Auto merge of #122096 - matthiaskrgr:rollup-s8sh1rn, r=matthiaskrgr

Rollup of 10 pull requests

Successful merges:

 - #121958 (Fix redundant import errors for preload extern crate)
 - #121976 (Add an option to have an external download/bootstrap cache)
 - #122022 (loongarch: add frecipe and relax target feature)
 - #122026 (Do not try to format removed files)
 - #122027 (Uplift some feeding out of `associated_type_for_impl_trait_in_impl` and into queries)
 - #122063 (Make the lowering of `thir::ExprKind::If` easier to follow)
 - #122066 (Add proper cfgs for struct HirIdValidator used only with debug-assert)
 - #122074 (Add missing PartialOrd trait implementation doc for array)
 - #122082 (remove outdated fixme comment)
 - #122091 (Note why we're using a new thread in `test_get_os_named_thread`)

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

Author: bors

Diff for: compiler/rustc_hir_analysis/src/collect/generics_of.rs

@@ -14,6 +14,43 @@ use rustc_span::Span;
 pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
     use rustc_hir::*;
 
+    // For an RPITIT, synthesize generics which are equal to the opaque's generics
+    // and parent fn's generics compressed into one list.
+    if let Some(ty::ImplTraitInTraitData::Trait { fn_def_id, opaque_def_id }) =
+        tcx.opt_rpitit_info(def_id.to_def_id())
+    {
+        let trait_def_id = tcx.parent(fn_def_id);
+        let opaque_ty_generics = tcx.generics_of(opaque_def_id);
+        let opaque_ty_parent_count = opaque_ty_generics.parent_count;
+        let mut params = opaque_ty_generics.params.clone();
+
+        let parent_generics = tcx.generics_of(trait_def_id);
+        let parent_count = parent_generics.parent_count + parent_generics.params.len();
+
+        let mut trait_fn_params = tcx.generics_of(fn_def_id).params.clone();
+
+        for param in &mut params {
+            param.index = param.index + parent_count as u32 + trait_fn_params.len() as u32
+                - opaque_ty_parent_count as u32;
+        }
+
+        trait_fn_params.extend(params);
+        params = trait_fn_params;
+
+        let param_def_id_to_index =
+            params.iter().map(|param| (param.def_id, param.index)).collect();
+
+        return ty::Generics {
+            parent: Some(trait_def_id),
+            parent_count,
+            params,
+            param_def_id_to_index,
+            has_self: opaque_ty_generics.has_self,
+            has_late_bound_regions: opaque_ty_generics.has_late_bound_regions,
+            host_effect_index: parent_generics.host_effect_index,
+        };
+    }
+
     let hir_id = tcx.local_def_id_to_hir_id(def_id);
 
     let node = tcx.hir_node(hir_id);

Diff for: compiler/rustc_hir_analysis/src/collect/type_of.rs

@@ -5,7 +5,7 @@ use rustc_hir::HirId;
 use rustc_middle::query::plumbing::CyclePlaceholder;
 use rustc_middle::ty::print::with_forced_trimmed_paths;
 use rustc_middle::ty::util::IntTypeExt;
-use rustc_middle::ty::{self, ImplTraitInTraitData, IsSuggestable, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{self, IsSuggestable, Ty, TyCtxt, TypeVisitableExt};
 use rustc_span::symbol::Ident;
 use rustc_span::{Span, DUMMY_SP};
 
@@ -350,22 +350,31 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<Ty
     // If we are computing `type_of` the synthesized associated type for an RPITIT in the impl
     // side, use `collect_return_position_impl_trait_in_trait_tys` to infer the value of the
     // associated type in the impl.
-    if let Some(ImplTraitInTraitData::Impl { fn_def_id, .. }) =
-        tcx.opt_rpitit_info(def_id.to_def_id())
-    {
-        match tcx.collect_return_position_impl_trait_in_trait_tys(fn_def_id) {
-            Ok(map) => {
-                let assoc_item = tcx.associated_item(def_id);
-                return map[&assoc_item.trait_item_def_id.unwrap()];
-            }
-            Err(_) => {
-                return ty::EarlyBinder::bind(Ty::new_error_with_message(
-                    tcx,
-                    DUMMY_SP,
-                    "Could not collect return position impl trait in trait tys",
-                ));
+    match tcx.opt_rpitit_info(def_id.to_def_id()) {
+        Some(ty::ImplTraitInTraitData::Impl { fn_def_id }) => {
+            match tcx.collect_return_position_impl_trait_in_trait_tys(fn_def_id) {
+                Ok(map) => {
+                    let assoc_item = tcx.associated_item(def_id);
+                    return map[&assoc_item.trait_item_def_id.unwrap()];
+                }
+                Err(_) => {
+                    return ty::EarlyBinder::bind(Ty::new_error_with_message(
+                        tcx,
+                        DUMMY_SP,
+                        "Could not collect return position impl trait in trait tys",
+                    ));
+                }
             }
         }
+        // For an RPITIT in a trait, just return the corresponding opaque.
+        Some(ty::ImplTraitInTraitData::Trait { opaque_def_id, .. }) => {
+            return ty::EarlyBinder::bind(Ty::new_opaque(
+                tcx,
+                opaque_def_id,
+                ty::GenericArgs::identity_for_item(tcx, opaque_def_id),
+            ));
+        }
+        None => {}
     }
 
     let hir_id = tcx.local_def_id_to_hir_id(def_id);

Diff for: compiler/rustc_interface/src/passes.rs

@@ -686,6 +686,11 @@ pub fn create_global_ctxt<'tcx>(
 /// Runs the type-checking, region checking and other miscellaneous analysis
 /// passes on the crate.
 fn analysis(tcx: TyCtxt<'_>, (): ()) -> Result<()> {
+    if tcx.sess.opts.unstable_opts.hir_stats {
+        rustc_passes::hir_stats::print_hir_stats(tcx);
+    }
+
+    #[cfg(debug_assertions)]
     rustc_passes::hir_id_validator::check_crate(tcx);
 
     let sess = tcx.sess;

Diff for: compiler/rustc_lint/src/context/diagnostics.rs

@@ -143,7 +143,11 @@ pub(super) fn builtin(sess: &Session, diagnostic: BuiltinLintDiag, diag: &mut Di
         BuiltinLintDiag::RedundantImport(spans, ident) => {
             for (span, is_imported) in spans {
                 let introduced = if is_imported { "imported" } else { "defined" };
-                diag.span_label(span, format!("the item `{ident}` is already {introduced} here"));
+                let span_msg = if span.is_dummy() { "by prelude" } else { "here" };
+                diag.span_label(
+                    span,
+                    format!("the item `{ident}` is already {introduced} {span_msg}"),
+                );
             }
         }
         BuiltinLintDiag::DeprecatedMacro(suggestion, span) => {

Diff for: compiler/rustc_middle/src/query/mod.rs

@@ -826,15 +826,15 @@ rustc_queries! {
     /// creates and returns the associated items that correspond to each impl trait in return position
     /// of the implemented trait.
     query associated_types_for_impl_traits_in_associated_fn(fn_def_id: DefId) -> &'tcx [DefId] {
-        desc { |tcx| "creating associated items for impl trait in trait returned by `{}`", tcx.def_path_str(fn_def_id) }
+        desc { |tcx| "creating associated items for opaque types returned by `{}`", tcx.def_path_str(fn_def_id) }
         cache_on_disk_if { fn_def_id.is_local() }
         separate_provide_extern
     }
 
     /// Given an impl trait in trait `opaque_ty_def_id`, create and return the corresponding
     /// associated item.
     query associated_type_for_impl_trait_in_trait(opaque_ty_def_id: LocalDefId) -> LocalDefId {
-        desc { |tcx| "creates the associated item corresponding to the opaque type `{}`", tcx.def_path_str(opaque_ty_def_id.to_def_id()) }
+        desc { |tcx| "creating the associated item corresponding to the opaque type `{}`", tcx.def_path_str(opaque_ty_def_id.to_def_id()) }
         cache_on_disk_if { true }
     }
 

Diff for: compiler/rustc_mir_build/src/build/expr/into.rs

@@ -58,52 +58,61 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 this.thir[scrutinee].span,
             ),
             ExprKind::If { cond, then, else_opt, if_then_scope } => {
-                let then_blk;
                 let then_span = this.thir[then].span;
                 let then_source_info = this.source_info(then_span);
                 let condition_scope = this.local_scope();
 
-                let mut else_blk = unpack!(
-                    then_blk = this.in_scope(
-                        (if_then_scope, then_source_info),
-                        LintLevel::Inherited,
-                        |this| {
-                            let source_info = if this.is_let(cond) {
-                                let variable_scope =
-                                    this.new_source_scope(then_span, LintLevel::Inherited, None);
-                                this.source_scope = variable_scope;
-                                SourceInfo { span: then_span, scope: variable_scope }
-                            } else {
-                                this.source_info(then_span)
-                            };
-                            let (then_block, else_block) =
-                                this.in_if_then_scope(condition_scope, then_span, |this| {
-                                    let then_blk = unpack!(this.then_else_break(
-                                        block,
-                                        cond,
-                                        Some(condition_scope), // Temp scope
-                                        condition_scope,
-                                        source_info,
-                                        true, // Declare `let` bindings normally
-                                    ));
-
-                                    this.expr_into_dest(destination, then_blk, then)
-                                });
-                            then_block.and(else_block)
-                        },
-                    )
+                let then_and_else_blocks = this.in_scope(
+                    (if_then_scope, then_source_info),
+                    LintLevel::Inherited,
+                    |this| {
+                        // FIXME: Does this need extra logic to handle let-chains?
+                        let source_info = if this.is_let(cond) {
+                            let variable_scope =
+                                this.new_source_scope(then_span, LintLevel::Inherited, None);
+                            this.source_scope = variable_scope;
+                            SourceInfo { span: then_span, scope: variable_scope }
+                        } else {
+                            this.source_info(then_span)
+                        };
+
+                        // Lower the condition, and have it branch into `then` and `else` blocks.
+                        let (then_block, else_block) =
+                            this.in_if_then_scope(condition_scope, then_span, |this| {
+                                let then_blk = unpack!(this.then_else_break(
+                                    block,
+                                    cond,
+                                    Some(condition_scope), // Temp scope
+                                    condition_scope,
+                                    source_info,
+                                    true, // Declare `let` bindings normally
+                                ));
+
+                                // Lower the `then` arm into its block.
+                                this.expr_into_dest(destination, then_blk, then)
+                            });
+
+                        // Pack `(then_block, else_block)` into `BlockAnd<BasicBlock>`.
+                        then_block.and(else_block)
+                    },
                 );
 
-                else_blk = if let Some(else_opt) = else_opt {
-                    unpack!(this.expr_into_dest(destination, else_blk, else_opt))
+                // Unpack `BlockAnd<BasicBlock>` into `(then_blk, else_blk)`.
+                let (then_blk, mut else_blk);
+                else_blk = unpack!(then_blk = then_and_else_blocks);
+
+                // If there is an `else` arm, lower it into `else_blk`.
+                if let Some(else_expr) = else_opt {
+                    unpack!(else_blk = this.expr_into_dest(destination, else_blk, else_expr));
                 } else {
-                    // Body of the `if` expression without an `else` clause must return `()`, thus
-                    // we implicitly generate an `else {}` if it is not specified.
+                    // There is no `else` arm, so we know both arms have type `()`.
+                    // Generate the implicit `else {}` by assigning unit.
                     let correct_si = this.source_info(expr_span.shrink_to_hi());
                     this.cfg.push_assign_unit(else_blk, correct_si, destination, this.tcx);
-                    else_blk
-                };
+                }
 
+                // The `then` and `else` arms have been lowered into their respective
+                // blocks, so make both of them meet up in a new block.
                 let join_block = this.cfg.start_new_block();
                 this.cfg.goto(then_blk, source_info, join_block);
                 this.cfg.goto(else_blk, source_info, join_block);

Diff for: compiler/rustc_passes/src/hir_id_validator.rs

@@ -1,38 +1,26 @@
 use rustc_data_structures::sync::Lock;
 use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
-use rustc_hir::intravisit;
-use rustc_hir::{HirId, ItemLocalId};
+use rustc_hir::{intravisit, HirId, ItemLocalId};
 use rustc_index::bit_set::GrowableBitSet;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::ty::TyCtxt;
 
 pub fn check_crate(tcx: TyCtxt<'_>) {
-    if tcx.sess.opts.unstable_opts.hir_stats {
-        crate::hir_stats::print_hir_stats(tcx);
-    }
-
-    #[cfg(debug_assertions)]
-    {
-        let errors = Lock::new(Vec::new());
+    let errors = Lock::new(Vec::new());
 
-        tcx.hir().par_for_each_module(|module_id| {
-            let mut v = HirIdValidator {
-                tcx,
-                owner: None,
-                hir_ids_seen: Default::default(),
-                errors: &errors,
-            };
+    tcx.hir().par_for_each_module(|module_id| {
+        let mut v =
+            HirIdValidator { tcx, owner: None, hir_ids_seen: Default::default(), errors: &errors };
 
-            tcx.hir().visit_item_likes_in_module(module_id, &mut v);
-        });
+        tcx.hir().visit_item_likes_in_module(module_id, &mut v);
+    });
 
-        let errors = errors.into_inner();
+    let errors = errors.into_inner();
 
-        if !errors.is_empty() {
-            let message = errors.iter().fold(String::new(), |s1, s2| s1 + "\n" + s2);
-            tcx.dcx().delayed_bug(message);
-        }
+    if !errors.is_empty() {
+        let message = errors.iter().fold(String::new(), |s1, s2| s1 + "\n" + s2);
+        tcx.dcx().delayed_bug(message);
     }
 }
 
@@ -90,7 +78,7 @@ impl<'a, 'hir> HirIdValidator<'a, 'hir> {
             self.error(|| {
                 format!(
                     "ItemLocalIds not assigned densely in {pretty_owner}. \
-                Max ItemLocalId = {max}, missing IDs = {missing_items:#?}; seen IDs = {seen_items:#?}"
+            Max ItemLocalId = {max}, missing IDs = {missing_items:#?}; seen IDs = {seen_items:#?}"
                 )
             });
         }

Diff for: compiler/rustc_passes/src/lib.rs

@@ -28,6 +28,7 @@ mod debugger_visualizer;
 mod diagnostic_items;
 pub mod entry;
 mod errors;
+#[cfg(debug_assertions)]
 pub mod hir_id_validator;
 pub mod hir_stats;
 mod lang_items;