Print the type of istrs as 'str' in error messages. Issue rust-lang#855

Author: brson

src/comp/util/ppaux.rs

@@ -107,7 +107,7 @@ fn ty_to_str(cx: &ctxt, typ: &t) -> str {
           ty_uint. { "uint" }
           ty_machine(tm) { ty_mach_to_str(tm) }
           ty_char. { "char" }
-          ty_istr. { "istr" }
+          ty_istr. { "str" }
           ty_box(tm) { "@" + mt_to_str(cx, tm) }
           ty_uniq(t) { "~" + ty_to_str(cx, t) }
           ty_vec(tm) { "[" + mt_to_str(cx, tm) + "]" }

src/test/compile-fail/binop-bitxor-str.rs

@@ -1,3 +1,3 @@
-// error-pattern:^ cannot be applied to type `istr`
+// error-pattern:^ cannot be applied to type `str`
 
 fn main() { let x = "a" ^ "b"; }

src/test/compile-fail/fail-type-err.rs

@@ -1,2 +1,2 @@
-// error-pattern:expected istr but found [int]
+// error-pattern:expected str but found [int]
 fn main() { fail [0]; }

src/test/compile-fail/minus-string.rs

@@ -1,3 +1,3 @@
-// error-pattern:applying unary minus to non-numeric type istr
+// error-pattern:applying unary minus to non-numeric type str
 
 fn main() { -"foo"; }