Infer whether a closure implements Fn, FnMut, etc based on what actions it takes

src/librustc/metadata/common.rs

@@ -139,10 +139,11 @@ pub enum astencode_tag { // Reserves 0x40 -- 0x5f
     tag_table_adjustments = 0x51,
     tag_table_moves_map = 0x52,
     tag_table_capture_map = 0x53,
-    tag_table_closures = 0x54,
-    tag_table_upvar_capture_map = 0x55,
-    tag_table_capture_modes = 0x56,
-    tag_table_object_cast_map = 0x57,
+    tag_table_closure_tys = 0x54,
+    tag_table_closure_kinds = 0x55,
+    tag_table_upvar_capture_map = 0x56,
+    tag_table_capture_modes = 0x57,
+    tag_table_object_cast_map = 0x58,
 }
 
 static first_astencode_tag: uint = tag_ast as uint;
@@ -225,10 +226,7 @@ pub struct LinkMeta {
     pub crate_hash: Svh,
 }
 
-pub const tag_closures: uint = 0x95;
-pub const tag_closure: uint = 0x96;
-pub const tag_closure_type: uint = 0x97;
-pub const tag_closure_kind: uint = 0x98;
+// GAP 0x94...0x98
 
 pub const tag_struct_fields: uint = 0x99;
 pub const tag_struct_field: uint = 0x9a;

src/librustc/metadata/encoder.rs

@@ -618,17 +618,6 @@ fn encode_visibility(rbml_w: &mut Encoder, visibility: ast::Visibility) {
     rbml_w.end_tag();
 }
 
-fn encode_closure_kind(rbml_w: &mut Encoder, kind: ty::ClosureKind) {
-    rbml_w.start_tag(tag_closure_kind);
-    let ch = match kind {
-        ty::FnClosureKind => 'f',
-        ty::FnMutClosureKind => 'm',
-        ty::FnOnceClosureKind => 'o',
-    };
-    rbml_w.wr_str(&ch.to_string()[]);
-    rbml_w.end_tag();
-}
-
 fn encode_explicit_self(rbml_w: &mut Encoder,
                         explicit_self: &ty::ExplicitSelfCategory) {
     rbml_w.start_tag(tag_item_trait_method_explicit_self);
@@ -1843,24 +1832,6 @@ fn encode_macro_defs(rbml_w: &mut Encoder,
     rbml_w.end_tag();
 }
 
-fn encode_closures<'a>(ecx: &'a EncodeContext, rbml_w: &'a mut Encoder) {
-    rbml_w.start_tag(tag_closures);
-    for (closure_id, closure) in ecx.tcx.closures.borrow().iter() {
-        if closure_id.krate != ast::LOCAL_CRATE {
-            continue
-        }
-
-        rbml_w.start_tag(tag_closure);
-        encode_def_id(rbml_w, *closure_id);
-        rbml_w.start_tag(tag_closure_type);
-        write_closure_type(ecx, rbml_w, &closure.closure_type);
-        rbml_w.end_tag();
-        encode_closure_kind(rbml_w, closure.kind);
-        rbml_w.end_tag();
-    }
-    rbml_w.end_tag();
-}
-
 fn encode_struct_field_attrs(rbml_w: &mut Encoder, krate: &ast::Crate) {
     struct StructFieldVisitor<'a, 'b:'a> {
         rbml_w: &'a mut Encoder<'b>,
@@ -2069,7 +2040,6 @@ fn encode_metadata_inner(wr: &mut SeekableMemWriter,
         native_lib_bytes: u64,
         plugin_registrar_fn_bytes: u64,
         macro_defs_bytes: u64,
-        closure_bytes: u64,
         impl_bytes: u64,
         misc_bytes: u64,
         item_bytes: u64,
@@ -2084,7 +2054,6 @@ fn encode_metadata_inner(wr: &mut SeekableMemWriter,
         native_lib_bytes: 0,
         plugin_registrar_fn_bytes: 0,
         macro_defs_bytes: 0,
-        closure_bytes: 0,
         impl_bytes: 0,
         misc_bytes: 0,
         item_bytes: 0,
@@ -2154,11 +2123,6 @@ fn encode_metadata_inner(wr: &mut SeekableMemWriter,
     encode_macro_defs(&mut rbml_w, krate);
     stats.macro_defs_bytes = rbml_w.writer.tell().unwrap() - i;
 
-    // Encode the types of all closures in this crate.
-    i = rbml_w.writer.tell().unwrap();
-    encode_closures(&ecx, &mut rbml_w);
-    stats.closure_bytes = rbml_w.writer.tell().unwrap() - i;
-
     // Encode the def IDs of impls, for coherence checking.
     i = rbml_w.writer.tell().unwrap();
     encode_impls(&ecx, krate, &mut rbml_w);
@@ -2199,7 +2163,6 @@ fn encode_metadata_inner(wr: &mut SeekableMemWriter,
         println!("          native bytes: {}", stats.native_lib_bytes);
         println!("plugin registrar bytes: {}", stats.plugin_registrar_fn_bytes);
         println!("       macro def bytes: {}", stats.macro_defs_bytes);
-        println!("         closure bytes: {}", stats.closure_bytes);
         println!("            impl bytes: {}", stats.impl_bytes);
         println!("            misc bytes: {}", stats.misc_bytes);
         println!("            item bytes: {}", stats.item_bytes);

src/librustc/middle/astencode.rs

@@ -647,30 +647,7 @@ impl<'tcx> tr for MethodOrigin<'tcx> {
 }
 
 pub fn encode_closure_kind(ebml_w: &mut Encoder, kind: ty::ClosureKind) {
-    use serialize::Encoder;
-
-    ebml_w.emit_enum("ClosureKind", |ebml_w| {
-        match kind {
-            ty::FnClosureKind => {
-                ebml_w.emit_enum_variant("FnClosureKind", 0, 3, |_| {
-                    Ok(())
-                })
-            }
-            ty::FnMutClosureKind => {
-                ebml_w.emit_enum_variant("FnMutClosureKind", 1, 3, |_| {
-                    Ok(())
-                })
-            }
-            ty::FnOnceClosureKind => {
-                ebml_w.emit_enum_variant("FnOnceClosureKind",
-                                         2,
-                                         3,
-                                         |_| {
-                    Ok(())
-                })
-            }
-        }
-    }).unwrap()
+    kind.encode(ebml_w).unwrap();
 }
 
 pub trait vtable_decoder_helpers<'tcx> {
@@ -1310,12 +1287,20 @@ fn encode_side_tables_for_id(ecx: &e::EncodeContext,
         })
     }
 
-    for closure in tcx.closures.borrow().get(&ast_util::local_def(id)).iter() {
-        rbml_w.tag(c::tag_table_closures, |rbml_w| {
+    for &closure_type in tcx.closure_tys.borrow().get(&ast_util::local_def(id)).iter() {
+        rbml_w.tag(c::tag_table_closure_tys, |rbml_w| {
+            rbml_w.id(id);
+            rbml_w.tag(c::tag_table_val, |rbml_w| {
+                rbml_w.emit_closure_type(ecx, closure_type);
+            })
+        })
+    }
+
+    for &&closure_kind in tcx.closure_kinds.borrow().get(&ast_util::local_def(id)).iter() {
+        rbml_w.tag(c::tag_table_closure_kinds, |rbml_w| {
             rbml_w.id(id);
             rbml_w.tag(c::tag_table_val, |rbml_w| {
-                rbml_w.emit_closure_type(ecx, &closure.closure_type);
-                encode_closure_kind(rbml_w, closure.kind)
+                encode_closure_kind(rbml_w, closure_kind)
             })
         })
     }
@@ -1354,8 +1339,10 @@ trait rbml_decoder_decoder_helpers<'tcx> {
                            -> subst::Substs<'tcx>;
     fn read_auto_adjustment<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
                                     -> ty::AutoAdjustment<'tcx>;
-    fn read_closure<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
-                            -> ty::Closure<'tcx>;
+    fn read_closure_kind<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
+                                 -> ty::ClosureKind;
+    fn read_closure_ty<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
+                               -> ty::ClosureTy<'tcx>;
     fn read_auto_deref_ref<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
                                    -> ty::AutoDerefRef<'tcx>;
     fn read_autoref<'a, 'b>(&mut self, dcx: &DecodeContext<'a, 'b, 'tcx>)
@@ -1782,35 +1769,23 @@ impl<'a, 'tcx> rbml_decoder_decoder_helpers<'tcx> for reader::Decoder<'a> {
         }).unwrap()
     }
 
-    fn read_closure<'b, 'c>(&mut self, dcx: &DecodeContext<'b, 'c, 'tcx>)
-                            -> ty::Closure<'tcx> {
-        let closure_type = self.read_opaque(|this, doc| {
+    fn read_closure_kind<'b, 'c>(&mut self, _dcx: &DecodeContext<'b, 'c, 'tcx>)
+                                 -> ty::ClosureKind
+    {
+        Decodable::decode(self).ok().unwrap()
+    }
+
+    fn read_closure_ty<'b, 'c>(&mut self, dcx: &DecodeContext<'b, 'c, 'tcx>)
+                               -> ty::ClosureTy<'tcx>
+    {
+        self.read_opaque(|this, doc| {
             Ok(tydecode::parse_ty_closure_data(
                 doc.data,
                 dcx.cdata.cnum,
                 doc.start,
                 dcx.tcx,
                 |s, a| this.convert_def_id(dcx, s, a)))
-        }).unwrap();
-        let variants = &[
-            "FnClosureKind",
-            "FnMutClosureKind",
-            "FnOnceClosureKind"
-        ];
-        let kind = self.read_enum("ClosureKind", |this| {
-            this.read_enum_variant(variants, |_, i| {
-                Ok(match i {
-                    0 => ty::FnClosureKind,
-                    1 => ty::FnMutClosureKind,
-                    2 => ty::FnOnceClosureKind,
-                    _ => panic!("bad enum variant for ty::ClosureKind"),
-                })
-            })
-        }).unwrap();
-        ty::Closure {
-            closure_type: closure_type,
-            kind: kind,
-        }
+        }).unwrap()
     }
 
     /// Converts a def-id that appears in a type.  The correct
@@ -1937,11 +1912,17 @@ fn decode_side_tables(dcx: &DecodeContext,
                         let adj: ty::AutoAdjustment = val_dsr.read_auto_adjustment(dcx);
                         dcx.tcx.adjustments.borrow_mut().insert(id, adj);
                     }
-                    c::tag_table_closures => {
-                        let closure =
-                            val_dsr.read_closure(dcx);
-                        dcx.tcx.closures.borrow_mut().insert(ast_util::local_def(id),
-                                                             closure);
+                    c::tag_table_closure_tys => {
+                        let closure_ty =
+                            val_dsr.read_closure_ty(dcx);
+                        dcx.tcx.closure_tys.borrow_mut().insert(ast_util::local_def(id),
+                                                                closure_ty);
+                    }
+                    c::tag_table_closure_kinds => {
+                        let closure_kind =
+                            val_dsr.read_closure_kind(dcx);
+                        dcx.tcx.closure_kinds.borrow_mut().insert(ast_util::local_def(id),
+                                                                  closure_kind);
                     }
                     _ => {
                         dcx.tcx.sess.bug(

src/librustc/middle/expr_use_visitor.rs

@@ -260,12 +260,10 @@ impl OverloadedCallType {
     fn from_closure(tcx: &ty::ctxt, closure_did: ast::DefId)
                     -> OverloadedCallType {
         let trait_did =
-            tcx.closures
+            tcx.closure_kinds
                .borrow()
                .get(&closure_did)
-               .expect("OverloadedCallType::from_closure: didn't \
-                        find closure id")
-               .kind
+               .expect("OverloadedCallType::from_closure: didn't find closure id")
                .trait_did(tcx);
         OverloadedCallType::from_trait_id(tcx, trait_did)
     }

src/librustc/middle/mem_categorization.rs

@@ -594,8 +594,16 @@ impl<'t,'tcx,TYPER:Typer<'tcx>> MemCategorizationContext<'t,TYPER> {
               let ty = try!(self.node_ty(fn_node_id));
               match ty.sty {
                   ty::ty_closure(closure_id, _, _) => {
-                      let kind = self.typer.closure_kind(closure_id);
-                      self.cat_upvar(id, span, var_id, fn_node_id, kind)
+                      match self.typer.closure_kind(closure_id) {
+                          Some(kind) => {
+                              self.cat_upvar(id, span, var_id, fn_node_id, kind)
+                          }
+                          None => {
+                              self.tcx().sess.span_bug(
+                                  span,
+                                  &*format!("No closure kind for {:?}", closure_id));
+                          }
+                      }
                   }
                   _ => {
                       self.tcx().sess.span_bug(

src/librustc/middle/traits/select.rs

@@ -1024,12 +1024,17 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                kind,
                obligation.repr(self.tcx()));
 
-        let closure_kind = self.closure_typer.closure_kind(closure_def_id);
-
-        debug!("closure_kind = {:?}", closure_kind);
-
-        if closure_kind == kind {
-            candidates.vec.push(ClosureCandidate(closure_def_id, substs.clone()));
+        match self.closure_typer.closure_kind(closure_def_id) {
+            Some(closure_kind) => {
+                debug!("assemble_unboxed_candidates: closure_kind = {:?}", closure_kind);
+                if closure_kind == kind {
+                    candidates.vec.push(ClosureCandidate(closure_def_id, substs.clone()));
+                }
+            }
+            None => {
+                debug!("assemble_unboxed_candidates: closure_kind not yet known");
+                candidates.ambiguous = true;
+            }
         }
 
         Ok(())