Auto merge of #56381 - kennytm:rollup, r=kennytm

Rollup of 19 pull requests

Successful merges:

 - #55011 (Add libstd Cargo feature "panic_immediate_abort")
 - #55821 (Use sort_by_cached_key when the key function is not trivial/free)
 - #56014 (add test for issue #21335)
 - #56131 (Assorted tweaks)
 - #56214 (Implement chalk unification routines)
 - #56216 (Add TryFrom<&[T]> for [T; $N] where T: Copy)
 - #56268 (Reuse the `P` in `InvocationCollector::fold_{,opt_}expr`.)
 - #56324 (Use raw_entry for more efficient interning)
 - #56336 (Clean up and streamline the pretty-printer)
 - #56337 (Fix const_fn ICE with non-const function pointer)
 - #56339 (Remove not used option)
 - #56341 (Rename conversion util; remove duplicate util in librustc_codegen_llvm.)
 - #56349 (rustc 1.30.0's linker flavor inference is a non-backwards compat change to -Clinker)
 - #56355 (Add inline attributes and add unit to CommonTypes)
 - #56360 (Optimize local linkchecker program)
 - #56364 (Fix panic with outlives in existential type)
 - #56365 (Stabilize self_struct_ctor feature.)
 - #56367 (Moved some feature gate tests to correct location)
 - #56373 (Update books)

.gitmodules

@@ -65,3 +65,6 @@
 [submodule "src/doc/rustc-guide"]
 	path = src/doc/rustc-guide
 	url = https://github.com/rust-lang/rustc-guide.git
+[submodule "src/doc/edition-guide"]
+	path = src/doc/edition-guide
+	url = https://github.com/rust-lang-nursery/edition-guide

src/bootstrap/doc.rs

@@ -70,6 +70,7 @@ macro_rules! book {
 book!(
     Nomicon, "src/doc/nomicon", "nomicon";
     Reference, "src/doc/reference", "reference";
+    EditionGuide, "src/doc/edition-guide", "edition-guide";
     RustdocBook, "src/doc/rustdoc", "rustdoc";
     RustcBook, "src/doc/rustc", "rustc";
     RustByExample, "src/doc/rust-by-example", "rust-by-example";

src/liballoc/string.rs

@@ -618,6 +618,8 @@ impl String {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn from_utf16(v: &[u16]) -> Result<String, FromUtf16Error> {
+        // This isn't done via collect::<Result<_, _>>() for performance reasons.
+        // FIXME: the function can be simplified again when #48994 is closed.
         let mut ret = String::with_capacity(v.len());
         for c in decode_utf16(v.iter().cloned()) {
             if let Ok(c) = c {

src/libarena/lib.rs

@@ -298,6 +298,7 @@ pub struct DroplessArena {
 unsafe impl Send for DroplessArena {}
 
 impl Default for DroplessArena {
+    #[inline]
     fn default() -> DroplessArena {
         DroplessArena {
             ptr: Cell::new(0 as *mut u8),
@@ -319,6 +320,7 @@ impl DroplessArena {
         false
     }
 
+    #[inline]
     fn align(&self, align: usize) {
         let final_address = ((self.ptr.get() as usize) + align - 1) & !(align - 1);
         self.ptr.set(final_address as *mut u8);

src/libcore/Cargo.toml

@@ -21,3 +21,7 @@ path = "../libcore/benches/lib.rs"
 
 [dev-dependencies]
 rand = "0.5"
+
+[features]
+# Make panics and failed asserts immediately abort without formatting any message
+panic_immediate_abort = []

src/libcore/array.rs

@@ -148,6 +148,15 @@ macro_rules! array_impls {
                 }
             }
 
+            #[unstable(feature = "try_from", issue = "33417")]
+            impl<'a, T> TryFrom<&'a [T]> for [T; $N] where T: Copy {
+                type Error = TryFromSliceError;
+
+                fn try_from(slice: &[T]) -> Result<[T; $N], TryFromSliceError> {
+                    <&Self>::try_from(slice).map(|r| *r)
+                }
+            }
+
             #[unstable(feature = "try_from", issue = "33417")]
             impl<'a, T> TryFrom<&'a [T]> for &'a [T; $N] {
                 type Error = TryFromSliceError;

src/libcore/num/mod.rs

@@ -1989,6 +1989,19 @@ big endian.
 ```
 let value = ", stringify!($SelfT), "::from_be_bytes(", $be_bytes, ");
 assert_eq!(value, ", $swap_op, ");
+```
+
+When starting from a slice rather than an array, fallible conversion APIs can be used:
+
+```
+#![feature(try_from)]
+use std::convert::TryInto;
+
+fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {
+    let (int_bytes, rest) = input.split_at(std::mem::size_of::<", stringify!($SelfT), ">());
+    *input = rest;
+    ", stringify!($SelfT), "::from_be_bytes(int_bytes.try_into().unwrap())
+}
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
             #[rustc_const_unstable(feature = "const_int_conversion")]
@@ -2008,6 +2021,19 @@ little endian.
 ```
 let value = ", stringify!($SelfT), "::from_le_bytes(", $le_bytes, ");
 assert_eq!(value, ", $swap_op, ");
+```
+
+When starting from a slice rather than an array, fallible conversion APIs can be used:
+
+```
+#![feature(try_from)]
+use std::convert::TryInto;
+
+fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {
+    let (int_bytes, rest) = input.split_at(std::mem::size_of::<", stringify!($SelfT), ">());
+    *input = rest;
+    ", stringify!($SelfT), "::from_be_bytes(int_bytes.try_into().unwrap())
+}
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
             #[rustc_const_unstable(feature = "const_int_conversion")]
@@ -2037,6 +2063,19 @@ let value = ", stringify!($SelfT), "::from_ne_bytes(if cfg!(target_endian = \"bi
         ", $le_bytes, "
     });
 assert_eq!(value, ", $swap_op, ");
+```
+
+When starting from a slice rather than an array, fallible conversion APIs can be used:
+
+```
+#![feature(try_from)]
+use std::convert::TryInto;
+
+fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {
+    let (int_bytes, rest) = input.split_at(std::mem::size_of::<", stringify!($SelfT), ">());
+    *input = rest;
+    ", stringify!($SelfT), "::from_be_bytes(int_bytes.try_into().unwrap())
+}
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
             #[rustc_const_unstable(feature = "const_int_conversion")]
@@ -3614,6 +3653,7 @@ assert_eq!(3", stringify!($SelfT), ".checked_next_power_of_two(), Some(4));
 assert_eq!(", stringify!($SelfT), "::max_value().checked_next_power_of_two(), None);",
 $EndFeature, "
 ```"),
+            #[inline]
             #[stable(feature = "rust1", since = "1.0.0")]
             pub fn checked_next_power_of_two(self) -> Option<Self> {
                 self.one_less_than_next_power_of_two().checked_add(1)
@@ -3719,6 +3759,19 @@ big endian.
 ```
 let value = ", stringify!($SelfT), "::from_be_bytes(", $be_bytes, ");
 assert_eq!(value, ", $swap_op, ");
+```
+
+When starting from a slice rather than an array, fallible conversion APIs can be used:
+
+```
+#![feature(try_from)]
+use std::convert::TryInto;
+
+fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {
+    let (int_bytes, rest) = input.split_at(std::mem::size_of::<", stringify!($SelfT), ">());
+    *input = rest;
+    ", stringify!($SelfT), "::from_be_bytes(int_bytes.try_into().unwrap())
+}
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
             #[rustc_const_unstable(feature = "const_int_conversion")]
@@ -3738,6 +3791,19 @@ little endian.
 ```
 let value = ", stringify!($SelfT), "::from_le_bytes(", $le_bytes, ");
 assert_eq!(value, ", $swap_op, ");
+```
+
+When starting from a slice rather than an array, fallible conversion APIs can be used:
+
+```
+#![feature(try_from)]
+use std::convert::TryInto;
+
+fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {
+    let (int_bytes, rest) = input.split_at(std::mem::size_of::<", stringify!($SelfT), ">());
+    *input = rest;
+    ", stringify!($SelfT), "::from_be_bytes(int_bytes.try_into().unwrap())
+}
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
             #[rustc_const_unstable(feature = "const_int_conversion")]
@@ -3767,6 +3833,19 @@ let value = ", stringify!($SelfT), "::from_ne_bytes(if cfg!(target_endian = \"bi
         ", $le_bytes, "
     });
 assert_eq!(value, ", $swap_op, ");
+```
+
+When starting from a slice rather than an array, fallible conversion APIs can be used:
+
+```
+#![feature(try_from)]
+use std::convert::TryInto;
+
+fn read_be_", stringify!($SelfT), "(input: &mut &[u8]) -> ", stringify!($SelfT), " {
+    let (int_bytes, rest) = input.split_at(std::mem::size_of::<", stringify!($SelfT), ">());
+    *input = rest;
+    ", stringify!($SelfT), "::from_be_bytes(int_bytes.try_into().unwrap())
+}
 ```"),
             #[stable(feature = "int_to_from_bytes", since = "1.32.0")]
             #[rustc_const_unstable(feature = "const_int_conversion")]

src/libcore/panicking.rs

@@ -39,9 +39,16 @@
 use fmt;
 use panic::{Location, PanicInfo};
 
-#[cold] #[inline(never)] // this is the slow path, always
+#[cold]
+// never inline unless panic_immediate_abort to avoid code
+// bloat at the call sites as much as possible
+#[cfg_attr(not(feature="panic_immediate_abort"),inline(never))]
 #[lang = "panic"]
 pub fn panic(expr_file_line_col: &(&'static str, &'static str, u32, u32)) -> ! {
+    if cfg!(feature = "panic_immediate_abort") {
+        unsafe { super::intrinsics::abort() }
+    }
+
     // Use Arguments::new_v1 instead of format_args!("{}", expr) to potentially
     // reduce size overhead. The format_args! macro uses str's Display trait to
     // write expr, which calls Formatter::pad, which must accommodate string
@@ -52,16 +59,27 @@ pub fn panic(expr_file_line_col: &(&'static str, &'static str, u32, u32)) -> ! {
     panic_fmt(fmt::Arguments::new_v1(&[expr], &[]), &(file, line, col))
 }
 
-#[cold] #[inline(never)]
+#[cold]
+#[cfg_attr(not(feature="panic_immediate_abort"),inline(never))]
 #[lang = "panic_bounds_check"]
 fn panic_bounds_check(file_line_col: &(&'static str, u32, u32),
                      index: usize, len: usize) -> ! {
+    if cfg!(feature = "panic_immediate_abort") {
+        unsafe { super::intrinsics::abort() }
+    }
+
     panic_fmt(format_args!("index out of bounds: the len is {} but the index is {}",
                            len, index), file_line_col)
 }
 
-#[cold] #[inline(never)]
+#[cold]
+#[cfg_attr(not(feature="panic_immediate_abort"),inline(never))]
+#[cfg_attr(    feature="panic_immediate_abort" ,inline)]
 pub fn panic_fmt(fmt: fmt::Arguments, file_line_col: &(&'static str, u32, u32)) -> ! {
+    if cfg!(feature = "panic_immediate_abort") {
+        unsafe { super::intrinsics::abort() }
+    }
+
     // NOTE This function never crosses the FFI boundary; it's a Rust-to-Rust call
     #[allow(improper_ctypes)] // PanicInfo contains a trait object which is not FFI safe
     extern "Rust" {

src/librustc/hir/lowering.rs

@@ -67,7 +67,6 @@ use syntax::ast;
 use syntax::ast::*;
 use syntax::errors;
 use syntax::ext::hygiene::{Mark, SyntaxContext};
-use syntax::feature_gate::{emit_feature_err, GateIssue};
 use syntax::print::pprust;
 use syntax::ptr::P;
 use syntax::source_map::{self, respan, CompilerDesugaringKind, Spanned};
@@ -3628,7 +3627,6 @@ impl<'a> LoweringContext<'a> {
                     ParamMode::Optional,
                     ImplTraitContext::disallowed(),
                 );
-                self.check_self_struct_ctor_feature(&qpath);
                 hir::PatKind::TupleStruct(
                     qpath,
                     pats.iter().map(|x| self.lower_pat(x)).collect(),
@@ -3643,7 +3641,6 @@ impl<'a> LoweringContext<'a> {
                     ParamMode::Optional,
                     ImplTraitContext::disallowed(),
                 );
-                self.check_self_struct_ctor_feature(&qpath);
                 hir::PatKind::Path(qpath)
             }
             PatKind::Struct(ref path, ref fields, etc) => {
@@ -4039,7 +4036,6 @@ impl<'a> LoweringContext<'a> {
                     ParamMode::Optional,
                     ImplTraitContext::disallowed(),
                 );
-                self.check_self_struct_ctor_feature(&qpath);
                 hir::ExprKind::Path(qpath)
             }
             ExprKind::Break(opt_label, ref opt_expr) => {
@@ -5102,18 +5098,6 @@ impl<'a> LoweringContext<'a> {
                                             ThinVec::new()));
         P(self.expr_call(e.span, from_err, hir_vec![e]))
     }
-
-    fn check_self_struct_ctor_feature(&self, qp: &hir::QPath) {
-        if let hir::QPath::Resolved(_, ref p) = qp {
-            if p.segments.len() == 1 &&
-               p.segments[0].ident.name == keywords::SelfType.name() &&
-               !self.sess.features_untracked().self_struct_ctor {
-                emit_feature_err(&self.sess.parse_sess, "self_struct_ctor",
-                                 p.span, GateIssue::Language,
-                                 "`Self` struct constructors are unstable");
-            }
-        }
-    }
 }
 
 fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body>) -> Vec<hir::BodyId> {