Fix vtable calculations when translating static methods. Closes #4165

Author: brson

src/librustc/middle/trans/meth.rs

@@ -515,15 +515,7 @@ fn combine_impl_and_methods_origins(bcx: block,
     let m_boundss = vec::view(*r_m_bounds, n_r_m_tps - n_m_tps, n_r_m_tps);
 
     // Flatten out to find the number of vtables the method expects.
-    let m_vtables = m_boundss.foldl(0, |sum, m_bounds| {
-        m_bounds.foldl(*sum, |sum, m_bound| {
-            (*sum) + match (*m_bound) {
-                ty::bound_copy | ty::bound_owned |
-                ty::bound_send | ty::bound_const => 0,
-                ty::bound_trait(_) => 1
-            }
-        })
-    });
+    let m_vtables = ty::count_traits_and_supertraits(tcx, m_boundss);
 
     // Find the vtables we computed at type check time and monomorphize them
     let r_m_origins = match node_vtables(bcx, callee_id) {

src/test/run-pass/static-methods-in-traits2.rs

@@ -0,0 +1,19 @@
+pub trait Number: NumConv {
+    static pure fn from<T:Number>(n: T) -> self;
+}
+
+pub impl float: Number {
+    static pure fn from<T:Number>(n: T) -> float { n.to_float() }
+}
+
+pub trait NumConv {
+    pure fn to_float(&self) -> float;
+}
+
+pub impl float: NumConv {
+    pure fn to_float(&self) -> float { *self }
+}
+
+fn main() {
+    let _: float = Number::from(0.0f);
+}