diff --git a/src/librustc/metadata/decoder.rs b/src/librustc/metadata/decoder.rs
index 6e166cfbfc85a..480661b263ab8 100644
--- a/src/librustc/metadata/decoder.rs
+++ b/src/librustc/metadata/decoder.rs
@@ -23,7 +23,7 @@ use metadata::tydecode::{parse_ty_data, parse_def_id,
 use middle::ty;
 
 use std::hash::HashUtil;
-use std::int;
+use std::uint;
 use std::io::WriterUtil;
 use std::io;
 use std::option;
@@ -200,9 +200,9 @@ fn each_reexport(d: ebml::Doc, f: &fn(ebml::Doc) -> bool) -> bool {
     return true;
 }
 
-fn variant_disr_val(d: ebml::Doc) -> Option<int> {
+fn variant_disr_val(d: ebml::Doc) -> Option<uint> {
     do reader::maybe_get_doc(d, tag_disr_val).chain |val_doc| {
-        do reader::with_doc_data(val_doc) |data| { int::parse_bytes(data, 10u) }
+        do reader::with_doc_data(val_doc) |data| { uint::parse_bytes(data, 10u) }
     }
 }
 
diff --git a/src/librustc/metadata/encoder.rs b/src/librustc/metadata/encoder.rs
index 78e1a579d741b..8d1f086b3a776 100644
--- a/src/librustc/metadata/encoder.rs
+++ b/src/librustc/metadata/encoder.rs
@@ -21,7 +21,6 @@ use middle;
 
 use std::hash::HashUtil;
 use std::hashmap::{HashMap, HashSet};
-use std::int;
 use std::io;
 use std::str;
 use std::uint;
@@ -290,9 +289,9 @@ fn encode_discriminant(ecx: &EncodeContext,
 
 fn encode_disr_val(_: &EncodeContext,
                    ebml_w: &mut writer::Encoder,
-                   disr_val: int) {
+                   disr_val: uint) {
     ebml_w.start_tag(tag_disr_val);
-    let s = int::to_str(disr_val);
+    let s = uint::to_str(disr_val);
     ebml_w.writer.write(s.as_bytes());
     ebml_w.end_tag();
 }
diff --git a/src/librustc/middle/trans/_match.rs b/src/librustc/middle/trans/_match.rs
index 843aa2b749cfa..648dd0332876b 100644
--- a/src/librustc/middle/trans/_match.rs
+++ b/src/librustc/middle/trans/_match.rs
@@ -193,7 +193,7 @@ pub enum Lit {
 // range)
 pub enum Opt {
     lit(Lit),
-    var(/* disr val */int, @adt::Repr),
+    var(/* disr val */ uint, @adt::Repr),
     range(@ast::expr, @ast::expr),
     vec_len_eq(uint),
     vec_len_ge(uint, /* slice */uint)
@@ -874,7 +874,7 @@ pub struct ExtractedBlock {
 
 pub fn extract_variant_args(bcx: @mut Block,
                             repr: &adt::Repr,
-                            disr_val: int,
+                            disr_val: uint,
                             val: ValueRef)
     -> ExtractedBlock {
     let _icx = push_ctxt("match::extract_variant_args");
diff --git a/src/librustc/middle/trans/adt.rs b/src/librustc/middle/trans/adt.rs
index ee53bfdcbda78..4a541c17a23a2 100644
--- a/src/librustc/middle/trans/adt.rs
+++ b/src/librustc/middle/trans/adt.rs
@@ -64,7 +64,7 @@ use middle::trans::type_::Type;
 /// Representations.
 pub enum Repr {
     /// C-like enums; basically an int.
-    CEnum(int, int), // discriminant range
+    CEnum(uint, uint), // discriminant range
     /**
      * Single-case variants, and structs/tuples/records.
      *
@@ -89,7 +89,7 @@ pub enum Repr {
      * is represented such that `None` is a null pointer and `Some` is the
      * identity function.
      */
-    NullablePointer{ nonnull: Struct, nndiscr: int, ptrfield: uint,
+    NullablePointer{ nonnull: Struct, nndiscr: uint, ptrfield: uint,
                      nullfields: ~[ty::t] }
 }
 
@@ -140,7 +140,7 @@ fn represent_type_uncached(cx: &mut CrateContext, t: ty::t) -> Repr {
             return Univariant(mk_struct(cx, ftys, packed), dtor)
         }
         ty::ty_enum(def_id, ref substs) => {
-            struct Case { discr: int, tys: ~[ty::t] };
+            struct Case { discr: uint, tys: ~[ty::t] };
             impl Case {
                 fn is_zerolen(&self, cx: &mut CrateContext) -> bool {
                     mk_struct(cx, self.tys, false).size == 0
@@ -177,7 +177,7 @@ fn represent_type_uncached(cx: &mut CrateContext, t: ty::t) -> Repr {
             // Since there's at least one
             // non-empty body, explicit discriminants should have
             // been rejected by a checker before this point.
-            if !cases.iter().enumerate().all(|(i,c)| c.discr == (i as int)) {
+            if !cases.iter().enumerate().all(|(i,c)| c.discr == i) {
                 cx.sess.bug(fmt!("non-C-like enum %s with specified \
                                   discriminants",
                                  ty::item_path_str(cx.tcx, def_id)))
@@ -206,7 +206,7 @@ fn represent_type_uncached(cx: &mut CrateContext, t: ty::t) -> Repr {
             }
 
             // The general case.
-            let discr = ~[ty::mk_int()];
+            let discr = ~[ty::mk_uint()];
             return General(cases.map(|c| mk_struct(cx, discr + c.tys, false)))
         }
         _ => cx.sess.bug("adt::represent_type called on non-ADT type")
@@ -305,9 +305,8 @@ pub fn trans_get_discr(bcx: @mut Block, r: &Repr, scrutinee: ValueRef)
     -> ValueRef {
     match *r {
         CEnum(min, max) => load_discr(bcx, scrutinee, min, max),
-        Univariant(*) => C_int(bcx.ccx(), 0),
-        General(ref cases) => load_discr(bcx, scrutinee, 0,
-                                         (cases.len() - 1) as int),
+        Univariant(*) => C_uint(bcx.ccx(), 0),
+        General(ref cases) => load_discr(bcx, scrutinee, 0, cases.len() - 1),
         NullablePointer{ nonnull: ref nonnull, nndiscr, ptrfield, _ } => {
             ZExt(bcx, nullable_bitdiscr(bcx, nonnull, nndiscr, ptrfield, scrutinee),
                  Type::enum_discrim(bcx.ccx()))
@@ -315,7 +314,7 @@ pub fn trans_get_discr(bcx: @mut Block, r: &Repr, scrutinee: ValueRef)
     }
 }
 
-fn nullable_bitdiscr(bcx: @mut Block, nonnull: &Struct, nndiscr: int, ptrfield: uint,
+fn nullable_bitdiscr(bcx: @mut Block, nonnull: &Struct, nndiscr: uint, ptrfield: uint,
                      scrutinee: ValueRef) -> ValueRef {
     let cmp = if nndiscr == 0 { IntEQ } else { IntNE };
     let llptr = Load(bcx, GEPi(bcx, scrutinee, [0, ptrfield]));
@@ -324,7 +323,7 @@ fn nullable_bitdiscr(bcx: @mut Block, nonnull: &Struct, nndiscr: int, ptrfield:
 }
 
 /// Helper for cases where the discriminant is simply loaded.
-fn load_discr(bcx: @mut Block, scrutinee: ValueRef, min: int, max: int)
+fn load_discr(bcx: @mut Block, scrutinee: ValueRef, min: uint, max: uint)
     -> ValueRef {
     let ptr = GEPi(bcx, scrutinee, [0, 0]);
     if max + 1 == min {
@@ -348,16 +347,16 @@ fn load_discr(bcx: @mut Block, scrutinee: ValueRef, min: int, max: int)
  *
  * This should ideally be less tightly tied to `_match`.
  */
-pub fn trans_case(bcx: @mut Block, r: &Repr, discr: int) -> _match::opt_result {
+pub fn trans_case(bcx: @mut Block, r: &Repr, discr: uint) -> _match::opt_result {
     match *r {
         CEnum(*) => {
-            _match::single_result(rslt(bcx, C_int(bcx.ccx(), discr)))
+            _match::single_result(rslt(bcx, C_uint(bcx.ccx(), discr)))
         }
         Univariant(*) => {
             bcx.ccx().sess.bug("no cases for univariants or structs")
         }
         General(*) => {
-            _match::single_result(rslt(bcx, C_int(bcx.ccx(), discr)))
+            _match::single_result(rslt(bcx, C_uint(bcx.ccx(), discr)))
         }
         NullablePointer{ _ } => {
             assert!(discr == 0 || discr == 1);
@@ -371,11 +370,11 @@ pub fn trans_case(bcx: @mut Block, r: &Repr, discr: int) -> _match::opt_result {
  * representation.  The fields, if any, should then be initialized via
  * `trans_field_ptr`.
  */
-pub fn trans_start_init(bcx: @mut Block, r: &Repr, val: ValueRef, discr: int) {
+pub fn trans_start_init(bcx: @mut Block, r: &Repr, val: ValueRef, discr: uint) {
     match *r {
         CEnum(min, max) => {
             assert!(min <= discr && discr <= max);
-            Store(bcx, C_int(bcx.ccx(), discr), GEPi(bcx, val, [0, 0]))
+            Store(bcx, C_uint(bcx.ccx(), discr), GEPi(bcx, val, [0, 0]))
         }
         Univariant(ref st, true) => {
             assert_eq!(discr, 0);
@@ -386,7 +385,7 @@ pub fn trans_start_init(bcx: @mut Block, r: &Repr, val: ValueRef, discr: int) {
             assert_eq!(discr, 0);
         }
         General(*) => {
-            Store(bcx, C_int(bcx.ccx(), discr), GEPi(bcx, val, [0, 0]))
+            Store(bcx, C_uint(bcx.ccx(), discr), GEPi(bcx, val, [0, 0]))
         }
         NullablePointer{ nonnull: ref nonnull, nndiscr, ptrfield, _ } => {
             if discr != nndiscr {
@@ -402,14 +401,14 @@ pub fn trans_start_init(bcx: @mut Block, r: &Repr, val: ValueRef, discr: int) {
  * The number of fields in a given case; for use when obtaining this
  * information from the type or definition is less convenient.
  */
-pub fn num_args(r: &Repr, discr: int) -> uint {
+pub fn num_args(r: &Repr, discr: uint) -> uint {
     match *r {
         CEnum(*) => 0,
         Univariant(ref st, dtor) => {
             assert_eq!(discr, 0);
             st.fields.len() - (if dtor { 1 } else { 0 })
         }
-        General(ref cases) => cases[discr as uint].fields.len() - 1,
+        General(ref cases) => cases[discr].fields.len() - 1,
         NullablePointer{ nonnull: ref nonnull, nndiscr, nullfields: ref nullfields, _ } => {
             if discr == nndiscr { nonnull.fields.len() } else { nullfields.len() }
         }
@@ -417,7 +416,7 @@ pub fn num_args(r: &Repr, discr: int) -> uint {
 }
 
 /// Access a field, at a point when the value's case is known.
-pub fn trans_field_ptr(bcx: @mut Block, r: &Repr, val: ValueRef, discr: int,
+pub fn trans_field_ptr(bcx: @mut Block, r: &Repr, val: ValueRef, discr: uint,
                        ix: uint) -> ValueRef {
     // Note: if this ever needs to generate conditionals (e.g., if we
     // decide to do some kind of cdr-coding-like non-unique repr
@@ -431,7 +430,7 @@ pub fn trans_field_ptr(bcx: @mut Block, r: &Repr, val: ValueRef, discr: int,
             struct_field_ptr(bcx, st, val, ix, false)
         }
         General(ref cases) => {
-            struct_field_ptr(bcx, &cases[discr as uint], val, ix + 1, true)
+            struct_field_ptr(bcx, &cases[discr], val, ix + 1, true)
         }
         NullablePointer{ nonnull: ref nonnull, nullfields: ref nullfields, nndiscr, _ } => {
             if (discr == nndiscr) {
@@ -495,22 +494,22 @@ pub fn trans_drop_flag_ptr(bcx: @mut Block, r: &Repr, val: ValueRef) -> ValueRef
  * this could be changed in the future to avoid allocating unnecessary
  * space after values of shorter-than-maximum cases.
  */
-pub fn trans_const(ccx: &mut CrateContext, r: &Repr, discr: int,
+pub fn trans_const(ccx: &mut CrateContext, r: &Repr, discr: uint,
                    vals: &[ValueRef]) -> ValueRef {
     match *r {
         CEnum(min, max) => {
             assert_eq!(vals.len(), 0);
             assert!(min <= discr && discr <= max);
-            C_int(ccx, discr)
+            C_uint(ccx, discr)
         }
         Univariant(ref st, _dro) => {
             assert_eq!(discr, 0);
             C_struct(build_const_struct(ccx, st, vals))
         }
         General(ref cases) => {
-            let case = &cases[discr as uint];
+            let case = &cases[discr];
             let max_sz = cases.iter().transform(|x| x.size).max().unwrap();
-            let discr_ty = C_int(ccx, discr);
+            let discr_ty = C_uint(ccx, discr);
             let contents = build_const_struct(ccx, case,
                                               ~[discr_ty] + vals);
             C_struct(contents + &[padding(max_sz - case.size)])
@@ -582,13 +581,18 @@ fn roundup(x: u64, a: u64) -> u64 { ((x + (a - 1)) / a) * a }
 
 /// Get the discriminant of a constant value.  (Not currently used.)
 pub fn const_get_discrim(ccx: &mut CrateContext, r: &Repr, val: ValueRef)
-    -> int {
+    -> uint {
     match *r {
-        CEnum(*) => const_to_int(val) as int,
+        CEnum(*) => const_to_uint(val) as uint,
         Univariant(*) => 0,
-        General(*) => const_to_int(const_get_elt(ccx, val, [0])) as int,
+        General(*) => const_to_uint(const_get_elt(ccx, val, [0])) as uint,
         NullablePointer{ nndiscr, ptrfield, _ } => {
-            if is_null(const_struct_field(ccx, val, ptrfield)) { 1 - nndiscr } else { nndiscr }
+            if is_null(const_struct_field(ccx, val, ptrfield)) {
+                /* subtraction as uint is ok because nndiscr is either 0 or 1 */
+                (1 - nndiscr) as uint
+            } else {
+                nndiscr
+            }
         }
     }
 }
@@ -601,7 +605,7 @@ pub fn const_get_discrim(ccx: &mut CrateContext, r: &Repr, val: ValueRef)
  * raw LLVM-level structs and arrays.)
  */
 pub fn const_get_field(ccx: &mut CrateContext, r: &Repr, val: ValueRef,
-                       _discr: int, ix: uint) -> ValueRef {
+                       _discr: uint, ix: uint) -> ValueRef {
     match *r {
         CEnum(*) => ccx.sess.bug("element access in C-like enum const"),
         Univariant(*) => const_struct_field(ccx, val, ix),
diff --git a/src/librustc/middle/trans/base.rs b/src/librustc/middle/trans/base.rs
index d3ae69b23dae4..437d1a50d185e 100644
--- a/src/librustc/middle/trans/base.rs
+++ b/src/librustc/middle/trans/base.rs
@@ -67,7 +67,6 @@ use middle::trans::type_::Type;
 
 use std::hash;
 use std::hashmap::{HashMap, HashSet};
-use std::int;
 use std::io;
 use std::libc::c_uint;
 use std::uint;
@@ -732,7 +731,7 @@ pub fn iter_structural_ty(cx: @mut Block, av: ValueRef, t: ty::t,
                   for (*variants).iter().advance |variant| {
                       let variant_cx =
                           sub_block(cx, ~"enum-iter-variant-" +
-                                    int::to_str(variant.disr_val));
+                                    uint::to_str(variant.disr_val));
                       let variant_cx =
                           iter_variant(variant_cx, repr, av, *variant,
                                        substs.tps, |x,y,z| f(x,y,z));
@@ -1979,7 +1978,7 @@ pub fn trans_enum_variant(ccx: @mut CrateContext,
                           _enum_id: ast::node_id,
                           variant: &ast::variant,
                           args: &[ast::variant_arg],
-                          disr: int,
+                          disr: uint,
                           param_substs: Option<@param_substs>,
                           llfndecl: ValueRef) {
     let _icx = push_ctxt("trans_enum_variant");
@@ -2028,7 +2027,7 @@ pub fn trans_enum_variant_or_tuple_like_struct<A:IdAndTy>(
     ccx: @mut CrateContext,
     ctor_id: ast::node_id,
     args: &[A],
-    disr: int,
+    disr: uint,
     param_substs: Option<@param_substs>,
     llfndecl: ValueRef)
 {
@@ -2628,7 +2627,7 @@ pub fn trans_constant(ccx: &mut CrateContext, it: @ast::item) {
                 }
             };
             unsafe {
-                llvm::LLVMSetInitializer(discrim_gvar, C_int(ccx, disr_val));
+                llvm::LLVMSetInitializer(discrim_gvar, C_uint(ccx, disr_val));
                 llvm::LLVMSetGlobalConstant(discrim_gvar, True);
             }
             ccx.discrims.insert(
diff --git a/src/librustc/middle/trans/consts.rs b/src/librustc/middle/trans/consts.rs
index 15793ea747f3f..db9e3db2c0fda 100644
--- a/src/librustc/middle/trans/consts.rs
+++ b/src/librustc/middle/trans/consts.rs
@@ -446,7 +446,7 @@ fn const_expr_unadjusted(cx: @mut CrateContext, e: &ast::expr) -> ValueRef {
               (expr::cast_enum, expr::cast_float)  => {
                 let repr = adt::represent_type(cx, basety);
                 let discr = adt::const_get_discrim(cx, repr, v);
-                let iv = C_int(cx, discr);
+                let iv = C_uint(cx, discr);
                 let ety_cast = expr::cast_type_kind(ety);
                 match ety_cast {
                     expr::cast_integral => {
diff --git a/src/librustc/middle/trans/expr.rs b/src/librustc/middle/trans/expr.rs
index f552eded1638a..c038ca710aa4f 100644
--- a/src/librustc/middle/trans/expr.rs
+++ b/src/librustc/middle/trans/expr.rs
@@ -1083,7 +1083,7 @@ pub fn trans_local_var(bcx: @mut Block, def: ast::def) -> Datum {
 pub fn with_field_tys<R>(tcx: ty::ctxt,
                          ty: ty::t,
                          node_id_opt: Option<ast::node_id>,
-                         op: &fn(int, (&[ty::field])) -> R) -> R {
+                         op: &fn(uint, (&[ty::field])) -> R) -> R {
     match ty::get(ty).sty {
         ty::ty_struct(did, ref substs) => {
             op(0, struct_fields(tcx, did, substs))
@@ -1200,7 +1200,7 @@ struct StructBaseInfo {
  * - `optbase` contains information on the base struct (if any) from
  * which remaining fields are copied; see comments on `StructBaseInfo`.
  */
-fn trans_adt(bcx: @mut Block, repr: &adt::Repr, discr: int,
+fn trans_adt(bcx: @mut Block, repr: &adt::Repr, discr: uint,
              fields: &[(uint, @ast::expr)],
              optbase: Option<StructBaseInfo>,
              dest: Dest) -> @mut Block {
diff --git a/src/librustc/middle/trans/reflect.rs b/src/librustc/middle/trans/reflect.rs
index 84b001953e045..3d23828979f44 100644
--- a/src/librustc/middle/trans/reflect.rs
+++ b/src/librustc/middle/trans/reflect.rs
@@ -321,7 +321,7 @@ impl Reflector {
                 for variants.iter().enumerate().advance |(i, v)| {
                     let name = ccx.sess.str_of(v.name);
                     let variant_args = ~[this.c_uint(i),
-                                         this.c_int(v.disr_val),
+                                         this.c_uint(v.disr_val),
                                          this.c_uint(v.args.len()),
                                          this.c_slice(name)];
                     do this.bracketed("enum_variant", variant_args) |this| {
diff --git a/src/librustc/middle/ty.rs b/src/librustc/middle/ty.rs
index 7eea20175f9fc..20c39cc84eff9 100644
--- a/src/librustc/middle/ty.rs
+++ b/src/librustc/middle/ty.rs
@@ -49,7 +49,7 @@ use syntax::opt_vec;
 use syntax::abi::AbiSet;
 use syntax;
 
-pub static INITIAL_DISCRIMINANT_VALUE: int = 0;
+pub static INITIAL_DISCRIMINANT_VALUE: uint = 0;
 
 // Data types
 
@@ -3689,7 +3689,7 @@ pub struct VariantInfo {
     ctor_ty: t,
     name: ast::ident,
     id: ast::def_id,
-    disr_val: int,
+    disr_val: uint,
     vis: visibility
 }
 
@@ -3700,7 +3700,7 @@ impl VariantInfo {
     /// Does not do any caching of the value in the type context.
     pub fn from_ast_variant(cx: ctxt,
                             ast_variant: &ast::variant,
-                            discriminant: int) -> VariantInfo {
+                            discriminant: uint) -> VariantInfo {
 
         let ctor_ty = node_id_to_type(cx, ast_variant.node.id);
 
@@ -3894,7 +3894,7 @@ pub fn enum_variants(cx: ctxt, id: ast::def_id) -> @~[@VariantInfo] {
                     node: ast::item_enum(ref enum_definition, _),
                     _
                 }, _) => {
-            let mut last_discriminant: Option<int> = None;
+            let mut last_discriminant: Option<uint> = None;
             @enum_definition.variants.iter().transform(|variant| {
 
                 let mut discriminant = match last_discriminant {
@@ -3904,7 +3904,8 @@ pub fn enum_variants(cx: ctxt, id: ast::def_id) -> @~[@VariantInfo] {
 
                 match variant.node.disr_expr {
                     Some(e) => match const_eval::eval_const_expr_partial(&cx, e) {
-                        Ok(const_eval::const_int(val)) => discriminant = val as int,
+                        Ok(const_eval::const_int(val)) => discriminant = val as uint,
+                        Ok(const_eval::const_uint(val)) => discriminant = val as uint,
                         Ok(_) => {
                             cx.sess.span_err(e.span, "expected signed integer constant");
                         }
diff --git a/src/librustc/middle/typeck/check/mod.rs b/src/librustc/middle/typeck/check/mod.rs
index c04e1c2515cc5..e5f9cf0d14674 100644
--- a/src/librustc/middle/typeck/check/mod.rs
+++ b/src/librustc/middle/typeck/check/mod.rs
@@ -3139,8 +3139,8 @@ pub fn check_enum_variants(ccx: @mut CrateCtxt,
 
         let rty = ty::node_id_to_type(ccx.tcx, id);
         let mut variants: ~[@ty::VariantInfo] = ~[];
-        let mut disr_vals: ~[int] = ~[];
-        let mut prev_disr_val: Option<int> = None;
+        let mut disr_vals: ~[uint] = ~[];
+        let mut prev_disr_val: Option<uint> = None;
 
         for vs.iter().advance |v| {
 
@@ -3155,15 +3155,16 @@ pub fn check_enum_variants(ccx: @mut CrateCtxt,
                 Some(e) => {
                     debug!("disr expr, checking %s", pprust::expr_to_str(e, ccx.tcx.sess.intr()));
 
-                    let declty = ty::mk_int();
                     let fcx = blank_fn_ctxt(ccx, rty, e.id);
+                    let declty = ty::mk_int_var(ccx.tcx, fcx.infcx().next_int_var_id());
                     check_const_with_ty(fcx, e.span, e, declty);
                     // check_expr (from check_const pass) doesn't guarantee
                     // that the expression is in an form that eval_const_expr can
                     // handle, so we may still get an internal compiler error
 
                     match const_eval::eval_const_expr_partial(&ccx.tcx, e) {
-                        Ok(const_eval::const_int(val)) => current_disr_val = val as int,
+                        Ok(const_eval::const_int(val)) => current_disr_val = val as uint,
+                        Ok(const_eval::const_uint(val)) => current_disr_val = val as uint,
                         Ok(_) => {
                             ccx.tcx.sess.span_err(e.span, "expected signed integer constant");
                         }