Remove unused const error variant

src/librustc/ich/impls_ty.rs

@@ -505,9 +505,6 @@ for ::middle::const_val::ErrKind<'gcx> {
                 len.hash_stable(hcx, hasher);
                 index.hash_stable(hcx, hasher);
             }
-            Math(ref const_math_err) => {
-                const_math_err.hash_stable(hcx, hasher);
-            }
             LayoutError(ref layout_error) => {
                 layout_error.hash_stable(hcx, hasher);
             }

src/librustc/middle/const_val.rs

@@ -11,7 +11,6 @@
 use hir::def_id::DefId;
 use ty::{self, TyCtxt, layout};
 use ty::subst::Substs;
-use rustc_const_math::*;
 use mir::interpret::{Value, PrimVal};
 use errors::DiagnosticBuilder;
 
@@ -62,7 +61,6 @@ pub enum ErrKind<'tcx> {
     UnimplementedConstVal(&'static str),
     IndexOutOfBounds { len: u64, index: u64 },
 
-    Math(ConstMathErr),
     LayoutError(layout::LayoutError<'tcx>),
 
     TypeckError,
@@ -76,12 +74,6 @@ pub struct FrameInfo {
     pub location: String,
 }
 
-impl<'tcx> From<ConstMathErr> for ErrKind<'tcx> {
-    fn from(err: ConstMathErr) -> ErrKind<'tcx> {
-        ErrKind::Math(err)
-    }
-}
-
 #[derive(Clone, Debug)]
 pub enum ConstEvalErrDescription<'a, 'tcx: 'a> {
     Simple(Cow<'a, str>),
@@ -119,7 +111,6 @@ impl<'a, 'gcx, 'tcx> ConstEvalErr<'tcx> {
                         len, index)
             }
 
-            Math(ref err) => Simple(err.description().into_cow()),
             LayoutError(ref err) => Simple(err.to_string().into_cow()),
 
             TypeckError => simple!("type-checking failed"),

src/librustc/ty/structural_impls.rs

@@ -585,7 +585,6 @@ impl<'a, 'tcx> Lift<'tcx> for const_val::ErrKind<'a> {
             NonConstPath => NonConstPath,
             UnimplementedConstVal(s) => UnimplementedConstVal(s),
             IndexOutOfBounds { len, index } => IndexOutOfBounds { len, index },
-            Math(ref e) => Math(e.clone()),
 
             LayoutError(ref e) => {
                 return tcx.lift(e).map(LayoutError)