Prevent copies of resources into various things

src/comp/middle/kind.rs

@@ -142,6 +142,52 @@ fn need_shared_lhs_rhs(tcx: ty::ctxt, a: @ast::expr, b: @ast::expr, op: str) {
     need_expr_kind(tcx, b, ast::kind_shared, op + " rhs");
 }
 
+/*
+This ... is a hack (I find myself writing that too often *sadface*).
+
+We need to be able to put pinned kinds into other types but such operations
+are conceptually copies, and pinned kinds can't do that, e.g.
+
+let a = my_resource(x);
+let b = @a; // no-go
+
+So this function attempts to make a loophole where resources can be put into
+other types as long as it's done in a safe way, specifically like
+
+let b = @my_resource(x);
+*/
+fn need_shared_or_pinned_ctor(tcx: ty::ctxt, a: @ast::expr, descr: str) {
+    let tk = type_and_kind(tcx, a);
+    if tk.kind == ast::kind_pinned && !pinned_ctor(a) {
+        let err =
+            #fmt["mismatched kinds for %s: cannot copy pinned type %s",
+                 descr, util::ppaux::ty_to_str(tcx, tk.ty)];
+        tcx.sess.span_err(a.span, err);
+        let note =
+            #fmt["try constructing %s directly into %s",
+                 util::ppaux::ty_to_str(tcx, tk.ty), descr];
+        tcx.sess.span_note(a.span, note);
+    } else if tk.kind != ast::kind_pinned {
+        need_expr_kind(tcx, a, ast::kind_shared, descr);
+    }
+
+    fn pinned_ctor(a: @ast::expr) -> bool {
+        // FIXME: Technically a lambda block is also a pinned ctor
+        alt a.node {
+          ast::expr_call(cexpr, _) {
+            // Assuming that if it's a call that it's safe to move in, mostly
+            // because I don't know offhand how to ensure that it's a call
+            // specifically to a resource constructor
+            true
+          }
+          ast::expr_rec(_, _) {
+            true
+          }
+          _ { false }
+        }
+    }
+}
+
 fn check_expr(tcx: ty::ctxt, e: @ast::expr) {
     alt e.node {
 
@@ -189,6 +235,27 @@ fn check_expr(tcx: ty::ctxt, e: @ast::expr) {
             }
         }
       }
+      ast::expr_unary(op, a) {
+        alt op {
+          ast::box(_) {
+            need_shared_or_pinned_ctor(tcx, a, "'@' operand");
+          }
+          ast::uniq(_) {
+            need_shared_or_pinned_ctor(tcx, a, "'~' operand");
+          }
+          _ { /* fall through */ }
+        }
+      }
+      ast::expr_rec(fields, _) {
+        for field in fields {
+            need_shared_or_pinned_ctor(tcx, field.node.expr, "record field");
+        }
+      }
+      ast::expr_tup(exprs) {
+        for expr in exprs {
+            need_shared_or_pinned_ctor(tcx, expr, "tuple parameter");
+        }
+      }
       _ { }
     }
 }

src/fuzzer/fuzzer.rs

@@ -230,7 +230,7 @@ fn check_variants_of_ast(crate: ast::crate, codemap: codemap::codemap,
     check_variants_T(crate, codemap, filename, "ty", stolen.tys, pprust::ty_to_str, replace_ty_in_crate, cx);
 }
 
-fn check_variants_T<T>(
+fn check_variants_T<@T>(
   crate: ast::crate,
   codemap: codemap::codemap,
   filename: str,

src/test/compile-fail/copy-res-into-box.rs

@@ -1,5 +1,4 @@
-// xfail-test
-// error-pattern:mismatched kinds
+// error-pattern:mismatched kinds for '@' operand
 resource r(i: @mutable int) {
     *i = *i + 1;
 }
@@ -9,7 +8,7 @@ fn main() {
     {
         let j <- r(i);
         // No no no no no
-        let k = @j;
+        let k <- @j;
     }
     log_err *i;
     assert *i == 2;

src/test/compile-fail/copy-res-into-rec.rs

@@ -1,5 +1,4 @@
-// xfail-test
-// error-pattern:mismatched kinds
+// error-pattern:mismatched kinds for record field
 resource r(i: @mutable int) {
     *i = *i + 1;
 }

src/test/compile-fail/copy-res-into-tag.rs

@@ -1,5 +1,5 @@
 // xfail-test
-// error-pattern:mismatched kinds
+// error-pattern:mismatched kinds for tag parameter
 resource r(i: @mutable int) {
     *i = *i + 1;
 }

src/test/compile-fail/copy-res-into-tup.rs

@@ -1,5 +1,4 @@
-// xfail-test
-// error-pattern:mismatched kinds
+// error-pattern:mismatched kinds for tuple parameter
 resource r(i: @mutable int) {
     *i = *i + 1;
 }

src/test/compile-fail/copy-res-into-unique.rs

@@ -0,0 +1,15 @@
+// error-pattern:mismatched kinds for '~' operand
+resource r(i: @mutable int) {
+    *i = *i + 1;
+}
+
+fn main() {
+    let i = @mutable 0;
+    {
+        let j <- r(i);
+        // No no no no no
+        let k <- ~j;
+    }
+    log_err *i;
+    assert *i == 2;
+}

src/test/run-pass/foreach-box-drop.rs

@@ -1,6 +1,6 @@
 
 
-obj ob<K>(k: K) {
+obj ob<@K>(k: K) {
     iter foo() -> @{a: K} { put @{a: k}; }
 }
 

src/test/run-pass/foreach-unique-drop.rs

@@ -1,5 +1,5 @@
 
-obj ob<K>(k: K) {
+obj ob<@K>(k: K) {
     iter foo() -> ~{a: K} { put ~{a: k}; }
 }
 

src/test/run-pass/generic-box.rs

@@ -1,6 +1,6 @@
 
 
-fn box<T>(x: {x: T, y: T, z: T}) -> @{x: T, y: T, z: T} { ret @x; }
+fn box<@T>(x: {x: T, y: T, z: T}) -> @{x: T, y: T, z: T} { ret @x; }
 
 fn main() {
     let x: @{x: int, y: int, z: int} = box::<int>({x: 1, y: 2, z: 3});

src/test/run-pass/generic-exterior-box.rs

@@ -2,7 +2,7 @@
 
 type recbox<T> = {x: @T};
 
-fn reclift<T>(t: T) -> recbox<T> { ret {x: @t}; }
+fn reclift<@T>(t: T) -> recbox<T> { ret {x: @t}; }
 
 fn main() {
     let foo: int = 17;

src/test/run-pass/init-res-into-things.rs

@@ -0,0 +1,70 @@
+// Resources can't be copied into other types but still need to be able
+// to find their way into things.
+
+resource r(i: @mutable int) {
+    *i = *i + 1;
+}
+
+fn test_box() {
+    let i = @mutable 0;
+    {
+        let a <- @r(i);
+    }
+    assert *i == 1;
+}
+
+fn test_rec() {
+    let i = @mutable 0;
+    {
+        let a <- {x: r(i)};
+    }
+    assert *i == 1;
+}
+
+fn test_tag() {
+    tag t {
+        t0(r);
+    }
+
+    let i = @mutable 0;
+    {
+        let a <- t0(r(i));
+    }
+    assert *i == 1;
+}
+
+fn test_tup() {
+    let i = @mutable 0;
+    {
+        let a <- (r(i), 0);
+    }
+    assert *i == 1;
+}
+
+fn test_unique() {
+    let i = @mutable 0;
+    {
+        let a <- ~r(i);
+    }
+    assert *i == 1;
+}
+
+fn test_box_rec() {
+    let i = @mutable 0;
+    {
+        let a <- @{
+            x: r(i)
+        };
+    }
+    assert *i == 1;
+}
+
+fn main() {
+    test_box();
+    test_rec();
+    // FIXME: tag constructors don't optimize their arguments into moves
+    // test_tag();
+    test_tup();
+    test_unique();
+    test_box_rec();
+}