rustboot: Emit an error instead of asserting in trans when a T is passed by value

Author: pcwalton

src/boot/me/type.ml

@@ -1308,6 +1308,23 @@ let process_crate (cx:Semant.ctxt) (crate:Ast.crate) : unit =
         Common.err (Some item_id) "this function must return a value"
     in
 
+    let check_fn_ty_validity item_id (ty_sig, _) =
+      let check_input_slot i slot =
+        match slot with
+            {
+              Ast.slot_ty = Some (Ast.TY_param _);
+              Ast.slot_mode = Ast.MODE_local
+            } ->
+              Common.err
+                (Some item_id)
+                "parameter %d of this type-parametric function must be \
+                passed by reference, not by value"
+                (i + 1)
+          | _ -> ()
+      in
+      Array.iteri check_input_slot ty_sig.Ast.sig_input_slots
+    in
+
     let visit_mod_item_pre _ _ item =
       let { Common.node = item; Common.id = item_id } = item in
       match item.Ast.decl_item with
@@ -1316,7 +1333,9 @@ let process_crate (cx:Semant.ctxt) (crate:Ast.crate) : unit =
             let fn_ty = Hashtbl.find cx.Semant.ctxt_all_item_types item_id in
             begin
               match fn_ty with
-                  Ast.TY_fn ty_fn -> push_fn_ctx_of_ty_fn ty_fn
+                  Ast.TY_fn ty_fn ->
+                    check_fn_ty_validity item_id ty_fn;
+                    push_fn_ctx_of_ty_fn ty_fn
                 | _ ->
                   Common.bug ()
                     "Type.visit_mod_item_pre: fn item didn't have a fn type"

src/lib/list.rs

@@ -12,7 +12,7 @@ tag list[T] {
     nil;
 }
 
-fn foldl[T,U](&list[T] ls, U u, fn(&T t, U u) -> U f) -> U {
+fn foldl[T,U](&list[T] ls, &U u, fn(&T t, U u) -> U f) -> U {
   alt(ls) {
     case (cons[T](?hd, ?tl)) {
       auto u_ = f(hd, u);

src/test/run-pass/drop-parametric-closure-with-bound-box.rs

@@ -1,5 +1,5 @@
-fn f[T](@int i, T t) {}
+fn f[T](@int i, &T t) {}
 
 fn main() {
   auto x = bind f[char](@0xdeafbeef, _);
-}
+}

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

@@ -1,8 +1,8 @@
-fn id[T](T t) -> T {
+fn id[T](&T t) -> T {
   ret t;
 }
 
 fn main() {
   auto f = bind id[int](_);
   check (f(10) == 10);
-}
+}

src/test/run-pass/generic-derived-type.rs

@@ -1,8 +1,8 @@
-fn g[X](X x) -> X {
+fn g[X](&X x) -> X {
   ret x;
 }
 
-fn f[T](T t) -> tup(T,T) {
+fn f[T](&T t) -> tup(T,T) {
   type pair = tup(T,T);
   let pair x = tup(t,t);
   ret g[pair](x);

src/test/run-pass/generic-drop-glue.rs

@@ -1,9 +1,9 @@
-fn f[T](T t) {
+fn f[T](&T t) {
   log "dropping";
 }
 
 fn main() {
   type r = rec(@int x, @int y);
   auto x = rec(x=@10, y=@12);
   f[r](x);
-}
+}

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

@@ -1,8 +1,8 @@
 type tupbox[T] = tup(@T);
 type recbox[T] = rec(@T x);
 
-fn tuplift[T](T t) -> tupbox[T] { ret tup(@t); }
-fn reclift[T](T t) -> recbox[T] { ret rec(x=@t); }
+fn tuplift[T](&T t) -> tupbox[T] { ret tup(@t); }
+fn reclift[T](&T t) -> recbox[T] { ret rec(x=@t); }
 
 fn main() {
   let int foo = 17;

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

@@ -1,6 +1,6 @@
 // -*- rust -*-
 
-fn id[T](T x) -> T {
+fn id[T](&T x) -> T {
    ret x;
 }
 

src/test/run-pass/generic-iter-frame.rs

@@ -4,7 +4,7 @@ iter i() -> () {
   put ();
 }
 
-fn foo[T](T t) {
+fn foo[T](&T t) {
   let int x = 10;
   for each (() j in i()) {
     log x;

src/test/run-pass/leak-box-as-tydesc.rs

@@ -1,7 +1,7 @@
-fn leaky[T](T t) {
+fn leaky[T](&T t) {
 }
 
 fn main() {
   auto x = @10;
   leaky[@int](x);
-}
+}

src/test/run-pass/lib-deque.rs

@@ -92,7 +92,7 @@ fn test_boxes(@int a, @int b, @int c, @int d) {
 
 type eqfn[T] = fn(T a, T b) -> bool;
 
-fn test_parameterized[T](eqfn[T] e, T a, T b, T c, T d) {
+fn test_parameterized[T](eqfn[T] e, &T a, &T b, &T c, &T d) {
   let deque.t[T] deq = deque.create[T]();
   check (deq.size() == 0u);
   deq.add_front(a);