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.

5 files changed, 23 insertions, 16 deletions

diff --git a/src/libstd/num/int_macros.rs b/src/libstd/num/int_macros.rs
index 694e5e7f6bf..ba1a7a4f912 100644
--- a/src/libstd/num/int_macros.rs
+++ b/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]
diff --git a/src/libstd/reflect.rs b/src/libstd/reflect.rs
index d63b14f982d..19fa9abc0da 100644
--- a/src/libstd/reflect.rs
+++ b/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;
diff --git a/src/libstd/repr.rs b/src/libstd/repr.rs
index d03621eb60d..dd68c57e37e 100644
--- a/src/libstd/repr.rs
+++ b/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 {
diff --git a/src/libstd/rt/io/signal.rs b/src/libstd/rt/io/signal.rs
index 4c6c675df03..b782d713950 100644
--- a/src/libstd/rt/io/signal.rs
+++ b/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.
diff --git a/src/libstd/unstable/intrinsics.rs b/src/libstd/unstable/intrinsics.rs
index 1900d9d5801..20563718a6c 100644
--- a/src/libstd/unstable/intrinsics.rs
+++ b/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,