Rollup merge of #135914 - compiler-errors:vanquish-query-norm, r=jackh726

Remove usages of `QueryNormalizer` in the compiler

I want to get rid of the `QueryNormalizer`, possibly changing it to be special cased just for normalizing erasing regions, or perhaps adapting `normalize_erasing_regions` to use the assoc type normalizer if caching is sufficient and removing it altogther.

This removes the last two usages of `.query_normalize` in the *compiler*. There are a few usages left in rustdoc and clippy, which exist only because the query normalizer is more resilient to errors and non-well-formed alias types. I will remove those next.

r? lcnr or reassign

compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs

@@ -6,8 +6,7 @@ use rustc_span::{DUMMY_SP, Span};
 use tracing::{debug, instrument};
 
 use crate::traits::query::NoSolution;
-use crate::traits::query::normalize::QueryNormalizeExt;
+use crate::traits::{ObligationCause, ObligationCtxt};
-use crate::traits::{Normalized, ObligationCause, ObligationCtxt};
 
 /// This returns true if the type `ty` is "trivial" for
 /// dropck-outlives -- that is, if it doesn't require any types to
@@ -172,13 +171,18 @@ pub fn compute_dropck_outlives_inner<'tcx>(
         // do not themselves define a destructor", more or less. We have
         // to push them onto the stack to be expanded.
         for ty in constraints.dtorck_types.drain(..) {
-            let Normalized { value: ty, obligations } =
+            let normalized_ty = ocx.normalize(&cause, param_env, ty);
-                ocx.infcx.at(&cause, param_env).query_normalize(ty)?;
-            ocx.register_obligations(obligations);
 
-            debug!("dropck_outlives: ty from dtorck_types = {:?}", ty);
+            let errors = ocx.select_where_possible();
+            if !errors.is_empty() {
+                debug!("failed to normalize dtorck type: {ty} ~> {errors:#?}");
+                return Err(NoSolution);
+            }
 
-            match ty.kind() {
+            let normalized_ty = ocx.infcx.resolve_vars_if_possible(normalized_ty);
+            debug!("dropck_outlives: ty from dtorck_types = {:?}", normalized_ty);
+
+            match normalized_ty.kind() {
                 // All parameters live for the duration of the
                 // function.
                 ty::Param(..) => {}
@@ -186,12 +190,12 @@ pub fn compute_dropck_outlives_inner<'tcx>(
                 // A projection that we couldn't resolve - it
                 // might have a destructor.
                 ty::Alias(..) => {
-                    result.kinds.push(ty.into());
+                    result.kinds.push(normalized_ty.into());
                 }
 
                 _ => {
-                    if ty_set.insert(ty) {
+                    if ty_set.insert(normalized_ty) {
-                        ty_stack.push((ty, depth + 1));
+                        ty_stack.push((normalized_ty, depth + 1));
                     }
                 }
             }

compiler/rustc_traits/src/type_op.rs

@@ -6,13 +6,12 @@ use rustc_middle::query::Providers;
 use rustc_middle::traits::query::NoSolution;
 use rustc_middle::ty::{Clause, FnSig, ParamEnvAnd, PolyFnSig, Ty, TyCtxt, TypeFoldable};
 use rustc_trait_selection::infer::InferCtxtBuilderExt;
-use rustc_trait_selection::traits::query::normalize::QueryNormalizeExt;
 use rustc_trait_selection::traits::query::type_op::ascribe_user_type::{
     AscribeUserType, type_op_ascribe_user_type_with_span,
 };
 use rustc_trait_selection::traits::query::type_op::normalize::Normalize;
 use rustc_trait_selection::traits::query::type_op::prove_predicate::ProvePredicate;
-use rustc_trait_selection::traits::{Normalized, Obligation, ObligationCause, ObligationCtxt};
+use rustc_trait_selection::traits::{Obligation, ObligationCause, ObligationCtxt};
 
 pub(crate) fn provide(p: &mut Providers) {
     *p = Providers {
@@ -43,10 +42,7 @@ where
     T: fmt::Debug + TypeFoldable<TyCtxt<'tcx>>,
 {
     let (param_env, Normalize { value }) = key.into_parts();
-    let Normalized { value, obligations } =
+    Ok(ocx.normalize(&ObligationCause::dummy(), param_env, value))
-        ocx.infcx.at(&ObligationCause::dummy(), param_env).query_normalize(value)?;
-    ocx.register_obligations(obligations);
-    Ok(value)
 }
 
 fn type_op_normalize_ty<'tcx>(

tests/ui/higher-ranked/trait-bounds/normalize-under-binder/issue-71955.rs

@@ -43,9 +43,9 @@ fn main() {
     }
 
     foo(bar, "string", |s| s.len() == 5);
-    //~^ ERROR implementation of `FnOnce` is not general enough
+    //~^ ERROR implementation of `Parser` is not general enough
-    //~| ERROR implementation of `FnOnce` is not general enough
+    //~| ERROR implementation of `Parser` is not general enough
     foo(baz, "string", |s| s.0.len() == 5);
-    //~^ ERROR implementation of `FnOnce` is not general enough
+    //~^ ERROR implementation of `Parser` is not general enough
-    //~| ERROR implementation of `FnOnce` is not general enough
+    //~| ERROR implementation of `Parser` is not general enough
 }

tests/ui/higher-ranked/trait-bounds/normalize-under-binder/issue-71955.stderr

@@ -1,39 +1,39 @@
-error: implementation of `FnOnce` is not general enough
+error: implementation of `Parser` is not general enough
   --> $DIR/issue-71955.rs:45:5
    |
 LL |     foo(bar, "string", |s| s.len() == 5);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `FnOnce` is not general enough
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `Parser` is not general enough
    |
-   = note: closure with signature `for<'a> fn(&'a &'2 str) -> bool` must implement `FnOnce<(&&'1 str,)>`, for any lifetime `'1`...
+   = note: `for<'a> fn(&'a str) -> (&'a str, &'a str) {bar}` must implement `Parser<'0>`, for any lifetime `'0`...
-   = note: ...but it actually implements `FnOnce<(&&'2 str,)>`, for some specific lifetime `'2`
+   = note: ...but it actually implements `Parser<'1>`, for some specific lifetime `'1`
 
-error: implementation of `FnOnce` is not general enough
+error: implementation of `Parser` is not general enough
   --> $DIR/issue-71955.rs:45:5
    |
 LL |     foo(bar, "string", |s| s.len() == 5);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `FnOnce` is not general enough
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `Parser` is not general enough
    |
-   = note: closure with signature `for<'a> fn(&'a &'2 str) -> bool` must implement `FnOnce<(&&'1 str,)>`, for any lifetime `'1`...
+   = note: `for<'a> fn(&'a str) -> (&'a str, &'a str) {bar}` must implement `Parser<'0>`, for any lifetime `'0`...
-   = note: ...but it actually implements `FnOnce<(&&'2 str,)>`, for some specific lifetime `'2`
+   = note: ...but it actually implements `Parser<'1>`, for some specific lifetime `'1`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-error: implementation of `FnOnce` is not general enough
+error: implementation of `Parser` is not general enough
   --> $DIR/issue-71955.rs:48:5
    |
 LL |     foo(baz, "string", |s| s.0.len() == 5);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `FnOnce` is not general enough
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `Parser` is not general enough
    |
-   = note: closure with signature `for<'a> fn(&'a Wrapper<'2>) -> bool` must implement `FnOnce<(&Wrapper<'1>,)>`, for any lifetime `'1`...
+   = note: `for<'a> fn(&'a str) -> (&'a str, Wrapper<'a>) {baz}` must implement `Parser<'0>`, for any lifetime `'0`...
-   = note: ...but it actually implements `FnOnce<(&Wrapper<'2>,)>`, for some specific lifetime `'2`
+   = note: ...but it actually implements `Parser<'1>`, for some specific lifetime `'1`
 
-error: implementation of `FnOnce` is not general enough
+error: implementation of `Parser` is not general enough
   --> $DIR/issue-71955.rs:48:5
    |
 LL |     foo(baz, "string", |s| s.0.len() == 5);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `FnOnce` is not general enough
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `Parser` is not general enough
    |
-   = note: closure with signature `for<'a> fn(&'a Wrapper<'2>) -> bool` must implement `FnOnce<(&Wrapper<'1>,)>`, for any lifetime `'1`...
+   = note: `for<'a> fn(&'a str) -> (&'a str, Wrapper<'a>) {baz}` must implement `Parser<'0>`, for any lifetime `'0`...
-   = note: ...but it actually implements `FnOnce<(&Wrapper<'2>,)>`, for some specific lifetime `'2`
+   = note: ...but it actually implements `Parser<'1>`, for some specific lifetime `'1`
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: aborting due to 4 previous errors