Remove unused ConstMutability

Author: nikomatsakis

src/librustc/middle/borrowck/check_loans.rs

@@ -222,7 +222,6 @@ impl<'a> CheckLoanCtxt<'a> {
         let illegal_if = match loan2.mutbl {
             MutableMutability   => RESTR_ALIAS | RESTR_FREEZE | RESTR_CLAIM,
             ImmutableMutability => RESTR_ALIAS | RESTR_FREEZE,
-            ConstMutability     => RESTR_ALIAS,
         };
         debug!("illegal_if={:?}", illegal_if);
 
@@ -598,8 +597,7 @@ impl<'a> CheckLoanCtxt<'a> {
 
                 // Check for a non-const loan of `loan_path`
                 let cont = this.each_in_scope_loan(expr.id, |loan| {
-                    if loan.loan_path == loan_path &&
-                            loan.mutbl != ConstMutability {
+                    if loan.loan_path == loan_path {
                         this.report_illegal_mutation(expr,
                                                      full_loan_path,
                                                      loan);

src/librustc/middle/borrowck/gather_loans/mod.rs

@@ -568,11 +568,6 @@ impl<'a> GatherLoanCtxt<'a> {
             //! Implements the M-* rules in doc.rs.
 
             match req_mutbl {
-                ConstMutability => {
-                    // Data of any mutability can be lent as const.
-                    Ok(())
-                }
-
                 ImmutableMutability => {
                     // both imm and mut data can be lent as imm;
                     // for mutable data, this is a freeze
@@ -596,7 +591,6 @@ impl<'a> GatherLoanCtxt<'a> {
     pub fn restriction_set(&self, req_mutbl: LoanMutability)
                            -> RestrictionSet {
         match req_mutbl {
-            ConstMutability => RESTR_EMPTY,
             ImmutableMutability => RESTR_EMPTY | RESTR_MUTATE | RESTR_CLAIM,
             MutableMutability => {
                 RESTR_EMPTY | RESTR_MUTATE | RESTR_CLAIM | RESTR_FREEZE

src/librustc/middle/borrowck/mod.rs

@@ -214,7 +214,6 @@ pub enum PartialTotal {
 #[deriving(Clone, Eq)]
 pub enum LoanMutability {
     ImmutableMutability,
-    ConstMutability,
     MutableMutability,
 }
 
@@ -232,7 +231,6 @@ impl ToStr for LoanMutability {
     fn to_str(&self) -> ~str {
         match *self {
             ImmutableMutability => ~"immutable",
-            ConstMutability => ~"read-only",
             MutableMutability => ~"mutable",
         }
     }