---

yaml
---
r: 224866
b: refs/heads/tmp
c: 68f7928
h: refs/heads/master
v: v3

Author: bors

[refs]

@@ -25,7 +25,7 @@ refs/tags/0.11.0: e1247cb1d0d681be034adb4b558b5a0c0d5720f9
 refs/tags/0.12.0: f0c419429ef30723ceaf6b42f9b5a2aeb5d2e2d1
 refs/heads/beta: 83dee3dfbb452a7558193f3ce171b3c60bf4a499
 refs/tags/1.0.0-alpha: e42bd6d93a1d3433c486200587f8f9e12590a4d7
-refs/heads/tmp: d3e089f08bd55fc5e663400f513f77e567636628
+refs/heads/tmp: 68f79288bf1ac2b014277750cbf59416c91f7d04
 refs/tags/1.0.0-alpha.2: 4c705f6bc559886632d3871b04f58aab093bfa2f
 refs/tags/homu-tmp: e58601ab085591c71a27ae82137fc313222c2270
 refs/tags/1.0.0-beta: 8cbb92b53468ee2b0c2d3eeb8567005953d40828

branches/tmp/src/doc/nomicon/exotic-sizes.md

@@ -85,8 +85,8 @@ support values.
 Safe code need not worry about ZSTs, but *unsafe* code must be careful about the
 consequence of types with no size. In particular, pointer offsets are no-ops,
 and standard allocators (including jemalloc, the one used by default in Rust)
-generally consider passing in `0` for the size of an allocation as Undefined
-Behaviour.
+may return `nullptr` when a zero-sized allocation is requested, which is
+indistinguishable from out of memory.
 
 
 

branches/tmp/src/doc/nomicon/repr-rust.md

@@ -36,9 +36,9 @@ struct A {
 }
 ```
 
-will be 32-bit aligned assuming these primitives are aligned to their size.
-It will therefore have a size that is a multiple of 32-bits. It will potentially
-*really* become:
+will be 32-bit aligned on an architecture that aligns these primitives to their
+respective sizes. The whole struct will therefore have a size that is a multiple
+of 32-bits. It will potentially become:
 
 ```rust
 struct A {
@@ -50,10 +50,10 @@ struct A {
 }
 ```
 
-There is *no indirection* for these types; all data is stored contiguously as
-you would expect in C. However with the exception of arrays (which are densely
-packed and in-order), the layout of data is not by default specified in Rust.
-Given the two following struct definitions:
+There is *no indirection* for these types; all data is stored within the struct,
+as you would expect in C. However with the exception of arrays (which are
+densely packed and in-order), the layout of data is not by default specified in
+Rust. Given the two following struct definitions:
 
 ```rust
 struct A {
@@ -62,18 +62,17 @@ struct A {
 }
 
 struct B {
-    x: i32,
+    a: i32,
     b: u64,
 }
 ```
 
 Rust *does* guarantee that two instances of A have their data laid out in
-exactly the same way. However Rust *does not* guarantee that an instance of A
-has the same field ordering or padding as an instance of B (in practice there's
-no particular reason why they wouldn't, other than that its not currently
-guaranteed).
+exactly the same way. However Rust *does not* currently guarantee that an
+instance of A has the same field ordering or padding as an instance of B, though
+in practice there's no reason why they wouldn't.
 
-With A and B as written, this is basically nonsensical, but several other
+With A and B as written, this point would seem to be pedantic, but several other
 features of Rust make it desirable for the language to play with data layout in
 complex ways.
 
@@ -133,18 +132,21 @@ struct FooRepr {
 }
 ```
 
-And indeed this is approximately how it would be laid out in general
-(modulo the size and position of `tag`). However there are several cases where
-such a representation is inefficient. The classic case of this is Rust's
-"null pointer optimization". Given a pointer that is known to not be null
-(e.g. `&u32`), an enum can *store* a discriminant bit *inside* the pointer
-by using null as a special value. The net result is that
-`size_of::<Option<&T>>() == size_of::<&T>()`
+And indeed this is approximately how it would be laid out in general (modulo the
+size and position of `tag`).
+
+However there are several cases where such a representation is inefficient. The
+classic case of this is Rust's "null pointer optimization": an enum consisting
+of a single outer unit variant (e.g. `None`) and a (potentially nested) non-
+nullable pointer variant (e.g. `&T`) makes the tag unnecessary, because a null
+pointer value can safely be interpreted to mean that the unit variant is chosen
+instead. The net result is that, for example, `size_of::<Option<&T>>() ==
+size_of::<&T>()`.
 
-There are many types in Rust that are, or contain, "not null" pointers such as
+There are many types in Rust that are, or contain, non-nullable pointers such as
 `Box<T>`, `Vec<T>`, `String`, `&T`, and `&mut T`. Similarly, one can imagine
 nested enums pooling their tags into a single discriminant, as they are by
-definition known to have a limited range of valid values. In principle enums can
+definition known to have a limited range of valid values. In principle enums could
 use fairly elaborate algorithms to cache bits throughout nested types with
 special constrained representations. As such it is *especially* desirable that
 we leave enum layout unspecified today.

branches/tmp/src/librustc_typeck/astconv.rs

@@ -1662,6 +1662,9 @@ pub fn ast_ty_to_ty<'tcx>(this: &AstConv<'tcx>,
             // handled specially and will not descend into this routine.
             this.ty_infer(None, None, None, ast_ty.span)
         }
+        ast::TyMac(_) => {
+            tcx.sess.span_bug(ast_ty.span, "unexpanded type macro found conversion")
+        }
     };
 
     tcx.ast_ty_to_ty_cache.borrow_mut().insert(ast_ty.id, typ);

branches/tmp/src/librustdoc/clean/mod.rs

@@ -1611,6 +1611,9 @@ impl Clean<Type> for ast::Ty {
             TyTypeof(..) => {
                 panic!("Unimplemented type {:?}", self.node)
             },
+            TyMac(ref m) => {
+                cx.tcx().sess.span_bug(m.span, "unexpanded type macro found during cleaning")
+            }
         }
     }
 }

branches/tmp/src/libsyntax/ast.rs

@@ -1471,6 +1471,8 @@ pub enum Ty_ {
     /// TyInfer means the type should be inferred instead of it having been
     /// specified. This can appear anywhere in a type.
     TyInfer,
+    // A macro in the type position.
+    TyMac(Mac)
 }
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]

branches/tmp/src/libsyntax/ext/base.rs

@@ -290,6 +290,10 @@ pub trait MacResult {
     fn make_stmts(self: Box<Self>) -> Option<SmallVector<P<ast::Stmt>>> {
         make_stmts_default!(self)
     }
+
+    fn make_ty(self: Box<Self>) -> Option<P<ast::Ty>> {
+        None
+    }
 }
 
 macro_rules! make_MacEager {
@@ -322,6 +326,7 @@ make_MacEager! {
     items: SmallVector<P<ast::Item>>,
     impl_items: SmallVector<P<ast::ImplItem>>,
     stmts: SmallVector<P<ast::Stmt>>,
+    ty: P<ast::Ty>,
 }
 
 impl MacResult for MacEager {
@@ -359,6 +364,10 @@ impl MacResult for MacEager {
         }
         None
     }
+
+    fn make_ty(self: Box<Self>) -> Option<P<ast::Ty>> {
+        self.ty
+    }
 }
 
 /// Fill-in macro expansion result, to allow compilation to continue
@@ -405,15 +414,24 @@ impl DummyResult {
         }
     }
 
+    pub fn raw_ty(sp: Span) -> P<ast::Ty> {
+        P(ast::Ty {
+            id: ast::DUMMY_NODE_ID,
+            node: ast::TyInfer,
+            span: sp
+        })
+    }
 }
 
 impl MacResult for DummyResult {
     fn make_expr(self: Box<DummyResult>) -> Option<P<ast::Expr>> {
         Some(DummyResult::raw_expr(self.span))
     }
+
     fn make_pat(self: Box<DummyResult>) -> Option<P<ast::Pat>> {
         Some(P(DummyResult::raw_pat(self.span)))
     }
+
     fn make_items(self: Box<DummyResult>) -> Option<SmallVector<P<ast::Item>>> {
         // this code needs a comment... why not always just return the Some() ?
         if self.expr_only {
@@ -422,13 +440,15 @@ impl MacResult for DummyResult {
             Some(SmallVector::zero())
         }
     }
+
     fn make_impl_items(self: Box<DummyResult>) -> Option<SmallVector<P<ast::ImplItem>>> {
         if self.expr_only {
             None
         } else {
             Some(SmallVector::zero())
         }
     }
+
     fn make_stmts(self: Box<DummyResult>) -> Option<SmallVector<P<ast::Stmt>>> {
         Some(SmallVector::one(P(
             codemap::respan(self.span,

branches/tmp/src/libsyntax/ext/expand.rs

@@ -1542,6 +1542,45 @@ fn expand_and_rename_method(sig: ast::MethodSig, body: P<ast::Block>,
     }, rewritten_body)
 }
 
+pub fn expand_type(t: P<ast::Ty>, fld: &mut MacroExpander) -> P<ast::Ty> {
+    let t = match t.node.clone() {
+        ast::Ty_::TyMac(mac) => {
+            if fld.cx.ecfg.features.unwrap().type_macros {
+                let expanded_ty = match expand_mac_invoc(mac, t.span,
+                                                         |r| r.make_ty(),
+                                                         mark_ty,
+                                                         fld) {
+                    Some(ty) => ty,
+                    None => {
+                        return DummyResult::raw_ty(t.span);
+                    }
+                };
+
+                // Keep going, outside-in.
+                let fully_expanded = fld.fold_ty(expanded_ty);
+                fld.cx.bt_pop();
+
+                fully_expanded.map(|t| ast::Ty {
+                    id: ast::DUMMY_NODE_ID,
+                    node: t.node,
+                    span: t.span,
+                    })
+            } else {
+                feature_gate::emit_feature_err(
+                    &fld.cx.parse_sess.span_diagnostic,
+                    "type_macros",
+                    t.span,
+                    "type macros are experimental (see issue: #27336)");
+
+                DummyResult::raw_ty(t.span)
+            }
+        }
+        _ => t
+    };
+
+    fold::noop_fold_ty(t, fld)
+}
+
 /// A tree-folder that performs macro expansion
 pub struct MacroExpander<'a, 'b:'a> {
     pub cx: &'a mut ExtCtxt<'b>,
@@ -1592,6 +1631,10 @@ impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
             .into_iter().map(|i| i.expect_impl_item()).collect()
     }
 
+    fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
+        expand_type(ty, self)
+    }
+
     fn new_span(&mut self, span: Span) -> Span {
         new_span(self.cx, span)
     }
@@ -1744,6 +1787,10 @@ fn mark_impl_item(ii: P<ast::ImplItem>, m: Mrk) -> P<ast::ImplItem> {
         .expect_one("marking an impl item didn't return exactly one impl item")
 }
 
+fn mark_ty(ty: P<ast::Ty>, m: Mrk) -> P<ast::Ty> {
+    Marker { mark: m }.fold_ty(ty)
+}
+
 /// Check that there are no macro invocations left in the AST:
 pub fn check_for_macros(sess: &parse::ParseSess, krate: &ast::Crate) {
     visit::walk_crate(&mut MacroExterminator{sess:sess}, krate);

branches/tmp/src/libsyntax/ext/tt/macro_rules.rs

@@ -117,6 +117,12 @@ impl<'a> MacResult for ParserAnyMacro<'a> {
         self.ensure_complete_parse(false);
         Some(ret)
     }
+
+    fn make_ty(self: Box<ParserAnyMacro<'a>>) -> Option<P<ast::Ty>> {
+        let ret = self.parser.borrow_mut().parse_ty();
+        self.ensure_complete_parse(true);
+        Some(ret)
+    }
 }
 
 struct MacroRulesMacroExpander {

branches/tmp/src/libsyntax/feature_gate.rs

@@ -172,6 +172,9 @@ const KNOWN_FEATURES: &'static [(&'static str, &'static str, Status)] = &[
 
     // Allows associated type defaults
     ("associated_type_defaults", "1.2.0", Active),
+    // Allows macros to appear in the type position.
+
+    ("type_macros", "1.3.0", Active),
 ];
 // (changing above list without updating src/doc/reference.md makes @cmr sad)
 
@@ -354,6 +357,7 @@ pub struct Features {
     pub const_fn: bool,
     pub static_recursion: bool,
     pub default_type_parameter_fallback: bool,
+    pub type_macros: bool,
 }
 
 impl Features {
@@ -380,6 +384,7 @@ impl Features {
             const_fn: false,
             static_recursion: false,
             default_type_parameter_fallback: false,
+            type_macros: false,
         }
     }
 }
@@ -883,6 +888,7 @@ fn check_crate_inner<F>(cm: &CodeMap, span_handler: &SpanHandler,
         const_fn: cx.has_feature("const_fn"),
         static_recursion: cx.has_feature("static_recursion"),
         default_type_parameter_fallback: cx.has_feature("default_type_parameter_fallback"),
+        type_macros: cx.has_feature("type_macros"),
     }
 }
 

branches/tmp/src/libsyntax/fold.rs

@@ -429,6 +429,9 @@ pub fn noop_fold_ty<T: Folder>(t: P<Ty>, fld: &mut T) -> P<Ty> {
             TyPolyTraitRef(bounds) => {
                 TyPolyTraitRef(bounds.move_map(|b| fld.fold_ty_param_bound(b)))
             }
+            TyMac(mac) => {
+                TyMac(fld.fold_mac(mac))
+            }
         },
         span: fld.new_span(span)
     })

branches/tmp/src/libsyntax/parse/parser.rs

@@ -51,6 +51,7 @@ use ast::{SelfExplicit, SelfRegion, SelfStatic, SelfValue};
 use ast::{Delimited, SequenceRepetition, TokenTree, TraitItem, TraitRef};
 use ast::{TtDelimited, TtSequence, TtToken};
 use ast::{TupleVariantKind, Ty, Ty_, TypeBinding};
+use ast::{TyMac};
 use ast::{TyFixedLengthVec, TyBareFn, TyTypeof, TyInfer};
 use ast::{TyParam, TyParamBound, TyParen, TyPath, TyPolyTraitRef, TyPtr};
 use ast::{TyRptr, TyTup, TyU32, TyVec, UnUniq};
@@ -1369,8 +1370,20 @@ impl<'a> Parser<'a> {
         } else if self.check(&token::ModSep) ||
                   self.token.is_ident() ||
                   self.token.is_path() {
-            // NAMED TYPE
-            try!(self.parse_ty_path())
+            let path = try!(self.parse_path(LifetimeAndTypesWithoutColons));
+            if self.check(&token::Not) {
+                // MACRO INVOCATION
+                try!(self.bump());
+                let delim = try!(self.expect_open_delim());
+                let tts = try!(self.parse_seq_to_end(&token::CloseDelim(delim),
+                                                     seq_sep_none(),
+                                                     |p| p.parse_token_tree()));
+                let hi = self.span.hi;
+                TyMac(spanned(lo, hi, MacInvocTT(path, tts, EMPTY_CTXT)))
+            } else {
+                // NAMED TYPE
+                TyPath(None, path)
+            }
         } else if try!(self.eat(&token::Underscore) ){
             // TYPE TO BE INFERRED
             TyInfer

branches/tmp/src/libsyntax/print/pprust.rs

@@ -734,6 +734,9 @@ impl<'a> State<'a> {
             ast::TyInfer => {
                 try!(word(&mut self.s, "_"));
             }
+            ast::TyMac(ref m) => {
+                try!(self.print_mac(m, token::Paren));
+            }
         }
         self.end()
     }

branches/tmp/src/libsyntax/visit.rs

@@ -405,6 +405,9 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty) {
             visitor.visit_expr(&**expression)
         }
         TyInfer => {}
+        TyMac(ref mac) => {
+            visitor.visit_mac(mac)
+        }
     }
 }