auto merge of #9613 : jld/rust/enum-discrim-size.r0, r=alexcrichton

Allows an enum with a discriminant to use any of the primitive integer types to store it.  By default the smallest usable type is chosen, but this can be overridden with an attribute: `#[repr(int)]` etc., or `#[repr(C)]` to match the target's C ABI for the equivalent C enum.

Also adds a lint pass for using non-FFI safe enums in extern declarations, checks that specified discriminants can be stored in the specified type if any, and fixes assorted code that was assuming int.

mk/tests.mk

@@ -465,6 +465,17 @@ $(foreach host,$(CFG_HOST_TRIPLES), \
       $(eval $(call DEF_TEST_CRATE_RULES,$(stage),$(target),$(host),$(crate))) \
      ))))))
 
+# FIXME (#10104): Raise the stack size to work around rustpkg bypassing
+# the code in rustc that would take care of it.
+define DEF_RUSTPKG_STACK_FIX
+$$(call TEST_OK_FILE,$(1),$(2),$(3),rustpkg): export RUST_MIN_STACK=8000000
+endef
+
+$(foreach host,$(CFG_HOST_TRIPLES), \
+ $(foreach target,$(CFG_TARGET_TRIPLES), \
+  $(foreach stage,$(STAGES), \
+   $(eval $(call DEF_RUSTPKG_STACK_FIX,$(stage),$(target),$(host))))))
+
 
 ######################################################################
 # Rules for the compiletest tests (rpass, rfail, etc.)

src/compiletest/runtest.rs

@@ -281,7 +281,7 @@ fn run_debuginfo_test(config: &config, props: &TestProps, testfile: &Path) {
     };
     let config = &mut config;
     let cmds = props.debugger_cmds.connect("\n");
-    let check_lines = props.check_lines.clone();
+    let check_lines = &props.check_lines;
 
     // compile test file (it shoud have 'compile-flags:-g' in the header)
     let mut ProcRes = compile_test(config, props, testfile);
@@ -315,11 +315,34 @@ fn run_debuginfo_test(config: &config, props: &TestProps, testfile: &Path) {
 
     let num_check_lines = check_lines.len();
     if num_check_lines > 0 {
+        // Allow check lines to leave parts unspecified (e.g., uninitialized
+        // bits in the wrong case of an enum) with the notation "[...]".
+        let check_fragments: ~[~[&str]] = check_lines.map(|s| s.split_str_iter("[...]").collect());
         // check if each line in props.check_lines appears in the
         // output (in order)
         let mut i = 0u;
         for line in ProcRes.stdout.line_iter() {
-            if check_lines[i].trim() == line.trim() {
+            let mut rest = line.trim();
+            let mut first = true;
+            let mut failed = false;
+            for &frag in check_fragments[i].iter() {
+                let found = if first {
+                    if rest.starts_with(frag) { Some(0) } else { None }
+                } else {
+                    rest.find_str(frag)
+                };
+                match found {
+                    None => {
+                        failed = true;
+                        break;
+                    }
+                    Some(i) => {
+                        rest = rest.slice_from(i + frag.len());
+                    }
+                }
+                first = false;
+            }
+            if !failed && rest.len() == 0 {
                 i += 1u;
             }
             if i == num_check_lines {

src/libextra/enum_set.rs

@@ -140,6 +140,7 @@ mod test {
     use enum_set::*;
 
     #[deriving(Eq)]
+    #[repr(uint)]
     enum Foo {
         A, B, C
     }

src/librustc/lib/llvm.rs

@@ -147,6 +147,7 @@ pub static Vector: TypeKind    = 13;
 pub static Metadata: TypeKind  = 14;
 pub static X86_MMX: TypeKind   = 15;
 
+#[repr(C)]
 pub enum AtomicBinOp {
     Xchg = 0,
     Add  = 1,
@@ -161,6 +162,7 @@ pub enum AtomicBinOp {
     UMin = 10,
 }
 
+#[repr(C)]
 pub enum AtomicOrdering {
     NotAtomic = 0,
     Unordered = 1,
@@ -173,6 +175,7 @@ pub enum AtomicOrdering {
 }
 
 // Consts for the LLVMCodeGenFileType type (in include/llvm/c/TargetMachine.h)
+#[repr(C)]
 pub enum FileType {
     AssemblyFile = 0,
     ObjectFile = 1
@@ -194,6 +197,7 @@ pub enum AsmDialect {
 }
 
 #[deriving(Eq)]
+#[repr(C)]
 pub enum CodeGenOptLevel {
     CodeGenLevelNone = 0,
     CodeGenLevelLess = 1,
@@ -201,6 +205,7 @@ pub enum CodeGenOptLevel {
     CodeGenLevelAggressive = 3,
 }
 
+#[repr(C)]
 pub enum RelocMode {
     RelocDefault = 0,
     RelocStatic = 1,
@@ -208,6 +213,7 @@ pub enum RelocMode {
     RelocDynamicNoPic = 3,
 }
 
+#[repr(C)]
 pub enum CodeGenModel {
     CodeModelDefault = 0,
     CodeModelJITDefault = 1,

src/librustc/metadata/common.rs

@@ -112,6 +112,7 @@ pub static tag_items_data_item_reexport_name: uint = 0x4f;
 
 // used to encode crate_ctxt side tables
 #[deriving(Eq)]
+#[repr(uint)]
 pub enum astencode_tag { // Reserves 0x50 -- 0x6f
     tag_ast = 0x50,
 
@@ -143,7 +144,7 @@ impl astencode_tag {
     pub fn from_uint(value : uint) -> Option<astencode_tag> {
         let is_a_tag = first_astencode_tag <= value && value <= last_astencode_tag;
         if !is_a_tag { None } else {
-            Some(unsafe { cast::transmute(value as int) })
+            Some(unsafe { cast::transmute(value) })
         }
     }
 }

src/librustc/metadata/encoder.rs

@@ -989,6 +989,7 @@ fn encode_info_for_item(ecx: &EncodeContext,
         encode_family(ebml_w, 't');
         encode_bounds_and_type(ebml_w, ecx, &lookup_item_type(tcx, def_id));
         encode_name(ecx, ebml_w, item.ident);
+        encode_attributes(ebml_w, item.attrs);
         for v in (*enum_definition).variants.iter() {
             encode_variant_id(ebml_w, local_def(v.node.id));
         }

src/librustc/middle/lint.rs

@@ -34,6 +34,7 @@
 //! Context itself, span_lint should be used instead of add_lint.
 
 use driver::session;
+use middle::trans::adt; // for `adt::is_ffi_safe`
 use middle::ty;
 use middle::pat_util;
 use metadata::csearch;
@@ -627,6 +628,14 @@ fn check_item_ctypes(cx: &Context, it: &ast::item) {
                                 "found rust type `uint` in foreign module, while \
                                 libc::c_uint or libc::c_ulong should be used");
                     }
+                    ast::DefTy(def_id) => {
+                        if !adt::is_ffi_safe(cx.tcx, def_id) {
+                            cx.span_lint(ctypes, ty.span,
+                                         "found enum type without foreign-function-safe \
+                                          representation annotation in foreign module");
+                            // NOTE this message could be more helpful
+                        }
+                    }
                     _ => ()
                 }
             }

src/librustc/middle/trans/adt.rs

@@ -14,7 +14,8 @@
  * This module determines how to represent enums, structs, and tuples
  * based on their monomorphized types; it is responsible both for
  * choosing a representation and translating basic operations on
- * values of those types.
+ * values of those types.  (Note: exporting the representations for
+ * debuggers is handled in debuginfo.rs, not here.)
  *
  * Note that the interface treats everything as a general case of an
  * enum, so structs/tuples/etc. have one pseudo-variant with
@@ -29,8 +30,6 @@
  *   that might contain one and adjust GEP indices accordingly.  See
  *   issue #4578.
  *
- * - Using smaller integer types for discriminants.
- *
  * - Store nested enums' discriminants in the same word.  Rather, if
  *   some variants start with enums, and those enums representations
  *   have unused alignment padding between discriminant and body, the
@@ -56,16 +55,21 @@ use middle::trans::machine;
 use middle::trans::type_of;
 use middle::ty;
 use middle::ty::Disr;
+use syntax::abi::{X86, X86_64, Arm, Mips};
 use syntax::ast;
+use syntax::attr;
+use syntax::attr::IntType;
 use util::ppaux::ty_to_str;
 
 use middle::trans::type_::Type;
 
+type Hint = attr::ReprAttr;
+
 
 /// Representations.
 pub enum Repr {
     /// C-like enums; basically an int.
-    CEnum(Disr, Disr), // discriminant range
+    CEnum(IntType, Disr, Disr), // discriminant range (signedness based on the IntType)
     /**
      * Single-case variants, and structs/tuples/records.
      *
@@ -78,7 +82,7 @@ pub enum Repr {
      * General-case enums: for each case there is a struct, and they
      * all start with a field for the discriminant.
      */
-    General(~[Struct]),
+    General(IntType, ~[Struct]),
     /**
      * Two cases distinguished by a nullable pointer: the case with discriminant
      * `nndiscr` is represented by the struct `nonnull`, where the `ptrfield`th
@@ -141,38 +145,26 @@ 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: Disr, tys: ~[ty::t] };
+            let cases = get_cases(cx.tcx, def_id, substs);
-            impl Case {
+            let hint = ty::lookup_repr_hint(cx.tcx, def_id);
-                fn is_zerolen(&self, cx: &mut CrateContext) -> bool {
-                    mk_struct(cx, self.tys, false).size == 0
-                }
-                fn find_ptr(&self) -> Option<uint> {
-                    self.tys.iter().position(|&ty| mono_data_classify(ty) == MonoNonNull)
-                }
-            }
-
-            let cases = do ty::enum_variants(cx.tcx, def_id).map |vi| {
-                let arg_tys = do vi.args.map |&raw_ty| {
-                    ty::subst(cx.tcx, substs, raw_ty)
-                };
-                Case { discr: vi.disr_val, tys: arg_tys }
-            };
 
             if cases.len() == 0 {
                 // Uninhabitable; represent as unit
+                // (Typechecking will reject discriminant-sizing attrs.)
+                assert_eq!(hint, attr::ReprAny);
                 return Univariant(mk_struct(cx, [], false), false);
             }
 
             if cases.iter().all(|c| c.tys.len() == 0) {
                 // All bodies empty -> intlike
                 let discrs = cases.map(|c| c.discr);
-                return CEnum(*discrs.iter().min().unwrap(), *discrs.iter().max().unwrap());
+                let bounds = IntBounds {
-            }
+                    ulo: *discrs.iter().min().unwrap(),
-
+                    uhi: *discrs.iter().max().unwrap(),
-            if cases.len() == 1 {
+                    slo: discrs.iter().map(|n| *n as i64).min().unwrap(),
-                // Equivalent to a struct/tuple/newtype.
+                    shi: discrs.iter().map(|n| *n as i64).max().unwrap()
-                assert_eq!(cases[0].discr, 0);
+                };
-                return Univariant(mk_struct(cx, cases[0].tys, false), false)
+                return mk_cenum(cx, hint, &bounds);
             }
 
             // Since there's at least one
@@ -184,7 +176,15 @@ fn represent_type_uncached(cx: &mut CrateContext, t: ty::t) -> Repr {
                                  ty::item_path_str(cx.tcx, def_id)))
             }
 
-            if cases.len() == 2 {
+            if cases.len() == 1 {
+                // Equivalent to a struct/tuple/newtype.
+                // (Typechecking will reject discriminant-sizing attrs.)
+                assert_eq!(hint, attr::ReprAny);
+                return Univariant(mk_struct(cx, cases[0].tys, false), false)
+            }
+
+            if cases.len() == 2 && hint == attr::ReprAny {
+                // Nullable pointer optimization
                 let mut discr = 0;
                 while discr < 2 {
                     if cases[1 - discr].is_zerolen(cx) {
@@ -207,13 +207,67 @@ fn represent_type_uncached(cx: &mut CrateContext, t: ty::t) -> Repr {
             }
 
             // The general case.
-            let discr = ~[ty::mk_uint()];
+            assert!((cases.len() - 1) as i64 >= 0);
-            return General(cases.map(|c| mk_struct(cx, discr + c.tys, false)))
+            let bounds = IntBounds { ulo: 0, uhi: (cases.len() - 1) as u64,
+                                     slo: 0, shi: (cases.len() - 1) as i64 };
+            let ity = range_to_inttype(cx, hint, &bounds);
+            let discr = ~[ty_of_inttype(ity)];
+            return General(ity, cases.map(|c| mk_struct(cx, discr + c.tys, false)))
         }
         _ => cx.sess.bug("adt::represent_type called on non-ADT type")
     }
 }
 
+/// Determine, without doing translation, whether an ADT must be FFI-safe.
+/// For use in lint or similar, where being sound but slightly incomplete is acceptable.
+pub fn is_ffi_safe(tcx: ty::ctxt, def_id: ast::DefId) -> bool {
+    match ty::get(ty::lookup_item_type(tcx, def_id).ty).sty {
+        ty::ty_enum(def_id, _) => {
+            let variants = ty::enum_variants(tcx, def_id);
+            // Univariant => like struct/tuple.
+            if variants.len() <= 1 {
+                return true;
+            }
+            let hint = ty::lookup_repr_hint(tcx, def_id);
+            // Appropriate representation explicitly selected?
+            if hint.is_ffi_safe() {
+                return true;
+            }
+            // Option<~T> and similar are used in FFI.  Rather than try to resolve type parameters
+            // and recognize this case exactly, this overapproximates -- assuming that if a
+            // non-C-like enum is being used in FFI then the user knows what they're doing.
+            if variants.iter().any(|vi| !vi.args.is_empty()) {
+                return true;
+            }
+            false
+        }
+        // struct, tuple, etc.
+        // (is this right in the present of typedefs?)
+        _ => true
+    }
+}
+
+// NOTE this should probably all be in ty
+struct Case { discr: Disr, tys: ~[ty::t] }
+impl Case {
+    fn is_zerolen(&self, cx: &mut CrateContext) -> bool {
+        mk_struct(cx, self.tys, false).size == 0
+    }
+    fn find_ptr(&self) -> Option<uint> {
+        self.tys.iter().position(|&ty| mono_data_classify(ty) == MonoNonNull)
+    }
+}
+
+fn get_cases(tcx: ty::ctxt, def_id: ast::DefId, substs: &ty::substs) -> ~[Case] {
+    do ty::enum_variants(tcx, def_id).map |vi| {
+        let arg_tys = do vi.args.map |&raw_ty| {
+            ty::subst(tcx, substs, raw_ty)
+        };
+        Case { discr: vi.disr_val, tys: arg_tys }
+    }
+}
+
+
 fn mk_struct(cx: &mut CrateContext, tys: &[ty::t], packed: bool) -> Struct {
     let lltys = tys.map(|&ty| type_of::sizing_type_of(cx, ty));
     let llty_rec = Type::struct_(lltys, packed);
@@ -225,6 +279,92 @@ fn mk_struct(cx: &mut CrateContext, tys: &[ty::t], packed: bool) -> Struct {
     }
 }
 
+struct IntBounds {
+    slo: i64,
+    shi: i64,
+    ulo: u64,
+    uhi: u64
+}
+
+fn mk_cenum(cx: &mut CrateContext, hint: Hint, bounds: &IntBounds) -> Repr {
+    let it = range_to_inttype(cx, hint, bounds);
+    match it {
+        attr::SignedInt(_) => CEnum(it, bounds.slo as Disr, bounds.shi as Disr),
+        attr::UnsignedInt(_) => CEnum(it, bounds.ulo, bounds.uhi)
+    }
+}
+
+fn range_to_inttype(cx: &mut CrateContext, hint: Hint, bounds: &IntBounds) -> IntType {
+    debug!("range_to_inttype: {:?} {:?}", hint, bounds);
+    // Lists of sizes to try.  u64 is always allowed as a fallback.
+    static choose_shortest: &'static[IntType] = &[
+        attr::UnsignedInt(ast::ty_u8), attr::SignedInt(ast::ty_i8),
+        attr::UnsignedInt(ast::ty_u16), attr::SignedInt(ast::ty_i16),
+        attr::UnsignedInt(ast::ty_u32), attr::SignedInt(ast::ty_i32)];
+    static at_least_32: &'static[IntType] = &[
+        attr::UnsignedInt(ast::ty_u32), attr::SignedInt(ast::ty_i32)];
+
+    let attempts;
+    match hint {
+        attr::ReprInt(span, ity) => {
+            if !bounds_usable(cx, ity, bounds) {
+                cx.sess.span_bug(span, "representation hint insufficient for discriminant range")
+            }
+            return ity;
+        }
+        attr::ReprExtern => {
+            attempts = match cx.sess.targ_cfg.arch {
+                X86 | X86_64 => at_least_32,
+                // WARNING: the ARM EABI has two variants; the one corresponding to `at_least_32`
+                // appears to be used on Linux and NetBSD, but some systems may use the variant
+                // corresponding to `choose_shortest`.  However, we don't run on those yet...?
+                Arm => at_least_32,
+                Mips => at_least_32,
+            }
+        }
+        attr::ReprAny => {
+            attempts = choose_shortest;
+        }
+    }
+    for &ity in attempts.iter() {
+        if bounds_usable(cx, ity, bounds) {
+            return ity;
+        }
+    }
+    return attr::UnsignedInt(ast::ty_u64);
+}
+
+pub fn ll_inttype(cx: &mut CrateContext, ity: IntType) -> Type {
+    match ity {
+        attr::SignedInt(t) => Type::int_from_ty(cx, t),
+        attr::UnsignedInt(t) => Type::uint_from_ty(cx, t)
+    }
+}
+
+fn bounds_usable(cx: &mut CrateContext, ity: IntType, bounds: &IntBounds) -> bool {
+    debug!("bounds_usable: {:?} {:?}", ity, bounds);
+    match ity {
+        attr::SignedInt(_) => {
+            let lllo = C_integral(ll_inttype(cx, ity), bounds.slo as u64, true);
+            let llhi = C_integral(ll_inttype(cx, ity), bounds.shi as u64, true);
+            bounds.slo == const_to_int(lllo) as i64 && bounds.shi == const_to_int(llhi) as i64
+        }
+        attr::UnsignedInt(_) => {
+            let lllo = C_integral(ll_inttype(cx, ity), bounds.ulo, false);
+            let llhi = C_integral(ll_inttype(cx, ity), bounds.uhi, false);
+            bounds.ulo == const_to_uint(lllo) as u64 && bounds.uhi == const_to_uint(llhi) as u64
+        }
+    }
+}
+
+pub fn ty_of_inttype(ity: IntType) -> ty::t {
+    match ity {
+        attr::SignedInt(t) => ty::mk_mach_int(t),
+        attr::UnsignedInt(t) => ty::mk_mach_uint(t)
+    }
+}
+
+
 /**
  * Returns the fields of a struct for the given representation.
  * All nominal types are LLVM structs, in order to be able to use
@@ -239,33 +379,41 @@ pub fn sizing_fields_of(cx: &mut CrateContext, r: &Repr) -> ~[Type] {
 }
 fn generic_fields_of(cx: &mut CrateContext, r: &Repr, sizing: bool) -> ~[Type] {
     match *r {
-        CEnum(*) => ~[Type::enum_discrim(cx)],
+        CEnum(ity, _, _) => ~[ll_inttype(cx, ity)],
         Univariant(ref st, _dtor) => struct_llfields(cx, st, sizing),
         NullablePointer{ nonnull: ref st, _ } => struct_llfields(cx, st, sizing),
-        General(ref sts) => {
+        General(ity, ref sts) => {
-            // To get "the" type of a general enum, we pick the case
+            // We need a representation that has:
-            // with the largest alignment (so it will always align
+            // * The alignment of the most-aligned field
-            // correctly in containing structures) and pad it out.
+            // * The size of the largest variant (rounded up to that alignment)
-            assert!(sts.len() >= 1);
+            // * No alignment padding anywhere any variant has actual data
-            let mut most_aligned = None;
+            //   (currently matters only for enums small enough to be immediate)
-            let mut largest_align = 0;
+            // * The discriminant in an obvious place.
-            let mut largest_size = 0;
+            //
-            for st in sts.iter() {
+            // So we start with the discriminant, pad it up to the alignment with
-                if largest_size < st.size {
+            // more of its own type, then use alignment-sized ints to get the rest
-                    largest_size = st.size;
+            // of the size.
-                }
+            //
-                if largest_align < st.align {
+            // Note: if/when we start exposing SIMD vector types (or f80, on some
-                    // Clang breaks ties by size; it is unclear if
+            // platforms that have it), this will need some adjustment.
-                    // that accomplishes anything important.
+            let size = sts.iter().map(|st| st.size).max().unwrap();
-                    largest_align = st.align;
+            let most_aligned = sts.iter().max_by(|st| st.align).unwrap();
-                    most_aligned = Some(st);
+            let align = most_aligned.align;
-                }
+            let discr_ty = ll_inttype(cx, ity);
-            }
+            let discr_size = machine::llsize_of_alloc(cx, discr_ty) as u64;
-            let most_aligned = most_aligned.unwrap();
+            let pad_ty = match align {
-            let padding = largest_size - most_aligned.size;
+                1 => Type::i8(),
-
+                2 => Type::i16(),
-            struct_llfields(cx, most_aligned, sizing)
+                4 => Type::i32(),
-                + &[Type::array(&Type::i8(), padding)]
+                8 if machine::llalign_of_min(cx, Type::i64()) == 8 => Type::i64(),
+                _ => fail!("Unsupported enum alignment: {:?}", align)
+            };
+            assert_eq!(machine::llalign_of_min(cx, pad_ty) as u64, align);
+            let align_units = (size + align - 1) / align;
+            assert_eq!(align % discr_size, 0);
+            ~[discr_ty,
+              Type::array(&discr_ty, align / discr_size - 1),
+              Type::array(&pad_ty, align_units - 1)]
         }
     }
 }
@@ -288,7 +436,7 @@ pub fn trans_switch(bcx: @mut Block, r: &Repr, scrutinee: ValueRef)
     -> (_match::branch_kind, Option<ValueRef>) {
     match *r {
         CEnum(*) | General(*) => {
-            (_match::switch, Some(trans_get_discr(bcx, r, scrutinee)))
+            (_match::switch, Some(trans_get_discr(bcx, r, scrutinee, None)))
         }
         NullablePointer{ nonnull: ref nonnull, nndiscr, ptrfield, _ } => {
             (_match::switch, Some(nullable_bitdiscr(bcx, nonnull, nndiscr, ptrfield, scrutinee)))
@@ -302,16 +450,31 @@ pub fn trans_switch(bcx: @mut Block, r: &Repr, scrutinee: ValueRef)
 
 
 /// Obtain the actual discriminant of a value.
-pub fn trans_get_discr(bcx: @mut Block, r: &Repr, scrutinee: ValueRef)
+pub fn trans_get_discr(bcx: @mut Block, r: &Repr, scrutinee: ValueRef, cast_to: Option<Type>)
     -> ValueRef {
+    let signed;
+    let val;
     match *r {
-        CEnum(min, max) => load_discr(bcx, scrutinee, min, max),
+        CEnum(ity, min, max) => {
-        Univariant(*) => C_disr(bcx.ccx(), 0),
+            val = load_discr(bcx, ity, scrutinee, min, max);
-        General(ref cases) => load_discr(bcx, scrutinee, 0, (cases.len() - 1) as Disr),
+            signed = ity.is_signed();
-        NullablePointer{ nonnull: ref nonnull, nndiscr, ptrfield, _ } => {
-            ZExt(bcx, nullable_bitdiscr(bcx, nonnull, nndiscr, ptrfield, scrutinee),
-                 Type::enum_discrim(bcx.ccx()))
         }
+        General(ity, ref cases) => {
+            val = load_discr(bcx, ity, scrutinee, 0, (cases.len() - 1) as Disr);
+            signed = ity.is_signed();
+        }
+        Univariant(*) => {
+            val = C_u8(0);
+            signed = false;
+        }
+        NullablePointer{ nonnull: ref nonnull, nndiscr, ptrfield, _ } => {
+            val = nullable_bitdiscr(bcx, nonnull, nndiscr, ptrfield, scrutinee);
+            signed = false;
+        }
+    }
+    match cast_to {
+        None => val,
+        Some(llty) => if signed { SExt(bcx, val, llty) } else { ZExt(bcx, val, llty) }
     }
 }
 
@@ -324,10 +487,15 @@ fn nullable_bitdiscr(bcx: @mut Block, nonnull: &Struct, nndiscr: Disr, ptrfield:
 }
 
 /// Helper for cases where the discriminant is simply loaded.
-fn load_discr(bcx: @mut Block, scrutinee: ValueRef, min: Disr, max: Disr)
+fn load_discr(bcx: @mut Block, ity: IntType, scrutinee: ValueRef, min: Disr, max: Disr)
     -> ValueRef {
     let ptr = GEPi(bcx, scrutinee, [0, 0]);
-    if max + 1 == min {
+    let llty = ll_inttype(bcx.ccx(), ity);
+    assert_eq!(val_ty(ptr), llty.ptr_to());
+    let bits = machine::llbitsize_of_real(bcx.ccx(), llty);
+    assert!(bits <= 64);
+    let mask = (-1u64 >> (64 - bits)) as Disr;
+    if (max + 1) & mask == min & mask {
         // i.e., if the range is everything.  The lo==hi case would be
         // rejected by the LLVM verifier (it would mean either an
         // empty set, which is impossible, or the entire range of the
@@ -350,15 +518,17 @@ fn load_discr(bcx: @mut Block, scrutinee: ValueRef, min: Disr, max: Disr)
  */
 pub fn trans_case(bcx: @mut Block, r: &Repr, discr: Disr) -> _match::opt_result {
     match *r {
-        CEnum(*) => {
+        CEnum(ity, _, _) => {
-            _match::single_result(rslt(bcx, C_disr(bcx.ccx(), discr)))
+            _match::single_result(rslt(bcx, C_integral(ll_inttype(bcx.ccx(), ity),
+                                                       discr as u64, true)))
+        }
+        General(ity, _) => {
+            _match::single_result(rslt(bcx, C_integral(ll_inttype(bcx.ccx(), ity),
+                                                       discr as u64, true)))
         }
         Univariant(*) => {
             bcx.ccx().sess.bug("no cases for univariants or structs")
         }
-        General(*) => {
-            _match::single_result(rslt(bcx, C_disr(bcx.ccx(), discr)))
-        }
         NullablePointer{ _ } => {
             assert!(discr == 0 || discr == 1);
             _match::single_result(rslt(bcx, C_i1(discr != 0)))
@@ -373,9 +543,14 @@ pub fn trans_case(bcx: @mut Block, r: &Repr, discr: Disr) -> _match::opt_result
  */
 pub fn trans_start_init(bcx: @mut Block, r: &Repr, val: ValueRef, discr: Disr) {
     match *r {
-        CEnum(min, max) => {
+        CEnum(ity, min, max) => {
-            assert!(min <= discr && discr <= max);
+            assert_discr_in_range(ity, min, max, discr);
-            Store(bcx, C_disr(bcx.ccx(), discr), GEPi(bcx, val, [0, 0]))
+            Store(bcx, C_integral(ll_inttype(bcx.ccx(), ity), discr as u64, true),
+                  GEPi(bcx, val, [0, 0]))
+        }
+        General(ity, _) => {
+            Store(bcx, C_integral(ll_inttype(bcx.ccx(), ity), discr as u64, true),
+                  GEPi(bcx, val, [0, 0]))
         }
         Univariant(ref st, true) => {
             assert_eq!(discr, 0);
@@ -385,9 +560,6 @@ pub fn trans_start_init(bcx: @mut Block, r: &Repr, val: ValueRef, discr: Disr) {
         Univariant(*) => {
             assert_eq!(discr, 0);
         }
-        General(*) => {
-            Store(bcx, C_disr(bcx.ccx(), discr), GEPi(bcx, val, [0, 0]))
-        }
         NullablePointer{ nonnull: ref nonnull, nndiscr, ptrfield, _ } => {
             if discr != nndiscr {
                 let llptrptr = GEPi(bcx, val, [0, ptrfield]);
@@ -398,6 +570,13 @@ pub fn trans_start_init(bcx: @mut Block, r: &Repr, val: ValueRef, discr: Disr) {
     }
 }
 
+fn assert_discr_in_range(ity: IntType, min: Disr, max: Disr, discr: Disr) {
+    match ity {
+        attr::UnsignedInt(_) => assert!(min <= discr && discr <= max),
+        attr::SignedInt(_) => assert!(min as i64 <= discr as i64 && discr as i64 <= max as i64)
+    }
+}
+
 /**
  * The number of fields in a given case; for use when obtaining this
  * information from the type or definition is less convenient.
@@ -409,7 +588,7 @@ pub fn num_args(r: &Repr, discr: Disr) -> uint {
             assert_eq!(discr, 0);
             st.fields.len() - (if dtor { 1 } else { 0 })
         }
-        General(ref cases) => cases[discr].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() }
         }
@@ -430,7 +609,7 @@ pub fn trans_field_ptr(bcx: @mut Block, r: &Repr, val: ValueRef, discr: Disr,
             assert_eq!(discr, 0);
             struct_field_ptr(bcx, st, val, ix, false)
         }
-        General(ref cases) => {
+        General(_, ref cases) => {
             struct_field_ptr(bcx, &cases[discr], val, ix + 1, true)
         }
         NullablePointer{ nonnull: ref nonnull, nullfields: ref nullfields, nndiscr, _ } => {
@@ -498,24 +677,23 @@ pub fn trans_drop_flag_ptr(bcx: @mut Block, r: &Repr, val: ValueRef) -> ValueRef
 pub fn trans_const(ccx: &mut CrateContext, r: &Repr, discr: Disr,
                    vals: &[ValueRef]) -> ValueRef {
     match *r {
-        CEnum(min, max) => {
+        CEnum(ity, min, max) => {
             assert_eq!(vals.len(), 0);
-            assert!(min <= discr && discr <= max);
+            assert_discr_in_range(ity, min, max, discr);
-            C_disr(ccx, discr)
+            C_integral(ll_inttype(ccx, ity), discr as u64, true)
         }
-        Univariant(ref st, _dro) => {
+        General(ity, ref cases) => {
-            assert_eq!(discr, 0);
-            let contents = build_const_struct(ccx, st, vals);
-            C_struct(contents, st.packed)
-        }
-        General(ref cases) => {
             let case = &cases[discr];
             let max_sz = cases.iter().map(|x| x.size).max().unwrap();
-            let discr_ty = C_disr(ccx, discr);
+            let lldiscr = C_integral(ll_inttype(ccx, ity), discr as u64, true);
-            let contents = build_const_struct(ccx, case,
+            let contents = build_const_struct(ccx, case, ~[lldiscr] + vals);
-                                              ~[discr_ty] + vals);
             C_struct(contents + &[padding(max_sz - case.size)], false)
         }
+        Univariant(ref st, _dro) => {
+            assert!(discr == 0);
+            let contents = build_const_struct(ccx, st, vals);
+            C_struct(contents, st.packed)
+        }
         NullablePointer{ nonnull: ref nonnull, nndiscr, ptrfield, _ } => {
             if discr == nndiscr {
                 C_struct(build_const_struct(ccx, nonnull, vals), false)
@@ -585,9 +763,19 @@ fn roundup(x: u64, a: u64) -> u64 { ((x + (a - 1)) / a) * a }
 pub fn const_get_discrim(ccx: &mut CrateContext, r: &Repr, val: ValueRef)
     -> Disr {
     match *r {
-        CEnum(*) => const_to_uint(val) as Disr,
+        CEnum(ity, _, _) => {
+            match ity {
+                attr::SignedInt(*) => const_to_int(val) as Disr,
+                attr::UnsignedInt(*) => const_to_uint(val) as Disr
+            }
+        }
+        General(ity, _) => {
+            match ity {
+                attr::SignedInt(*) => const_to_int(const_get_elt(ccx, val, [0])) as Disr,
+                attr::UnsignedInt(*) => const_to_uint(const_get_elt(ccx, val, [0])) as Disr
+            }
+        }
         Univariant(*) => 0,
-        General(*) => const_to_uint(const_get_elt(ccx, val, [0])) as Disr,
         NullablePointer{ nndiscr, ptrfield, _ } => {
             if is_null(const_struct_field(ccx, val, ptrfield)) {
                 /* subtraction as uint is ok because nndiscr is either 0 or 1 */
@@ -646,7 +834,3 @@ pub fn is_newtypeish(r: &Repr) -> bool {
         _ => false
     }
 }
-
-fn C_disr(cx: &CrateContext, i: Disr) -> ValueRef {
-    return C_integral(cx.int_type, i, false);
-}

src/librustc/middle/trans/common.rs

@@ -868,6 +868,10 @@ pub fn C_i64(i: i64) -> ValueRef {
     return C_integral(Type::i64(), i as u64, true);
 }
 
+pub fn C_u64(i: u64) -> ValueRef {
+    return C_integral(Type::i64(), i, false);
+}
+
 pub fn C_int(cx: &CrateContext, i: int) -> ValueRef {
     return C_integral(cx.int_type, i as u64, true);
 }

src/librustc/middle/trans/debuginfo.rs

@@ -1251,7 +1251,7 @@ impl MemberDescriptionFactory for GeneralMemberDescriptionFactory {
                                   -> ~[MemberDescription] {
         // Capture type_rep, so we don't have to copy the struct_defs array
         let struct_defs = match *self.type_rep {
-            adt::General(ref struct_defs) => struct_defs,
+            adt::General(_, ref struct_defs) => struct_defs,
             _ => cx.sess.bug("unreachable")
         };
 
@@ -1400,14 +1400,6 @@ fn prepare_enum_metadata(cx: &mut CrateContext,
         return FinalMetadata(empty_type_metadata);
     }
 
-    // Prepare some data (llvm type, size, align, etc) about the discriminant. This data will be
-    // needed in all of the following cases.
-    let discriminant_llvm_type = Type::enum_discrim(cx);
-    let (discriminant_size, discriminant_align) = size_and_align_of(cx, discriminant_llvm_type);
-
-    assert!(Type::enum_discrim(cx) == cx.int_type);
-    let discriminant_base_type_metadata = type_metadata(cx, ty::mk_int(), codemap::dummy_sp());
-
     let variants = ty::enum_variants(cx.tcx, enum_def_id);
 
     let enumerators_metadata: ~[DIDescriptor] = variants
@@ -1427,26 +1419,32 @@ fn prepare_enum_metadata(cx: &mut CrateContext,
         })
         .collect();
 
-    let discriminant_type_metadata = do enum_name.with_c_str |enum_name| {
+    let discriminant_type_metadata = |inttype| {
-        unsafe {
+        let discriminant_llvm_type = adt::ll_inttype(cx, inttype);
-            llvm::LLVMDIBuilderCreateEnumerationType(
+        let (discriminant_size, discriminant_align) = size_and_align_of(cx, discriminant_llvm_type);
-                DIB(cx),
+        let discriminant_base_type_metadata = type_metadata(cx, adt::ty_of_inttype(inttype),
-                containing_scope,
+                                                            codemap::dummy_sp());
-                enum_name,
+        do enum_name.with_c_str |enum_name| {
-                file_metadata,
+            unsafe {
-                loc.line as c_uint,
+                llvm::LLVMDIBuilderCreateEnumerationType(
-                bytes_to_bits(discriminant_size),
+                    DIB(cx),
-                bytes_to_bits(discriminant_align),
+                    containing_scope,
-                create_DIArray(DIB(cx), enumerators_metadata),
+                    enum_name,
-                discriminant_base_type_metadata)
+                    file_metadata,
+                    loc.line as c_uint,
+                    bytes_to_bits(discriminant_size),
+                    bytes_to_bits(discriminant_align),
+                    create_DIArray(DIB(cx), enumerators_metadata),
+                    discriminant_base_type_metadata)
+            }
         }
     };
 
     let type_rep = adt::represent_type(cx, enum_type);
 
     return match *type_rep {
-        adt::CEnum(*) => {
+        adt::CEnum(inttype, _, _) => {
-            FinalMetadata(discriminant_type_metadata)
+            FinalMetadata(discriminant_type_metadata(inttype))
         }
         adt::Univariant(ref struct_def, _) => {
             assert!(variants.len() == 1);
@@ -1467,7 +1465,8 @@ fn prepare_enum_metadata(cx: &mut CrateContext,
                 member_description_factory: member_description_factory
             }
         }
-        adt::General(_) => {
+        adt::General(inttype, _) => {
+            let discriminant_type_metadata = discriminant_type_metadata(inttype);
             let enum_llvm_type = type_of::type_of(cx, enum_type);
             let (enum_type_size, enum_type_align) = size_and_align_of(cx, enum_llvm_type);
 

src/librustc/middle/trans/expr.rs

@@ -1727,9 +1727,14 @@ fn trans_imm_cast(bcx: @mut Block, expr: &ast::Expr,
             (cast_enum, cast_float) => {
                 let bcx = bcx;
                 let repr = adt::represent_type(ccx, t_in);
-                let slot = Alloca(bcx, ll_t_in, "");
+                let llexpr_ptr;
-                Store(bcx, llexpr, slot);
+                if type_is_immediate(ccx, t_in) {
-                let lldiscrim_a = adt::trans_get_discr(bcx, repr, slot);
+                    llexpr_ptr = Alloca(bcx, ll_t_in, "");
+                    Store(bcx, llexpr, llexpr_ptr);
+                } else {
+                    llexpr_ptr = llexpr;
+                }
+                let lldiscrim_a = adt::trans_get_discr(bcx, repr, llexpr_ptr, Some(Type::i64()));
                 match k_out {
                     cast_integral => int_cast(bcx, ll_t_out,
                                               val_ty(lldiscrim_a),

src/librustc/middle/trans/reflect.rs

@@ -25,7 +25,7 @@ use middle::ty;
 use util::ppaux::ty_to_str;
 
 use std::libc::c_uint;
-use std::option::None;
+use std::option::{Some,None};
 use std::vec;
 use syntax::ast::DefId;
 use syntax::ast;
@@ -292,11 +292,11 @@ impl Reflector {
                                                                sub_path,
                                                                "get_disr");
 
-                let llfdecl = decl_internal_rust_fn(ccx, [opaqueptrty], ty::mk_int(), sym);
+                let llfdecl = decl_internal_rust_fn(ccx, [opaqueptrty], ty::mk_u64(), sym);
                 let fcx = new_fn_ctxt(ccx,
                                       ~[],
                                       llfdecl,
-                                      ty::mk_uint(),
+                                      ty::mk_u64(),
                                       None);
                 let arg = unsafe {
                     //
@@ -308,7 +308,7 @@ impl Reflector {
                 };
                 let mut bcx = fcx.entry_bcx.unwrap();
                 let arg = BitCast(bcx, arg, llptrty);
-                let ret = adt::trans_get_discr(bcx, repr, arg);
+                let ret = adt::trans_get_discr(bcx, repr, arg, Some(Type::i64()));
                 Store(bcx, ret, fcx.llretptr.unwrap());
                 match fcx.llreturn {
                     Some(llreturn) => cleanup_and_Br(bcx, bcx, llreturn),
@@ -324,7 +324,7 @@ impl Reflector {
                 for (i, v) in variants.iter().enumerate() {
                     let name = ccx.sess.str_of(v.name);
                     let variant_args = ~[this.c_uint(i),
-                                         C_integral(self.bcx.ccx().int_type, v.disr_val, false),
+                                         C_u64(v.disr_val),
                                          this.c_uint(v.args.len()),
                                          this.c_slice(name)];
                     do this.bracketed("enum_variant", variant_args) |this| {

src/librustc/middle/ty.rs

@@ -38,6 +38,7 @@ use syntax::ast::*;
 use syntax::ast_util::is_local;
 use syntax::ast_util;
 use syntax::attr;
+use syntax::attr::AttrMetaMethods;
 use syntax::codemap::Span;
 use syntax::codemap;
 use syntax::parse::token;
@@ -715,6 +716,7 @@ pub struct ParamBounds {
 pub type BuiltinBounds = EnumSet<BuiltinBound>;
 
 #[deriving(Clone, Eq, IterBytes, ToStr)]
+#[repr(uint)]
 pub enum BuiltinBound {
     BoundStatic,
     BoundSend,
@@ -4102,27 +4104,42 @@ pub fn lookup_trait_def(cx: ctxt, did: ast::DefId) -> @ty::TraitDef {
     }
 }
 
-/// Determine whether an item is annotated with an attribute
+/// Iterate over meta_items of a definition.
-pub fn has_attr(tcx: ctxt, did: DefId, attr: &str) -> bool {
+// (This should really be an iterator, but that would require csearch and
+// decoder to use iterators instead of higher-order functions.)
+pub fn each_attr(tcx: ctxt, did: DefId, f: &fn(@MetaItem) -> bool) -> bool {
     if is_local(did) {
         match tcx.items.find(&did.node) {
-            Some(
+            Some(&ast_map::node_item(@ast::item {attrs: ref attrs, _}, _)) =>
-                &ast_map::node_item(@ast::item {
+                attrs.iter().advance(|attr| f(attr.node.value)),
-                    attrs: ref attrs,
-                    _
-                }, _)) => attr::contains_name(*attrs, attr),
             _ => tcx.sess.bug(format!("has_attr: {:?} is not an item",
-                                   did))
+                                      did))
         }
     } else {
-        let mut ret = false;
+        let mut cont = true;
         do csearch::get_item_attrs(tcx.cstore, did) |meta_items| {
-            ret = ret || attr::contains_name(meta_items, attr);
+            if cont {
+                cont = meta_items.iter().advance(|ptrptr| f(*ptrptr));
+            }
         }
-        ret
+        return cont;
     }
 }
 
+/// Determine whether an item is annotated with an attribute
+pub fn has_attr(tcx: ctxt, did: DefId, attr: &str) -> bool {
+    let mut found = false;
+    each_attr(tcx, did, |item| {
+        if attr == item.name() {
+            found = true;
+            false
+        } else {
+            true
+        }
+    });
+    return found;
+}
+
 /// Determine whether an item is annotated with `#[packed]`
 pub fn lookup_packed(tcx: ctxt, did: DefId) -> bool {
     has_attr(tcx, did, "packed")
@@ -4133,6 +4150,16 @@ pub fn lookup_simd(tcx: ctxt, did: DefId) -> bool {
     has_attr(tcx, did, "simd")
 }
 
+// Obtain the the representation annotation for a definition.
+pub fn lookup_repr_hint(tcx: ctxt, did: DefId) -> attr::ReprAttr {
+    let mut acc = attr::ReprAny;
+    ty::each_attr(tcx, did, |meta| {
+        acc = attr::find_repr_attr(tcx.sess.diagnostic(), meta, acc);
+        true
+    });
+    return acc;
+}
+
 // Look up a field ID, whether or not it's local
 // Takes a list of type substs in case the struct is generic
 pub fn lookup_field_type(tcx: ctxt,

src/librustc/middle/typeck/check/mod.rs

@@ -121,6 +121,7 @@ use syntax::ast;
 use syntax::ast_map;
 use syntax::ast_util::local_def;
 use syntax::ast_util;
+use syntax::attr;
 use syntax::codemap::Span;
 use syntax::codemap;
 use syntax::opt_vec::OptVec;
@@ -3169,9 +3170,38 @@ pub fn check_enum_variants(ccx: @mut CrateCtxt,
                            sp: Span,
                            vs: &[ast::variant],
                            id: ast::NodeId) {
+
+    fn disr_in_range(ccx: @mut CrateCtxt,
+                     ty: attr::IntType,
+                     disr: ty::Disr) -> bool {
+        fn uint_in_range(ccx: @mut CrateCtxt, ty: ast::uint_ty, disr: ty::Disr) -> bool {
+            match ty {
+                ast::ty_u8 => disr as u8 as Disr == disr,
+                ast::ty_u16 => disr as u16 as Disr == disr,
+                ast::ty_u32 => disr as u32 as Disr == disr,
+                ast::ty_u64 => disr as u64 as Disr == disr,
+                ast::ty_u => uint_in_range(ccx, ccx.tcx.sess.targ_cfg.uint_type, disr)
+            }
+        }
+        fn int_in_range(ccx: @mut CrateCtxt, ty: ast::int_ty, disr: ty::Disr) -> bool {
+            match ty {
+                ast::ty_i8 => disr as i8 as Disr == disr,
+                ast::ty_i16 => disr as i16 as Disr == disr,
+                ast::ty_i32 => disr as i32 as Disr == disr,
+                ast::ty_i64 => disr as i64 as Disr == disr,
+                ast::ty_i => int_in_range(ccx, ccx.tcx.sess.targ_cfg.int_type, disr)
+            }
+        }
+        match ty {
+            attr::UnsignedInt(ty) => uint_in_range(ccx, ty, disr),
+            attr::SignedInt(ty) => int_in_range(ccx, ty, disr)
+        }
+    }
+
     fn do_check(ccx: @mut CrateCtxt,
                 vs: &[ast::variant],
-                id: ast::NodeId)
+                id: ast::NodeId,
+                hint: attr::ReprAttr)
                 -> ~[@ty::VariantInfo] {
 
         let rty = ty::node_id_to_type(ccx.tcx, id);
@@ -3213,9 +3243,20 @@ pub fn check_enum_variants(ccx: @mut CrateCtxt,
                 None => ()
             };
 
-            // Check for duplicate discriminator values
+            // Check for duplicate discriminant values
             if disr_vals.contains(&current_disr_val) {
-                ccx.tcx.sess.span_err(v.span, "discriminator value already exists");
+                ccx.tcx.sess.span_err(v.span, "discriminant value already exists");
+            }
+            // Check for unrepresentable discriminant values
+            match hint {
+                attr::ReprAny | attr::ReprExtern => (),
+                attr::ReprInt(sp, ity) => {
+                    if !disr_in_range(ccx, ity, current_disr_val) {
+                        ccx.tcx.sess.span_err(v.span,
+                                              "discriminant value outside specified type");
+                        ccx.tcx.sess.span_note(sp, "discriminant type specified here");
+                    }
+                }
             }
             disr_vals.push(current_disr_val);
 
@@ -3229,8 +3270,13 @@ pub fn check_enum_variants(ccx: @mut CrateCtxt,
     }
 
     let rty = ty::node_id_to_type(ccx.tcx, id);
+    let hint = ty::lookup_repr_hint(ccx.tcx, ast::DefId { crate: ast::LOCAL_CRATE, node: id });
+    if hint != attr::ReprAny && vs.len() <= 1 {
+        ccx.tcx.sess.span_err(sp, format!("unsupported representation for {}variant enum",
+                                          if vs.len() == 1 { "uni" } else { "zero-" }))
+    }
 
-    let variants = do_check(ccx, vs, id);
+    let variants = do_check(ccx, vs, id, hint);
 
     // cache so that ty::enum_variants won't repeat this work
     ccx.tcx.enum_var_cache.insert(local_def(id), @variants);

src/libstd/num/int_macros.rs

@@ -29,7 +29,8 @@ pub static bits : uint = $bits;
 pub static bytes : uint = ($bits / 8);
 
 pub static min_value: $T = (-1 as $T) << (bits - 1);
-pub static max_value: $T = min_value - 1 as $T;
+// FIXME(#9837): Compute min_value like this so the high bits that shouldn't exist are 0.
+pub static max_value: $T = !min_value;
 
 impl CheckedDiv for $T {
     #[inline]

src/libstd/reflect.rs

@@ -16,7 +16,7 @@ Runtime type reflection
 
 #[allow(missing_doc)];
 
-use unstable::intrinsics::{Opaque, TyDesc, TyVisitor};
+use unstable::intrinsics::{Disr, Opaque, TyDesc, TyVisitor};
 use libc::c_void;
 use mem;
 use unstable::raw;
@@ -396,7 +396,7 @@ impl<V:TyVisitor + MovePtr> TyVisitor for MovePtrAdaptor<V> {
     }
 
     fn visit_enter_enum(&mut self, n_variants: uint,
-                        get_disr: extern unsafe fn(ptr: *Opaque) -> int,
+                        get_disr: extern unsafe fn(ptr: *Opaque) -> Disr,
                         sz: uint, align: uint)
                      -> bool {
         self.align(align);
@@ -407,7 +407,7 @@ impl<V:TyVisitor + MovePtr> TyVisitor for MovePtrAdaptor<V> {
     }
 
     fn visit_enter_enum_variant(&mut self, variant: uint,
-                                disr_val: int,
+                                disr_val: Disr,
                                 n_fields: uint,
                                 name: &str) -> bool {
         if ! self.inner.visit_enter_enum_variant(variant, disr_val,
@@ -426,7 +426,7 @@ impl<V:TyVisitor + MovePtr> TyVisitor for MovePtrAdaptor<V> {
     }
 
     fn visit_leave_enum_variant(&mut self, variant: uint,
-                                disr_val: int,
+                                disr_val: Disr,
                                 n_fields: uint,
                                 name: &str) -> bool {
         if ! self.inner.visit_leave_enum_variant(variant, disr_val,
@@ -437,7 +437,7 @@ impl<V:TyVisitor + MovePtr> TyVisitor for MovePtrAdaptor<V> {
     }
 
     fn visit_leave_enum(&mut self, n_variants: uint,
-                        get_disr: extern unsafe fn(ptr: *Opaque) -> int,
+                        get_disr: extern unsafe fn(ptr: *Opaque) -> Disr,
                         sz: uint, align: uint) -> bool {
         if ! self.inner.visit_leave_enum(n_variants, get_disr, sz, align) {
             return false;

src/libstd/repr.rs

@@ -29,7 +29,7 @@ use reflect::{MovePtr, align};
 use str::StrSlice;
 use to_str::ToStr;
 use vec::OwnedVector;
-use unstable::intrinsics::{Opaque, TyDesc, TyVisitor, get_tydesc, visit_tydesc};
+use unstable::intrinsics::{Disr, Opaque, TyDesc, TyVisitor, get_tydesc, visit_tydesc};
 use unstable::raw;
 
 /// Representations
@@ -92,7 +92,7 @@ num_repr!(f64, "f64")
 // New implementation using reflect::MovePtr
 
 enum VariantState {
-    SearchingFor(int),
+    SearchingFor(Disr),
     Matched,
     AlreadyFound
 }
@@ -473,7 +473,7 @@ impl<'self> TyVisitor for ReprVisitor<'self> {
 
     fn visit_enter_enum(&mut self,
                         _n_variants: uint,
-                        get_disr: extern unsafe fn(ptr: *Opaque) -> int,
+                        get_disr: extern unsafe fn(ptr: *Opaque) -> Disr,
                         _sz: uint,
                         _align: uint) -> bool {
         let disr = unsafe {
@@ -484,7 +484,7 @@ impl<'self> TyVisitor for ReprVisitor<'self> {
     }
 
     fn visit_enter_enum_variant(&mut self, _variant: uint,
-                                disr_val: int,
+                                disr_val: Disr,
                                 n_fields: uint,
                                 name: &str) -> bool {
         let mut write = false;
@@ -531,7 +531,7 @@ impl<'self> TyVisitor for ReprVisitor<'self> {
     }
 
     fn visit_leave_enum_variant(&mut self, _variant: uint,
-                                _disr_val: int,
+                                _disr_val: Disr,
                                 n_fields: uint,
                                 _name: &str) -> bool {
         match self.var_stk[self.var_stk.len() - 1] {
@@ -547,7 +547,7 @@ impl<'self> TyVisitor for ReprVisitor<'self> {
 
     fn visit_leave_enum(&mut self,
                         _n_variants: uint,
-                        _get_disr: extern unsafe fn(ptr: *Opaque) -> int,
+                        _get_disr: extern unsafe fn(ptr: *Opaque) -> Disr,
                         _sz: uint,
                         _align: uint)
                         -> bool {

src/libstd/rt/io/signal.rs

@@ -26,6 +26,7 @@ use result::{Err, Ok};
 use rt::io::io_error;
 use rt::rtio::{IoFactory, RtioSignal, with_local_io};
 
+#[repr(int)]
 #[deriving(Eq, IterBytes)]
 pub enum Signum {
     /// Equivalent to SIGBREAK, delivered when the user presses Ctrl-Break.

src/libstd/unstable/intrinsics.rs

@@ -75,6 +75,11 @@ pub struct TyDesc {
 #[cfg(not(test))]
 pub enum Opaque { }
 
+#[cfg(stage0)]
+pub type Disr = int;
+#[cfg(not(stage0))]
+pub type Disr = u64;
+
 #[lang="ty_visitor"]
 #[cfg(not(test))]
 pub trait TyVisitor {
@@ -140,19 +145,19 @@ pub trait TyVisitor {
                        sz: uint, align: uint) -> bool;
 
     fn visit_enter_enum(&mut self, n_variants: uint,
-                        get_disr: extern unsafe fn(ptr: *Opaque) -> int,
+                        get_disr: extern unsafe fn(ptr: *Opaque) -> Disr,
                         sz: uint, align: uint) -> bool;
     fn visit_enter_enum_variant(&mut self, variant: uint,
-                                disr_val: int,
+                                disr_val: Disr,
                                 n_fields: uint,
                                 name: &str) -> bool;
     fn visit_enum_variant_field(&mut self, i: uint, offset: uint, inner: *TyDesc) -> bool;
     fn visit_leave_enum_variant(&mut self, variant: uint,
-                                disr_val: int,
+                                disr_val: Disr,
                                 n_fields: uint,
                                 name: &str) -> bool;
     fn visit_leave_enum(&mut self, n_variants: uint,
-                        get_disr: extern unsafe fn(ptr: *Opaque) -> int,
+                        get_disr: extern unsafe fn(ptr: *Opaque) -> Disr,
                         sz: uint, align: uint) -> bool;
 
     fn visit_enter_fn(&mut self, purity: uint, proto: uint,

src/libsyntax/attr.rs

@@ -14,7 +14,7 @@ use extra;
 
 use ast;
 use ast::{Attribute, Attribute_, MetaItem, MetaWord, MetaNameValue, MetaList};
-use codemap::{Spanned, spanned, dummy_spanned};
+use codemap::{Span, Spanned, spanned, dummy_spanned};
 use codemap::BytePos;
 use diagnostic::span_handler;
 use parse::comments::{doc_comment_style, strip_doc_comment_decoration};
@@ -363,3 +363,115 @@ pub fn require_unique_names(diagnostic: @mut span_handler,
         }
     }
 }
+
+
+/**
+ * Fold this over attributes to parse #[repr(...)] forms.
+ *
+ * Valid repr contents: any of the primitive integral type names (see
+ * `int_type_of_word`, below) to specify the discriminant type; and `C`, to use
+ * the same discriminant size that the corresponding C enum would.  These are
+ * not allowed on univariant or zero-variant enums, which have no discriminant.
+ *
+ * If a discriminant type is so specified, then the discriminant will be
+ * present (before fields, if any) with that type; reprensentation
+ * optimizations which would remove it will not be done.
+ */
+pub fn find_repr_attr(diagnostic: @mut span_handler, attr: @ast::MetaItem, acc: ReprAttr)
+    -> ReprAttr {
+    let mut acc = acc;
+    match attr.node {
+        ast::MetaList(s, ref items) if "repr" == s => {
+            for item in items.iter() {
+                match item.node {
+                    ast::MetaWord(word) => {
+                        let hint = match word.as_slice() {
+                            // Can't use "extern" because it's not a lexical identifier.
+                            "C" => ReprExtern,
+                            _ => match int_type_of_word(word) {
+                                Some(ity) => ReprInt(item.span, ity),
+                                None => {
+                                    // Not a word we recognize
+                                    diagnostic.span_err(item.span,
+                                                        "unrecognized representation hint");
+                                    ReprAny
+                                }
+                            }
+                        };
+                        if hint != ReprAny {
+                            if acc == ReprAny {
+                                acc = hint;
+                            } else if acc != hint {
+                                diagnostic.span_warn(item.span,
+                                                     "conflicting representation hint ignored")
+                            }
+                        }
+                    }
+                    // Not a word:
+                    _ => diagnostic.span_err(item.span, "unrecognized representation hint")
+                }
+            }
+        }
+        // Not a "repr" hint: ignore.
+        _ => { }
+    }
+    return acc;
+}
+
+fn int_type_of_word(s: &str) -> Option<IntType> {
+    match s {
+        "i8" => Some(SignedInt(ast::ty_i8)),
+        "u8" => Some(UnsignedInt(ast::ty_u8)),
+        "i16" => Some(SignedInt(ast::ty_i16)),
+        "u16" => Some(UnsignedInt(ast::ty_u16)),
+        "i32" => Some(SignedInt(ast::ty_i32)),
+        "u32" => Some(UnsignedInt(ast::ty_u32)),
+        "i64" => Some(SignedInt(ast::ty_i64)),
+        "u64" => Some(UnsignedInt(ast::ty_u64)),
+        "int" => Some(SignedInt(ast::ty_i)),
+        "uint" => Some(UnsignedInt(ast::ty_u)),
+        _ => None
+    }
+}
+
+#[deriving(Eq)]
+pub enum ReprAttr {
+    ReprAny,
+    ReprInt(Span, IntType),
+    ReprExtern
+}
+
+impl ReprAttr {
+    pub fn is_ffi_safe(&self) -> bool {
+        match *self {
+            ReprAny => false,
+            ReprInt(_sp, ity) => ity.is_ffi_safe(),
+            ReprExtern => true
+        }
+    }
+}
+
+#[deriving(Eq)]
+pub enum IntType {
+    SignedInt(ast::int_ty),
+    UnsignedInt(ast::uint_ty)
+}
+
+impl IntType {
+    #[inline]
+    pub fn is_signed(self) -> bool {
+        match self {
+            SignedInt(*) => true,
+            UnsignedInt(*) => false
+        }
+    }
+    fn is_ffi_safe(self) -> bool {
+        match self {
+            SignedInt(ast::ty_i8) | UnsignedInt(ast::ty_u8) |
+            SignedInt(ast::ty_i16) | UnsignedInt(ast::ty_u16) |
+            SignedInt(ast::ty_i32) | UnsignedInt(ast::ty_u32) |
+            SignedInt(ast::ty_i64) | UnsignedInt(ast::ty_u64) => true,
+            _ => false
+        }
+    }
+}

src/test/compile-fail/enum-discrim-too-small.rs

@@ -0,0 +1,58 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[repr(u8)] //~ NOTE discriminant type specified here
+enum Eu8 {
+    Au8 = 23,
+    Bu8 = 223,
+    Cu8 = -23, //~ ERROR discriminant value outside specified type
+}
+
+#[repr(i8)] //~ NOTE discriminant type specified here
+enum Ei8 {
+    Ai8 = 23,
+    Bi8 = -23,
+    Ci8 = 223, //~ ERROR discriminant value outside specified type
+}
+
+#[repr(u16)] //~ NOTE discriminant type specified here
+enum Eu16 {
+    Au16 = 23,
+    Bu16 = 55555,
+    Cu16 = -22333, //~ ERROR discriminant value outside specified type
+}
+
+#[repr(i16)] //~ NOTE discriminant type specified here
+enum Ei16 {
+    Ai16 = 23,
+    Bi16 = -22333,
+    Ci16 = 55555, //~ ERROR discriminant value outside specified type
+}
+
+#[repr(u32)] //~ NOTE discriminant type specified here
+enum Eu32 {
+    Au32 = 23,
+    Bu32 = 3_000_000_000,
+    Cu32 = -2_000_000_000, //~ ERROR discriminant value outside specified type
+}
+
+#[repr(i32)] //~ NOTE discriminant type specified here
+enum Ei32 {
+    Ai32 = 23,
+    Bi32 = -2_000_000_000,
+    Ci32 = 3_000_000_000, //~ ERROR discriminant value outside specified type
+}
+
+// u64 currently allows negative numbers, and i64 allows numbers greater than `1<<63`.  This is a
+// little counterintuitive, but since the discriminant can store all the bits, and extracting it
+// with a cast requires specifying the signedness, there is no loss of information in those cases.
+// This also applies to int and uint on 64-bit targets.
+
+pub fn main() { }

src/test/compile-fail/lint-ctypes-enum.rs

@@ -0,0 +1,25 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[deny(ctypes)];
+
+enum Z { }
+enum U { A }
+enum B { C, D }
+enum T { E, F, G }
+
+extern {
+   fn zf(x: Z);
+   fn uf(x: U);
+   fn bf(x: B); //~ ERROR found enum type without foreign-function-safe
+   fn tf(x: T); //~ ERROR found enum type without foreign-function-safe
+}
+
+pub fn main() { }

src/test/compile-fail/tag-variant-disr-dup.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-//error-pattern:discriminator value already exists
+//error-pattern:discriminant value already exists
 
 // black and white have the same discriminator value ...
 

src/test/debug-info/method-on-enum.rs

@@ -15,7 +15,7 @@
 // STACK BY REF
 // debugger:finish
 // debugger:print *self
-// check:$1 = {{Variant2, x = 1799, y = 1799}, {Variant2, 117901063}}
+// check:$1 = {{Variant2, [...]}, {Variant2, 117901063}}
 // debugger:print arg1
 // check:$2 = -1
 // debugger:print arg2
@@ -25,7 +25,7 @@
 // STACK BY VAL
 // debugger:finish
 // d ebugger:print self -- ignored for now because of issue #8512
-// c heck:$X = {{Variant2, x = 1799, y = 1799}, {Variant2, 117901063}}
+// c heck:$X = {{Variant2, [...]}, {Variant2, 117901063}}
 // debugger:print arg1
 // check:$4 = -3
 // debugger:print arg2
@@ -35,7 +35,7 @@
 // OWNED BY REF
 // debugger:finish
 // debugger:print *self
-// check:$6 = {{Variant1, x = 1799, y = 1799}, {Variant1, 117901063}}
+// check:$6 = {{Variant1, x = 1799, y = 1799}, {Variant1, [...]}}
 // debugger:print arg1
 // check:$7 = -5
 // debugger:print arg2
@@ -45,7 +45,7 @@
 // OWNED BY VAL
 // debugger:finish
 // d ebugger:print self -- ignored for now because of issue #8512
-// c heck:$X = {{Variant1, x = 1799, y = 1799}, {Variant1, 117901063}}
+// c heck:$X = {{Variant1, x = 1799, y = 1799}, {Variant1, [...]}}
 // debugger:print arg1
 // check:$9 = -7
 // debugger:print arg2
@@ -55,7 +55,7 @@
 // OWNED MOVED
 // debugger:finish
 // debugger:print *self
-// check:$11 = {{Variant1, x = 1799, y = 1799}, {Variant1, 117901063}}
+// check:$11 = {{Variant1, x = 1799, y = 1799}, {Variant1, [...]}}
 // debugger:print arg1
 // check:$12 = -9
 // debugger:print arg2
@@ -65,7 +65,7 @@
 // MANAGED BY REF
 // debugger:finish
 // debugger:print *self
-// check:$14 = {{Variant2, x = 1799, y = 1799}, {Variant2, 117901063}}
+// check:$14 = {{Variant2, [...]}, {Variant2, 117901063}}
 // debugger:print arg1
 // check:$15 = -11
 // debugger:print arg2
@@ -75,7 +75,7 @@
 // MANAGED BY VAL
 // debugger:finish
 // d ebugger:print self -- ignored for now because of issue #8512
-// c heck:$X = {{Variant2, x = 1799, y = 1799}, {Variant2, 117901063}}
+// c heck:$X = {{Variant2, [...]}, {Variant2, 117901063}}
 // debugger:print arg1
 // check:$17 = -13
 // debugger:print arg2
@@ -85,7 +85,7 @@
 // MANAGED SELF
 // debugger:finish
 // debugger:print self->val
-// check:$19 = {{Variant2, x = 1799, y = 1799}, {Variant2, 117901063}}
+// check:$19 = {{Variant2, [...]}, {Variant2, 117901063}}
 // debugger:print arg1
 // check:$20 = -15
 // debugger:print arg2

src/test/run-pass/enum-discrim-autosizing.rs

@@ -0,0 +1,62 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::mem::size_of;
+
+enum Ei8 {
+    Ai8 = -1,
+    Bi8 = 0
+}
+
+enum Eu8 {
+    Au8 = 0,
+    Bu8 = 0x80
+}
+
+enum Ei16 {
+    Ai16 = -1,
+    Bi16 = 0x80
+}
+
+enum Eu16 {
+    Au16 = 0,
+    Bu16 = 0x8000
+}
+
+enum Ei32 {
+    Ai32 = -1,
+    Bi32 = 0x8000
+}
+
+enum Eu32 {
+    Au32 = 0,
+    Bu32 = 0x8000_0000
+}
+
+enum Ei64 {
+    Ai64 = -1,
+    Bi64 = 0x8000_0000
+}
+
+enum Eu64 {
+    Au64 = 0,
+    Bu64 = 0x8000_0000_0000_0000
+}
+
+pub fn main() {
+    assert_eq!(size_of::<Ei8>(), 1);
+    assert_eq!(size_of::<Eu8>(), 1);
+    assert_eq!(size_of::<Ei16>(), 2);
+    assert_eq!(size_of::<Eu16>(), 2);
+    assert_eq!(size_of::<Ei32>(), 4);
+    assert_eq!(size_of::<Eu32>(), 4);
+    assert_eq!(size_of::<Ei64>(), 8);
+    assert_eq!(size_of::<Eu64>(), 8);
+}

src/test/run-pass/enum-discrim-manual-sizing.rs

@@ -0,0 +1,84 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::mem::size_of;
+
+#[repr(i8)]
+enum Ei8 {
+    Ai8 = 0,
+    Bi8 = 1
+}
+
+#[repr(u8)]
+enum Eu8 {
+    Au8 = 0,
+    Bu8 = 1
+}
+
+#[repr(i16)]
+enum Ei16 {
+    Ai16 = 0,
+    Bi16 = 1
+}
+
+#[repr(u16)]
+enum Eu16 {
+    Au16 = 0,
+    Bu16 = 1
+}
+
+#[repr(i32)]
+enum Ei32 {
+    Ai32 = 0,
+    Bi32 = 1
+}
+
+#[repr(u32)]
+enum Eu32 {
+    Au32 = 0,
+    Bu32 = 1
+}
+
+#[repr(i64)]
+enum Ei64 {
+    Ai64 = 0,
+    Bi64 = 1
+}
+
+#[repr(u64)]
+enum Eu64 {
+    Au64 = 0,
+    Bu64 = 1
+}
+
+#[repr(int)]
+enum Eint {
+    Aint = 0,
+    Bint = 1
+}
+
+#[repr(uint)]
+enum Euint {
+    Auint = 0,
+    Buint = 1
+}
+
+pub fn main() {
+    assert_eq!(size_of::<Ei8>(), 1);
+    assert_eq!(size_of::<Eu8>(), 1);
+    assert_eq!(size_of::<Ei16>(), 2);
+    assert_eq!(size_of::<Eu16>(), 2);
+    assert_eq!(size_of::<Ei32>(), 4);
+    assert_eq!(size_of::<Eu32>(), 4);
+    assert_eq!(size_of::<Ei64>(), 8);
+    assert_eq!(size_of::<Eu64>(), 8);
+    assert_eq!(size_of::<Eint>(), size_of::<int>());
+    assert_eq!(size_of::<Euint>(), size_of::<uint>());
+}

src/test/run-pass/enum-discrim-width-stuff.rs

@@ -8,18 +8,48 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::mem;
+#[feature(macro_rules)];
+
+macro_rules! check {
+    ($m:ident, $t:ty, $v:expr) => {{
+        mod $m {
+            use std::mem::size_of;
+            enum E {
+                V = $v,
+                A = 0
+            }
+            static C: E = V;
+            pub fn check() {
+                assert_eq!(size_of::<E>(), size_of::<$t>());
+                assert_eq!(V as $t, $v);
+                assert_eq!(C as $t, $v);
+                assert_eq!(format!("{:?}", V), ~"V");
+                assert_eq!(format!("{:?}", C), ~"V");
+            }
+        }
+        $m::check();
+    }}
+}
 
 pub fn main() {
-    enum E { V = 0x1717171717171717 }
+    check!(a, u8, 0x17);
-    static C: E = V;
+    check!(b, u8, 0xe8);
-    let expected: u64 = if mem::size_of::<uint>() < 8 {
+    check!(c, u16, 0x1727);
-        0x17171717
+    check!(d, u16, 0xe8d8);
-    } else {
+    check!(e, u32, 0x17273747);
-        0x1717171717171717
+    check!(f, u32, 0xe8d8c8b8);
-    };
+    check!(g, u64, 0x1727374757677787u64);
-    assert_eq!(expected, V as u64);
+    check!(h, u64, 0xe8d8c8b8a8988878u64);
-    assert_eq!(expected, C as u64);
+
-    assert_eq!(format!("{:?}", V), ~"V");
+    check!(z, i8, 0x17);
-    assert_eq!(format!("{:?}", C), ~"V");
+    check!(y, i8, -0x17);
+    check!(x, i16, 0x1727);
+    check!(w, i16, -0x1727);
+    check!(v, i32, 0x17273747);
+    check!(u, i32, -0x17273747);
+    check!(t, i64, 0x1727374757677787);
+    check!(s, i64, -0x1727374757677787);
+
+    enum Simple { A, B }
+    assert_eq!(::std::mem::size_of::<Simple>(), 1);
 }

src/test/run-pass/issue-2718.rs

@@ -27,6 +27,7 @@ pub mod pipes {
     }
 
     #[deriving(Eq)]
+    #[repr(int)]
     pub enum state {
         empty,
         full,

src/test/run-pass/reflect-visit-data.rs

@@ -15,7 +15,7 @@
 use std::libc::c_void;
 use std::ptr;
 use std::mem;
-use std::unstable::intrinsics::{TyDesc, get_tydesc, visit_tydesc, TyVisitor, Opaque};
+use std::unstable::intrinsics::{TyDesc, get_tydesc, visit_tydesc, TyVisitor, Disr, Opaque};
 use std::unstable::raw::Vec;
 
 #[doc = "High-level interfaces to `std::unstable::intrinsics::visit_ty` reflection system."]
@@ -380,7 +380,7 @@ impl<V:TyVisitor + movable_ptr> TyVisitor for ptr_visit_adaptor<V> {
     }
 
     fn visit_enter_enum(&mut self, n_variants: uint,
-                        get_disr: extern unsafe fn(ptr: *Opaque) -> int,
+                        get_disr: extern unsafe fn(ptr: *Opaque) -> Disr,
                         sz: uint, align: uint)
                      -> bool {
         self.align(align);
@@ -389,7 +389,7 @@ impl<V:TyVisitor + movable_ptr> TyVisitor for ptr_visit_adaptor<V> {
     }
 
     fn visit_enter_enum_variant(&mut self, variant: uint,
-                                disr_val: int,
+                                disr_val: Disr,
                                 n_fields: uint,
                                 name: &str) -> bool {
         if ! self.inner.visit_enter_enum_variant(variant, disr_val,
@@ -405,7 +405,7 @@ impl<V:TyVisitor + movable_ptr> TyVisitor for ptr_visit_adaptor<V> {
     }
 
     fn visit_leave_enum_variant(&mut self, variant: uint,
-                                disr_val: int,
+                                disr_val: Disr,
                                 n_fields: uint,
                                 name: &str) -> bool {
         if ! self.inner.visit_leave_enum_variant(variant, disr_val,
@@ -416,7 +416,7 @@ impl<V:TyVisitor + movable_ptr> TyVisitor for ptr_visit_adaptor<V> {
     }
 
     fn visit_leave_enum(&mut self, n_variants: uint,
-                        get_disr: extern unsafe fn(ptr: *Opaque) -> int,
+                        get_disr: extern unsafe fn(ptr: *Opaque) -> Disr,
                         sz: uint, align: uint)
                      -> bool {
         if ! self.inner.visit_leave_enum(n_variants, get_disr, sz, align) { return false; }
@@ -578,24 +578,24 @@ impl TyVisitor for my_visitor {
                        _sz: uint, _align: uint) -> bool { true }
 
     fn visit_enter_enum(&mut self, _n_variants: uint,
-                        _get_disr: extern unsafe fn(ptr: *Opaque) -> int,
+                        _get_disr: extern unsafe fn(ptr: *Opaque) -> Disr,
                         _sz: uint, _align: uint) -> bool {
         // FIXME (#3732): this needs to rewind between enum variants, or something.
         true
     }
     fn visit_enter_enum_variant(&mut self, _variant: uint,
-                                _disr_val: int,
+                                _disr_val: Disr,
                                 _n_fields: uint,
                                 _name: &str) -> bool { true }
     fn visit_enum_variant_field(&mut self, _i: uint, _offset: uint, inner: *TyDesc) -> bool {
         self.visit_inner(inner)
     }
     fn visit_leave_enum_variant(&mut self, _variant: uint,
-                                _disr_val: int,
+                                _disr_val: Disr,
                                 _n_fields: uint,
                                 _name: &str) -> bool { true }
     fn visit_leave_enum(&mut self, _n_variants: uint,
-                        _get_disr: extern unsafe fn(ptr: *Opaque) -> int,
+                        _get_disr: extern unsafe fn(ptr: *Opaque) -> Disr,
                         _sz: uint, _align: uint) -> bool { true }
 
     fn visit_enter_fn(&mut self, _purity: uint, _proto: uint,

src/test/run-pass/reflect-visit-type.rs

@@ -10,7 +10,7 @@
 
 #[feature(managed_boxes)];
 
-use std::unstable::intrinsics::{TyDesc, get_tydesc, visit_tydesc, TyVisitor, Opaque};
+use std::unstable::intrinsics::{TyDesc, get_tydesc, visit_tydesc, TyVisitor, Disr, Opaque};
 
 struct MyVisitor {
     types: @mut ~[~str],
@@ -114,22 +114,22 @@ impl TyVisitor for MyVisitor {
                        _sz: uint, _align: uint) -> bool { true }
 
     fn visit_enter_enum(&mut self, _n_variants: uint,
-                        _get_disr: extern unsafe fn(ptr: *Opaque) -> int,
+                        _get_disr: extern unsafe fn(ptr: *Opaque) -> Disr,
                         _sz: uint, _align: uint) -> bool { true }
     fn visit_enter_enum_variant(&mut self,
                                 _variant: uint,
-                                _disr_val: int,
+                                _disr_val: Disr,
                                 _n_fields: uint,
                                 _name: &str) -> bool { true }
     fn visit_enum_variant_field(&mut self, _i: uint, _offset: uint, _inner: *TyDesc) -> bool { true }
     fn visit_leave_enum_variant(&mut self,
                                 _variant: uint,
-                                _disr_val: int,
+                                _disr_val: Disr,
                                 _n_fields: uint,
                                 _name: &str) -> bool { true }
     fn visit_leave_enum(&mut self,
                         _n_variants: uint,
-                        _get_disr: extern unsafe fn(ptr: *Opaque) -> int,
+                        _get_disr: extern unsafe fn(ptr: *Opaque) -> Disr,
                         _sz: uint, _align: uint) -> bool { true }
 
     fn visit_enter_fn(&mut self, _purity: uint, _proto: uint,

src/test/run-pass/small-enum-range-edge.rs

@@ -0,0 +1,32 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+/*!
+ * Tests the range assertion wraparound case in trans::middle::adt::load_discr.
+ */
+
+#[repr(u8)]
+enum Eu { Lu = 0, Hu = 255 }
+static CLu: Eu = Lu;
+static CHu: Eu = Hu;
+
+#[repr(i8)]
+enum Es { Ls = -128, Hs = 127 }
+static CLs: Es = Ls;
+static CHs: Es = Hs;
+
+pub fn main() {
+    assert_eq!((Hu as u8) + 1, Lu as u8);
+    assert_eq!((Hs as i8) + 1, Ls as i8);
+    assert_eq!(CLu as u8, Lu as u8);
+    assert_eq!(CHu as u8, Hu as u8);
+    assert_eq!(CLs as i8, Ls as i8);
+    assert_eq!(CHs as i8, Hs as i8);
+}

src/test/run-pass/small-enums-with-fields.rs

@@ -0,0 +1,41 @@
+// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#[feature(macro_rules)];
+
+use std::mem::size_of;
+
+macro_rules! check {
+    ($t:ty, $sz:expr, $($e:expr, $s:expr),*) => {{
+        assert_eq!(size_of::<$t>(), $sz);
+        $({
+            static S: $t = $e;
+            let v: $t = $e;
+            assert_eq!(S, v);
+            assert_eq!(format!("{:?}", v), ~$s);
+            assert_eq!(format!("{:?}", S), ~$s);
+        });*
+    }}
+}
+
+pub fn main() {
+    check!(Option<u8>, 2,
+           None, "None",
+           Some(129u8), "Some(129u8)");
+    check!(Option<i16>, 4,
+           None, "None",
+           Some(-20000i16), "Some(-20000i16)");
+    check!(Either<u8, i8>, 2,
+           Left(132u8), "Left(132u8)",
+           Right(-32i8), "Right(-32i8)");
+    check!(Either<u8, i16>, 4,
+           Left(132u8), "Left(132u8)",
+           Right(-20000i16), "Right(-20000i16)");
+}