---

yaml
---
r: 28366
b: refs/heads/try
c: ac1f84c
h: refs/heads/master
v: v3

Author: catamorphism

[refs]

@@ -2,7 +2,7 @@
 refs/heads/master: cd6f24f9d14ac90d167386a56e7a6ac1f0318195
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: cd6f24f9d14ac90d167386a56e7a6ac1f0318195
-refs/heads/try: c6b51547c14780a0473a5bcae90c8d4b0530b7c8
+refs/heads/try: ac1f84c153a171e641233e5d2d11404a0b520986
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b
 refs/heads/try2: d0c6ce338884ee21843f4b40bf6bf18d222ce5df

branches/try/src/rustc/middle/typeck/collect.rs

@@ -24,6 +24,8 @@ use astconv::{ast_conv, ty_of_fn_decl, ty_of_arg, ast_ty_to_ty};
 use ast_util::trait_method_to_ty_method;
 use rscope::*;
 use ty::{FnTyBase, FnMeta, FnSig};
+use util::common::pluralize;
+use util::ppaux::bound_to_str;
 
 fn collect_item_types(ccx: @crate_ctxt, crate: @ast::crate) {
 
@@ -263,9 +265,13 @@ fn compare_impl_method(tcx: ty::ctxt, sp: span,
                           self type", tcx.sess.str_of(impl_m.ident)));
     }
 
-    if impl_m.tps != trait_m.tps {
-        tcx.sess.span_err(sp, ~"method `" + tcx.sess.str_of(trait_m.ident) +
-                          ~"` has an incompatible set of type parameters");
+    if impl_m.tps.len() != trait_m.tps.len() {
+        tcx.sess.span_err(sp, #fmt("method `%s` \
+           has %u type %s, but its trait declaration has %u type %s",
+           tcx.sess.str_of(trait_m.ident), impl_m.tps.len(),
+           pluralize(impl_m.tps.len(), ~"parameter"),
+           trait_m.tps.len(),
+           pluralize(trait_m.tps.len(), ~"parameter")));
         return;
     }
 
@@ -278,6 +284,28 @@ fn compare_impl_method(tcx: ty::ctxt, sp: span,
         return;
     }
 
+    for trait_m.tps.eachi() |i, trait_param_bounds| {
+        // For each of the corresponding impl ty param's bounds...
+        let impl_param_bounds = impl_m.tps[i];
+        // Make sure the bounds lists have the same length
+        // Would be nice to use the ty param names in the error message,
+        // but we don't have easy access to them here
+        if impl_param_bounds.len() != trait_param_bounds.len() {
+           tcx.sess.span_err(sp, #fmt("in method `%s`, \
+             type parameter %u has %u %s, but the same type \
+             parameter in its trait declaration has %u %s",
+             tcx.sess.str_of(trait_m.ident),
+             i, impl_param_bounds.len(),
+             pluralize(impl_param_bounds.len(), ~"bound"),
+             trait_param_bounds.len(),
+             pluralize(trait_param_bounds.len(), ~"bound")));
+           return;
+        }
+        // tjc: I'm mildly worried that there's something I'm
+        // not checking that require_same_types doesn't catch,
+        // but I can't figure out what.
+    }
+
     // Perform substitutions so that the trait/impl methods are expressed
     // in terms of the same set of type/region parameters:
     // - replace trait type parameters with those from `trait_substs`

branches/try/src/rustc/util/common.rs

@@ -94,6 +94,11 @@ fn is_main_name(path: syntax::ast_map::path) -> bool {
     )
 }
 
+fn pluralize(n: uint, s: ~str) -> ~str {
+    if n == 1 { s }
+    else { str::concat([s, ~"s"]) }
+}
+
 //
 // Local Variables:
 // mode: rust

branches/try/src/rustc/util/ppaux.rs

@@ -1,9 +1,11 @@
 use std::map::hashmap;
 use middle::ty;
 use middle::ty::{arg, canon_mode};
+use middle::ty::{bound_copy, bound_const, bound_owned, bound_send,
+        bound_trait};
 use middle::ty::{bound_region, br_anon, br_named, br_self, br_cap_avoid};
 use middle::ty::{ck_block, ck_box, ck_uniq, ctxt, field, method};
-use middle::ty::{mt, t};
+use middle::ty::{mt, t, param_bound};
 use middle::ty::{re_bound, re_free, re_scope, re_var, re_static, region};
 use middle::ty::{ty_bool, ty_bot, ty_box, ty_class, ty_enum};
 use middle::ty::{ty_estr, ty_evec, ty_float, ty_fn, ty_trait, ty_int};
@@ -233,6 +235,16 @@ fn tys_to_str(cx: ctxt, ts: ~[t]) -> ~str {
     rs
 }
 
+fn bound_to_str(cx: ctxt, b: param_bound) -> ~str {
+    match b {
+      bound_copy     => ~"copy",
+      bound_owned    => ~"owned",
+      bound_send     => ~"send",
+      bound_const    => ~"const",
+      bound_trait(t) => ty_to_str(cx, t)
+    }
+}
+
 fn ty_to_str(cx: ctxt, typ: t) -> ~str {
     fn fn_input_to_str(cx: ctxt, input: {mode: ast::mode, ty: t}) ->
        ~str {

branches/try/src/test/compile-fail/issue-2611-3.rs

@@ -0,0 +1,21 @@
+// Tests that impl methods are matched to traits exactly:
+// we might be tempted to think matching is contravariant, but if
+// we let an impl method can have more permissive bounds than the trait
+// method it's implementing, the return type might be less specific than
+// needed. Just punt and make it invariant.
+import iter;
+import iter::BaseIter;
+
+trait A {
+  fn b<C:copy const, D>(x: C) -> C;
+}
+
+struct E {
+ f: int;
+}
+
+impl E: A {
+  fn b<F:copy, G>(_x: F) -> F { fail } //~ ERROR in method `b`, type parameter 0 has 1 bound, but
+}
+
+fn main() {}

branches/try/src/test/compile-fail/issue-2611-4.rs

@@ -0,0 +1,18 @@
+// Tests that an impl method's bounds aren't *more* restrictive
+// than the trait method it's implementing
+import iter;
+import iter::BaseIter;
+
+trait A {
+  fn b<C:copy, D>(x: C) -> C;
+}
+
+struct E {
+ f: int;
+}
+
+impl E: A {
+  fn b<F:copy const, G>(_x: F) -> F { fail } //~ ERROR in method `b`, type parameter 0 has 2 bounds, but
+}
+
+fn main() {}

branches/try/src/test/compile-fail/issue-2611-5.rs

@@ -0,0 +1,19 @@
+// Tests that ty params get matched correctly when comparing
+// an impl against a trait
+import iter;
+import iter::BaseIter;
+
+trait A {
+  fn b<C:copy, D>(x: C) -> C;
+}
+
+struct E {
+ f: int;
+}
+
+impl E: A {
+  // n.b. The error message is awful -- see #3404
+  fn b<F:copy, G>(_x: G) -> G { fail } //~ ERROR method `b` has an incompatible type
+}
+
+fn main() {}

branches/try/src/test/run-pass/issue-2611.rs

@@ -1,9 +1,12 @@
-// xfail-test
-use iter::base_iter;
+use iter::BaseIter;
 
-impl Q<A> for base_iter<A> {
-   fn flat_map_to_vec<B:copy, IB:base_iter<B>>(op: fn(B) -> IB) -> ~[B] {
-      iter::flat_map_to_vec(self, op)
+trait FlatMapToVec<A> {
+  fn flat_map_to_vec<B:copy, IB:BaseIter<B>>(op: fn(A) -> IB) -> ~[B];
+}
+
+impl<A:copy> BaseIter<A>: FlatMapToVec<A> {
+   fn flat_map_to_vec<B:copy, IB:BaseIter<B>>(op: fn(A) -> IB) -> ~[B] {
+     iter::flat_map_to_vec(self, op)
    }
 }