<usize>).fuse();
     match (parsed_ints.next(), parsed_ints.next()) {
         (Some(Ok(major)), Some(Ok(minor))) => Some((major, minor)),
         _ => None

src/tools/tidy/src/deps.rs

@@ -165,7 +165,7 @@ pub fn id_str(&self) -> String {
 impl<'a> CrateVersion<'a> {
     /// Returns the struct and whether or not the dep is in-tree
     pub fn from_str(s: &'a str) -> (Self, bool) {
-        let mut parts = s.split(" ");
+        let mut parts = s.split(' ');
         let name = parts.next().unwrap();
         let version = parts.next().unwrap();
         let path = parts.next().unwrap();

src/tools/tidy/src/features.rs

@@ -257,7 +257,7 @@ pub fn collect_lang_features(base_src_path: &Path, bad: &mut bool) -> Features {
                 None
             } else {
                 next_feature_is_rustc_internal = false;
-                let s = issue_str.split("(").nth(1).unwrap().split(")").nth(0).unwrap();
+                let s = issue_str.split('(').nth(1).unwrap().split(')').nth(0).unwrap();
                 Some(s.parse().unwrap())
             };
             Some((name.to_owned(),

src/tools/tidy/src/style.rs

@@ -131,7 +131,7 @@ pub fn check(path: &Path, bad: &mut bool) {
         let skip_length = contents.contains("ignore-tidy-linelength");
         let skip_end_whitespace = contents.contains("ignore-tidy-end-whitespace");
         let mut trailing_new_lines = 0;
-        for (i, line) in contents.split("\n").enumerate() {
+        for (i, line) in contents.split('\n').enumerate() {
             let mut err = |msg: &str| {
                 tidy_error!(bad, "{}:{}: {}", file.display(), i + 1, msg);
             };