Rollup of 14 pull requests

config.toml.example

@@ -243,19 +243,36 @@
 # =============================================================================
 [rust]
 
-# Indicates that the build should be optimized for debugging Rust. Note that
-# this is typically not what you want as it takes an incredibly large amount of
-# time to have a debug-mode rustc compile any code (notably libstd). If this
-# value is set to `true` it will affect a number of configuration options below
-# as well, if unconfigured.
-#debug = false
-
-# Whether or not to optimize the compiler and standard library
+# Whether or not to optimize the compiler and standard library.
+#
 # Note: the slowness of the non optimized compiler compiling itself usually
 #       outweighs the time gains in not doing optimizations, therefore a
-#       full bootstrap takes much more time with optimize set to false.
+#       full bootstrap takes much more time with `optimize` set to false.
 #optimize = true
 
+# Indicates that the build should be configured for debugging Rust. A
+# `debug`-enabled compiler and standard library will be somewhat
+# slower (due to e.g. checking of debug assertions) but should remain
+# usable.
+#
+# Note: If this value is set to `true`, it will affect a number of
+#       configuration options below as well, if they have been left
+#       unconfigured in this file.
+#
+# Note: changes to the `debug` setting do *not* affect `optimize`
+#       above. In theory, a "maximally debuggable" environment would
+#       set `optimize` to `false` above to assist the introspection
+#       facilities of debuggers like lldb and gdb. To recreate such an
+#       environment, explicitly set `optimize` to `false` and `debug`
+#       to `true`. In practice, everyone leaves `optimize` set to
+#       `true`, because an unoptimized rustc with debugging
+#       enabled becomes *unusably slow* (e.g. rust-lang/rust#24840
+#       reported a 25x slowdown) and bootstrapping the supposed
+#       "maximally debuggable" environment (notably libstd) takes
+#       hours to build.
+#
+#debug = false
+
 # Number of codegen units to use for each compiler invocation. A value of 0
 # means "the number of cores on this machine", and 1+ is passed through to the
 # compiler.

src/Cargo.lock

@@ -204,7 +204,7 @@ dependencies = [
  "env_logger 0.5.12 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "filetime 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "flate2 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "flate2 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "fs2 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "fwdansi 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "git2 0.7.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -737,7 +737,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "flate2"
-version = "1.0.2"
+version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "libc 0.2.43 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -969,7 +969,7 @@ version = "0.0.0"
 dependencies = [
  "clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "error-chain 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "flate2 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "flate2 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rayon 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "tar 0.4.16 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1659,7 +1659,7 @@ dependencies = [
 
 [[package]]
 name = "racer"
-version = "2.1.6"
+version = "2.1.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1807,7 +1807,7 @@ dependencies = [
  "log 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "ordslice 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "racer 2.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "racer 2.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "rayon 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1824,6 +1824,7 @@ dependencies = [
  "serde 1.0.75 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_derive 1.0.75 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.31 (registry+https://github.com/rust-lang/crates.io-index)",
+ "toml 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "url 1.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "walkdir 2.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1899,7 +1900,7 @@ dependencies = [
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 1.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "chalk-engine 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "flate2 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "flate2 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "fmt_macros 0.0.0",
  "graphviz 0.0.0",
  "jobserver 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2143,7 +2144,7 @@ dependencies = [
 name = "rustc_codegen_utils"
 version = "0.0.0"
 dependencies = [
- "flate2 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "flate2 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc 0.0.0",
  "rustc_data_structures 0.0.0",
@@ -2286,7 +2287,7 @@ dependencies = [
 name = "rustc_metadata"
 version = "0.0.0"
 dependencies = [
- "flate2 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "flate2 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc_macro 0.0.0",
  "rustc 0.0.0",
@@ -3233,7 +3234,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum failure_derive 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "946d0e98a50d9831f5d589038d2ca7f8f455b1c21028c0db0e84116a12696426"
 "checksum filetime 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "da4b9849e77b13195302c174324b5ba73eec9b236b24c221a61000daefb95c5f"
 "checksum fixedbitset 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)" = "86d4de0081402f5e88cdac65c8dcdcc73118c1a7a465e2a05f0da05843a8ea33"
-"checksum flate2 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "37847f133aae7acf82bb9577ccd8bda241df836787642654286e79679826a54b"
+"checksum flate2 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4af030962d89d62aa52cd9492083b1cd9b2d1a77764878102a6c0f86b4d5444d"
 "checksum fnv 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)" = "2fad85553e09a6f881f739c29f0b00b0f01357c743266d478b68951ce23285f3"
 "checksum foreign-types 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f6f339eb8adc052cd2ca78910fda869aefa38d22d5cb648e6485e4d3fc06f3b1"
 "checksum foreign-types-shared 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "00b0228411908ca8685dba7fc2cdd70ec9990a6e753e89b6ac91a84c40fbaf4b"
@@ -3331,7 +3332,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum quote 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)" = "7a6e920b65c65f10b2ae65c831a81a073a89edd28c7cce89475bff467ab4167a"
 "checksum quote 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "9949cfe66888ffe1d53e6ec9d9f3b70714083854be20fd5e271b232a017401e8"
 "checksum quote 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)" = "dd636425967c33af890042c483632d33fa7a18f19ad1d7ea72e8998c6ef8dea5"
-"checksum racer 2.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "99e820b7f7701c834c3f6f8226f388c19c0ea948a3ef79ddc96aa7398b5ba87a"
+"checksum racer 2.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "0beefbfaed799c3554021a48856113ad53862311395f6d75376192884ba5fbe6"
 "checksum rand 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8356f47b32624fef5b3301c1be97e5944ecdd595409cc5da11d05f211db6cfbd"
 "checksum rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)" = "e464cd887e869cddcae8792a4ee31d23c7edd516700695608f5b98c67ee0131c"
 "checksum rand_core 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "edecf0f94da5551fc9b492093e30b041a891657db7940ee221f9d2f66e82eef2"

src/bootstrap/config.rs

@@ -628,6 +628,9 @@ impl Config {
         let default = false;
         config.llvm_assertions = llvm_assertions.unwrap_or(default);
 
+        let default = true;
+        config.rust_optimize = optimize.unwrap_or(default);
+
         let default = match &config.channel[..] {
             "stable" | "beta" | "nightly" => true,
             _ => false,
@@ -640,7 +643,6 @@ impl Config {
         config.debug_jemalloc = debug_jemalloc.unwrap_or(default);
         config.rust_debuginfo = debuginfo.unwrap_or(default);
         config.rust_debug_assertions = debug_assertions.unwrap_or(default);
-        config.rust_optimize = optimize.unwrap_or(!default);
 
         let default = config.channel == "dev";
         config.ignore_git = ignore_git.unwrap_or(default);

src/build_helper/lib.rs

@@ -91,13 +91,13 @@ pub fn try_run_suppressed(cmd: &mut Command) -> bool {
     output.status.success()
 }
 
-pub fn gnu_target(target: &str) -> String {
+pub fn gnu_target(target: &str) -> &str {
     match target {
-        "i686-pc-windows-msvc" => "i686-pc-win32".to_string(),
-        "x86_64-pc-windows-msvc" => "x86_64-pc-win32".to_string(),
-        "i686-pc-windows-gnu" => "i686-w64-mingw32".to_string(),
-        "x86_64-pc-windows-gnu" => "x86_64-w64-mingw32".to_string(),
-        s => s.to_string(),
+        "i686-pc-windows-msvc" => "i686-pc-win32",
+        "x86_64-pc-windows-msvc" => "x86_64-pc-win32",
+        "i686-pc-windows-gnu" => "i686-w64-mingw32",
+        "x86_64-pc-windows-gnu" => "x86_64-w64-mingw32",
+        s => s,
     }
 }
 

src/doc/rustc/src/lints/listing/warn-by-default.md

@@ -279,7 +279,7 @@ warning: functions generic over types must be mangled
 1 |   #[no_mangle]
   |   ------------ help: remove this attribute
 2 | / fn foo<T>(t: T) {
-3 | |     
+3 | |
 4 | | }
   | |_^
   |
@@ -513,7 +513,7 @@ This will produce:
 warning: borrow of packed field requires unsafe function or block (error E0133)
   --> src/main.rs:11:13
    |
-11 |     let y = &x.data.0; 
+11 |     let y = &x.data.0;
    |             ^^^^^^^^^
    |
    = note: #[warn(safe_packed_borrows)] on by default
@@ -874,7 +874,7 @@ fn main() {
 This will produce:
 
 ```text
-warning: unused `std::result::Result` which must be used
+warning: unused `std::result::Result` that must be used
  --> src/main.rs:6:5
   |
 6 |     returns_result();

src/liballoc/vec.rs

@@ -120,11 +120,17 @@ use raw_vec::RawVec;
 /// assert_eq!(vec, [1, 2, 3, 4]);
 /// ```
 ///
-/// It can also initialize each element of a `Vec<T>` with a given value:
+/// It can also initialize each element of a `Vec<T>` with a given value.
+/// This may be more efficient than performing allocation and initialization
+/// in separate steps, especially when initializing a vector of zeros:
 ///
 /// ```
 /// let vec = vec![0; 5];
 /// assert_eq!(vec, [0, 0, 0, 0, 0]);
+///
+/// // The following is equivalent, but potentially slower:
+/// let mut vec1 = Vec::with_capacity(5);
+/// vec1.resize(5, 0);
 /// ```
 ///
 /// Use a `Vec<T>` as an efficient stack:

src/libcore/iter/mod.rs

@@ -253,7 +253,7 @@
 //! using it. The compiler will warn us about this kind of behavior:
 //!
 //! ```text
-//! warning: unused result which must be used: iterator adaptors are lazy and
+//! warning: unused result that must be used: iterator adaptors are lazy and
 //! do nothing unless consumed
 //! ```
 //!

src/librustc/macros.rs

@@ -62,6 +62,16 @@ macro_rules! span_bug {
     })
 }
 
+#[macro_export]
+macro_rules! static_assert {
+    ($name:ident: $test:expr) => {
+        // Use the bool to access an array such that if the bool is false, the access
+        // is out-of-bounds.
+        #[allow(dead_code)]
+        static $name: () = [()][!$test as usize];
+    }
+}
+
 #[macro_export]
 macro_rules! __impl_stable_hash_field {
     ($field:ident, $ctx:expr, $hasher:expr) => ($field.hash_stable($ctx, $hasher));

src/librustc/middle/region.rs

@@ -167,8 +167,7 @@ newtype_index! {
 impl_stable_hash_for!(struct ::middle::region::FirstStatementIndex { private });
 
 // compilation error if size of `ScopeData` is not the same as a `u32`
-#[allow(dead_code)]
-static ASSERT: () = [()][!(mem::size_of::<ScopeData>() == 4) as usize];
+static_assert!(ASSERT_SCOPE_DATA: mem::size_of::<ScopeData>() == 4);
 
 impl Scope {
     /// Returns a item-local id associated with this scope.

src/librustc/ty/context.rs

@@ -829,12 +829,9 @@ impl<'tcx> CommonTypes<'tcx> {
     fn new(interners: &CtxtInterners<'tcx>) -> CommonTypes<'tcx> {
         // Ensure our type representation does not grow
         #[cfg(target_pointer_width = "64")]
-        #[allow(dead_code)]
-        static ASSERT_TY_KIND: () =
-            [()][!(::std::mem::size_of::<ty::TyKind<'_>>() <= 24) as usize];
+        static_assert!(ASSERT_TY_KIND: ::std::mem::size_of::<ty::TyKind<'_>>() <= 24);
         #[cfg(target_pointer_width = "64")]
-        #[allow(dead_code)]
-        static ASSERT_TYS: () = [()][!(::std::mem::size_of::<ty::TyS<'_>>() <= 32) as usize];
+        static_assert!(ASSERT_TYS: ::std::mem::size_of::<ty::TyS<'_>>() <= 32);
 
         let mk = |sty| CtxtInterners::intern_ty(interners, interners, sty);
         let mk_region = |r| {

src/librustc_errors/diagnostic.rs

@@ -76,9 +76,9 @@ pub enum StringPart {
 }
 
 impl StringPart {
-    pub fn content(&self) -> String {
+    pub fn content(&self) -> &str {
         match self {
-            &StringPart::Normal(ref s) | & StringPart::Highlighted(ref s) => s.to_owned()
+            &StringPart::Normal(ref s) | & StringPart::Highlighted(ref s) => s
         }
     }
 }
@@ -398,7 +398,7 @@ impl Diagnostic {
     }
 
     pub fn message(&self) -> String {
-        self.message.iter().map(|i| i.0.to_owned()).collect::<String>()
+        self.message.iter().map(|i| i.0.as_str()).collect::<String>()
     }
 
     pub fn styled_message(&self) -> &Vec<(String, Style)> {
@@ -448,7 +448,7 @@ impl Diagnostic {
 
 impl SubDiagnostic {
     pub fn message(&self) -> String {
-        self.message.iter().map(|i| i.0.to_owned()).collect::<String>()
+        self.message.iter().map(|i| i.0.as_str()).collect::<String>()
     }
 
     pub fn styled_message(&self) -> &Vec<(String, Style)> {

src/librustc_lint/unused.rs

@@ -59,15 +59,17 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
         }
 
         let t = cx.tables.expr_ty(&expr);
-        let ty_warned = match t.sty {
-            ty::Tuple(ref tys) if tys.is_empty() => return,
-            ty::Never => return,
+        // FIXME(varkor): replace with `t.is_unit() || t.conservative_is_uninhabited()`.
+        let type_permits_no_use = match t.sty {
+            ty::Tuple(ref tys) if tys.is_empty() => true,
+            ty::Never => true,
             ty::Adt(def, _) => {
                 if def.variants.is_empty() {
-                    return;
+                    true
+                } else {
+                    check_must_use(cx, def.did, s.span, "")
                 }
-                check_must_use(cx, def.did, s.span, "")
-            },
+            }
             _ => false,
         };
 
@@ -95,7 +97,12 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
         if let Some(def) = maybe_def {
             let def_id = def.def_id();
             fn_warned = check_must_use(cx, def_id, s.span, "return value of ");
+        } else if type_permits_no_use {
+            // We don't warn about unused unit or uninhabited types.
+            // (See https://github.com/rust-lang/rust/issues/43806 for details.)
+            return;
         }
+
         let must_use_op = match expr.node {
             // Hardcoding operators here seemed more expedient than the
             // refactoring that would be needed to look up the `#[must_use]`
@@ -135,18 +142,18 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
 
         if let Some(must_use_op) = must_use_op {
             cx.span_lint(UNUSED_MUST_USE, expr.span,
-                         &format!("unused {} which must be used", must_use_op));
+                         &format!("unused {} that must be used", must_use_op));
             op_warned = true;
         }
 
-        if !(ty_warned || fn_warned || op_warned) {
+        if !(type_permits_no_use || fn_warned || op_warned) {
             cx.span_lint(UNUSED_RESULTS, s.span, "unused result");
         }
 
         fn check_must_use(cx: &LateContext, def_id: DefId, sp: Span, describe_path: &str) -> bool {
             for attr in cx.tcx.get_attrs(def_id).iter() {
                 if attr.check_name("must_use") {
-                    let msg = format!("unused {}`{}` which must be used",
+                    let msg = format!("unused {}`{}` that must be used",
                                           describe_path, cx.tcx.item_path_str(def_id));
                     let mut err = cx.struct_span_lint(UNUSED_MUST_USE, sp, &msg);
                     // check for #[must_use = "..."]
@@ -233,7 +240,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedAttributes {
                 .find(|&&(builtin, ty, _)| name == builtin && ty == AttributeType::CrateLevel)
                 .is_some();
 
-            // Has a plugin registered this attribute as one which must be used at
+            // Has a plugin registered this attribute as one that must be used at
             // the crate level?
             let plugin_crate = plugin_attributes.iter()
                 .find(|&&(ref x, t)| name == &**x && AttributeType::CrateLevel == t)