Rollup merge of #133751 - lcnr:no-trait-solving-on-type, r=compiler-errors

remove `Ty::is_copy_modulo_regions`

Using these functions is likely incorrect if an `InferCtxt` is available, I moved this function to `TyCtxt` (and added it to `LateContext`) and added a note to the documentation that one should prefer `Infer::type_is_copy_modulo_regions` instead.

I didn't yet move `is_sized` and `is_freeze`, though I think we should move these as well.

r? `@compiler-errors` cc #132279

Author: GuillaumeGomez

compiler/rustc_hir_analysis/src/check/check.rs

@@ -103,7 +103,7 @@ fn allowed_union_or_unsafe_field<'tcx>(
             // Fallback case: allow `ManuallyDrop` and things that are `Copy`,
             // also no need to report an error if the type is unresolved.
             ty.ty_adt_def().is_some_and(|adt_def| adt_def.is_manually_drop())
-                || ty.is_copy_modulo_regions(tcx, typing_env)
+                || tcx.type_is_copy_modulo_regions(typing_env, ty)
                 || ty.references_error()
         }
     };

compiler/rustc_hir_analysis/src/check/intrinsicck.rs

@@ -178,7 +178,7 @@ impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
 
         // Check that the type implements Copy. The only case where this can
         // possibly fail is for SIMD types which don't #[derive(Copy)].
-        if !ty.is_copy_modulo_regions(self.tcx, self.typing_env) {
+        if !self.tcx.type_is_copy_modulo_regions(self.typing_env, ty) {
             let msg = "arguments for inline assembly must be copyable";
             self.tcx
                 .dcx()

compiler/rustc_hir_typeck/src/expr_use_visitor.rs

@@ -228,7 +228,7 @@ impl<'tcx> TypeInformationCtxt<'tcx> for (&LateContext<'tcx>, LocalDefId) {
     }
 
     fn type_is_copy_modulo_regions(&self, ty: Ty<'tcx>) -> bool {
-        ty.is_copy_modulo_regions(self.0.tcx, self.0.typing_env())
+        self.0.type_is_copy_modulo_regions(ty)
     }
 
     fn body_owner_def_id(&self) -> LocalDefId {

compiler/rustc_lint/src/builtin.rs

@@ -586,7 +586,7 @@ impl<'tcx> LateLintPass<'tcx> for MissingCopyImplementations {
                 return;
             }
         }
-        if ty.is_copy_modulo_regions(cx.tcx, cx.typing_env()) {
+        if cx.type_is_copy_modulo_regions(ty) {
             return;
         }
         if type_implements_negative_copy_modulo_regions(cx.tcx, ty, cx.typing_env()) {

compiler/rustc_lint/src/context.rs

@@ -710,6 +710,10 @@ impl<'tcx> LateContext<'tcx> {
         TypingEnv { typing_mode: self.typing_mode(), param_env: self.param_env }
     }
 
+    pub fn type_is_copy_modulo_regions(&self, ty: Ty<'tcx>) -> bool {
+        self.tcx.type_is_copy_modulo_regions(self.typing_env(), ty)
+    }
+
     /// Gets the type-checking results for the current body,
     /// or `None` if outside a body.
     pub fn maybe_typeck_results(&self) -> Option<&'tcx ty::TypeckResults<'tcx>> {

compiler/rustc_lint/src/drop_forget_useless.rs

@@ -144,7 +144,7 @@ impl<'tcx> LateLintPass<'tcx> for DropForgetUseless {
             && let Some(fn_name) = cx.tcx.get_diagnostic_name(def_id)
         {
             let arg_ty = cx.typeck_results().expr_ty(arg);
-            let is_copy = arg_ty.is_copy_modulo_regions(cx.tcx, cx.typing_env());
+            let is_copy = cx.type_is_copy_modulo_regions(arg_ty);
             let drop_is_single_call_in_arm = is_single_call_in_arm(cx, arg, expr);
             let let_underscore_ignore_sugg = || {
                 if let Some((_, node)) = cx.tcx.hir().parent_iter(expr.hir_id).nth(0)

compiler/rustc_lint/src/internal.rs

@@ -242,17 +242,10 @@ fn is_ty_or_ty_ctxt(cx: &LateContext<'_>, path: &Path<'_>) -> Option<String> {
         }
         // Only lint on `&Ty` and `&TyCtxt` if it is used outside of a trait.
         Res::SelfTyAlias { alias_to: did, is_trait_impl: false, .. } => {
-            if let ty::Adt(adt, args) = cx.tcx.type_of(did).instantiate_identity().kind() {
-                if let Some(name @ (sym::Ty | sym::TyCtxt)) = cx.tcx.get_diagnostic_name(adt.did())
-                {
-                    // NOTE: This path is currently unreachable as `Ty<'tcx>` is
-                    // defined as a type alias meaning that `impl<'tcx> Ty<'tcx>`
-                    // is not actually allowed.
-                    //
-                    // I(@lcnr) still kept this branch in so we don't miss this
-                    // if we ever change it in the future.
-                    return Some(format!("{}<{}>", name, args[0]));
-                }
+            if let ty::Adt(adt, args) = cx.tcx.type_of(did).instantiate_identity().kind()
+                && let Some(name @ (sym::Ty | sym::TyCtxt)) = cx.tcx.get_diagnostic_name(adt.did())
+            {
+                return Some(format!("{}<{}>", name, args[0]));
             }
         }
         _ => (),

compiler/rustc_middle/src/ty/util.rs

@@ -172,6 +172,24 @@ impl<'tcx> TyCtxt<'tcx> {
         }
     }
 
+    /// Checks whether `ty: Copy` holds while ignoring region constraints.
+    ///
+    /// This impacts whether values of `ty` are *moved* or *copied*
+    /// when referenced. This means that we may generate MIR which
+    /// does copies even when the type actually doesn't satisfy the
+    /// full requirements for the `Copy` trait (cc #29149) -- this
+    /// winds up being reported as an error during NLL borrow check.
+    ///
+    /// This function should not be used if there is an `InferCtxt` available.
+    /// Use `InferCtxt::type_is_copy_modulo_regions` instead.
+    pub fn type_is_copy_modulo_regions(
+        self,
+        typing_env: ty::TypingEnv<'tcx>,
+        ty: Ty<'tcx>,
+    ) -> bool {
+        ty.is_trivially_pure_clone_copy() || self.is_copy_raw(typing_env.as_query_input(ty))
+    }
+
     /// Returns the deeply last field of nested structures, or the same type if
     /// not a structure at all. Corresponds to the only possible unsized field,
     /// and its type can be used to determine unsizing strategy.
@@ -1174,21 +1192,6 @@ impl<'tcx> Ty<'tcx> {
             .map(|(min, _)| ty::Const::from_bits(tcx, min, typing_env, self))
     }
 
-    /// Checks whether values of this type `T` are *moved* or *copied*
-    /// when referenced -- this amounts to a check for whether `T:
-    /// Copy`, but note that we **don't** consider lifetimes when
-    /// doing this check. This means that we may generate MIR which
-    /// does copies even when the type actually doesn't satisfy the
-    /// full requirements for the `Copy` trait (cc #29149) -- this
-    /// winds up being reported as an error during NLL borrow check.
-    pub fn is_copy_modulo_regions(
-        self,
-        tcx: TyCtxt<'tcx>,
-        typing_env: ty::TypingEnv<'tcx>,
-    ) -> bool {
-        self.is_trivially_pure_clone_copy() || tcx.is_copy_raw(typing_env.as_query_input(self))
-    }
-
     /// Checks whether values of this type `T` have a size known at
     /// compile time (i.e., whether `T: Sized`). Lifetimes are ignored
     /// for the purposes of this check, so it can be an

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

@@ -176,7 +176,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             let ty = expr.ty;
             if !ty.is_sized(tcx, this.typing_env()) {
                 // !sized means !copy, so this is an unsized move
-                assert!(!ty.is_copy_modulo_regions(tcx, this.typing_env()));
+                assert!(!tcx.type_is_copy_modulo_regions(this.typing_env(), ty));
 
                 // As described above, detect the case where we are passing a value of unsized
                 // type, and that value is coming from the deref of a box.

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

@@ -780,7 +780,7 @@ fn check_borrow_conflicts_in_at_patterns<'tcx>(cx: &MatchVisitor<'_, 'tcx>, pat:
         return;
     };
 
-    let is_binding_by_move = |ty: Ty<'tcx>| !ty.is_copy_modulo_regions(cx.tcx, cx.typing_env);
+    let is_binding_by_move = |ty: Ty<'tcx>| !cx.tcx.type_is_copy_modulo_regions(cx.typing_env, ty);
 
     let sess = cx.tcx.sess;