Updated E0306 to new format.

src/librustc_const_eval/eval.rs

@@ -1337,10 +1337,13 @@ pub fn eval_length<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
             Ok(val as usize)
         },
         Ok(const_val) => {
-            span_err!(tcx.sess, count_expr.span, E0306,
-                      "expected usize for {}, found {}",
-                      reason,
-                      const_val.description());
+            struct_span_err!(tcx.sess, count_expr.span, E0306,
+                             "expected `usize` for {}, found {}",
+                             reason,
+                             const_val.description())
+                .span_label(count_expr.span, &format!("expected `usize`"))
+                .emit();
+
             Err(ErrorReported)
         }
         Err(err) => {

src/test/compile-fail/E0306.rs

@@ -8,9 +8,17 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-const A: [u32; "hello"] = []; //~ ERROR E0306
-const B: [u32; true] = []; //~ ERROR E0306
-const C: [u32; 0.0] = []; //~ ERROR E0306
+const A: [u32; "hello"] = [];
+//~^ ERROR expected `usize` for array length, found string literal [E0306]
+//~| NOTE expected `usize`
+
+const B: [u32; true] = [];
+//~^ ERROR expected `usize` for array length, found boolean [E0306]
+//~| NOTE expected `usize`
+
+const C: [u32; 0.0] = [];
+//~^ ERROR expected `usize` for array length, found float [E0306]
+//~| NOTE expected `usize`
 
 fn main() {
 }

src/test/compile-fail/const-integer-bool-ops.rs

@@ -25,17 +25,35 @@ const X3: usize = -42 && -39; //~ ERROR E0080
 const ARR3: [i32; X3] = [99; 6]; //~ NOTE: for array length here
 
 const Y: usize = 42.0 == 42.0;
-const ARRR: [i32; Y] = [99; 1]; //~ ERROR: expected usize for array length
+const ARRR: [i32; Y] = [99; 1];
+//~^ ERROR: expected `usize` for array length, found boolean [E0306]
+//~| NOTE expected `usize`
+
 const Y1: usize = 42.0 >= 42.0;
-const ARRR1: [i32; Y] = [99; 1]; //~ ERROR: expected usize for array length
+const ARRR1: [i32; Y] = [99; 1];
+//~^ ERROR: expected `usize` for array length, found boolean [E0306]
+//~| NOTE expected `usize`
+
 const Y2: usize = 42.0 <= 42.0;
-const ARRR2: [i32; Y] = [99; 1]; //~ ERROR: expected usize for array length
+const ARRR2: [i32; Y] = [99; 1];
+//~^ ERROR: expected `usize` for array length, found boolean [E0306]
+//~| NOTE expected `usize`
+
 const Y3: usize = 42.0 > 42.0;
-const ARRR3: [i32; Y] = [99; 0]; //~ ERROR: expected usize for array length
+const ARRR3: [i32; Y] = [99; 0];
+//~^ ERROR: expected `usize` for array length, found boolean [E0306]
+//~| NOTE expected `usize`
+
 const Y4: usize = 42.0 < 42.0;
-const ARRR4: [i32; Y] = [99; 0]; //~ ERROR: expected usize for array length
+const ARRR4: [i32; Y] = [99; 0];
+//~^ ERROR: expected `usize` for array length, found boolean [E0306]
+//~| NOTE expected `usize`
+
 const Y5: usize = 42.0 != 42.0;
-const ARRR5: [i32; Y] = [99; 0]; //~ ERROR: expected usize for array length
+const ARRR5: [i32; Y] = [99; 0];
+//~^ ERROR: expected `usize` for array length, found boolean [E0306]
+//~| NOTE expected `usize`
+
 
 fn main() {
     let _ = ARR;

src/test/compile-fail/issue-27008.rs

@@ -16,5 +16,6 @@ fn main() {
     //~| expected type `usize`
     //~| found type `S`
     //~| expected usize, found struct `S`
-    //~| ERROR expected usize for repeat count, found struct
+    //~| ERROR expected `usize` for repeat count, found struct [E0306]
+    //~| expected `usize`
 }

src/test/compile-fail/repeat_count.rs

@@ -20,23 +20,27 @@ fn main() {
     //~| expected type `usize`
     //~| found type `()`
     //~| expected usize, found ()
-    //~| ERROR expected usize for repeat count, found tuple [E0306]
+    //~| ERROR expected `usize` for repeat count, found tuple [E0306]
+    //~| expected `usize`
     let c = [0; true];
     //~^ ERROR mismatched types
     //~| expected usize, found bool
-    //~| ERROR expected usize for repeat count, found boolean [E0306]
+    //~| ERROR expected `usize` for repeat count, found boolean [E0306]
+    //~| expected `usize`
     let d = [0; 0.5];
     //~^ ERROR mismatched types
     //~| expected type `usize`
     //~| found type `{float}`
     //~| expected usize, found floating-point variable
-    //~| ERROR expected usize for repeat count, found float [E0306]
+    //~| ERROR expected `usize` for repeat count, found float [E0306]
+    //~| expected `usize`
     let e = [0; "foo"];
     //~^ ERROR mismatched types
     //~| expected type `usize`
     //~| found type `&'static str`
     //~| expected usize, found &-ptr
-    //~| ERROR expected usize for repeat count, found string literal [E0306]
+    //~| ERROR expected `usize` for repeat count, found string literal [E0306]
+    //~| expected `usize`
     let f = [0; -4_isize];
     //~^ ERROR constant evaluation error
     //~| expected usize, found isize
@@ -55,5 +59,6 @@ fn main() {
     //~| expected type `usize`
     //~| found type `main::G`
     //~| expected usize, found struct `main::G`
-    //~| ERROR expected usize for repeat count, found struct [E0306]
+    //~| ERROR expected `usize` for repeat count, found struct [E0306]
+    //~| expected `usize`
 }