Kind-check closure freevars against destination builtin bounds, take 2.

src/librustc/middle/kind.rs

@@ -81,8 +81,6 @@ pub fn check_crate(tcx: ty::ctxt,
     tcx.sess.abort_if_errors();
 }
 
-type check_fn = @fn(Context, @freevar_entry);
-
 fn check_struct_safe_for_destructor(cx: Context,
                                     span: span,
                                     struct_did: def_id) {
@@ -162,30 +160,43 @@ fn check_item(item: @item, (cx, visitor): (Context, visit::vt<Context>)) {
 // Yields the appropriate function to check the kind of closed over
 // variables. `id` is the node_id for some expression that creates the
 // closure.
-fn with_appropriate_checker(cx: Context, id: node_id, b: &fn(check_fn)) {
-    fn check_for_uniq(cx: Context, fv: @freevar_entry) {
+fn with_appropriate_checker(cx: Context, id: node_id,
+                            b: &fn(checker: &fn(Context, @freevar_entry))) {
+    fn check_for_uniq(cx: Context, fv: @freevar_entry, bounds: ty::BuiltinBounds) {
         // all captured data must be owned, regardless of whether it is
         // moved in or copied in.
         let id = ast_util::def_id_of_def(fv.def).node;
         let var_t = ty::node_id_to_type(cx.tcx, id);
+
+        // FIXME(#3569): Once closure capabilities are restricted based on their
+        // incoming bounds, make this check conditional based on the bounds.
         if !check_owned(cx, var_t, fv.span) { return; }
 
         // check that only immutable variables are implicitly copied in
         check_imm_free_var(cx, fv.def, fv.span);
+
+        check_freevar_bounds(cx, fv.span, var_t, bounds);
     }
 
-    fn check_for_box(cx: Context, fv: @freevar_entry) {
+    fn check_for_box(cx: Context, fv: @freevar_entry, bounds: ty::BuiltinBounds) {
         // all captured data must be owned
         let id = ast_util::def_id_of_def(fv.def).node;
         let var_t = ty::node_id_to_type(cx.tcx, id);
+
+        // FIXME(#3569): Once closure capabilities are restricted based on their
+        // incoming bounds, make this check conditional based on the bounds.
         if !check_durable(cx.tcx, var_t, fv.span) { return; }
 
         // check that only immutable variables are implicitly copied in
         check_imm_free_var(cx, fv.def, fv.span);
+
+        check_freevar_bounds(cx, fv.span, var_t, bounds);
     }
 
-    fn check_for_block(_cx: Context, _fv: @freevar_entry) {
-        // no restrictions
+    fn check_for_block(cx: Context, fv: @freevar_entry, bounds: ty::BuiltinBounds) {
+        let id = ast_util::def_id_of_def(fv.def).node;
+        let var_t = ty::node_id_to_type(cx.tcx, id);
+        check_freevar_bounds(cx, fv.span, var_t, bounds);
     }
 
     fn check_for_bare(cx: Context, fv: @freevar_entry) {
@@ -196,14 +207,14 @@ fn with_appropriate_checker(cx: Context, id: node_id, b: &fn(check_fn)) {
 
     let fty = ty::node_id_to_type(cx.tcx, id);
     match ty::get(fty).sty {
-        ty::ty_closure(ty::ClosureTy {sigil: OwnedSigil, _}) => {
-            b(check_for_uniq)
+        ty::ty_closure(ty::ClosureTy {sigil: OwnedSigil, bounds: bounds, _}) => {
+            b(|cx, fv| check_for_uniq(cx, fv, bounds))
         }
-        ty::ty_closure(ty::ClosureTy {sigil: ManagedSigil, _}) => {
-            b(check_for_box)
+        ty::ty_closure(ty::ClosureTy {sigil: ManagedSigil, bounds: bounds, _}) => {
+            b(|cx, fv| check_for_box(cx, fv, bounds))
         }
-        ty::ty_closure(ty::ClosureTy {sigil: BorrowedSigil, _}) => {
-            b(check_for_block)
+        ty::ty_closure(ty::ClosureTy {sigil: BorrowedSigil, bounds: bounds, _}) => {
+            b(|cx, fv| check_for_block(cx, fv, bounds))
         }
         ty::ty_bare_fn(_) => {
             b(check_for_bare)
@@ -271,7 +282,7 @@ pub fn check_expr(e: @expr, (cx, v): (Context, visit::vt<Context>)) {
                       type_param_defs.repr(cx.tcx));
             }
             for ts.iter().zip(type_param_defs.iter()).advance |(&ty, type_param_def)| {
-                check_bounds(cx, type_parameter_id, e.span, ty, type_param_def)
+                check_typaram_bounds(cx, type_parameter_id, e.span, ty, type_param_def)
             }
         }
     }
@@ -314,7 +325,7 @@ fn check_ty(aty: @Ty, (cx, v): (Context, visit::vt<Context>)) {
               let type_param_defs =
                   ty::lookup_item_type(cx.tcx, did).generics.type_param_defs;
               for ts.iter().zip(type_param_defs.iter()).advance |(&ty, type_param_def)| {
-                  check_bounds(cx, aty.id, aty.span, ty, type_param_def)
+                  check_typaram_bounds(cx, aty.id, aty.span, ty, type_param_def)
               }
           }
       }
@@ -323,19 +334,26 @@ fn check_ty(aty: @Ty, (cx, v): (Context, visit::vt<Context>)) {
     visit::visit_ty(aty, (cx, v));
 }
 
-pub fn check_bounds(cx: Context,
-                    _type_parameter_id: node_id,
-                    sp: span,
-                    ty: ty::t,
-                    type_param_def: &ty::TypeParameterDef)
+pub fn check_builtin_bounds(cx: Context, ty: ty::t, bounds: ty::BuiltinBounds)
+                           -> ty::BuiltinBounds // returns the missing bounds
 {
     let kind = ty::type_contents(cx.tcx, ty);
     let mut missing = ty::EmptyBuiltinBounds();
-    for type_param_def.bounds.builtin_bounds.each |bound| {
+    for bounds.each |bound| {
         if !kind.meets_bound(cx.tcx, bound) {
             missing.add(bound);
         }
     }
+    missing
+}
+
+pub fn check_typaram_bounds(cx: Context,
+                    _type_parameter_id: node_id,
+                    sp: span,
+                    ty: ty::t,
+                    type_param_def: &ty::TypeParameterDef)
+{
+    let missing = check_builtin_bounds(cx, ty, type_param_def.bounds.builtin_bounds);
     if !missing.is_empty() {
         cx.tcx.sess.span_err(
             sp,
@@ -346,6 +364,23 @@ pub fn check_bounds(cx: Context,
     }
 }
 
+pub fn check_freevar_bounds(cx: Context, sp: span, ty: ty::t,
+                            bounds: ty::BuiltinBounds)
+{
+    let missing = check_builtin_bounds(cx, ty, bounds);
+    if !missing.is_empty() {
+        cx.tcx.sess.span_err(
+            sp,
+            fmt!("cannot capture variable of type `%s`, which does not fulfill \
+                  `%s`, in a bounded closure",
+                 ty_to_str(cx.tcx, ty), missing.user_string(cx.tcx)));
+        cx.tcx.sess.span_note(
+            sp,
+            fmt!("this closure's environment must satisfy `%s`",
+                 bounds.user_string(cx.tcx)));
+    }
+}
+
 fn is_nullary_variant(cx: Context, ex: @expr) -> bool {
     match ex.node {
       expr_path(_) => {

src/librustc/middle/ty.rs

@@ -1850,7 +1850,7 @@ impl TypeContents {
     }
 
     pub fn noncopyable(_cx: ctxt) -> TypeContents {
-        TC_DTOR + TC_BORROWED_MUT + TC_ONCE_CLOSURE + TC_OWNED_CLOSURE +
+        TC_DTOR + TC_BORROWED_MUT + TC_ONCE_CLOSURE + TC_NONCOPY_TRAIT +
             TC_EMPTY_ENUM
     }
 
@@ -1899,13 +1899,19 @@ impl TypeContents {
     }
 
     pub fn needs_drop(&self, cx: ctxt) -> bool {
+        if self.intersects(TC_NONCOPY_TRAIT) {
+            // Currently all noncopyable existentials are 2nd-class types
+            // behind owned pointers. With dynamically-sized types, remove
+            // this assertion.
+            assert!(self.intersects(TC_OWNED_POINTER));
+        }
         let tc = TC_MANAGED + TC_DTOR + TypeContents::owned(cx);
         self.intersects(tc)
     }
 
     pub fn owned(_cx: ctxt) -> TypeContents {
         //! Any kind of owned contents.
-        TC_OWNED_CLOSURE + TC_OWNED_POINTER + TC_OWNED_VEC
+        TC_OWNED_POINTER + TC_OWNED_VEC
     }
 }
 
@@ -1939,8 +1945,8 @@ static TC_OWNED_POINTER: TypeContents =    TypeContents{bits: 0b0000_0000_0010};
 /// Contains an owned vector ~[] or owned string ~str
 static TC_OWNED_VEC: TypeContents =        TypeContents{bits: 0b0000_0000_0100};
 
-/// Contains a ~fn() or a ~Trait, which is non-copyable.
-static TC_OWNED_CLOSURE: TypeContents =    TypeContents{bits: 0b0000_0000_1000};
+/// Contains a non-copyable ~fn() or a ~Trait (NOT a ~fn:Copy() or ~Trait:Copy).
+static TC_NONCOPY_TRAIT: TypeContents =    TypeContents{bits: 0b0000_0000_1000};
 
 /// Type with a destructor
 static TC_DTOR: TypeContents =             TypeContents{bits: 0b0000_0001_0000};
@@ -2055,7 +2061,8 @@ pub fn type_contents(cx: ctxt, ty: t) -> TypeContents {
             }
 
             ty_trait(_, _, UniqTraitStore, _) => {
-                TC_OWNED_CLOSURE
+                // FIXME(#3569): Make this conditional on the trait's bounds.
+                TC_NONCOPY_TRAIT + TC_OWNED_POINTER
             }
 
             ty_trait(_, _, BoxTraitStore, mutbl) => {
@@ -2179,7 +2186,9 @@ pub fn type_contents(cx: ctxt, ty: t) -> TypeContents {
                 match sigil {
                     ast::BorrowedSigil => TC_BORROWED_POINTER,
                     ast::ManagedSigil => TC_MANAGED,
-                    ast::OwnedSigil => TC_OWNED_CLOSURE
+                    // FIXME(#3569): Looks like noncopyability should depend
+                    // on the bounds, but I don't think this case ever comes up.
+                    ast::OwnedSigil => TC_NONCOPY_TRAIT + TC_OWNED_POINTER,
                 }
             }
 
@@ -2253,7 +2262,11 @@ pub fn type_contents(cx: ctxt, ty: t) -> TypeContents {
         let st = match cty.sigil {
             ast::BorrowedSigil => TC_BORROWED_POINTER,
             ast::ManagedSigil => TC_MANAGED,
-            ast::OwnedSigil => TC_OWNED_CLOSURE
+            ast::OwnedSigil => if cty.bounds.contains_elem(BoundCopy) {
+                TC_OWNED_POINTER
+            } else {
+                TC_OWNED_POINTER + TC_NONCOPY_TRAIT
+            }
         };
         let rt = borrowed_contents(cty.region, m_imm);
         let ot = match cty.onceness {

src/test/compile-fail/closure-bounds-cant-promote-superkind-in-struct.rs

@@ -0,0 +1,20 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+struct X {
+    field: @fn:Copy(),
+}
+
+fn foo(blk: @fn()) -> X {
+    return X { field: blk }; //~ ERROR expected bounds `Copy` but found no bounds
+}
+
+fn main() {
+}

src/test/compile-fail/closure-bounds-copy-cant-capture-noncopyable.rs

@@ -0,0 +1,26 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::comm;
+
+// If this were legal you could use it to copy captured noncopyables.
+// Issue (#2828)
+
+fn foo(blk: ~fn:Copy()) {
+    blk();
+}
+
+fn main() {
+    let (p,c) = comm::stream();
+    do foo {
+        c.send(()); //~ ERROR does not fulfill `Copy`
+    }
+    p.recv();
+}

src/test/compile-fail/closure-bounds-static-cant-capture-borrowed.rs

@@ -0,0 +1,21 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn bar(blk: &fn:'static()) {
+}
+
+fn foo(x: &()) {
+    do bar {
+        let _ = x; //~ ERROR does not fulfill `'static`
+    }
+}
+
+fn main() {
+}

src/test/compile-fail/closure-bounds-subtype.rs

@@ -1,3 +1,4 @@
+
 fn take_any(_: &fn()) {
 }
 
@@ -7,6 +8,9 @@ fn take_copyable(_: &fn:Copy()) {
 fn take_copyable_owned(_: &fn:Copy+Owned()) {
 }
 
+fn take_const_owned(_: &fn:Const+Owned()) {
+}
+
 fn give_any(f: &fn()) {
     take_any(f);
     take_copyable(f); //~ ERROR expected bounds `Copy` but found no bounds
@@ -29,6 +33,7 @@ fn give_copyable_owned(f: &fn:Copy+Owned()) {
     take_any(f);
     take_copyable(f);
     take_copyable_owned(f);
+    take_const_owned(f); //~ ERROR expected bounds `Owned+Const` but found bounds `Copy+Owned`
 }
 
-fn main() {}
+fn main() {}

src/test/run-pass/closure-bounds-can-capture-chan.rs

@@ -0,0 +1,23 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::comm;
+
+fn foo(blk: ~fn:Owned()) {
+    blk();
+}
+
+fn main() {
+    let (p,c) = comm::stream();
+    do foo {
+        c.send(());
+    }
+    p.recv();
+}

src/test/run-pass/closure-bounds-copyable-squiggle-closure.rs

@@ -0,0 +1,23 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Tests correct copying of heap closures' environments.
+
+fn foo(x: ~fn:Copy()) -> (~fn(), ~fn()) {
+    (copy x, x)
+}
+fn main() {
+    let v = ~[~[1,2,3],~[4,5,6]]; // shouldn't get double-freed
+    let (f1,f2) = do foo {
+        assert!(v.len() == 2);
+    };
+    f1();
+    f2();
+}

src/test/run-pass/closure-bounds-squiggle-closure-as-copyable-typaram.rs

@@ -0,0 +1,26 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Tests correct copying of heap closures' environments.
+
+fn bar<T: Copy>(x: T) -> (T, T) {
+    (copy x, x)
+}
+fn foo(x: ~fn:Copy()) -> (~fn(), ~fn()) {
+    bar(x)
+}
+fn main() {
+    let v = ~[~[1,2,3],~[4,5,6]]; // shouldn't get double-freed
+    let (f1,f2) = do foo {
+        assert!(v.len() == 2);
+    };
+    f1();
+    f2();
+}