Add a Ranged wrapper struct to replace the rustc_scalar_range_valid attributes

Author: oli-obk

Diff for: compiler/rustc_codegen_cranelift/example/mini_core.rs

@@ -34,13 +34,13 @@ impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for *mut T {}
 pub trait DispatchFromDyn<T> {}
 
 // &T -> &U
-impl<'a, T: ?Sized+Unsize<U>, U: ?Sized> DispatchFromDyn<&'a U> for &'a T {}
+impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<&'a U> for &'a T {}
 // &mut T -> &mut U
-impl<'a, T: ?Sized+Unsize<U>, U: ?Sized> DispatchFromDyn<&'a mut U> for &'a mut T {}
+impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<&'a mut U> for &'a mut T {}
 // *const T -> *const U
-impl<T: ?Sized+Unsize<U>, U: ?Sized> DispatchFromDyn<*const U> for *const T {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<*const U> for *const T {}
 // *mut T -> *mut U
-impl<T: ?Sized+Unsize<U>, U: ?Sized> DispatchFromDyn<*mut U> for *mut T {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<*mut U> for *mut T {}
 impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<Box<U>> for Box<T> {}
 
 #[lang = "receiver"]
@@ -285,7 +285,6 @@ impl PartialEq for u32 {
     }
 }
 
-
 impl PartialEq for u64 {
     fn eq(&self, other: &u64) -> bool {
         (*self) == (*other)
@@ -358,7 +357,7 @@ impl<T: ?Sized> PartialEq for *const T {
     }
 }
 
-impl <T: PartialEq> PartialEq for Option<T> {
+impl<T: PartialEq> PartialEq for Option<T> {
     fn eq(&self, other: &Self) -> bool {
         match (self, other) {
             (Some(lhs), Some(rhs)) => *lhs == *rhs,
@@ -469,7 +468,11 @@ pub fn panic(_msg: &'static str) -> ! {
 #[track_caller]
 fn panic_bounds_check(index: usize, len: usize) -> ! {
     unsafe {
-        libc::printf("index out of bounds: the len is %d but the index is %d\n\0" as *const str as *const i8, len, index);
+        libc::printf(
+            "index out of bounds: the len is %d but the index is %d\n\0" as *const str as *const i8,
+            len,
+            index,
+        );
         intrinsics::abort();
     }
 }
@@ -495,9 +498,8 @@ pub trait Deref {
 }
 
 #[repr(transparent)]
-#[rustc_layout_scalar_valid_range_start(1)]
 #[rustc_nonnull_optimization_guaranteed]
-pub struct NonNull<T: ?Sized>(pub *const T);
+pub struct NonNull<T: ?Sized>(pub Ranged<*const T, { 1..=(usize::MAX as u128) }>);
 
 impl<T: ?Sized, U: ?Sized> CoerceUnsized<NonNull<U>> for NonNull<T> where T: Unsize<U> {}
 impl<T: ?Sized, U: ?Sized> DispatchFromDyn<NonNull<U>> for NonNull<T> where T: Unsize<U> {}
@@ -585,7 +587,7 @@ pub mod libc {
     // functions. legacy_stdio_definitions.lib which provides the printf wrapper functions as normal
     // symbols to link against.
     #[cfg_attr(unix, link(name = "c"))]
-    #[cfg_attr(target_env="msvc", link(name="legacy_stdio_definitions"))]
+    #[cfg_attr(target_env = "msvc", link(name = "legacy_stdio_definitions"))]
     extern "C" {
         pub fn printf(format: *const i8, ...) -> i32;
     }
@@ -624,7 +626,7 @@ impl<T> Index<usize> for [T] {
     }
 }
 
-extern {
+extern "C" {
     type VaListImpl;
 }
 
@@ -634,23 +636,33 @@ pub struct VaList<'a>(&'a mut VaListImpl);
 
 #[rustc_builtin_macro]
 #[rustc_macro_transparency = "semitransparent"]
-pub macro stringify($($t:tt)*) { /* compiler built-in */ }
+pub macro stringify($($t:tt)*) {
+    /* compiler built-in */
+}
 
 #[rustc_builtin_macro]
 #[rustc_macro_transparency = "semitransparent"]
-pub macro file() { /* compiler built-in */ }
+pub macro file() {
+    /* compiler built-in */
+}
 
 #[rustc_builtin_macro]
 #[rustc_macro_transparency = "semitransparent"]
-pub macro line() { /* compiler built-in */ }
+pub macro line() {
+    /* compiler built-in */
+}
 
 #[rustc_builtin_macro]
 #[rustc_macro_transparency = "semitransparent"]
-pub macro cfg() { /* compiler built-in */ }
+pub macro cfg() {
+    /* compiler built-in */
+}
 
 #[rustc_builtin_macro]
 #[rustc_macro_transparency = "semitransparent"]
-pub macro global_asm() { /* compiler built-in */ }
+pub macro global_asm() {
+    /* compiler built-in */
+}
 
 pub static A_STATIC: u8 = 42;
 

Diff for: compiler/rustc_const_eval/src/interpret/validity.rs

@@ -761,7 +761,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
 
         // *After* all of this, check the ABI.  We need to check the ABI to handle
         // types like `NonNull` where the `Scalar` info is more restrictive than what
-        // the fields say (`rustc_layout_scalar_valid_range_start`).
+        // the fields say (`Ranged<T, ...>`).
         // But in most cases, this will just propagate what the fields say,
         // and then we want the error to point at the field -- so, first recurse,
         // then check ABI.
@@ -783,6 +783,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
                 }
             }
             Abi::ScalarPair(a_layout, b_layout) => {
+                // FIXME: range restrictions work on the first element of a pair.
                 // There is no `rustc_layout_scalar_valid_range_start` for pairs, so
                 // we would validate these things as we descend into the fields,
                 // but that can miss bugs in layout computation. Layout computation

Diff for: compiler/rustc_const_eval/src/interpret/visitor.rs

@@ -466,7 +466,10 @@ macro_rules! make_value_visitor {
                         );
                         // ... that contains a `NonNull`... (gladly, only a single field here)
                         assert_eq!(nonnull_ptr.layout().fields.count(), 1);
-                        let raw_ptr = nonnull_ptr.project_field(self.ecx(), 0)?; // the actual raw ptr
+                        let ranged = nonnull_ptr.project_field(self.ecx(), 0)?; // the Ranged struct
+                        // ... which then contains a `Ranged<*const T>` ...
+                        assert_eq!(ranged.layout().fields.count(), 1);
+                        let raw_ptr = ranged.project_field(self.ecx(), 0)?; // the actual raw ptr
                         // ... whose only field finally is a raw ptr we can dereference.
                         self.visit_box(&raw_ptr)?;
 

Diff for: compiler/rustc_const_eval/src/transform/validate.rs

@@ -121,6 +121,7 @@ struct TypeChecker<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
+    #[track_caller]
     fn fail(&self, location: Location, msg: impl AsRef<str>) {
         let span = self.body.source_info(location).span;
         // We use `delay_span_bug` as we might see broken MIR when other errors have already
@@ -281,12 +282,12 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                 let check_equal = |this: &Self, location, f_ty| {
                     if !this.mir_assign_valid_types(ty, f_ty) {
                         this.fail(
-                        location,
-                        format!(
-                            "Field projection `{:?}.{:?}` specified type `{:?}`, but actual type is `{:?}`",
-                            parent, f, ty, f_ty
+                            location,
+                            format!(
+                                "Field projection `{:?}.{:?}` specified type `{:?}`, but actual type is `{:?}`",
+                                parent, f, ty, f_ty
+                            )
                         )
-                    )
                     }
                 };
 

Diff for: compiler/rustc_error_messages/locales/en-US/passes.ftl

@@ -211,13 +211,6 @@ passes_export_name =
     attribute should be applied to a free function, impl method or static
     .label = not a free function, impl method or static
 
-passes_rustc_layout_scalar_valid_range_not_struct =
-    attribute should be applied to a struct
-    .label = not a struct
-
-passes_rustc_layout_scalar_valid_range_arg =
-    expected exactly one integer literal argument
-
 passes_rustc_legacy_const_generics_only =
     #[rustc_legacy_const_generics] functions must only have const generics
     .label = non-const generic parameter

Diff for: compiler/rustc_feature/src/builtin_attrs.rs

@@ -659,16 +659,6 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     // Internal attributes, Layout related:
     // ==========================================================================
 
-    rustc_attr!(
-        rustc_layout_scalar_valid_range_start, Normal, template!(List: "value"), ErrorFollowing,
-        "the `#[rustc_layout_scalar_valid_range_start]` attribute is just used to enable \
-        niche optimizations in libcore and libstd and will never be stable",
-    ),
-    rustc_attr!(
-        rustc_layout_scalar_valid_range_end, Normal, template!(List: "value"), ErrorFollowing,
-        "the `#[rustc_layout_scalar_valid_range_end]` attribute is just used to enable \
-        niche optimizations in libcore and libstd and will never be stable",
-    ),
     rustc_attr!(
         rustc_nonnull_optimization_guaranteed, Normal, template!(Word), WarnFollowing,
         "the `#[rustc_nonnull_optimization_guaranteed]` attribute is just used to enable \

Diff for: compiler/rustc_hir/src/lang_items.rs

@@ -193,6 +193,8 @@ language_item_table! {
     Index,                   sym::index,               index_trait,                Target::Trait,          GenericRequirement::Exact(1);
     IndexMut,                sym::index_mut,           index_mut_trait,            Target::Trait,          GenericRequirement::Exact(1);
 
+    Ranged,                  sym::ranged     ,         ranged_type,                Target::Struct,         GenericRequirement::None;
+
     UnsafeCell,              sym::unsafe_cell,         unsafe_cell_type,           Target::Struct,         GenericRequirement::None;
     VaList,                  sym::va_list,             va_list,                    Target::Struct,         GenericRequirement::None;
 

Diff for: compiler/rustc_lint/src/builtin.rs

@@ -52,7 +52,7 @@ use rustc_span::edition::Edition;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{BytePos, InnerSpan, Span};
-use rustc_target::abi::VariantIdx;
+use rustc_target::abi::{Abi, VariantIdx};
 use rustc_trait_selection::traits::{self, misc::can_type_implement_copy};
 
 use crate::nonstandard_style::{method_context, MethodLateContext};
@@ -2524,32 +2524,27 @@ impl<'tcx> LateLintPass<'tcx> for InvalidValue {
                 }
                 // Recurse and checks for some compound types. (but not unions)
                 Adt(adt_def, substs) if !adt_def.is_union() => {
-                    // First check if this ADT has a layout attribute (like `NonNull` and friends).
-                    use std::ops::Bound;
-                    match cx.tcx.layout_scalar_valid_range(adt_def.did()) {
-                        // We exploit here that `layout_scalar_valid_range` will never
-                        // return `Bound::Excluded`.  (And we have tests checking that we
-                        // handle the attribute correctly.)
-                        // We don't add a span since users cannot declare such types anyway.
-                        (Bound::Included(lo), Bound::Included(hi)) if 0 < lo && lo < hi => {
-                            return Some((format!("`{}` must be non-null", ty), None));
-                        }
-                        (Bound::Included(lo), Bound::Unbounded) if 0 < lo => {
-                            return Some((format!("`{}` must be non-null", ty), None));
-                        }
-                        (Bound::Included(_), _) | (_, Bound::Included(_))
-                            if init == InitKind::Uninit =>
-                        {
-                            return Some((
-                                format!(
-                                    "`{}` must be initialized inside its custom valid range",
-                                    ty,
-                                ),
-                                None,
-                            ));
+                    // First check if this ADT has a constrained layout (like `NonNull` and friends).
+                    if let Ok(layout) = cx.tcx.layout_of(cx.param_env.and(ty)) {
+                        match &layout.abi {
+                            Abi::Scalar(scalar) | Abi::ScalarPair(scalar, _) => {
+                                let range = scalar.valid_range(cx);
+                                if !range.contains(0) {
+                                    return Some((format!("`{}` must be non-null", ty), None));
+                                } else if init == InitKind::Uninit && !scalar.is_always_valid(cx) {
+                                    return Some((
+                                        format!(
+                                            "`{}` must be initialized inside its custom valid range",
+                                            ty,
+                                        ),
+                                        None,
+                                    ));
+                                }
+                            }
+                            _ => {}
                         }
-                        _ => {}
                     }
+
                     // Handle structs.
                     if adt_def.is_struct() {
                         return variant_find_init_error(

Diff for: compiler/rustc_macros/src/lib.rs

@@ -47,7 +47,7 @@ pub fn symbols(input: TokenStream) -> TokenStream {
 /// `u32::MAX`. You can also customize things like the `Debug` impl,
 /// what traits are derived, and so forth via the macro.
 #[proc_macro]
-#[allow_internal_unstable(step_trait, rustc_attrs, trusted_step)]
+#[allow_internal_unstable(step_trait, rustc_attrs, ranged_int, trusted_step)]
 pub fn newtype_index(input: TokenStream) -> TokenStream {
     newtype::newtype(input)
 }

Diff for: compiler/rustc_macros/src/newtype.rs

@@ -138,7 +138,7 @@ impl Parse for Newtype {
                 }
                 impl<E: ::rustc_serialize::Encoder> ::rustc_serialize::Encodable<E> for #name {
                     fn encode(&self, e: &mut E) {
-                        e.emit_u32(self.private);
+                        e.emit_u32(self.as_u32());
                     }
                 }
             }
@@ -196,10 +196,10 @@ impl Parse for Newtype {
         Ok(Self(quote! {
             #(#attrs)*
             #[derive(Clone, Copy, PartialEq, Eq, Hash, #(#derive_paths),*)]
-            #[rustc_layout_scalar_valid_range_end(#max)]
+            #[cfg_attr(bootstrap, rustc_layout_scalar_valid_range_end(#max))]
             #[rustc_pass_by_value]
             #vis struct #name {
-                private: u32,
+                private: std::num::Ranged<u32, {0..=#max}>,
             }
 
             #(#consts)*
@@ -249,7 +249,7 @@ impl Parse for Newtype {
                 /// Prefer using `from_u32`.
                 #[inline]
                 #vis const unsafe fn from_u32_unchecked(value: u32) -> Self {
-                    Self { private: value }
+                    Self { private: std::num::Ranged::new_unchecked(value) }
                 }
 
                 /// Extracts the value of this index as a `usize`.
@@ -261,7 +261,7 @@ impl Parse for Newtype {
                 /// Extracts the value of this index as a `u32`.
                 #[inline]
                 #vis const fn as_u32(self) -> u32 {
-                    self.private
+                    self.private.get()
                 }
 
                 /// Extracts the value of this index as a `usize`.

Diff for: compiler/rustc_middle/src/mir/query.rs

@@ -30,14 +30,11 @@ pub enum UnsafetyViolationKind {
 pub enum UnsafetyViolationDetails {
     CallToUnsafeFunction,
     UseOfInlineAssembly,
-    InitializingTypeWith,
     CastOfPointerToInt,
     UseOfMutableStatic,
     UseOfExternStatic,
     DerefOfRawPointer,
     AccessToUnionField,
-    MutationOfLayoutConstrainedField,
-    BorrowOfLayoutConstrainedField,
     CallToFunctionWith,
 }
 
@@ -54,11 +51,6 @@ impl UnsafetyViolationDetails {
                 "use of inline assembly",
                 "inline assembly is entirely unchecked and can cause undefined behavior",
             ),
-            InitializingTypeWith => (
-                "initializing type with `rustc_layout_scalar_valid_range` attr",
-                "initializing a layout restricted type's field with a value outside the valid \
-                 range is undefined behavior",
-            ),
             CastOfPointerToInt => {
                 ("cast of pointer to int", "casting pointers to integers in constants")
             }
@@ -82,15 +74,6 @@ impl UnsafetyViolationDetails {
                 "the field may not be properly initialized: using uninitialized data will cause \
                  undefined behavior",
             ),
-            MutationOfLayoutConstrainedField => (
-                "mutation of layout constrained field",
-                "mutating layout constrained fields cannot statically be checked for valid values",
-            ),
-            BorrowOfLayoutConstrainedField => (
-                "borrow of layout constrained field with interior mutability",
-                "references to fields of layout constrained fields lose the constraints. Coupled \
-                 with interior mutability, the field can be changed to invalid values",
-            ),
             CallToFunctionWith => (
                 "call to function with `#[target_feature]`",
                 "can only be called if the required target features are available",

Diff for: compiler/rustc_middle/src/ty/adt.rs

@@ -51,6 +51,8 @@ bitflags! {
         const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8;
         /// Indicates whether the type is `UnsafeCell`.
         const IS_UNSAFE_CELL              = 1 << 9;
+        /// Indicates whether the type is `Ranged`.
+        const IS_RANGED              = 1 << 10;
     }
 }
 
@@ -249,6 +251,9 @@ impl AdtDefData {
         if Some(did) == tcx.lang_items().unsafe_cell_type() {
             flags |= AdtFlags::IS_UNSAFE_CELL;
         }
+        if Some(did) == tcx.lang_items().ranged_type() {
+            flags |= AdtFlags::IS_RANGED;
+        }
 
         AdtDefData { did, variants, flags, repr }
     }
@@ -341,6 +346,12 @@ impl<'tcx> AdtDef<'tcx> {
         self.flags().contains(AdtFlags::IS_UNSAFE_CELL)
     }
 
+    /// Returns `true` if this is `Ranged<T, RANGE>`.
+    #[inline]
+    pub fn is_ranged(self) -> bool {
+        self.flags().contains(AdtFlags::IS_RANGED)
+    }
+
     /// Returns `true` if this is `ManuallyDrop<T>`.
     #[inline]
     pub fn is_manually_drop(self) -> bool {