auto merge of #14874 : pcwalton/rust/enum-to-float-casts-part-deux, r=alexcrichton

Closes #14794.

If you're casting from an enum to a float, cast through an integer
first.

[breaking-change]

r? @alexcrichton

src/test/compile-fail/enum-to-float-cast.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// Tests that enum-to-float-casts do *signed* integer-to-float conversion.
+// Tests that enum-to-float casts are disallowed.
 
 enum E {
     L0 = -1,
@@ -20,13 +20,13 @@ enum F {
     H1 = 0xFFFFFFFFFFFFFFFF
 }
 
-static C0: f32 = L0 as f32;
-static C1: f32 = H1 as f32;
+static C0: f32 = L0 as f32; //~ ERROR illegal cast
+static C1: f32 = H1 as f32; //~ ERROR illegal cast
 
 pub fn main() {
-    let a = L0 as f32;
+    let a = L0 as f32;  //~ ERROR illegal cast
     let b = C0;
-    let c = H1 as f32;
+    let c = H1 as f32;  //~ ERROR illegal cast
     let d = C1;
     assert_eq!(a, -1.0f32);
     assert_eq!(b, -1.0f32);

src/test/run-pass/const-enum-cast.rs

@@ -14,18 +14,10 @@ enum B { B1=0, B2=2 }
 pub fn main () {
     static c1: int = A2 as int;
     static c2: int = B2 as int;
-    static c3: f64 = A2 as f64;
-    static c4: f64 = B2 as f64;
     let a1 = A2 as int;
     let a2 = B2 as int;
-    let a3 = A2 as f64;
-    let a4 = B2 as f64;
     assert_eq!(c1, 1);
     assert_eq!(c2, 2);
-    assert_eq!(c3, 1.0);
-    assert_eq!(c4, 2.0);
     assert_eq!(a1, 1);
     assert_eq!(a2, 2);
-    assert_eq!(a3, 1.0);
-    assert_eq!(a4, 2.0);
 }

src/test/run-pass/enum-disr-val-pretty.rs

@@ -21,5 +21,4 @@ pub fn main() {
 
 fn test_color(color: color, val: int, _name: String) {
     assert!(color as int == val);
-    assert!(color as f64 == val as f64);
 }

src/test/run-pass/tag-variant-disr-val.rs

@@ -40,7 +40,6 @@ pub fn main() {
 fn test_color(color: color, val: int, name: String) {
     //assert!(unsafe::transmute(color) == val);
     assert_eq!(color as int, val);
-    assert_eq!(color as f64, val as f64);
     assert!(get_color_alt(color) == name);
     assert!(get_color_if(color) == name);
 }