Auto merge of #55095 - Manishearth:rollup, r=Manishearth

Rollup of 11 pull requests

Successful merges:

 - #54820 (Closes #54538: `unused_patterns` lint)
 - #54963 (Cleanup rustc/session)
 - #54991 (add test for #23189)
 - #55025 (Add missing lifetime fragment specifier to error message.)
 - #55047 (doc: make core::fmt::Error example more simple)
 - #55048 (Don't collect to vectors where unnecessary)
 - #55060 (clarify pointer add/sub function safety concerns)
 - #55062 (Make EvalContext::step public again)
 - #55066 (Fix incorrect link in println! documentation)
 - #55081 (Deduplicate tests)
 - #55088 (Update rustc documentation link)

Failed merges:

r? @ghost

Author: bors

CONTRIBUTING.md

@@ -646,7 +646,7 @@ are:
 * Don't be afraid to ask! The Rust community is friendly and helpful.
 
 [rustc guide]: https://rust-lang-nursery.github.io/rustc-guide/about-this-guide.html
-[gdfrustc]: http://manishearth.github.io/rust-internals-docs/rustc/
+[gdfrustc]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/
 [gsearchdocs]: https://www.google.com/search?q=site:doc.rust-lang.org+your+query+here
 [rif]: http://internals.rust-lang.org
 [rr]: https://doc.rust-lang.org/book/README.html

src/libcore/fmt/mod.rs

@@ -96,9 +96,8 @@ pub type Result = result::Result<(), Error>;
 /// use std::fmt::{self, write};
 ///
 /// let mut output = String::new();
-/// match write(&mut output, format_args!("Hello {}!", "world")) {
-///     Err(fmt::Error) => panic!("An error occurred"),
-///     _ => (),
+/// if let Err(fmt::Error) = write(&mut output, format_args!("Hello {}!", "world")) {
+///     panic!("An error occurred");
 /// }
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]

src/libcore/ptr.rs

@@ -1037,7 +1037,7 @@ impl<T: ?Sized> *const T {
     /// Behavior:
     ///
     /// * Both the starting and resulting pointer must be either in bounds or one
-    ///   byte past the end of *the same* allocated object.
+    ///   byte past the end of the same allocated object.
     ///
     /// * The computed offset, **in bytes**, cannot overflow an `isize`.
     ///
@@ -1255,7 +1255,7 @@ impl<T: ?Sized> *const T {
     /// Behavior:
     ///
     /// * Both the starting and resulting pointer must be either in bounds or one
-    ///   byte past the end of an allocated object.
+    ///   byte past the end of the same allocated object.
     ///
     /// * The computed offset, **in bytes**, cannot overflow an `isize`.
     ///
@@ -1312,7 +1312,7 @@ impl<T: ?Sized> *const T {
     /// Behavior:
     ///
     /// * Both the starting and resulting pointer must be either in bounds or one
-    ///   byte past the end of an allocated object.
+    ///   byte past the end of the same allocated object.
     ///
     /// * The computed offset cannot exceed `isize::MAX` **bytes**.
     ///
@@ -1657,7 +1657,7 @@ impl<T: ?Sized> *mut T {
     /// Behavior:
     ///
     /// * Both the starting and resulting pointer must be either in bounds or one
-    ///   byte past the end of *the same* allocated object.
+    ///   byte past the end of the same allocated object.
     ///
     /// * The computed offset, **in bytes**, cannot overflow an `isize`.
     ///
@@ -1893,7 +1893,7 @@ impl<T: ?Sized> *mut T {
     /// Behavior:
     ///
     /// * Both the starting and resulting pointer must be either in bounds or one
-    ///   byte past the end of an allocated object.
+    ///   byte past the end of the same allocated object.
     ///
     /// * The computed offset, **in bytes**, cannot overflow an `isize`.
     ///
@@ -1950,7 +1950,7 @@ impl<T: ?Sized> *mut T {
     /// Behavior:
     ///
     /// * Both the starting and resulting pointer must be either in bounds or one
-    ///   byte past the end of an allocated object.
+    ///   byte past the end of the same allocated object.
     ///
     /// * The computed offset cannot exceed `isize::MAX` **bytes**.
     ///

src/librustc/hir/lowering.rs

@@ -60,7 +60,6 @@ use util::nodemap::{DefIdMap, NodeMap};
 
 use std::collections::BTreeMap;
 use std::fmt::Debug;
-use std::iter;
 use std::mem;
 use smallvec::SmallVec;
 use syntax::attr;
@@ -3888,9 +3887,7 @@ impl<'a> LoweringContext<'a> {
                     .collect::<P<[hir::Field]>>();
 
                 let is_unit = fields.is_empty();
-                let struct_path = iter::once("ops")
-                    .chain(iter::once(path))
-                    .collect::<Vec<_>>();
+                let struct_path = ["ops", path];
                 let struct_path = self.std_path(e.span, &struct_path, None, is_unit);
                 let struct_path = hir::QPath::Resolved(None, P(struct_path));
 

src/librustc/session/config.rs

@@ -490,10 +490,10 @@ pub enum Input {
 }
 
 impl Input {
-    pub fn filestem(&self) -> String {
+    pub fn filestem(&self) -> &str {
         match *self {
-            Input::File(ref ifile) => ifile.file_stem().unwrap().to_str().unwrap().to_string(),
-            Input::Str { .. } => "rust_out".to_string(),
+            Input::File(ref ifile) => ifile.file_stem().unwrap().to_str().unwrap(),
+            Input::Str { .. } => "rust_out",
         }
     }
 
@@ -765,7 +765,6 @@ macro_rules! options {
     }
 
     impl<'a> dep_tracking::DepTrackingHash for $struct_name {
-
         fn hash(&self, hasher: &mut DefaultHasher, error_format: ErrorOutputType) {
             let mut sub_hashes = BTreeMap::new();
             $({
@@ -1313,13 +1312,11 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
     profile: bool = (false, parse_bool, [TRACKED],
                      "insert profiling code"),
     pgo_gen: Option<String> = (None, parse_opt_string, [TRACKED],
-        "Generate PGO profile data, to a given file, or to the default \
-         location if it's empty."),
+        "Generate PGO profile data, to a given file, or to the default location if it's empty."),
     pgo_use: String = (String::new(), parse_string, [TRACKED],
         "Use PGO profile data from the given profile file."),
-    disable_instrumentation_preinliner: bool =
-        (false, parse_bool, [TRACKED], "Disable the instrumentation pre-inliner, \
-        useful for profiling / PGO."),
+    disable_instrumentation_preinliner: bool = (false, parse_bool, [TRACKED],
+        "Disable the instrumentation pre-inliner, useful for profiling / PGO."),
     relro_level: Option<RelroLevel> = (None, parse_relro_level, [TRACKED],
         "choose which RELRO level to use"),
     nll_subminimal_causes: bool = (false, parse_bool, [UNTRACKED],
@@ -1409,6 +1406,7 @@ pub fn default_configuration(sess: &Session) -> ast::CrateConfig {
     let atomic_cas = sess.target.target.options.atomic_cas;
 
     let mut ret = FxHashSet::default();
+    ret.reserve(6); // the minimum number of insertions
     // Target bindings.
     ret.insert((Symbol::intern("target_os"), Some(Symbol::intern(os))));
     if let Some(ref fam) = sess.target.target.options.target_family {
@@ -1455,7 +1453,7 @@ pub fn default_configuration(sess: &Session) -> ast::CrateConfig {
     if sess.opts.crate_types.contains(&CrateType::ProcMacro) {
         ret.insert((Symbol::intern("proc_macro"), None));
     }
-    return ret;
+    ret
 }
 
 pub fn build_configuration(sess: &Session, mut user_cfg: ast::CrateConfig) -> ast::CrateConfig {
@@ -1471,15 +1469,12 @@ pub fn build_configuration(sess: &Session, mut user_cfg: ast::CrateConfig) -> as
 }
 
 pub fn build_target_config(opts: &Options, sp: &Handler) -> Config {
-    let target = match Target::search(&opts.target_triple) {
-        Ok(t) => t,
-        Err(e) => {
+    let target = Target::search(&opts.target_triple).unwrap_or_else(|e| {
         sp.struct_fatal(&format!("Error loading target specification: {}", e))
           .help("Use `--print target-list` for a list of built-in targets")
           .emit();
         FatalError.raise();
-        }
-    };
+    });
 
     let (isize_ty, usize_ty) = match &target.target_pointer_width[..] {
         "16" => (ast::IntTy::I16, ast::UintTy::U16),
@@ -1502,7 +1497,6 @@ pub fn build_target_config(opts: &Options, sp: &Handler) -> Config {
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum OptionStability {
     Stable,
-
     Unstable,
 }
 
@@ -1845,9 +1839,8 @@ pub fn build_session_options_and_crate_config(
     };
 
     let edition = match matches.opt_str("edition") {
-        Some(arg) => match Edition::from_str(&arg){
-            Ok(edition) => edition,
-            Err(_) => early_error(
+        Some(arg) => Edition::from_str(&arg).unwrap_or_else(|_|
+            early_error(
                 ErrorOutputType::default(),
                 &format!(
                     "argument for --edition must be one of: \
@@ -1856,7 +1849,7 @@ pub fn build_session_options_and_crate_config(
                     arg
                 ),
             ),
-        }
+        ),
         None => DEFAULT_EDITION,
     };
 
@@ -1925,17 +1918,16 @@ pub fn build_session_options_and_crate_config(
             for output_type in list.split(',') {
                 let mut parts = output_type.splitn(2, '=');
                 let shorthand = parts.next().unwrap();
-                let output_type = match OutputType::from_shorthand(shorthand) {
-                    Some(output_type) => output_type,
-                    None => early_error(
+                let output_type = OutputType::from_shorthand(shorthand).unwrap_or_else(||
+                    early_error(
                         error_format,
                         &format!(
                             "unknown emission type: `{}` - expected one of: {}",
                             shorthand,
                             OutputType::shorthands_display(),
                         ),
                     ),
-                };
+                );
                 let path = parts.next().map(PathBuf::from);
                 output_types.insert(output_type, path);
             }
@@ -2063,12 +2055,8 @@ pub fn build_session_options_and_crate_config(
     let target_triple = if let Some(target) = matches.opt_str("target") {
         if target.ends_with(".json") {
             let path = Path::new(&target);
-            match TargetTriple::from_path(&path) {
-                Ok(triple) => triple,
-                Err(_) => {
-                    early_error(error_format, &format!("target file {:?} does not exist", path))
-                }
-            }
+            TargetTriple::from_path(&path).unwrap_or_else(|_|
+                early_error(error_format, &format!("target file {:?} does not exist", path)))
         } else {
             TargetTriple::TargetTriple(target)
         }
@@ -2169,7 +2157,7 @@ pub fn build_session_options_and_crate_config(
             let mut name_parts = name.splitn(2, ':');
             let name = name_parts.next().unwrap();
             let new_name = name_parts.next();
-            (name.to_string(), new_name.map(|n| n.to_string()), kind)
+            (name.to_owned(), new_name.map(|n| n.to_owned()), kind)
         })
         .collect();
 
@@ -2223,10 +2211,8 @@ pub fn build_session_options_and_crate_config(
     let mut externs: BTreeMap<_, BTreeSet<_>> = BTreeMap::new();
     for arg in &matches.opt_strs("extern") {
         let mut parts = arg.splitn(2, '=');
-        let name = match parts.next() {
-            Some(s) => s,
-            None => early_error(error_format, "--extern value must not be empty"),
-        };
+        let name = parts.next().unwrap_or_else(||
+            early_error(error_format, "--extern value must not be empty"));
         let location = parts.next().map(|s| s.to_string());
         if location.is_none() && !is_unstable_enabled {
             early_error(
@@ -2237,7 +2223,7 @@ pub fn build_session_options_and_crate_config(
         };
 
         externs
-            .entry(name.to_string())
+            .entry(name.to_owned())
             .or_default()
             .insert(location);
     }
@@ -2308,9 +2294,7 @@ pub fn parse_crate_types_from_list(list_list: Vec<String>) -> Result<Vec<CrateTy
                 "cdylib" => CrateType::Cdylib,
                 "bin" => CrateType::Executable,
                 "proc-macro" => CrateType::ProcMacro,
-                _ => {
-                    return Err(format!("unknown crate type: `{}`", part));
-                }
+                _ => return Err(format!("unknown crate type: `{}`", part))
             };
             if !crate_types.contains(&new_part) {
                 crate_types.push(new_part)

src/librustc/session/filesearch.rs

@@ -41,7 +41,7 @@ impl<'a> FileSearch<'a> {
         F: FnMut(&Path, PathKind)
     {
         let mut visited_dirs = FxHashSet::default();
-
+        visited_dirs.reserve(self.search_paths.paths.len() + 1);
         for (path, kind) in self.search_paths.iter(self.kind) {
             f(path, kind);
             visited_dirs.insert(path.to_path_buf());
@@ -160,7 +160,7 @@ pub fn get_or_default_sysroot() -> PathBuf {
     match env::current_exe() {
         Ok(exe) => {
             match canonicalize(Some(exe)) {
-                Some(mut p) => { p.pop(); p.pop(); return p; },
+                Some(mut p) => { p.pop(); p.pop(); p },
                 None => bug!("can't determine value for sysroot")
             }
         }
@@ -178,22 +178,22 @@ fn find_libdir(sysroot: &Path) -> Cow<'static, str> {
     // If --libdir is set during configuration to the value other than
     // "lib" (i.e. non-default), this value is used (see issue #16552).
 
-    match option_env!("CFG_LIBDIR_RELATIVE") {
-        Some(libdir) if libdir != "lib" => return libdir.into(),
-        _ => if sysroot.join(PRIMARY_LIB_DIR).join(RUST_LIB_DIR).exists() {
-            return PRIMARY_LIB_DIR.into();
-        } else {
-            return SECONDARY_LIB_DIR.into();
-        }
-    }
-
     #[cfg(target_pointer_width = "64")]
     const PRIMARY_LIB_DIR: &'static str = "lib64";
 
     #[cfg(target_pointer_width = "32")]
     const PRIMARY_LIB_DIR: &'static str = "lib32";
 
     const SECONDARY_LIB_DIR: &'static str = "lib";
+
+    match option_env!("CFG_LIBDIR_RELATIVE") {
+        Some(libdir) if libdir != "lib" => libdir.into(),
+        _ => if sysroot.join(PRIMARY_LIB_DIR).join(RUST_LIB_DIR).exists() {
+            PRIMARY_LIB_DIR.into()
+        } else {
+            SECONDARY_LIB_DIR.into()
+        }
+    }
 }
 
 // The name of rustc's own place to organize libraries.