Auto merge of #111913 - oli-obk:valtrees2, r=lcnr

Only rewrite valtree-constants to patterns and keep other constants opaque

Now that we can reliably fall back to comparing constants with `PartialEq::eq` to the match scrutinee, we can

1. eagerly try to convert constants to valtrees
2. then deeply convert the valtree to a pattern
3. if the to-valtree conversion failed, create an "opaque constant" pattern.

This PR specifically avoids any behavioral changes or major cleanups. What we can now do as follow ups is

* move the two remaining call sites to `destructure_mir_constant` off that query
* make valtree to pattern conversion infallible
    * this needs to be done after careful analysis of the effects. There may be user visible changes from that.

based on #111768

Author: bors

compiler/rustc_const_eval/src/const_eval/mod.rs

@@ -2,10 +2,8 @@
 
 use crate::errors::MaxNumNodesInConstErr;
 use crate::interpret::{
-    intern_const_alloc_recursive, ConstValue, InternKind, InterpCx, InterpResult, MemPlaceMeta,
-    Scalar,
+    intern_const_alloc_recursive, ConstValue, InternKind, InterpCx, InterpResult, Scalar,
 };
-use rustc_hir::Mutability;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::{EvalToValTreeResult, GlobalId};
 use rustc_middle::ty::{self, TyCtxt};
@@ -131,38 +129,3 @@ pub(crate) fn try_destructure_mir_constant<'tcx>(
 
     Ok(mir::DestructuredConstant { variant, fields })
 }
-
-#[instrument(skip(tcx), level = "debug")]
-pub(crate) fn deref_mir_constant<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
-    val: mir::ConstantKind<'tcx>,
-) -> mir::ConstantKind<'tcx> {
-    let ecx = mk_eval_cx(tcx, DUMMY_SP, param_env, false);
-    let op = ecx.eval_mir_constant(&val, None, None).unwrap();
-    let mplace = ecx.deref_operand(&op).unwrap();
-    if let Some(alloc_id) = mplace.ptr.provenance {
-        assert_eq!(
-            tcx.global_alloc(alloc_id).unwrap_memory().0.0.mutability,
-            Mutability::Not,
-            "deref_mir_constant cannot be used with mutable allocations as \
-            that could allow pattern matching to observe mutable statics",
-        );
-    }
-
-    let ty = match mplace.meta {
-        MemPlaceMeta::None => mplace.layout.ty,
-        // In case of unsized types, figure out the real type behind.
-        MemPlaceMeta::Meta(scalar) => match mplace.layout.ty.kind() {
-            ty::Str => bug!("there's no sized equivalent of a `str`"),
-            ty::Slice(elem_ty) => tcx.mk_array(*elem_ty, scalar.to_target_usize(&tcx).unwrap()),
-            _ => bug!(
-                "type {} should not have metadata, but had {:?}",
-                mplace.layout.ty,
-                mplace.meta
-            ),
-        },
-    };
-
-    mir::ConstantKind::Val(op_to_const(&ecx, &mplace.into()), ty)
-}

compiler/rustc_const_eval/src/lib.rs

@@ -56,10 +56,6 @@ pub fn provide(providers: &mut Providers) {
     providers.valtree_to_const_val = |tcx, (ty, valtree)| {
         const_eval::valtree_to_const_value(tcx, ty::ParamEnv::empty().and(ty), valtree)
     };
-    providers.deref_mir_constant = |tcx, param_env_and_value| {
-        let (param_env, value) = param_env_and_value.into_parts();
-        const_eval::deref_mir_constant(tcx, param_env, value)
-    };
     providers.check_validity_requirement = |tcx, (init_kind, param_env_and_ty)| {
         util::check_validity_requirement(tcx, init_kind, param_env_and_ty)
     };

compiler/rustc_metadata/src/rmeta/table.rs

@@ -439,7 +439,7 @@ where
     /// Given the metadata, extract out the value at a particular index (if any).
     #[inline(never)]
     pub(super) fn get<'a, 'tcx, M: Metadata<'a, 'tcx>>(&self, metadata: M, i: I) -> T::Value<'tcx> {
-        debug!("LazyTable::lookup: index={:?} len={:?}", i, self.encoded_size);
+        trace!("LazyTable::lookup: index={:?} len={:?}", i, self.encoded_size);
 
         let start = self.position.get();
         let bytes = &metadata.blob()[start..start + self.encoded_size];

compiler/rustc_middle/src/mir/mod.rs

@@ -3,7 +3,7 @@
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/mir/index.html
 
 use crate::mir::interpret::{
-    AllocRange, ConstAllocation, ConstValue, ErrorHandled, GlobalAlloc, LitToConstInput, Scalar,
+    AllocRange, ConstAllocation, ConstValue, ErrorHandled, GlobalAlloc, Scalar,
 };
 use crate::mir::visit::MirVisitable;
 use crate::ty::codec::{TyDecoder, TyEncoder};
@@ -2461,51 +2461,6 @@ impl<'tcx> ConstantKind<'tcx> {
         Self::Val(val, ty)
     }
 
-    #[instrument(skip(tcx), level = "debug", ret)]
-    pub fn from_inline_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
-        let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
-        let body_id = match tcx.hir().get(hir_id) {
-            hir::Node::AnonConst(ac) => ac.body,
-            _ => span_bug!(
-                tcx.def_span(def_id.to_def_id()),
-                "from_inline_const can only process anonymous constants"
-            ),
-        };
-        let expr = &tcx.hir().body(body_id).value;
-        let ty = tcx.typeck(def_id).node_type(hir_id);
-
-        let lit_input = match expr.kind {
-            hir::ExprKind::Lit(ref lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
-            hir::ExprKind::Unary(hir::UnOp::Neg, ref expr) => match expr.kind {
-                hir::ExprKind::Lit(ref lit) => {
-                    Some(LitToConstInput { lit: &lit.node, ty, neg: true })
-                }
-                _ => None,
-            },
-            _ => None,
-        };
-        if let Some(lit_input) = lit_input {
-            // If an error occurred, ignore that it's a literal and leave reporting the error up to
-            // mir.
-            match tcx.at(expr.span).lit_to_mir_constant(lit_input) {
-                Ok(c) => return c,
-                Err(_) => {}
-            }
-        }
-
-        let typeck_root_def_id = tcx.typeck_root_def_id(def_id.to_def_id());
-        let parent_substs =
-            tcx.erase_regions(InternalSubsts::identity_for_item(tcx, typeck_root_def_id));
-        let substs =
-            ty::InlineConstSubsts::new(tcx, ty::InlineConstSubstsParts { parent_substs, ty })
-                .substs;
-
-        let uneval = UnevaluatedConst { def: def_id.to_def_id(), substs, promoted: None };
-        debug_assert!(!uneval.has_free_regions());
-
-        Self::Unevaluated(uneval, ty)
-    }
-
     /// Literals are converted to `ConstantKindVal`, const generic parameters are eagerly
     /// converted to a constant, everything else becomes `Unevaluated`.
     #[instrument(skip(tcx), level = "debug", ret)]

compiler/rustc_middle/src/query/mod.rs

@@ -1081,14 +1081,6 @@ rustc_queries! {
         desc { "destructuring MIR constant"}
     }
 
-    /// Dereference a constant reference or raw pointer and turn the result into a constant
-    /// again.
-    query deref_mir_constant(
-        key: ty::ParamEnvAnd<'tcx, mir::ConstantKind<'tcx>>
-    ) -> mir::ConstantKind<'tcx> {
-        desc { "dereferencing MIR constant" }
-    }
-
     query const_caller_location(key: (rustc_span::Symbol, u32, u32)) -> ConstValue<'tcx> {
         desc { "getting a &core::panic::Location referring to a span" }
     }
@@ -1100,10 +1092,6 @@ rustc_queries! {
         desc { "converting literal to const" }
     }
 
-    query lit_to_mir_constant(key: LitToConstInput<'tcx>) -> Result<mir::ConstantKind<'tcx>, LitToConstError> {
-        desc { "converting literal to mir constant" }
-    }
-
     query check_match(key: LocalDefId) -> Result<(), rustc_errors::ErrorGuaranteed> {
         desc { |tcx| "match-checking `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { true }

compiler/rustc_mir_build/src/build/expr/as_constant.rs

@@ -106,7 +106,7 @@ pub fn as_constant_inner<'tcx>(
 }
 
 #[instrument(skip(tcx, lit_input))]
-pub(crate) fn lit_to_mir_constant<'tcx>(
+fn lit_to_mir_constant<'tcx>(
     tcx: TyCtxt<'tcx>,
     lit_input: LitToConstInput<'tcx>,
 ) -> Result<ConstantKind<'tcx>, LitToConstError> {

compiler/rustc_mir_build/src/build/mod.rs

@@ -1,4 +1,3 @@
-pub(crate) use crate::build::expr::as_constant::lit_to_mir_constant;
 use crate::build::expr::as_place::PlaceBuilder;
 use crate::build::scope::DropKind;
 use rustc_apfloat::ieee::{Double, Single};

compiler/rustc_mir_build/src/lib.rs

@@ -32,7 +32,6 @@ fluent_messages! { "../messages.ftl" }
 pub fn provide(providers: &mut Providers) {
     providers.check_match = thir::pattern::check_match;
     providers.lit_to_const = thir::constant::lit_to_const;
-    providers.lit_to_mir_constant = build::lit_to_mir_constant;
     providers.mir_built = build::mir_built;
     providers.thir_check_unsafety = check_unsafety::thir_check_unsafety;
     providers.thir_body = thir::cx::thir_body;

compiler/rustc_mir_build/src/thir/constant.rs

@@ -3,6 +3,8 @@ use rustc_middle::mir::interpret::{LitToConstError, LitToConstInput};
 use rustc_middle::ty::{self, ParamEnv, ScalarInt, TyCtxt};
 use rustc_span::DUMMY_SP;
 
+use crate::build::parse_float_into_scalar;
+
 pub(crate) fn lit_to_const<'tcx>(
     tcx: TyCtxt<'tcx>,
     lit_input: LitToConstInput<'tcx>,
@@ -46,12 +48,28 @@ pub(crate) fn lit_to_const<'tcx>(
         (ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
             ty::ValTree::from_scalar_int((*n).into())
         }
+        (ast::LitKind::CStr(data, _), ty::Ref(_, inner_ty, _)) if matches!(inner_ty.kind(), ty::Adt(def, _) if Some(def.did()) == tcx.lang_items().c_str()) =>
+        {
+            let bytes = data as &[u8];
+            ty::ValTree::from_raw_bytes(tcx, bytes)
+        }
         (ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
             let scalar_int =
                 trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?;
             ty::ValTree::from_scalar_int(scalar_int)
         }
         (ast::LitKind::Bool(b), ty::Bool) => ty::ValTree::from_scalar_int((*b).into()),
+        (ast::LitKind::Float(n, _), ty::Float(fty)) => {
+            let bits = parse_float_into_scalar(*n, *fty, neg)
+                .ok_or_else(|| {
+                    LitToConstError::Reported(tcx.sess.delay_span_bug(
+                        DUMMY_SP,
+                        format!("couldn't parse float literal: {:?}", lit_input.lit),
+                    ))
+                })?
+                .assert_int();
+            ty::ValTree::from_scalar_int(bits)
+        }
         (ast::LitKind::Char(c), ty::Char) => ty::ValTree::from_scalar_int((*c).into()),
         (ast::LitKind::Err, _) => {
             return Err(LitToConstError::Reported(

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

@@ -53,11 +53,11 @@ use smallvec::{smallvec, SmallVec};
 use rustc_data_structures::captures::Captures;
 use rustc_hir::{HirId, RangeEnd};
 use rustc_index::Idx;
+use rustc_middle::middle::stability::EvalResult;
 use rustc_middle::mir;
 use rustc_middle::thir::{FieldPat, Pat, PatKind, PatRange};
 use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::{self, Ty, TyCtxt, VariantDef};
-use rustc_middle::{middle::stability::EvalResult, mir::interpret::ConstValue};
 use rustc_session::lint;
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{FieldIdx, Integer, Size, VariantIdx, FIRST_VARIANT};
@@ -140,28 +140,17 @@ impl IntRange {
         value: mir::ConstantKind<'tcx>,
     ) -> Option<IntRange> {
         let ty = value.ty();
-        if let Some((target_size, bias)) = Self::integral_size_and_signed_bias(tcx, ty) {
-            let val = if let mir::ConstantKind::Val(ConstValue::Scalar(scalar), _) = value {
-                // For this specific pattern we can skip a lot of effort and go
-                // straight to the result, after doing a bit of checking. (We
-                // could remove this branch and just fall through, which
-                // is more general but much slower.)
-                scalar.to_bits_or_ptr_internal(target_size).unwrap().left()?
-            } else {
-                if let mir::ConstantKind::Ty(c) = value
-                    && let ty::ConstKind::Value(_) = c.kind()
-                {
-                    bug!("encountered ConstValue in mir::ConstantKind::Ty, whereas this is expected to be in ConstantKind::Val");
-                }
+        let (target_size, bias) = Self::integral_size_and_signed_bias(tcx, ty)?;
+        let val = match value {
+            mir::ConstantKind::Ty(c) if let ty::ConstKind::Value(valtree) = c.kind() => {
+                valtree.unwrap_leaf().to_bits(target_size).ok()
+            },
+            // This is a more general form of the previous case.
+            _ => value.try_eval_bits(tcx, param_env, ty),
+        }?;
 
-                // This is a more general form of the previous case.
-                value.try_eval_bits(tcx, param_env, ty)?
-            };
-            let val = val ^ bias;
-            Some(IntRange { range: val..=val, bias })
-        } else {
-            None
-        }
+        let val = val ^ bias;
+        Some(IntRange { range: val..=val, bias })
     }
 
     #[inline]

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

@@ -18,14 +18,15 @@ use rustc_hir::pat_util::EnumerateAndAdjustIterator;
 use rustc_hir::RangeEnd;
 use rustc_index::Idx;
 use rustc_middle::mir::interpret::{
-    ConstValue, ErrorHandled, LitToConstError, LitToConstInput, Scalar,
+    ConstValue, ErrorHandled, GlobalId, LitToConstError, LitToConstInput, Scalar,
 };
-use rustc_middle::mir::{self, UserTypeProjection};
+use rustc_middle::mir::{self, ConstantKind, UserTypeProjection};
 use rustc_middle::mir::{BorrowKind, Mutability};
 use rustc_middle::thir::{Ascription, BindingMode, FieldPat, LocalVarId, Pat, PatKind, PatRange};
 use rustc_middle::ty::subst::{GenericArg, SubstsRef};
 use rustc_middle::ty::CanonicalUserTypeAnnotation;
-use rustc_middle::ty::{self, AdtDef, ConstKind, Region, Ty, TyCtxt, UserType};
+use rustc_middle::ty::TypeVisitableExt;
+use rustc_middle::ty::{self, AdtDef, Region, Ty, TyCtxt, UserType};
 use rustc_span::{Span, Symbol};
 use rustc_target::abi::FieldIdx;
 
@@ -518,16 +519,24 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             }
         };
 
-        // `mir_const_qualif` must be called with the `DefId` of the item where the const is
-        // defined, not where it is declared. The difference is significant for associated
-        // constants.
-        let mir_structural_match_violation = self.tcx.mir_const_qualif(instance.def_id()).custom_eq;
-        debug!("mir_structural_match_violation({:?}) -> {}", qpath, mir_structural_match_violation);
-
-        match self.tcx.const_eval_instance(param_env_reveal_all, instance, Some(span)) {
-            Ok(literal) => {
-                let const_ = mir::ConstantKind::Val(literal, ty);
-                let pattern = self.const_to_pat(const_, id, span, mir_structural_match_violation);
+        let cid = GlobalId { instance, promoted: None };
+        // Prefer valtrees over opaque constants.
+        let const_value = self
+            .tcx
+            .const_eval_global_id_for_typeck(param_env_reveal_all, cid, Some(span))
+            .map(|val| match val {
+                Some(valtree) => mir::ConstantKind::Ty(self.tcx.mk_const(valtree, ty)),
+                None => mir::ConstantKind::Val(
+                    self.tcx
+                        .const_eval_global_id(param_env_reveal_all, cid, Some(span))
+                        .expect("const_eval_global_id_for_typeck should have already failed"),
+                    ty,
+                ),
+            });
+
+        match const_value {
+            Ok(const_) => {
+                let pattern = self.const_to_pat(const_, id, span, Some(instance.def_id()));
 
                 if !is_associated_const {
                     return pattern;
@@ -577,27 +586,69 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
         id: hir::HirId,
         span: Span,
     ) -> PatKind<'tcx> {
-        let value = mir::ConstantKind::from_inline_const(self.tcx, anon_const.def_id);
-
-        // Evaluate early like we do in `lower_path`.
-        let value = value.eval(self.tcx, self.param_env);
-
-        match value {
-            mir::ConstantKind::Ty(c) => match c.kind() {
-                ConstKind::Param(_) => {
-                    self.tcx.sess.emit_err(ConstParamInPattern { span });
-                    return PatKind::Wild;
-                }
-                ConstKind::Error(_) => {
-                    return PatKind::Wild;
+        let tcx = self.tcx;
+        let def_id = anon_const.def_id;
+        let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
+        let body_id = match tcx.hir().get(hir_id) {
+            hir::Node::AnonConst(ac) => ac.body,
+            _ => span_bug!(
+                tcx.def_span(def_id.to_def_id()),
+                "from_inline_const can only process anonymous constants"
+            ),
+        };
+        let expr = &tcx.hir().body(body_id).value;
+        let ty = tcx.typeck(def_id).node_type(hir_id);
+
+        // Special case inline consts that are just literals. This is solely
+        // a performance optimization, as we could also just go through the regular
+        // const eval path below.
+        // FIXME: investigate the performance impact of removing this.
+        let lit_input = match expr.kind {
+            hir::ExprKind::Lit(ref lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
+            hir::ExprKind::Unary(hir::UnOp::Neg, ref expr) => match expr.kind {
+                hir::ExprKind::Lit(ref lit) => {
+                    Some(LitToConstInput { lit: &lit.node, ty, neg: true })
                 }
-                _ => bug!("Expected ConstKind::Param"),
+                _ => None,
             },
-            mir::ConstantKind::Val(_, _) => self.const_to_pat(value, id, span, false).kind,
-            mir::ConstantKind::Unevaluated(..) => {
-                // If we land here it means the const can't be evaluated because it's `TooGeneric`.
-                self.tcx.sess.emit_err(ConstPatternDependsOnGenericParameter { span });
-                return PatKind::Wild;
+            _ => None,
+        };
+        if let Some(lit_input) = lit_input {
+            match tcx.at(expr.span).lit_to_const(lit_input) {
+                Ok(c) => return self.const_to_pat(ConstantKind::Ty(c), id, span, None).kind,
+                // If an error occurred, ignore that it's a literal
+                // and leave reporting the error up to const eval of
+                // the unevaluated constant below.
+                Err(_) => {}
+            }
+        }
+
+        let typeck_root_def_id = tcx.typeck_root_def_id(def_id.to_def_id());
+        let parent_substs =
+            tcx.erase_regions(ty::InternalSubsts::identity_for_item(tcx, typeck_root_def_id));
+        let substs =
+            ty::InlineConstSubsts::new(tcx, ty::InlineConstSubstsParts { parent_substs, ty })
+                .substs;
+
+        let uneval = mir::UnevaluatedConst { def: def_id.to_def_id(), substs, promoted: None };
+        debug_assert!(!substs.has_free_regions());
+
+        let ct = ty::UnevaluatedConst { def: def_id.to_def_id(), substs: substs };
+        // First try using a valtree in order to destructure the constant into a pattern.
+        if let Ok(Some(valtree)) =
+            self.tcx.const_eval_resolve_for_typeck(self.param_env, ct, Some(span))
+        {
+            self.const_to_pat(ConstantKind::Ty(self.tcx.mk_const(valtree, ty)), id, span, None).kind
+        } else {
+            // If that fails, convert it to an opaque constant pattern.
+            match tcx.const_eval_resolve(self.param_env, uneval, None) {
+                Ok(val) => self.const_to_pat(mir::ConstantKind::Val(val, ty), id, span, None).kind,
+                Err(ErrorHandled::TooGeneric) => {
+                    // If we land here it means the const can't be evaluated because it's `TooGeneric`.
+                    self.tcx.sess.emit_err(ConstPatternDependsOnGenericParameter { span });
+                    PatKind::Wild
+                }
+                Err(ErrorHandled::Reported(_)) => PatKind::Wild,
             }
         }
     }
@@ -626,8 +677,10 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
 
         let lit_input =
             LitToConstInput { lit: &lit.node, ty: self.typeck_results.expr_ty(expr), neg };
-        match self.tcx.at(expr.span).lit_to_mir_constant(lit_input) {
-            Ok(constant) => self.const_to_pat(constant, expr.hir_id, lit.span, false).kind,
+        match self.tcx.at(expr.span).lit_to_const(lit_input) {
+            Ok(constant) => {
+                self.const_to_pat(ConstantKind::Ty(constant), expr.hir_id, lit.span, None).kind
+            }
             Err(LitToConstError::Reported(_)) => PatKind::Wild,
             Err(LitToConstError::TypeError) => bug!("lower_lit: had type error"),
         }
@@ -806,6 +859,9 @@ pub(crate) fn compare_const_vals<'tcx>(
                 mir::ConstantKind::Val(ConstValue::Scalar(Scalar::Int(a)), _a_ty),
                 mir::ConstantKind::Val(ConstValue::Scalar(Scalar::Int(b)), _b_ty),
             ) => return Some(a.cmp(&b)),
+            (mir::ConstantKind::Ty(a), mir::ConstantKind::Ty(b)) => {
+                return Some(a.kind().cmp(&b.kind()));
+            }
             _ => {}
         },
     }

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

@@ -17,8 +17,8 @@ impl<'tcx> Visitor<'tcx> for RequiredConstsVisitor<'_, 'tcx> {
         let literal = constant.literal;
         match literal {
             ConstantKind::Ty(c) => match c.kind() {
-                ConstKind::Param(_) | ConstKind::Error(_) => {}
-                _ => bug!("only ConstKind::Param should be encountered here, got {:#?}", c),
+                ConstKind::Param(_) | ConstKind::Error(_) | ConstKind::Value(_) => {}
+                _ => bug!("only ConstKind::Param/Value should be encountered here, got {:#?}", c),
             },
             ConstantKind::Unevaluated(..) => self.required_consts.push(*constant),
             ConstantKind::Val(..) => {}

compiler/rustc_mir_transform/src/required_consts.rs

@@ -1288,7 +1288,7 @@ pub fn decode_expn_id(
     decode_data: impl FnOnce(ExpnId) -> (ExpnData, ExpnHash),
 ) -> ExpnId {
     if index == 0 {
-        debug!("decode_expn_id: deserialized root");
+        trace!("decode_expn_id: deserialized root");
         return ExpnId::root();
     }
 
@@ -1321,7 +1321,7 @@ pub fn decode_syntax_context<D: Decoder, F: FnOnce(&mut D, u32) -> SyntaxContext
 ) -> SyntaxContext {
     let raw_id: u32 = Decodable::decode(d);
     if raw_id == 0 {
-        debug!("decode_syntax_context: deserialized root");
+        trace!("decode_syntax_context: deserialized root");
         // The root is special
         return SyntaxContext::root();
     }

compiler/rustc_span/src/hygiene.rs

@@ -2,6 +2,8 @@
 
 #![feature(inline_const)]
 
+// Test that we don't generate a memory allocation for the constant
+// and read the fields from that, but instead just create the value pair directly.
 pub fn foo() -> (i32, i32) {
     // CHECK: ret { i32, i32 } { i32 1, i32 2 }
     const { (1, 2) }

tests/codegen/const_scalar_pair.rs

@@ -1,27 +1,20 @@
-// revisions: cfail1
-// should-ice
-// error-pattern: forcing query
-// known-bug: #101518
+// revisions: cpass
 
 #[derive(PartialEq, Eq)]
 struct Id<'a> {
     ns: &'a str,
 }
 fn visit_struct() {
     let id = Id { ns: "random1" };
-    const FLAG: Id<'static> = Id {
-        ns: "needs_to_be_the_same",
-    };
+    const FLAG: Id<'static> = Id { ns: "needs_to_be_the_same" };
     match id {
         FLAG => {}
         _ => {}
     }
 }
 fn visit_struct2() {
     let id = Id { ns: "random2" };
-    const FLAG: Id<'static> = Id {
-        ns: "needs_to_be_the_same",
-    };
+    const FLAG: Id<'static> = Id { ns: "needs_to_be_the_same" };
     match id {
         FLAG => {}
         _ => {}

tests/incremental/issue-101518.rs

@@ -35,7 +35,7 @@ fn foo(_1: Option<String>) -> i32 {
                                          // + literal: Const { ty: for<'a, 'b> fn(&'a str, &'b str) -> bool {<str as PartialEq>::eq}, val: Value(<ZST>) }
                                          // mir::Constant
                                          // + span: $DIR/string.rs:9:14: 9:17
-                                         // + literal: Const { ty: &str, val: Value(Slice(..)) }
+                                         // + literal: Const { ty: &str, val: Value(ValTree::Branch(..)) }
     }
 
     bb3: {

tests/mir-opt/deref-patterns/string.foo.PreCodegen.after.mir

@@ -4,7 +4,7 @@ fn main() {
     let a: &dyn Send = &7u32;
     match a {
         F => panic!(),
-        //~^ ERROR `&dyn Send` cannot be used in patterns
+        //~^ ERROR `dyn Send` cannot be used in patterns
         _ => {}
     }
 }

tests/ui/match/issue-70972-dyn-trait.rs

@@ -1,4 +1,4 @@
-error: `&dyn Send` cannot be used in patterns
+error: `dyn Send` cannot be used in patterns
   --> $DIR/issue-70972-dyn-trait.rs:6:9
    |
 LL |         F => panic!(),

tests/ui/match/issue-70972-dyn-trait.stderr

@@ -3,6 +3,6 @@ const F: &'static dyn PartialEq<u32> = &7u32;
 fn main() {
     let a: &dyn PartialEq<u32> = &7u32;
     match a {
-        F => panic!(), //~ ERROR: `&dyn PartialEq<u32>` cannot be used in patterns
+        F => panic!(), //~ ERROR: `dyn PartialEq<u32>` cannot be used in patterns
     }
 }

tests/ui/pattern/issue-72565.rs

@@ -1,4 +1,4 @@
-error: `&dyn PartialEq<u32>` cannot be used in patterns
+error: `dyn PartialEq<u32>` cannot be used in patterns
   --> $DIR/issue-72565.rs:6:9
    |
 LL |         F => panic!(),