Rollup of 8 pull requests

Cargo.lock

@@ -3112,6 +3112,7 @@ dependencies = [
  "serialize",
  "smallvec",
  "syntax",
+ "syntax_expand",
  "syntax_pos",
 ]
 
@@ -3427,6 +3428,7 @@ dependencies = [
  "rustc_target",
  "serialize",
  "syntax",
+ "syntax_expand",
  "syntax_pos",
  "tempfile",
 ]
@@ -3559,6 +3561,7 @@ dependencies = [
  "serialize",
  "smallvec",
  "syntax",
+ "syntax_expand",
  "syntax_ext",
  "syntax_pos",
  "tempfile",
@@ -3630,6 +3633,7 @@ dependencies = [
  "smallvec",
  "stable_deref_trait",
  "syntax",
+ "syntax_expand",
  "syntax_pos",
 ]
 
@@ -3678,6 +3682,7 @@ dependencies = [
  "rustc_index",
  "rustc_target",
  "syntax",
+ "syntax_expand",
  "syntax_pos",
 ]
 
@@ -3695,6 +3700,7 @@ dependencies = [
  "rustc",
  "rustc_metadata",
  "syntax",
+ "syntax_expand",
  "syntax_pos",
 ]
 
@@ -3723,6 +3729,7 @@ dependencies = [
  "rustc_metadata",
  "smallvec",
  "syntax",
+ "syntax_expand",
  "syntax_pos",
 ]
 
@@ -4336,6 +4343,25 @@ dependencies = [
  "syntax_pos",
 ]
 
+[[package]]
+name = "syntax_expand"
+version = "0.0.0"
+dependencies = [
+ "bitflags",
+ "lazy_static 1.3.0",
+ "log",
+ "rustc_data_structures",
+ "rustc_errors",
+ "rustc_index",
+ "rustc_lexer",
+ "rustc_target",
+ "scoped-tls",
+ "serialize",
+ "smallvec",
+ "syntax",
+ "syntax_pos",
+]
+
 [[package]]
 name = "syntax_ext"
 version = "0.0.0"
@@ -4347,6 +4373,7 @@ dependencies = [
  "rustc_target",
  "smallvec",
  "syntax",
+ "syntax_expand",
  "syntax_pos",
 ]
 

src/liballoc/boxed.rs

@@ -142,6 +142,9 @@ impl<T> Box<T> {
     #[unstable(feature = "new_uninit", issue = "63291")]
     pub fn new_uninit() -> Box<mem::MaybeUninit<T>> {
         let layout = alloc::Layout::new::<mem::MaybeUninit<T>>();
+        if layout.size() == 0 {
+            return Box(NonNull::dangling().into())
+        }
         let ptr = unsafe {
             Global.alloc(layout)
                 .unwrap_or_else(|_| alloc::handle_alloc_error(layout))
@@ -182,9 +185,16 @@ impl<T> Box<[T]> {
     #[unstable(feature = "new_uninit", issue = "63291")]
     pub fn new_uninit_slice(len: usize) -> Box<[mem::MaybeUninit<T>]> {
         let layout = alloc::Layout::array::<mem::MaybeUninit<T>>(len).unwrap();
-        let ptr = unsafe { alloc::alloc(layout) };
-        let unique = Unique::new(ptr).unwrap_or_else(|| alloc::handle_alloc_error(layout));
-        let slice = unsafe { slice::from_raw_parts_mut(unique.cast().as_ptr(), len) };
+        let ptr = if layout.size() == 0 {
+            NonNull::dangling()
+        } else {
+            unsafe {
+                Global.alloc(layout)
+                    .unwrap_or_else(|_| alloc::handle_alloc_error(layout))
+                    .cast()
+            }
+        };
+        let slice = unsafe { slice::from_raw_parts_mut(ptr.as_ptr(), len) };
         Box(Unique::from(slice))
     }
 }

src/liballoc/tests/boxed.rs

@@ -0,0 +1,19 @@
+use std::ptr::NonNull;
+use std::mem::MaybeUninit;
+
+#[test]
+fn unitialized_zero_size_box() {
+    assert_eq!(
+        &*Box::<()>::new_uninit() as *const _,
+        NonNull::<MaybeUninit<()>>::dangling().as_ptr(),
+    );
+    assert_eq!(
+        Box::<[()]>::new_uninit_slice(4).as_ptr(),
+        NonNull::<MaybeUninit<()>>::dangling().as_ptr(),
+    );
+    assert_eq!(
+        Box::<[String]>::new_uninit_slice(0).as_ptr(),
+        NonNull::<MaybeUninit<String>>::dangling().as_ptr(),
+    );
+}
+

src/liballoc/tests/lib.rs

@@ -2,6 +2,7 @@
 #![feature(box_syntax)]
 #![feature(drain_filter)]
 #![feature(exact_size_is_empty)]
+#![feature(new_uninit)]
 #![feature(option_flattening)]
 #![feature(pattern)]
 #![feature(trusted_len)]
@@ -14,6 +15,7 @@ use std::collections::hash_map::DefaultHasher;
 
 mod arc;
 mod binary_heap;
+mod boxed;
 mod btree;
 mod cow_str;
 mod fmt;

src/libcore/any.rs

@@ -445,6 +445,15 @@ impl TypeId {
 ///
 /// The current implementation uses the same infrastructure as compiler
 /// diagnostics and debuginfo, but this is not guaranteed.
+///
+/// # Example
+///
+/// ```rust
+/// assert_eq!(
+///     std::any::type_name::<Option<String>>(),
+///     "core::option::Option<alloc::string::String>",
+/// );
+/// ```
 #[stable(feature = "type_name", since = "1.38.0")]
 #[rustc_const_unstable(feature = "const_type_name")]
 pub const fn type_name<T: ?Sized>() -> &'static str {

src/libcore/fmt/mod.rs

@@ -108,10 +108,10 @@ pub struct Error;
 /// [`io::Write`]: ../../std/io/trait.Write.html
 #[stable(feature = "rust1", since = "1.0.0")]
 pub trait Write {
-    /// Writes a slice of bytes into this writer, returning whether the write
+    /// Writes a string slice into this writer, returning whether the write
     /// succeeded.
     ///
-    /// This method can only succeed if the entire byte slice was successfully
+    /// This method can only succeed if the entire string slice was successfully
     /// written, and this method will not return until all data has been
     /// written or an error occurs.
     ///

src/librustc/Cargo.toml

@@ -29,6 +29,7 @@ rustc_index = { path = "../librustc_index" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 syntax = { path = "../libsyntax" }
+syntax_expand = { path = "../libsyntax_expand" }
 syntax_pos = { path = "../libsyntax_pos" }
 backtrace = "0.3.3"
 parking_lot = "0.9"

src/librustc/hir/def.rs

@@ -6,7 +6,7 @@ use crate::ty;
 use crate::util::nodemap::DefIdMap;
 
 use syntax::ast;
-use syntax::ext::base::MacroKind;
+use syntax_expand::base::MacroKind;
 use syntax::ast::NodeId;
 use syntax_pos::Span;
 use rustc_macros::HashStable;

src/librustc/hir/lowering.rs

@@ -64,15 +64,15 @@ use syntax::ast;
 use syntax::ptr::P as AstP;
 use syntax::ast::*;
 use syntax::errors;
-use syntax::ext::base::SpecialDerives;
-use syntax::ext::hygiene::ExpnId;
+use syntax_expand::base::SpecialDerives;
 use syntax::print::pprust;
-use syntax::tokenstream::{TokenStream, TokenTree};
 use syntax::parse::token::{self, Nonterminal, Token};
+use syntax::tokenstream::{TokenStream, TokenTree};
 use syntax::sess::ParseSess;
 use syntax::source_map::{respan, ExpnData, ExpnKind, DesugaringKind, Spanned};
 use syntax::symbol::{kw, sym, Symbol};
 use syntax::visit::{self, Visitor};
+use syntax_pos::hygiene::ExpnId;
 use syntax_pos::Span;
 
 const HIR_ID_COUNTER_LOCKED: u32 = 0xFFFFFFFF;

src/librustc/hir/lowering/item.rs

@@ -18,7 +18,7 @@ use smallvec::SmallVec;
 use syntax::attr;
 use syntax::ast::*;
 use syntax::visit::{self, Visitor};
-use syntax::ext::base::SpecialDerives;
+use syntax_expand::base::SpecialDerives;
 use syntax::source_map::{respan, DesugaringKind, Spanned};
 use syntax::symbol::{kw, sym};
 use syntax_pos::Span;

src/librustc/hir/map/def_collector.rs

@@ -2,7 +2,7 @@ use crate::hir::map::definitions::*;
 use crate::hir::def_id::DefIndex;
 
 use syntax::ast::*;
-use syntax::ext::hygiene::ExpnId;
+use syntax_expand::hygiene::ExpnId;
 use syntax::visit;
 use syntax::symbol::{kw, sym};
 use syntax::parse::token::{self, Token};

src/librustc/hir/map/definitions.rs

@@ -17,7 +17,7 @@ use std::borrow::Borrow;
 use std::fmt::Write;
 use std::hash::Hash;
 use syntax::ast;
-use syntax::ext::hygiene::ExpnId;
+use syntax_expand::hygiene::ExpnId;
 use syntax::symbol::{Symbol, sym, InternedString};
 use syntax_pos::{Span, DUMMY_SP};
 

src/librustc/hir/map/mod.rs

@@ -20,7 +20,7 @@ use rustc_data_structures::svh::Svh;
 use rustc_index::vec::IndexVec;
 use syntax::ast::{self, Name, NodeId};
 use syntax::source_map::Spanned;
-use syntax::ext::base::MacroKind;
+use syntax_expand::base::MacroKind;
 use syntax_pos::{Span, DUMMY_SP};
 
 pub mod blocks;

src/librustc/ich/hcx.rs

@@ -13,7 +13,7 @@ use std::cell::RefCell;
 
 use syntax::ast;
 use syntax::source_map::SourceMap;
-use syntax::ext::hygiene::SyntaxContext;
+use syntax_expand::hygiene::SyntaxContext;
 use syntax::symbol::Symbol;
 use syntax::tokenstream::DelimSpan;
 use syntax_pos::{Span, DUMMY_SP};

src/librustc/ich/impls_syntax.rs

@@ -59,7 +59,7 @@ impl_stable_hash_for!(enum ::syntax::ast::AsmDialect {
     Intel
 });
 
-impl_stable_hash_for!(enum ::syntax::ext::base::MacroKind {
+impl_stable_hash_for!(enum ::syntax_expand::base::MacroKind {
     Bang,
     Attr,
     Derive,

src/librustc/lint/mod.rs

@@ -39,7 +39,7 @@ use syntax::ast;
 use syntax::source_map::{MultiSpan, ExpnKind, DesugaringKind};
 use syntax::early_buffered_lints::BufferedEarlyLintId;
 use syntax::edition::Edition;
-use syntax::ext::base::MacroKind;
+use syntax_expand::base::MacroKind;
 use syntax::symbol::{Symbol, sym};
 use syntax_pos::Span;
 

src/librustc/session/mod.rs

@@ -24,7 +24,7 @@ use errors::emitter::HumanReadableErrorType;
 use errors::annotate_snippet_emitter_writer::{AnnotateSnippetEmitterWriter};
 use syntax::ast::{self, NodeId};
 use syntax::edition::Edition;
-use syntax::ext::allocator::AllocatorKind;
+use syntax_expand::allocator::AllocatorKind;
 use syntax::feature_gate::{self, AttributeType};
 use syntax::json::JsonEmitter;
 use syntax::source_map;

src/librustc/ty/mod.rs

@@ -45,7 +45,7 @@ use std::{mem, ptr};
 use std::ops::Range;
 use syntax::ast::{self, Name, Ident, NodeId};
 use syntax::attr;
-use syntax::ext::hygiene::ExpnId;
+use syntax_expand::hygiene::ExpnId;
 use syntax::symbol::{kw, sym, Symbol, InternedString};
 use syntax_pos::Span;
 

src/librustc_codegen_llvm/allocator.rs

@@ -3,7 +3,7 @@ use std::ffi::CString;
 use crate::attributes;
 use libc::c_uint;
 use rustc::ty::TyCtxt;
-use syntax::ext::allocator::{AllocatorKind, AllocatorTy, ALLOCATOR_METHODS};
+use syntax_expand::allocator::{AllocatorKind, AllocatorTy, ALLOCATOR_METHODS};
 
 use crate::ModuleLlvm;
 use crate::llvm::{self, False, True};

src/librustc_codegen_llvm/lib.rs

@@ -39,6 +39,7 @@ extern crate rustc_driver as _;
 
 #[macro_use] extern crate log;
 extern crate syntax;
+extern crate syntax_expand;
 extern crate syntax_pos;
 extern crate rustc_errors as errors;
 
@@ -48,7 +49,7 @@ use rustc_codegen_ssa::back::lto::{SerializedModule, LtoModuleCodegen, ThinModul
 use rustc_codegen_ssa::CompiledModule;
 use errors::{FatalError, Handler};
 use rustc::dep_graph::WorkProduct;
-use syntax::ext::allocator::AllocatorKind;
+use syntax_expand::allocator::AllocatorKind;
 use syntax_pos::symbol::InternedString;
 pub use llvm_util::target_features;
 use std::any::Any;

src/librustc_codegen_ssa/Cargo.toml

@@ -21,6 +21,7 @@ tempfile = "3.1"
 
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 syntax = { path = "../libsyntax" }
+syntax_expand = { path = "../libsyntax_expand" }
 syntax_pos = { path = "../libsyntax_pos" }
 rustc = { path = "../librustc" }
 rustc_apfloat = { path = "../librustc_apfloat" }

src/librustc_codegen_ssa/back/symbol_export.rs

@@ -14,7 +14,7 @@ use rustc::ty::query::Providers;
 use rustc::ty::subst::SubstsRef;
 use rustc::util::nodemap::{FxHashMap, DefIdMap};
 use rustc_index::vec::IndexVec;
-use syntax::ext::allocator::ALLOCATOR_METHODS;
+use syntax_expand::allocator::ALLOCATOR_METHODS;
 
 pub type ExportedSymbols = FxHashMap<
     CrateNum,

src/librustc_codegen_ssa/back/write.rs

@@ -27,7 +27,7 @@ use rustc_errors::{Handler, Level, FatalError, DiagnosticId, SourceMapperDyn};
 use rustc_errors::emitter::{Emitter};
 use rustc_target::spec::MergeFunctions;
 use syntax::attr;
-use syntax::ext::hygiene::ExpnId;
+use syntax_expand::hygiene::ExpnId;
 use syntax_pos::symbol::{Symbol, sym};
 use jobserver::{Client, Acquired};
 

src/librustc_codegen_ssa/traits/backend.rs

@@ -9,7 +9,7 @@ use rustc::ty::TyCtxt;
 use rustc_codegen_utils::codegen_backend::CodegenBackend;
 use std::sync::Arc;
 use std::sync::mpsc;
-use syntax::ext::allocator::AllocatorKind;
+use syntax_expand::allocator::AllocatorKind;
 use syntax_pos::symbol::InternedString;
 
 pub trait BackendTypes {

src/librustc_interface/Cargo.toml

@@ -15,6 +15,7 @@ rayon = { version = "0.3.0", package = "rustc-rayon" }
 smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
 syntax = { path = "../libsyntax" }
 syntax_ext = { path = "../libsyntax_ext" }
+syntax_expand = { path = "../libsyntax_expand" }
 syntax_pos = { path = "../libsyntax_pos" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 rustc = { path = "../librustc" }