libstd: Remove "dual impls" from the language and enforce coherence rules. r=brson

"Dual impls" are impls that are both type implementations and trait
implementations. They can lead to ambiguity and so this patch removes them
from the language.

This also enforces coherence rules. Without this patch, records can implement
traits not defined in the current crate. This patch fixes this, and updates
all of rustc to adhere to the new enforcement. Most of this patch is fixing
rustc to obey the coherence rules, which involves converting a bunch of records
to structs.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/libcore/num.rs b/src/libcore/num.rs
index 4c2daa458a4..6eb22e53a24 100644
--- a/src/libcore/num.rs
+++ b/src/libcore/num.rs
@@ -23,6 +23,11 @@ pub trait Num {
     static pure fn from_int(n: int) -> self;
 }
 
+pub trait IntConvertible {
+    pure fn to_int(&self) -> int;
+    static pure fn from_int(n: int) -> self;
+}
+
 pub trait Zero {
     static pure fn zero() -> self;
 }