Only look for a matching method when normal field access fails

We should probalby warn when defining a method foo on {foo: int} etc.

This should reduce the amount of useless typevars that are allocated.

Issue #1227

6 files changed, 93 insertions, 91 deletions

diff --git a/src/comp/middle/trans.rs b/src/comp/middle/trans.rs
index de5954796fc..acec464e6f8 100644
--- a/src/comp/middle/trans.rs
+++ b/src/comp/middle/trans.rs
@@ -2759,7 +2759,7 @@ fn trans_object_field_inner(bcx: @block_ctxt, o: ValueRef,
     let ccx = bcx_ccx(bcx), tcx = ccx.tcx;
     let mths = alt ty::struct(tcx, o_ty) { ty::ty_obj(ms) { ms } };
 
-    let ix = ty::method_idx(ccx.sess, bcx.sp, field, mths);
+    let ix = option::get(ty::method_idx(field, mths));
     let vtbl = Load(bcx, GEPi(bcx, o, [0, abi::obj_field_vtbl]));
     let vtbl_type = T_ptr(T_array(T_ptr(T_nil()), ix + 1u));
     vtbl = PointerCast(bcx, vtbl, vtbl_type);
@@ -2782,7 +2782,7 @@ fn trans_rec_field(bcx: @block_ctxt, base: @ast::expr,
     let {bcx, val} = trans_temp_expr(bcx, base);
     let {bcx, val, ty} = autoderef(bcx, val, ty::expr_ty(bcx_tcx(bcx), base));
     let fields = alt ty::struct(bcx_tcx(bcx), ty) { ty::ty_rec(fs) { fs } };
-    let ix = ty::field_idx(bcx_ccx(bcx).sess, bcx.sp, field, fields);
+    let ix = option::get(ty::field_idx(field, fields));
     // Silly check
     check type_is_tup_like(bcx, ty);
     let {bcx, val} = GEP_tup_like(bcx, ty, val, [0, ix as int]);
diff --git a/src/comp/middle/trans_alt.rs b/src/comp/middle/trans_alt.rs
index baf81ba296d..6e00521ef3b 100644
--- a/src/comp/middle/trans_alt.rs
+++ b/src/comp/middle/trans_alt.rs
@@ -413,8 +413,7 @@ fn compile_submatch(bcx: @block_ctxt, m: match, vals: [ValueRef], f: mk_fail,
             alt ty::struct(ccx.tcx, rec_ty) { ty::ty_rec(fields) { fields } };
         let rec_vals = [];
         for field_name: ast::ident in rec_fields {
-            let ix: uint =
-                ty::field_idx(ccx.sess, dummy_sp(), field_name, fields);
+            let ix = option::get(ty::field_idx(field_name, fields));
             // not sure how to get rid of this check
             check type_is_tup_like(bcx, rec_ty);
             let r = trans::GEP_tup_like(bcx, rec_ty, val, [0, ix as int]);
@@ -722,8 +721,7 @@ fn bind_irrefutable_pat(bcx: @block_ctxt, pat: @ast::pat, val: ValueRef,
         let rec_fields =
             alt ty::struct(ccx.tcx, rec_ty) { ty::ty_rec(fields) { fields } };
         for f: ast::field_pat in fields {
-            let ix: uint =
-                ty::field_idx(ccx.sess, pat.span, f.ident, rec_fields);
+            let ix = option::get(ty::field_idx(f.ident, rec_fields));
             // how to get rid of this check?
             check type_is_tup_like(bcx, rec_ty);
             let r = trans::GEP_tup_like(bcx, rec_ty, val, [0, ix as int]);
diff --git a/src/comp/middle/trans_objects.rs b/src/comp/middle/trans_objects.rs
index 72015faab22..b8c80da9ac7 100644
--- a/src/comp/middle/trans_objects.rs
+++ b/src/comp/middle/trans_objects.rs
@@ -642,7 +642,7 @@ fn process_bkwding_mthd(cx: @local_ctxt, sp: span, m: @ty::method,
     let ix: uint = 0u;
     alt ty::struct(bcx_tcx(bcx), outer_obj_ty) {
       ty::ty_obj(methods) {
-        ix = ty::method_idx(cx.ccx.sess, sp, m.ident, methods);
+        ix = option::get(ty::method_idx(m.ident, methods));
       }
       _ {
         // Shouldn't happen.
@@ -787,7 +787,7 @@ fn process_fwding_mthd(cx: @local_ctxt, sp: span, m: @ty::method,
     let ix: uint = 0u;
     alt ty::struct(bcx_tcx(bcx), inner_obj_ty) {
       ty::ty_obj(methods) {
-        ix = ty::method_idx(cx.ccx.sess, sp, m.ident, methods);
+        ix = option::get(ty::method_idx(m.ident, methods));
       }
       _ {
         // Shouldn't happen.
diff --git a/src/comp/middle/ty.rs b/src/comp/middle/ty.rs
index d27f3d79b75..521b73f3c11 100644
--- a/src/comp/middle/ty.rs
+++ b/src/comp/middle/ty.rs
@@ -1698,11 +1698,10 @@ fn stmt_node_id(s: @ast::stmt) -> ast::node_id {
     }
 }
 
-fn field_idx(sess: session::session, sp: span, id: ast::ident,
-             fields: [field]) -> uint {
-    let i: uint = 0u;
-    for f: field in fields { if str::eq(f.ident, id) { ret i; } i += 1u; }
-    sess.span_fatal(sp, "unknown field '" + id + "' of record");
+fn field_idx(id: ast::ident, fields: [field]) -> option::t<uint> {
+    let i = 0u;
+    for f in fields { if f.ident == id { ret some(i); } i += 1u; }
+    ret none;
 }
 
 fn get_field(tcx: ctxt, rec_ty: t, id: ast::ident) -> field {
@@ -1715,11 +1714,10 @@ fn get_field(tcx: ctxt, rec_ty: t, id: ast::ident) -> field {
     }
 }
 
-fn method_idx(sess: session::session, sp: span, id: ast::ident,
-              meths: [method]) -> uint {
-    let i: uint = 0u;
-    for m: method in meths { if str::eq(m.ident, id) { ret i; } i += 1u; }
-    sess.span_fatal(sp, "unknown method '" + id + "' of obj");
+fn method_idx(id: ast::ident, meths: [method]) -> option::t<uint> {
+    let i = 0u;
+    for m in meths { if m.ident == id { ret some(i); } i += 1u; }
+    ret none;
 }
 
 fn sort_methods(meths: [method]) -> [method] {
diff --git a/src/comp/middle/typeck.rs b/src/comp/middle/typeck.rs
index 2a8673a265a..ffe5004002e 100644
--- a/src/comp/middle/typeck.rs
+++ b/src/comp/middle/typeck.rs
@@ -1466,30 +1466,32 @@ fn lookup_method(fcx: @fn_ctxt, isc: resolve::iscopes,
     -> option::t<{method: @resolve::method_info, ids: [int]}> {
     let result = none;
     std::list::iter(isc) {|impls|
+        if option::is_some(result) { ret; }
         for @{did, methods, _} in *impls {
-            let (n_tps, self_ty) = if did.crate == ast::local_crate {
-                alt fcx.ccx.tcx.items.get(did.node) {
-                  ast_map::node_item(@{node: ast::item_impl(tps, st, _), _}) {
-                    (vec::len(tps), ast_ty_to_ty_crate(fcx.ccx, st))
-                  }
-                }
-            } else {
-                let tpt = csearch::get_type(fcx.ccx.tcx, did);
-                (vec::len(tpt.kinds), tpt.ty)
-            };
-            let {ids, ty: self_ty} = if n_tps > 0u {
-                bind_params_in_type(ast_util::dummy_sp(), fcx.ccx.tcx,
-                                    bind next_ty_var_id(fcx), self_ty, n_tps)
-            } else { {ids: [], ty: self_ty} };
-            // FIXME[impl] Don't unify in the current fcx, use
-            // scratch context
-            alt unify::unify(fcx, ty, self_ty) {
-              ures_ok(_) {
-                for m in methods {
-                    if m.ident == name {
-                        result = some({method: m, ids: ids});
-                        ret;
+            alt vec::find(methods, {|m| m.ident == name}) {
+              some(m) {
+                let (n_tps, self_ty) = if did.crate == ast::local_crate {
+                    alt fcx.ccx.tcx.items.get(did.node) {
+                      ast_map::node_item(@{node: ast::item_impl(tps, st, _),
+                                           _}) {
+                        (vec::len(tps), ast_ty_to_ty_crate(fcx.ccx, st))
+                      }
                     }
+                } else {
+                    let tpt = csearch::get_type(fcx.ccx.tcx, did);
+                    (vec::len(tpt.kinds), tpt.ty)
+                };
+                let {ids, ty: self_ty} = if n_tps > 0u {
+                    bind_params_in_type(ast_util::dummy_sp(), fcx.ccx.tcx,
+                                        bind next_ty_var_id(fcx), self_ty,
+                                        n_tps)
+                } else { {ids: [], ty: self_ty} };
+                alt unify::unify(fcx, ty, self_ty) {
+                  ures_ok(_) {
+                    result = some({method: m, ids: ids});
+                    ret;
+                  }
+                  _ {}
                 }
               }
               _ {}
@@ -2128,60 +2130,66 @@ fn check_expr_with_unifier(fcx: @fn_ctxt, expr: @ast::expr, unify: unifier,
       }
       ast::expr_field(base, field) {
         bot |= check_expr(fcx, base);
-        let base_t = expr_ty(tcx, base);
-        let iscope = fcx.ccx.impl_map.get(expr.id);
-        alt lookup_method(fcx, iscope, field, base_t) {
-          some({method, ids}) {
-            let fty = if method.did.crate == ast::local_crate {
-                alt tcx.items.get(method.did.node) {
-                  ast_map::node_method(m) {
-                    let mt = ty_of_method(tcx, m_check, m);
-                    ty::mk_fn(tcx, mt.proto, mt.inputs,
-                              mt.output, mt.cf, mt.constrs)
-                  }
-                }
-            } else { csearch::get_type(tcx, method.did).ty };
-            let ids = ids;
-            if method.n_tps > 0u {
-                let b = bind_params_in_type(expr.span, tcx,
-                                            bind next_ty_var_id(fcx),
-                                            fty, method.n_tps);
-                ids += b.ids;
-                fty = b.ty;
-            }
-            let substs = vec::map(ids, {|id| ty::mk_var(tcx, id)});
-            write::ty_fixup(fcx, id, {substs: some(substs), ty: fty});
-            fcx.ccx.method_map.insert(id, method.did);
-          }
-          _ {
-            base_t = do_autoderef(fcx, expr.span, base_t);
-            alt structure_of(fcx, expr.span, base_t) {
-              ty::ty_rec(fields) {
-                let ix = ty::field_idx(tcx.sess, expr.span, field, fields);
-                if ix >= vec::len::<ty::field>(fields) {
-                    tcx.sess.span_fatal(expr.span, "bad index on record");
-                }
+        let expr_t = expr_ty(tcx, base);
+        let base_t = do_autoderef(fcx, expr.span, expr_t);
+        let handled = false;
+        alt structure_of(fcx, expr.span, base_t) {
+          ty::ty_rec(fields) {
+            alt ty::field_idx(field, fields) {
+              some(ix) {
                 write::ty_only_fixup(fcx, id, fields[ix].mt.ty);
+                handled = true;
               }
-              ty::ty_obj(methods) {
-                let ix = ty::method_idx(tcx.sess, expr.span, field, methods);
-                if ix >= vec::len::<ty::method>(methods) {
-                    tcx.sess.span_fatal(expr.span, "bad index on obj");
-                }
+              _ {}
+            }
+          }
+          ty::ty_obj(methods) {
+            alt ty::method_idx(field, methods) {
+              some(ix) {
                 let meth = methods[ix];
-                let t = ty::mk_fn(tcx, meth.proto, meth.inputs, meth.output,
-                                  meth.cf, meth.constrs);
+                let t = ty::mk_fn(tcx, meth.proto, meth.inputs,
+                                  meth.output, meth.cf, meth.constrs);
                 write::ty_only_fixup(fcx, id, t);
+                handled = true;
               }
-              _ {
-                let t_err = resolve_type_vars_if_possible(fcx, base_t);
-                let msg = #fmt["attempted field access on type %s, but no \
-                                method implementation was found",
-                               ty_to_str(tcx, t_err)];
+              _ {}
+            }
+          }
+          _ {}
+        }
+        if !handled {
+            let iscope = fcx.ccx.impl_map.get(expr.id);
+            alt lookup_method(fcx, iscope, field, expr_t) {
+              some({method, ids}) {
+                let fty = if method.did.crate == ast::local_crate {
+                    alt tcx.items.get(method.did.node) {
+                      ast_map::node_method(m) {
+                        let mt = ty_of_method(tcx, m_check, m);
+                        ty::mk_fn(tcx, mt.proto, mt.inputs,
+                                  mt.output, mt.cf, mt.constrs)
+                      }
+                    }
+                } else { csearch::get_type(tcx, method.did).ty };
+                let ids = ids;
+                if method.n_tps > 0u {
+                    let b = bind_params_in_type(expr.span, tcx,
+                                                bind next_ty_var_id(fcx),
+                                                fty, method.n_tps);
+                    ids += b.ids;
+                    fty = b.ty;
+                }
+                let substs = vec::map(ids, {|id| ty::mk_var(tcx, id)});
+                write::ty_fixup(fcx, id, {substs: some(substs), ty: fty});
+                fcx.ccx.method_map.insert(id, method.did);
+              }
+              none. {
+                let t_err = resolve_type_vars_if_possible(fcx, expr_t);
+                let msg = #fmt["attempted access of field %s on type %s, but \
+                                no method implementation was found",
+                               field, ty_to_str(tcx, t_err)];
                 tcx.sess.span_fatal(expr.span, msg);
               }
             }
-          }
         }
       }
       ast::expr_index(base, idx) {
diff --git a/src/comp/syntax/print/pprust.rs b/src/comp/syntax/print/pprust.rs
index 54388102f53..9b3d047d435 100644
--- a/src/comp/syntax/print/pprust.rs
+++ b/src/comp/syntax/print/pprust.rs
@@ -467,11 +467,10 @@ fn print_item(s: ps, &&item: @ast::item) {
         space(s.s);
         bopen(s);
         for meth: @ast::method in _obj.methods {
-            let typarams: [ast::ty_param] = [];
             hardbreak_if_not_bol(s);
             maybe_print_comment(s, meth.span.lo);
             print_fn(s, meth.node.meth.decl, meth.node.meth.proto,
-                     meth.node.ident, typarams, []);
+                     meth.node.ident, meth.node.tps, []);
             word(s.s, " ");
             print_block(s, meth.node.meth.body);
         }
@@ -490,7 +489,7 @@ fn print_item(s: ps, &&item: @ast::item) {
             hardbreak_if_not_bol(s);
             maybe_print_comment(s, meth.span.lo);
             print_fn(s, meth.node.meth.decl, meth.node.meth.proto,
-                     meth.node.ident, [], []);
+                     meth.node.ident, meth.node.tps, []);
             word(s.s, " ");
             print_block(s, meth.node.meth.body);
         }
@@ -964,11 +963,10 @@ fn print_expr(s: ps, &&expr: @ast::expr) {
 
         // Methods
         for meth: @ast::method in anon_obj.methods {
-            let typarams: [ast::ty_param] = [];
             hardbreak_if_not_bol(s);
             maybe_print_comment(s, meth.span.lo);
             print_fn(s, meth.node.meth.decl, meth.node.meth.proto,
-                     meth.node.ident, typarams, []);
+                     meth.node.ident, meth.node.tps, []);
             word(s.s, " ");
             print_block(s, meth.node.meth.body);
         }