mGCA: Validate const literal against expected type

Co-authored-by: Boxy <rust@boxyuwu.dev>

Author: reddevilmidzy

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -745,6 +745,15 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                                 // Avoid ICE #86756 when type error recovery goes awry.
                                 return Ty::new_error(tcx, prev).into();
                             }
+                            if preceding_args.is_empty()
+                                && tcx.type_of(param.def_id).skip_binder().has_param()
+                            {
+                                let guar = self.lowerer.dcx().span_delayed_bug(
+                                    self.span,
+                                    "default type has params but no args",
+                                );
+                                return Ty::new_error(tcx, guar).into();
+                            }
                             tcx.at(self.span)
                                 .type_of(param.def_id)
                                 .instantiate(tcx, preceding_args)
@@ -2798,8 +2807,27 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         span: Span,
     ) -> Const<'tcx> {
         let tcx = self.tcx();
+        if let LitKind::Err(guar) = *kind {
+            return ty::Const::new_error(tcx, guar);
+        }
         let input = LitToConstInput { lit: *kind, ty, neg };
-        tcx.at(span).lit_to_const(input)
+        match tcx.at(span).lit_to_const(input) {
+            Some(value) => {
+                if value.ty == ty {
+                    ty::Const::new_value(tcx, value.valtree, value.ty)
+                } else {
+                    let e = tcx.dcx().span_err(
+                        span,
+                        format!("mismatched types: expected `{}`, found `{}`", ty, value.ty),
+                    );
+                    ty::Const::new_error(tcx, e)
+                }
+            }
+            None => {
+                let e = tcx.dcx().span_err(span, "type annotations needed for the literal");
+                ty::Const::new_error(tcx, e)
+            }
+        }
     }
 
     #[instrument(skip(self), level = "debug")]
@@ -2828,11 +2856,15 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             _ => None,
         };
 
-        lit_input
-            // Allow the `ty` to be an alias type, though we cannot handle it here, we just go through
-            // the more expensive anon const code path.
-            .filter(|l| !l.ty.has_aliases())
-            .map(|l| tcx.at(expr.span).lit_to_const(l))
+        lit_input.and_then(|l| {
+            tcx.at(expr.span).lit_to_const(l).and_then(|value| {
+                if value.ty == ty {
+                    Some(ty::Const::new_value(tcx, value.valtree, value.ty))
+                } else {
+                    None
+                }
+            })
+        })
     }
 
     fn require_type_const_attribute(

compiler/rustc_middle/src/queries.rs

@@ -1412,7 +1412,7 @@ rustc_queries! {
     // FIXME get rid of this with valtrees
     query lit_to_const(
         key: LitToConstInput<'tcx>
-    ) -> ty::Const<'tcx> {
+    ) -> Option<ty::Value<'tcx>> {
         desc { "converting literal to const" }
     }
 

compiler/rustc_middle/src/query/erase.rs

@@ -256,6 +256,10 @@ impl Erasable for Option<ty::EarlyBinder<'_, Ty<'_>>> {
     type Storage = [u8; size_of::<Option<ty::EarlyBinder<'static, Ty<'static>>>>()];
 }
 
+impl Erasable for Option<ty::Value<'_>> {
+    type Storage = [u8; size_of::<Option<ty::Value<'static>>>()];
+}
+
 impl Erasable for rustc_hir::MaybeOwner<'_> {
     type Storage = [u8; size_of::<rustc_hir::MaybeOwner<'static>>()];
 }

compiler/rustc_mir_build/src/thir/constant.rs

@@ -1,21 +1,20 @@
 use rustc_abi::Size;
 use rustc_ast::{self as ast, UintTy};
 use rustc_hir::LangItem;
-use rustc_middle::bug;
 use rustc_middle::mir::interpret::LitToConstInput;
-use rustc_middle::ty::{self, ScalarInt, TyCtxt, TypeVisitableExt as _};
+use rustc_middle::ty::{self, ScalarInt, Ty, TyCtxt, TypeVisitableExt as _};
 use tracing::trace;
 
 use crate::builder::parse_float_into_scalar;
 
 pub(crate) fn lit_to_const<'tcx>(
     tcx: TyCtxt<'tcx>,
     lit_input: LitToConstInput<'tcx>,
-) -> ty::Const<'tcx> {
-    let LitToConstInput { lit, ty, neg } = lit_input;
+) -> Option<ty::Value<'tcx>> {
+    let LitToConstInput { lit, ty: expected_ty, neg } = lit_input;
 
-    if let Err(guar) = ty.error_reported() {
-        return ty::Const::new_error(tcx, guar);
+    if expected_ty.error_reported().is_err() {
+        return None;
     }
 
     let trunc = |n, width: ty::UintTy| {
@@ -29,66 +28,76 @@ pub(crate) fn lit_to_const<'tcx>(
         trace!("trunc result: {}", result);
 
         ScalarInt::try_from_uint(result, width)
-            .unwrap_or_else(|| bug!("expected to create ScalarInt from uint {:?}", result))
     };
 
-    let valtree = match (lit, ty.kind()) {
-        (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
+    let (valtree, valtree_ty) = match (lit, expected_ty.kind()) {
+        (ast::LitKind::Str(s, _), _) => {
             let str_bytes = s.as_str().as_bytes();
-            ty::ValTree::from_raw_bytes(tcx, str_bytes)
-        }
-        (ast::LitKind::Str(s, _), ty::Str) if tcx.features().deref_patterns() => {
-            // String literal patterns may have type `str` if `deref_patterns` is enabled, in order
-            // to allow `deref!("..."): String`.
-            let str_bytes = s.as_str().as_bytes();
-            ty::ValTree::from_raw_bytes(tcx, str_bytes)
+            let valtree_ty = Ty::new_imm_ref(tcx, tcx.lifetimes.re_static, tcx.types.str_);
+            (ty::ValTree::from_raw_bytes(tcx, str_bytes), valtree_ty)
         }
         (ast::LitKind::ByteStr(byte_sym, _), ty::Ref(_, inner_ty, _))
             if let ty::Slice(ty) | ty::Array(ty, _) = inner_ty.kind()
                 && let ty::Uint(UintTy::U8) = ty.kind() =>
         {
-            ty::ValTree::from_raw_bytes(tcx, byte_sym.as_byte_str())
+            (ty::ValTree::from_raw_bytes(tcx, byte_sym.as_byte_str()), expected_ty)
         }
         (ast::LitKind::ByteStr(byte_sym, _), ty::Slice(inner_ty) | ty::Array(inner_ty, _))
             if tcx.features().deref_patterns()
                 && let ty::Uint(UintTy::U8) = inner_ty.kind() =>
         {
             // Byte string literal patterns may have type `[u8]` or `[u8; N]` if `deref_patterns` is
             // enabled, in order to allow, e.g., `deref!(b"..."): Vec<u8>`.
-            ty::ValTree::from_raw_bytes(tcx, byte_sym.as_byte_str())
+            (ty::ValTree::from_raw_bytes(tcx, byte_sym.as_byte_str()), expected_ty)
         }
-        (ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
-            ty::ValTree::from_scalar_int(tcx, n.into())
+        (ast::LitKind::ByteStr(byte_sym, _), _) => {
+            let valtree = ty::ValTree::from_raw_bytes(tcx, byte_sym.as_byte_str());
+            let valtree_ty = Ty::new_array(tcx, tcx.types.u8, byte_sym.as_byte_str().len() as u64);
+            (valtree, valtree_ty)
         }
-        (ast::LitKind::CStr(byte_sym, _), ty::Ref(_, inner_ty, _)) if matches!(inner_ty.kind(), ty::Adt(def, _) if tcx.is_lang_item(def.did(), LangItem::CStr)) =>
+        (ast::LitKind::Byte(n), _) => (ty::ValTree::from_scalar_int(tcx, n.into()), tcx.types.u8),
+        (ast::LitKind::CStr(byte_sym, _), _)
+            if let Some(cstr_def_id) = tcx.lang_items().get(LangItem::CStr) =>
         {
             // A CStr is a newtype around a byte slice, so we create the inner slice here.
             // We need a branch for each "level" of the data structure.
+            let cstr_ty = tcx.type_of(cstr_def_id).skip_binder();
             let bytes = ty::ValTree::from_raw_bytes(tcx, byte_sym.as_byte_str());
-            ty::ValTree::from_branches(tcx, [ty::Const::new_value(tcx, bytes, *inner_ty)])
+            let valtree =
+                ty::ValTree::from_branches(tcx, [ty::Const::new_value(tcx, bytes, cstr_ty)]);
+            let valtree_ty = Ty::new_imm_ref(tcx, tcx.lifetimes.re_static, cstr_ty);
+            (valtree, valtree_ty)
+        }
+        (ast::LitKind::Int(n, ast::LitIntType::Unsigned(ui)), _) if !neg => {
+            let scalar_int = trunc(n.get(), ui)?;
+            (ty::ValTree::from_scalar_int(tcx, scalar_int), Ty::new_uint(tcx, ui))
+        }
+        (ast::LitKind::Int(_, ast::LitIntType::Unsigned(_)), _) if neg => return None,
+        (ast::LitKind::Int(n, ast::LitIntType::Signed(i)), _) => {
+            let scalar_int =
+                trunc(if neg { u128::wrapping_neg(n.get()) } else { n.get() }, i.to_unsigned())?;
+            (ty::ValTree::from_scalar_int(tcx, scalar_int), Ty::new_int(tcx, i))
         }
-        (ast::LitKind::Int(n, _), ty::Uint(ui)) if !neg => {
-            let scalar_int = trunc(n.get(), *ui);
-            ty::ValTree::from_scalar_int(tcx, scalar_int)
+        (ast::LitKind::Int(n, ast::LitIntType::Unsuffixed), ty::Uint(ui)) if !neg => {
+            let scalar_int = trunc(n.get(), *ui)?;
+            (ty::ValTree::from_scalar_int(tcx, scalar_int), Ty::new_uint(tcx, *ui))
         }
-        (ast::LitKind::Int(n, _), ty::Int(i)) => {
+        (ast::LitKind::Int(n, ast::LitIntType::Unsuffixed), ty::Int(i)) => {
             // Unsigned "negation" has the same bitwise effect as signed negation,
             // which gets the result we want without additional casts.
             let scalar_int =
-                trunc(if neg { u128::wrapping_neg(n.get()) } else { n.get() }, i.to_unsigned());
-            ty::ValTree::from_scalar_int(tcx, scalar_int)
+                trunc(if neg { u128::wrapping_neg(n.get()) } else { n.get() }, i.to_unsigned())?;
+            (ty::ValTree::from_scalar_int(tcx, scalar_int), Ty::new_int(tcx, *i))
         }
-        (ast::LitKind::Bool(b), ty::Bool) => ty::ValTree::from_scalar_int(tcx, b.into()),
+        (ast::LitKind::Bool(b), _) => (ty::ValTree::from_scalar_int(tcx, b.into()), tcx.types.bool),
         (ast::LitKind::Float(n, _), ty::Float(fty)) => {
-            let bits = parse_float_into_scalar(n, *fty, neg).unwrap_or_else(|| {
-                tcx.dcx().bug(format!("couldn't parse float literal: {:?}", lit_input.lit))
-            });
-            ty::ValTree::from_scalar_int(tcx, bits)
+            let bits = parse_float_into_scalar(n, *fty, neg)?;
+            (ty::ValTree::from_scalar_int(tcx, bits), Ty::new_float(tcx, *fty))
         }
-        (ast::LitKind::Char(c), ty::Char) => ty::ValTree::from_scalar_int(tcx, c.into()),
-        (ast::LitKind::Err(guar), _) => return ty::Const::new_error(tcx, guar),
-        _ => return ty::Const::new_misc_error(tcx),
+        (ast::LitKind::Char(c), _) => (ty::ValTree::from_scalar_int(tcx, c.into()), tcx.types.char),
+        (ast::LitKind::Err(_), _) => return None,
+        _ => return None,
     };
 
-    ty::Const::new_value(tcx, valtree, ty)
+    Some(ty::Value { ty: valtree_ty, valtree })
 }

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -8,11 +8,12 @@ use std::cmp::Ordering;
 use std::sync::Arc;
 
 use rustc_abi::{FieldIdx, Integer};
+use rustc_ast::LitKind;
 use rustc_data_structures::assert_matches;
 use rustc_errors::codes::*;
 use rustc_hir::def::{CtorOf, DefKind, Res};
 use rustc_hir::pat_util::EnumerateAndAdjustIterator;
-use rustc_hir::{self as hir, RangeEnd};
+use rustc_hir::{self as hir, LangItem, RangeEnd};
 use rustc_index::Idx;
 use rustc_middle::mir::interpret::LitToConstInput;
 use rustc_middle::thir::{
@@ -197,8 +198,6 @@ impl<'tcx> PatCtxt<'tcx> {
         expr: Option<&'tcx hir::PatExpr<'tcx>>,
         ty: Ty<'tcx>,
     ) -> Result<(), ErrorGuaranteed> {
-        use rustc_ast::ast::LitKind;
-
         let Some(expr) = expr else {
             return Ok(());
         };
@@ -696,9 +695,61 @@ impl<'tcx> PatCtxt<'tcx> {
 
                 let pat_ty = self.typeck_results.node_type(pat.hir_id);
                 let lit_input = LitToConstInput { lit: lit.node, ty: pat_ty, neg: *negated };
-                let constant = self.tcx.at(expr.span).lit_to_const(lit_input);
+                let error_const = || {
+                    if let Some(guar) = self.typeck_results.tainted_by_errors {
+                        ty::Const::new_error(self.tcx, guar)
+                    } else {
+                        ty::Const::new_error_with_message(
+                            self.tcx,
+                            expr.span,
+                            "literal does not match expected type",
+                        )
+                    }
+                };
+                let constant = if self.const_lit_matches_ty(&lit.node, pat_ty, *negated) {
+                    match self.tcx.at(expr.span).lit_to_const(lit_input) {
+                        Some(value) => {
+                            let const_ty = if value.ty == pat_ty { value.ty } else { pat_ty };
+                            ty::Const::new_value(self.tcx, value.valtree, const_ty)
+                        }
+                        None => error_const(),
+                    }
+                } else {
+                    error_const()
+                };
                 self.const_to_pat(constant, pat_ty, expr.hir_id, lit.span)
             }
         }
     }
+
+    fn const_lit_matches_ty(&self, kind: &LitKind, ty: Ty<'tcx>, neg: bool) -> bool {
+        let tcx = self.tcx;
+        match (*kind, ty.kind()) {
+            (LitKind::Str(..), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => true,
+            (LitKind::Str(..), ty::Str) if tcx.features().deref_patterns() => true,
+            (LitKind::ByteStr(..), ty::Ref(_, inner_ty, _))
+                if let ty::Slice(ty) | ty::Array(ty, _) = inner_ty.kind()
+                    && matches!(ty.kind(), ty::Uint(ty::UintTy::U8)) =>
+            {
+                true
+            }
+            (LitKind::ByteStr(..), ty::Slice(inner_ty) | ty::Array(inner_ty, _))
+                if tcx.features().deref_patterns()
+                    && matches!(inner_ty.kind(), ty::Uint(ty::UintTy::U8)) =>
+            {
+                true
+            }
+            (LitKind::Byte(..), ty::Uint(ty::UintTy::U8)) => true,
+            (LitKind::CStr(..), ty::Ref(_, inner_ty, _)) if matches!(inner_ty.kind(), ty::Adt(def, _) if tcx.is_lang_item(def.did(), LangItem::CStr)) => {
+                true
+            }
+            (LitKind::Int(..), ty::Uint(_)) if !neg => true,
+            (LitKind::Int(..), ty::Int(_)) => true,
+            (LitKind::Bool(..), ty::Bool) => true,
+            (LitKind::Float(..), ty::Float(_)) => true,
+            (LitKind::Char(..), ty::Char) => true,
+            (LitKind::Err(..), _) => true,
+            _ => false,
+        }
+    }
 }

compiler/rustc_trait_selection/src/traits/wf.rs

@@ -1006,8 +1006,20 @@ impl<'a, 'tcx> TypeVisitor<TyCtxt<'tcx>> for WfPredicates<'a, 'tcx> {
                         self.add_wf_preds_for_inherent_projection(uv.into());
                         return; // Subtree is handled by above function
                     } else {
-                        let obligations = self.nominal_obligations(uv.def, uv.args);
-                        self.out.extend(obligations);
+                        if uv.args.is_empty()
+                            && tcx
+                                .predicates_of(uv.def)
+                                .predicates
+                                .iter()
+                                .any(|(pred, _)| pred.has_param())
+                        {
+                            tcx.dcx().delayed_bug(
+                                "unevaluated const has predicates with params but no args",
+                            );
+                        } else {
+                            let obligations = self.nominal_obligations(uv.def, uv.args);
+                            self.out.extend(obligations);
+                        }
                     }
                 }
             }

compiler/rustc_ty_utils/src/consts.rs

@@ -59,7 +59,10 @@ fn recurse_build<'tcx>(
         }
         &ExprKind::Literal { lit, neg } => {
             let sp = node.span;
-            tcx.at(sp).lit_to_const(LitToConstInput { lit: lit.node, ty: node.ty, neg })
+            match tcx.at(sp).lit_to_const(LitToConstInput { lit: lit.node, ty: node.ty, neg }) {
+                Some(value) => ty::Const::new_value(tcx, value.valtree, value.ty),
+                None => ty::Const::new_misc_error(tcx),
+            }
         }
         &ExprKind::NonHirLiteral { lit, user_ty: _ } => {
             let val = ty::ValTree::from_scalar_int(tcx, lit);

tests/ui/const-generics/adt_const_params/byte-string-u8-validation.rs

@@ -8,7 +8,7 @@
 struct ConstBytes<const T: &'static [*mut u8; 3]>
 //~^ ERROR rustc_dump_predicates
 //~| NOTE Binder { value: ConstArgHasType(T/#0, &'static [*mut u8; 3_usize]), bound_vars: [] }
-//~| NOTE Binder { value: TraitPredicate(<ConstBytes<{const error}> as std::marker::Sized>, polarity:Positive), bound_vars: [] }
+//~| NOTE Binder { value: TraitPredicate(<ConstBytes<b"AAA"> as std::marker::Sized>, polarity:Positive), bound_vars: [] }
 where
     ConstBytes<b"AAA">: Sized;
 //~^ ERROR mismatched types

tests/ui/const-generics/adt_const_params/byte-string-u8-validation.stderr

@@ -1,12 +1,3 @@
-error: rustc_dump_predicates
-  --> $DIR/byte-string-u8-validation.rs:8:1
-   |
-LL | struct ConstBytes<const T: &'static [*mut u8; 3]>
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: Binder { value: ConstArgHasType(T/#0, &'static [*mut u8; 3_usize]), bound_vars: [] }
-   = note: Binder { value: TraitPredicate(<ConstBytes<{const error}> as std::marker::Sized>, polarity:Positive), bound_vars: [] }
-
 error[E0308]: mismatched types
   --> $DIR/byte-string-u8-validation.rs:13:16
    |
@@ -16,6 +7,15 @@ LL |     ConstBytes<b"AAA">: Sized;
    = note: expected reference `&'static [*mut u8; 3]`
               found reference `&'static [u8; 3]`
 
+error: rustc_dump_predicates
+  --> $DIR/byte-string-u8-validation.rs:8:1
+   |
+LL | struct ConstBytes<const T: &'static [*mut u8; 3]>
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: Binder { value: ConstArgHasType(T/#0, &'static [*mut u8; 3_usize]), bound_vars: [] }
+   = note: Binder { value: TraitPredicate(<ConstBytes<b"AAA"> as std::marker::Sized>, polarity:Positive), bound_vars: [] }
+
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0308`.