Auto merge of #119110 - matthiaskrgr:rollup-vr6ha8x, r=matthiaskrgr

Rollup of 4 pull requests

Successful merges:

 - #119087 (Update books)
 - #119091 (Use alias-eq in structural normalization)
 - #119098 (Adjust the ignore-compare-mode-next-solver for hangs)
 - #119100 (Add the function body span to StableMIR)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -1498,7 +1498,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let ty = self.resolve_vars_with_obligations(ty);
 
         if self.next_trait_solver()
-            && let ty::Alias(ty::Projection | ty::Inherent | ty::Weak, _) = ty.kind()
+            && let ty::Alias(..) = ty.kind()
         {
             match self
                 .at(&self.misc(sp), self.param_env)

compiler/rustc_smir/src/rustc_smir/convert/mir.rs

@@ -37,6 +37,7 @@ impl<'tcx> Stable<'tcx> for mir::Body<'tcx> {
             self.arg_count,
             self.var_debug_info.iter().map(|info| info.stable(tables)).collect(),
             self.spread_arg.stable(tables),
+            self.span.stable(tables),
         )
     }
 }

compiler/rustc_trait_selection/src/traits/structural_normalize.rs

@@ -3,7 +3,7 @@ use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKi
 use rustc_infer::traits::{FulfillmentError, TraitEngine};
 use rustc_middle::ty::{self, Ty};
 
-use crate::traits::{query::evaluate_obligation::InferCtxtExt, NormalizeExt, Obligation};
+use crate::traits::{NormalizeExt, Obligation};
 
 pub trait StructurallyNormalizeExt<'tcx> {
     fn structurally_normalize(
@@ -16,42 +16,43 @@ pub trait StructurallyNormalizeExt<'tcx> {
 impl<'tcx> StructurallyNormalizeExt<'tcx> for At<'_, 'tcx> {
     fn structurally_normalize(
         &self,
-        mut ty: Ty<'tcx>,
+        ty: Ty<'tcx>,
         fulfill_cx: &mut dyn TraitEngine<'tcx>,
     ) -> Result<Ty<'tcx>, Vec<FulfillmentError<'tcx>>> {
         assert!(!ty.is_ty_var(), "should have resolved vars before calling");
 
         if self.infcx.next_trait_solver() {
-            // FIXME(-Znext-solver): correctly handle
-            // overflow here.
-            for _ in 0..256 {
-                let ty::Alias(ty::Projection | ty::Inherent | ty::Weak, alias) = *ty.kind() else {
-                    break;
-                };
-
-                let new_infer_ty = self.infcx.next_ty_var(TypeVariableOrigin {
-                    kind: TypeVariableOriginKind::NormalizeProjectionType,
-                    span: self.cause.span,
-                });
-                let obligation = Obligation::new(
-                    self.infcx.tcx,
-                    self.cause.clone(),
-                    self.param_env,
-                    ty::NormalizesTo { alias, term: new_infer_ty.into() },
-                );
-                if self.infcx.predicate_may_hold(&obligation) {
-                    fulfill_cx.register_predicate_obligation(self.infcx, obligation);
-                    let errors = fulfill_cx.select_where_possible(self.infcx);
-                    if !errors.is_empty() {
-                        return Err(errors);
-                    }
-                    ty = self.infcx.resolve_vars_if_possible(new_infer_ty);
-                } else {
-                    break;
-                }
+            // FIXME(-Znext-solver): Should we resolve opaques here?
+            let ty::Alias(ty::Projection | ty::Inherent | ty::Weak, _) = *ty.kind() else {
+                return Ok(ty);
+            };
+
+            let new_infer_ty = self.infcx.next_ty_var(TypeVariableOrigin {
+                kind: TypeVariableOriginKind::NormalizeProjectionType,
+                span: self.cause.span,
+            });
+
+            // We simply emit an `alias-eq` goal here, since that will take care of
+            // normalizing the LHS of the projection until it is a rigid projection
+            // (or a not-yet-defined opaque in scope).
+            let obligation = Obligation::new(
+                self.infcx.tcx,
+                self.cause.clone(),
+                self.param_env,
+                ty::PredicateKind::AliasRelate(
+                    ty.into(),
+                    new_infer_ty.into(),
+                    ty::AliasRelationDirection::Equate,
+                ),
+            );
+
+            fulfill_cx.register_predicate_obligation(self.infcx, obligation);
+            let errors = fulfill_cx.select_where_possible(self.infcx);
+            if !errors.is_empty() {
+                return Err(errors);
             }
 
-            Ok(ty)
+            Ok(self.infcx.resolve_vars_if_possible(new_infer_ty))
         } else {
             Ok(self.normalize(ty).into_value_registering_obligations(self.infcx, fulfill_cx))
         }

compiler/stable_mir/src/mir/body.rs

@@ -27,6 +27,9 @@ pub struct Body {
     ///
     /// This is used for the "rust-call" ABI such as closures.
     pub(super) spread_arg: Option<Local>,
+
+    /// The span that covers the entire function body.
+    pub span: Span,
 }
 
 pub type BasicBlockIdx = usize;
@@ -42,14 +45,15 @@ impl Body {
         arg_count: usize,
         var_debug_info: Vec<VarDebugInfo>,
         spread_arg: Option<Local>,
+        span: Span,
     ) -> Self {
         // If locals doesn't contain enough entries, it can lead to panics in
         // `ret_local`, `arg_locals`, and `inner_locals`.
         assert!(
             locals.len() > arg_count,
             "A Body must contain at least a local for the return value and each of the function's arguments"
         );
-        Self { blocks, locals, arg_count, var_debug_info, spread_arg }
+        Self { blocks, locals, arg_count, var_debug_info, spread_arg, span }
     }
 
     /// Return local that holds this function's return value.

compiler/stable_mir/src/mir/visit.rs

@@ -133,7 +133,7 @@ pub trait MirVisitor {
     }
 
     fn super_body(&mut self, body: &Body) {
-        let Body { blocks, locals: _, arg_count, var_debug_info, spread_arg: _ } = body;
+        let Body { blocks, locals: _, arg_count, var_debug_info, spread_arg: _, span } = body;
 
         for bb in blocks {
             self.visit_basic_block(bb);
@@ -153,6 +153,8 @@ pub trait MirVisitor {
         for info in var_debug_info.iter() {
             self.visit_var_debug_info(info);
         }
+
+        self.visit_span(span)
     }
 
     fn super_basic_block(&mut self, bb: &BasicBlock) {