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

Rollup of 4 pull requests

Successful merges:

 - rust-lang#119087 (Update books)
 - rust-lang#119091 (Use alias-eq in structural normalization)
 - rust-lang#119098 (Adjust the ignore-compare-mode-next-solver for hangs)
 - rust-lang#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) {

src/doc/edition-guide

@@ -1,6 +1,7 @@
 // build-fail
 // normalize-stderr-test: "<\{closure@.+`" -> "$$CLOSURE`"
 // normalize-stderr-test: ".nll/" -> "/"
+// ignore-compare-mode-next-solver (hangs)
 
 #![allow(unused)]
 

src/doc/embedded-book

@@ -1,11 +1,11 @@
 error: reached the recursion limit while instantiating `A::matches::$CLOSURE`
-  --> $DIR/issue-22638.rs:56:9
+  --> $DIR/issue-22638.rs:57:9
    |
 LL |         a.matches(f)
    |         ^^^^^^^^^^^^
    |
 note: `A::matches` defined here
-  --> $DIR/issue-22638.rs:15:5
+  --> $DIR/issue-22638.rs:16:5
    |
 LL |     pub fn matches<F: Fn()>(&self, f: &F) {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

src/doc/nomicon

@@ -1,7 +1,6 @@
 // build-fail
 // compile-flags: -Copt-level=0
 // normalize-stderr-test: ".nll/" -> "/"
-// ignore-compare-mode-next-solver (hangs)
 
 fn main() {
     rec(Empty);

src/doc/reference

@@ -1,11 +1,11 @@
 error: reached the recursion limit while instantiating `rec::<&mut &mut &mut &mut &mut ...>`
-  --> $DIR/issue-67552.rs:30:9
+  --> $DIR/issue-67552.rs:29:9
    |
 LL |         rec(identity(&mut it))
    |         ^^^^^^^^^^^^^^^^^^^^^^
    |
 note: `rec` defined here
-  --> $DIR/issue-67552.rs:23:1
+  --> $DIR/issue-67552.rs:22:1
    |
 LL | / fn rec<T>(mut it: T)
 LL | | where

src/doc/rust-by-example

@@ -3,7 +3,6 @@
 // compile-flags: -Copt-level=0
 // dont-check-failure-status
 // dont-check-compiler-stderr
-// ignore-compare-mode-next-solver (hangs)
 
 pub fn encode_num<Writer: ExampleWriter>(n: u32, mut writer: Writer) -> Result<(), Writer::Error> {
     if n > 15 {

src/doc/rustc-dev-guide

@@ -23,7 +23,7 @@ fn main() {
     let x = String::from("hello, world");
     drop(<() as Foo>::copy_me(&x));
     //~^ ERROR overflow evaluating the requirement `<() as Foo>::Item: Sized`
-    //~| ERROR overflow evaluating the requirement `<() as Foo>::Item normalizes-to _`
+    //~| ERROR overflow evaluating the requirement `<() as Foo>::Item == _`
     //~| ERROR overflow evaluating the requirement `<() as Foo>::Item well-formed`
     //~| ERROR overflow evaluating the requirement `String <: <() as Foo>::Item`
     //~| ERROR overflow evaluating the requirement `&<() as Foo>::Item well-formed`

tests/ui/issues/issue-22638.rs

@@ -19,7 +19,7 @@ LL |     drop(<() as Foo>::copy_me(&x));
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`alias_bound_unsound`)
 
-error[E0275]: overflow evaluating the requirement `<() as Foo>::Item normalizes-to _`
+error[E0275]: overflow evaluating the requirement `<() as Foo>::Item == _`
   --> $DIR/alias-bound-unsound.rs:24:10
    |
 LL |     drop(<() as Foo>::copy_me(&x));
@@ -59,7 +59,6 @@ LL |     drop(<() as Foo>::copy_me(&x));
    |          ^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`alias_bound_unsound`)
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: aborting due to 7 previous errors
 

tests/ui/issues/issue-22638.stderr

@@ -0,0 +1,15 @@
+// compile-flags: -Znext-solver
+// check-pass
+
+trait Trait {
+    type Assoc;
+}
+
+fn call<T: Trait>(_: <T as Trait>::Assoc, _: T) {}
+
+fn foo<T: Trait>(rigid: <T as Trait>::Assoc, t: T) {
+    // Check that we can coerce `<?0 as Trait>::Assoc` to `<T as Trait>::Assoc`.
+    call::<_ /* ?0 */>(rigid, t);
+}
+
+fn main() {}

tests/ui/issues/issue-67552.rs

@@ -13,7 +13,6 @@ pub fn copy_any<T>(t: &T) -> T {
     //~^ ERROR the type `&<dyn Setup<From = T> as Setup>::From` is not well-formed
     //~| ERROR the trait bound `dyn Setup<From = T>: Setup` is not satisfied
     //~| ERROR mismatched types
-    //~| ERROR mismatched types
     //~| ERROR the type `<dyn Setup<From = T> as Setup>::From` is not well-formed
     //~| ERROR the size for values of type `<dyn Setup<From = T> as Setup>::From` cannot be known at compilation time
 

tests/ui/issues/issue-67552.stderr

@@ -36,20 +36,6 @@ note: function defined here
 LL | fn copy<U: Setup + ?Sized>(from: &U::From) -> U::From {
    |    ^^^^                    --------------
 
-error[E0308]: mismatched types
-  --> $DIR/object-unsafety.rs:12:5
-   |
-LL | pub fn copy_any<T>(t: &T) -> T {
-   |                 -            - expected `T` because of return type
-   |                 |
-   |                 expected this type parameter
-LL |     copy::<dyn Setup<From=T>>(t)
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ types differ
-   |
-   = note: expected type parameter `T`
-             found associated type `<dyn Setup<From = T> as Setup>::From`
-   = note: you might be missing a type parameter or trait bound
-
 error: the type `<dyn Setup<From = T> as Setup>::From` is not well-formed
   --> $DIR/object-unsafety.rs:12:5
    |
@@ -72,7 +58,7 @@ help: consider further restricting the associated type
 LL | pub fn copy_any<T>(t: &T) -> T where <dyn Setup<From = T> as Setup>::From: Sized {
    |                                +++++++++++++++++++++++++++++++++++++++++++++++++
 
-error: aborting due to 6 previous errors
+error: aborting due to 5 previous errors
 
 Some errors have detailed explanations: E0277, E0308.
 For more information about an error, try `rustc --explain E0277`.

tests/ui/recursion/issue-95134.rs

@@ -1,3 +1,5 @@
+// ignore-compare-mode-next-solver (hangs)
+
 #![feature(type_alias_impl_trait)]
 
 type Bar<'a, 'b> = impl PartialEq<Bar<'a, 'b>> + std::fmt::Debug;

tests/ui/traits/next-solver/alias-bound-unsound.rs

@@ -1,5 +1,5 @@
 error[E0277]: can't compare `&i32` with `Bar<'a, 'b>`
-  --> $DIR/self-referential-3.rs:5:31
+  --> $DIR/self-referential-3.rs:7:31
    |
 LL | fn bar<'a, 'b>(i: &'a i32) -> Bar<'a, 'b> {
    |                               ^^^^^^^^^^^ no implementation for `&i32 == Bar<'a, 'b>`

tests/ui/traits/next-solver/alias-bound-unsound.stderr

@@ -1,3 +1,5 @@
+// ignore-compare-mode-next-solver (hangs)
+
 #![feature(type_alias_impl_trait)]
 
 type Bar<'a, 'b> = impl PartialEq<Bar<'b, 'static>> + std::fmt::Debug;

tests/ui/traits/next-solver/coerce-ambig-alias-to-rigid-alias.rs

@@ -1,5 +1,5 @@
 error[E0277]: can't compare `&i32` with `Bar<'b, 'static>`
-  --> $DIR/self-referential-4.rs:5:31
+  --> $DIR/self-referential-4.rs:7:31
    |
 LL | fn bar<'a, 'b>(i: &'a i32) -> Bar<'a, 'b> {
    |                               ^^^^^^^^^^^ no implementation for `&i32 == Bar<'b, 'static>`
@@ -10,7 +10,7 @@ LL |     i
    = help: the trait `PartialEq` is implemented for `i32`
 
 error[E0277]: can't compare `&i32` with `Foo<'static, 'b>`
-  --> $DIR/self-referential-4.rs:11:31
+  --> $DIR/self-referential-4.rs:13:31
    |
 LL | fn foo<'a, 'b>(i: &'a i32) -> Foo<'a, 'b> {
    |                               ^^^^^^^^^^^ no implementation for `&i32 == Foo<'static, 'b>`
@@ -21,7 +21,7 @@ LL |     i
    = help: the trait `PartialEq` is implemented for `i32`
 
 error[E0277]: can't compare `&i32` with `Moo<'static, 'a>`
-  --> $DIR/self-referential-4.rs:17:31
+  --> $DIR/self-referential-4.rs:19:31
    |
 LL | fn moo<'a, 'b>(i: &'a i32) -> Moo<'a, 'b> {
    |                               ^^^^^^^^^^^ no implementation for `&i32 == Moo<'static, 'a>`

tests/ui/traits/next-solver/object-unsafety.rs

@@ -1,3 +1,5 @@
+// ignore-compare-mode-next-solver (hangs)
+
 #![feature(type_alias_impl_trait)]
 
 type Bar<'a, 'b> = impl PartialEq<Bar<'b, 'a>> + std::fmt::Debug;

tests/ui/traits/next-solver/object-unsafety.stderr

@@ -1,5 +1,5 @@
 error[E0277]: can't compare `&i32` with `Bar<'b, 'a>`
-  --> $DIR/self-referential.rs:5:31
+  --> $DIR/self-referential.rs:7:31
    |
 LL | fn bar<'a, 'b>(i: &'a i32) -> Bar<'a, 'b> {
    |                               ^^^^^^^^^^^ no implementation for `&i32 == Bar<'b, 'a>`
@@ -11,7 +11,7 @@ LL |     i
    = help: the trait `PartialEq` is implemented for `i32`
 
 error[E0277]: can't compare `&i32` with `(i32, Foo<'a, 'b>::{opaque#0})`
-  --> $DIR/self-referential.rs:12:31
+  --> $DIR/self-referential.rs:14:31
    |
 LL | fn foo<'a, 'b>(i: &'a i32) -> Foo<'a, 'b> {
    |                               ^^^^^^^^^^^ no implementation for `&i32 == (i32, Foo<'a, 'b>::{opaque#0})`
@@ -23,7 +23,7 @@ LL |     (42, i)
    = help: the trait `PartialEq` is implemented for `i32`
 
 error[E0277]: can't compare `&i32` with `(i32, Moo<'b, 'a>::{opaque#0})`
-  --> $DIR/self-referential.rs:19:31
+  --> $DIR/self-referential.rs:21:31
    |
 LL | fn moo<'a, 'b>(i: &'a i32) -> Moo<'a, 'b> {
    |                               ^^^^^^^^^^^ no implementation for `&i32 == (i32, Moo<'b, 'a>::{opaque#0})`