rustc_ast_lowering: Stop lowering imports into multiple items

Lower them into a single item with multiple resolutions instead.
This also allows to remove additional `NodId`s and `DefId`s related to those additional items.

13 files changed, 52 insertions, 59 deletions

diff --git a/src/librustdoc/json/mod.rs b/src/librustdoc/json/mod.rs
index e4df1332521..83be1a16eb2 100644
--- a/src/librustdoc/json/mod.rs
+++ b/src/librustdoc/json/mod.rs
@@ -225,10 +225,10 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
 
                 types::ItemEnum::Function(_)
                 | types::ItemEnum::Module(_)
+                | types::ItemEnum::Import(_)
                 | types::ItemEnum::AssocConst { .. }
                 | types::ItemEnum::AssocType { .. } => true,
                 types::ItemEnum::ExternCrate { .. }
-                | types::ItemEnum::Import(_)
                 | types::ItemEnum::StructField(_)
                 | types::ItemEnum::Variant(_)
                 | types::ItemEnum::TraitAlias(_)
diff --git a/src/test/ui/consts/miri_unleashed/tls.stderr b/src/test/ui/consts/miri_unleashed/tls.stderr
index 436c5112360..7aaeadd0403 100644
--- a/src/test/ui/consts/miri_unleashed/tls.stderr
+++ b/src/test/ui/consts/miri_unleashed/tls.stderr
@@ -2,13 +2,13 @@ error[E0080]: could not evaluate static initializer
   --> $DIR/tls.rs:11:25
    |
 LL |     unsafe { let _val = A; }
-   |                         ^ cannot access thread local static (DefId(0:6 ~ tls[78b0]::A))
+   |                         ^ cannot access thread local static (DefId(0:4 ~ tls[78b0]::A))
 
 error[E0080]: could not evaluate static initializer
   --> $DIR/tls.rs:18:26
    |
 LL |     unsafe { let _val = &A; }
-   |                          ^ cannot access thread local static (DefId(0:6 ~ tls[78b0]::A))
+   |                          ^ cannot access thread local static (DefId(0:4 ~ tls[78b0]::A))
 
 warning: skipping const checks
    |
diff --git a/src/test/ui/generator/print/generator-print-verbose-1.stderr b/src/test/ui/generator/print/generator-print-verbose-1.stderr
index 2e020780480..ed0628bbbc3 100644
--- a/src/test/ui/generator/print/generator-print-verbose-1.stderr
+++ b/src/test/ui/generator/print/generator-print-verbose-1.stderr
@@ -9,7 +9,7 @@ note: generator is not `Send` as this value is used across a yield
   --> $DIR/generator-print-verbose-1.rs:35:9
    |
 LL |         let _non_send_gen = make_non_send_generator();
-   |             ------------- has type `Opaque(DefId(0:44 ~ generator_print_verbose_1[749a]::make_non_send_generator::{opaque#0}), [])` which is not `Send`
+   |             ------------- has type `Opaque(DefId(0:34 ~ generator_print_verbose_1[749a]::make_non_send_generator::{opaque#0}), [])` which is not `Send`
 LL |         yield;
    |         ^^^^^ yield occurs here, with `_non_send_gen` maybe used later
 LL |     };
@@ -35,17 +35,17 @@ note: required because it's used within this generator
    |
 LL |     || {
    |     ^^
-note: required because it appears within the type `Opaque(DefId(0:45 ~ generator_print_verbose_1[749a]::make_gen2::{opaque#0}), [std::sync::Arc<std::cell::RefCell<i32>>])`
+note: required because it appears within the type `Opaque(DefId(0:35 ~ generator_print_verbose_1[749a]::make_gen2::{opaque#0}), [std::sync::Arc<std::cell::RefCell<i32>>])`
   --> $DIR/generator-print-verbose-1.rs:41:30
    |
 LL | pub fn make_gen2<T>(t: T) -> impl Generator<Return = T> {
    |                              ^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: required because it appears within the type `Opaque(DefId(0:46 ~ generator_print_verbose_1[749a]::make_non_send_generator2::{opaque#0}), [])`
+note: required because it appears within the type `Opaque(DefId(0:36 ~ generator_print_verbose_1[749a]::make_non_send_generator2::{opaque#0}), [])`
   --> $DIR/generator-print-verbose-1.rs:47:34
    |
 LL | fn make_non_send_generator2() -> impl Generator<Return = Arc<RefCell<i32>>> {
    |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: required because it captures the following types: `Opaque(DefId(0:46 ~ generator_print_verbose_1[749a]::make_non_send_generator2::{opaque#0}), [])`, `()`
+   = note: required because it captures the following types: `Opaque(DefId(0:36 ~ generator_print_verbose_1[749a]::make_non_send_generator2::{opaque#0}), [])`, `()`
 note: required because it's used within this generator
   --> $DIR/generator-print-verbose-1.rs:52:20
    |
diff --git a/src/test/ui/generic-associated-types/self-outlives-lint.stderr b/src/test/ui/generic-associated-types/self-outlives-lint.stderr
index 58172bf06b5..9e9b2e18abe 100644
--- a/src/test/ui/generic-associated-types/self-outlives-lint.stderr
+++ b/src/test/ui/generic-associated-types/self-outlives-lint.stderr
@@ -108,17 +108,6 @@ LL |     type Bar<'b>;
    = note: this bound is currently required to ensure that impls have maximum flexibility
    = note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
 
-error: missing required bound on `Item`
-  --> $DIR/self-outlives-lint.rs:140:5
-   |
-LL |     type Item<'a>;
-   |     ^^^^^^^^^^^^^-
-   |                  |
-   |                  help: add the required where clause: `where Self: 'a`
-   |
-   = note: this bound is currently required to ensure that impls have maximum flexibility
-   = note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
-
 error: missing required bound on `Iterator`
   --> $DIR/self-outlives-lint.rs:142:5
    |
@@ -131,6 +120,17 @@ LL |     type Iterator<'a>: Iterator<Item = Self::Item<'a>>;
    = note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
 
 error: missing required bound on `Item`
+  --> $DIR/self-outlives-lint.rs:140:5
+   |
+LL |     type Item<'a>;
+   |     ^^^^^^^^^^^^^-
+   |                  |
+   |                  help: add the required where clause: `where Self: 'a`
+   |
+   = note: this bound is currently required to ensure that impls have maximum flexibility
+   = note: we are soliciting feedback, see issue #87479 <https://github.com/rust-lang/rust/issues/87479> for more information
+
+error: missing required bound on `Item`
   --> $DIR/self-outlives-lint.rs:148:5
    |
 LL |     type Item<'a>;
diff --git a/src/test/ui/privacy/effective_visibilities.rs b/src/test/ui/privacy/effective_visibilities.rs
index 8d0602fa79f..ff20e20d332 100644
--- a/src/test/ui/privacy/effective_visibilities.rs
+++ b/src/test/ui/privacy/effective_visibilities.rs
@@ -72,6 +72,5 @@ mod half_public_import {
 
 #[rustc_effective_visibility]
 pub use half_public_import::HalfPublicImport; //~ ERROR Direct: pub, Reexported: pub, Reachable: pub, ReachableThroughImplTrait: pub
-                                              //~^ ERROR Direct: pub, Reexported: pub, Reachable: pub, ReachableThroughImplTrait: pub
 
 fn main() {}
diff --git a/src/test/ui/privacy/effective_visibilities.stderr b/src/test/ui/privacy/effective_visibilities.stderr
index 6a99afe64fe..046b6095f4e 100644
--- a/src/test/ui/privacy/effective_visibilities.stderr
+++ b/src/test/ui/privacy/effective_visibilities.stderr
@@ -124,12 +124,6 @@ error: Direct: pub, Reexported: pub, Reachable: pub, ReachableThroughImplTrait:
 LL | pub use half_public_import::HalfPublicImport;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: Direct: pub, Reexported: pub, Reachable: pub, ReachableThroughImplTrait: pub
-  --> $DIR/effective_visibilities.rs:74:9
-   |
-LL | pub use half_public_import::HalfPublicImport;
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
 error: Direct: pub(crate), Reexported: pub, Reachable: pub, ReachableThroughImplTrait: pub
   --> $DIR/effective_visibilities.rs:14:13
    |
@@ -142,5 +136,5 @@ error: Direct: pub(crate), Reexported: pub, Reachable: pub, ReachableThroughImpl
 LL |             type B;
    |             ^^^^^^
 
-error: aborting due to 24 previous errors
+error: aborting due to 23 previous errors
 
diff --git a/src/test/ui/stats/hir-stats.stderr b/src/test/ui/stats/hir-stats.stderr
index 2a0e9497a21..15900bef7f6 100644
--- a/src/test/ui/stats/hir-stats.stderr
+++ b/src/test/ui/stats/hir-stats.stderr
@@ -120,59 +120,59 @@ hir-stats Name                Accumulated Size         Count     Item Size
 hir-stats ----------------------------------------------------------------
 hir-stats ForeignItemRef            24 ( 0.3%)             1            24
 hir-stats Lifetime                  24 ( 0.3%)             1            24
-hir-stats Mod                       32 ( 0.3%)             1            32
+hir-stats Mod                       32 ( 0.4%)             1            32
 hir-stats ExprField                 40 ( 0.4%)             1            40
 hir-stats TraitItemRef              56 ( 0.6%)             2            28
 hir-stats Local                     64 ( 0.7%)             1            64
 hir-stats Param                     64 ( 0.7%)             2            32
 hir-stats InlineAsm                 72 ( 0.8%)             1            72
 hir-stats ImplItemRef               72 ( 0.8%)             2            36
-hir-stats Body                      96 ( 1.0%)             3            32
-hir-stats FieldDef                  96 ( 1.0%)             2            48
-hir-stats Arm                       96 ( 1.0%)             2            48
-hir-stats Stmt                      96 ( 1.0%)             3            32
-hir-stats - Local                     32 ( 0.3%)             1
-hir-stats - Semi                      32 ( 0.3%)             1
-hir-stats - Expr                      32 ( 0.3%)             1
+hir-stats Body                      96 ( 1.1%)             3            32
+hir-stats FieldDef                  96 ( 1.1%)             2            48
+hir-stats Arm                       96 ( 1.1%)             2            48
+hir-stats Stmt                      96 ( 1.1%)             3            32
+hir-stats - Local                     32 ( 0.4%)             1
+hir-stats - Semi                      32 ( 0.4%)             1
+hir-stats - Expr                      32 ( 0.4%)             1
 hir-stats FnDecl                   120 ( 1.3%)             3            40
 hir-stats Attribute                128 ( 1.4%)             4            32
 hir-stats GenericArg               128 ( 1.4%)             4            32
-hir-stats - Type                      32 ( 0.3%)             1
-hir-stats - Lifetime                  96 ( 1.0%)             3
+hir-stats - Type                      32 ( 0.4%)             1
+hir-stats - Lifetime                  96 ( 1.1%)             3
 hir-stats GenericArgs              144 ( 1.6%)             3            48
 hir-stats Variant                  176 ( 1.9%)             2            88
 hir-stats GenericBound             192 ( 2.1%)             4            48
 hir-stats - Trait                    192 ( 2.1%)             4
 hir-stats WherePredicate           192 ( 2.1%)             3            64
 hir-stats - BoundPredicate           192 ( 2.1%)             3
-hir-stats Block                    288 ( 3.1%)             6            48
-hir-stats Pat                      360 ( 3.9%)             5            72
+hir-stats Block                    288 ( 3.2%)             6            48
+hir-stats Pat                      360 ( 4.0%)             5            72
 hir-stats - Wild                      72 ( 0.8%)             1
 hir-stats - Struct                    72 ( 0.8%)             1
 hir-stats - Binding                  216 ( 2.4%)             3
 hir-stats GenericParam             400 ( 4.4%)             5            80
-hir-stats Generics                 560 ( 6.1%)            10            56
-hir-stats Ty                       720 ( 7.9%)            15            48
+hir-stats Generics                 560 ( 6.2%)            10            56
+hir-stats Ty                       720 ( 8.0%)            15            48
 hir-stats - Ptr                       48 ( 0.5%)             1
 hir-stats - Rptr                      48 ( 0.5%)             1
-hir-stats - Path                     624 ( 6.8%)            13
-hir-stats Expr                     768 ( 8.4%)            12            64
+hir-stats - Path                     624 ( 6.9%)            13
+hir-stats Expr                     768 ( 8.5%)            12            64
 hir-stats - Path                      64 ( 0.7%)             1
 hir-stats - Struct                    64 ( 0.7%)             1
 hir-stats - Match                     64 ( 0.7%)             1
 hir-stats - InlineAsm                 64 ( 0.7%)             1
 hir-stats - Lit                      128 ( 1.4%)             2
 hir-stats - Block                    384 ( 4.2%)             6
-hir-stats Item                     960 (10.5%)            12            80
+hir-stats Item                     880 ( 9.7%)            11            80
 hir-stats - Trait                     80 ( 0.9%)             1
 hir-stats - Enum                      80 ( 0.9%)             1
 hir-stats - ExternCrate               80 ( 0.9%)             1
 hir-stats - ForeignMod                80 ( 0.9%)             1
 hir-stats - Impl                      80 ( 0.9%)             1
-hir-stats - Fn                       160 ( 1.7%)             2
-hir-stats - Use                      400 ( 4.4%)             5
-hir-stats Path                   1_280 (14.0%)            32            40
-hir-stats PathSegment            1_920 (20.9%)            40            48
+hir-stats - Fn                       160 ( 1.8%)             2
+hir-stats - Use                      320 ( 3.5%)             4
+hir-stats Path                   1_240 (13.7%)            31            40
+hir-stats PathSegment            1_920 (21.2%)            40            48
 hir-stats ----------------------------------------------------------------
-hir-stats Total                  9_168
+hir-stats Total                  9_048
 hir-stats
diff --git a/src/tools/clippy/clippy_lints/src/single_component_path_imports.rs b/src/tools/clippy/clippy_lints/src/single_component_path_imports.rs
index 2036e85db7e..d46f6a6352c 100644
--- a/src/tools/clippy/clippy_lints/src/single_component_path_imports.rs
+++ b/src/tools/clippy/clippy_lints/src/single_component_path_imports.rs
@@ -149,7 +149,7 @@ impl SingleComponentPathImports {
 
                 // keep track of `use some_module;` usages
                 if segments.len() == 1 {
-                    if let UseTreeKind::Simple(None, _, _) = use_tree.kind {
+                    if let UseTreeKind::Simple(None) = use_tree.kind {
                         let name = segments[0].ident.name;
                         if !macros.contains(&name) {
                             single_use_usages.push(SingleUse {
@@ -169,7 +169,7 @@ impl SingleComponentPathImports {
                         for tree in trees {
                             let segments = &tree.0.prefix.segments;
                             if segments.len() == 1 {
-                                if let UseTreeKind::Simple(None, _, _) = tree.0.kind {
+                                if let UseTreeKind::Simple(None) = tree.0.kind {
                                     let name = segments[0].ident.name;
                                     if !macros.contains(&name) {
                                         single_use_usages.push(SingleUse {
diff --git a/src/tools/clippy/clippy_lints/src/unnecessary_self_imports.rs b/src/tools/clippy/clippy_lints/src/unnecessary_self_imports.rs
index bc0dd263d88..397633f533b 100644
--- a/src/tools/clippy/clippy_lints/src/unnecessary_self_imports.rs
+++ b/src/tools/clippy/clippy_lints/src/unnecessary_self_imports.rs
@@ -57,7 +57,7 @@ impl EarlyLintPass for UnnecessarySelfImports {
                             format!(
                                 "{}{};",
                                 last_segment.ident,
-                                if let UseTreeKind::Simple(Some(alias), ..) = self_tree.kind { format!(" as {alias}") } else { String::new() },
+                                if let UseTreeKind::Simple(Some(alias)) = self_tree.kind { format!(" as {alias}") } else { String::new() },
                             ),
                             Applicability::MaybeIncorrect,
                         );
diff --git a/src/tools/clippy/clippy_lints/src/unsafe_removed_from_name.rs b/src/tools/clippy/clippy_lints/src/unsafe_removed_from_name.rs
index 95258652768..7ee785804f0 100644
--- a/src/tools/clippy/clippy_lints/src/unsafe_removed_from_name.rs
+++ b/src/tools/clippy/clippy_lints/src/unsafe_removed_from_name.rs
@@ -39,7 +39,7 @@ impl EarlyLintPass for UnsafeNameRemoval {
 
 fn check_use_tree(use_tree: &UseTree, cx: &EarlyContext<'_>, span: Span) {
     match use_tree.kind {
-        UseTreeKind::Simple(Some(new_name), ..) => {
+        UseTreeKind::Simple(Some(new_name)) => {
             let old_name = use_tree
                 .prefix
                 .segments
@@ -48,7 +48,7 @@ fn check_use_tree(use_tree: &UseTree, cx: &EarlyContext<'_>, span: Span) {
                 .ident;
             unsafe_to_safe_check(old_name, new_name, cx, span);
         },
-        UseTreeKind::Simple(None, ..) | UseTreeKind::Glob => {},
+        UseTreeKind::Simple(None) | UseTreeKind::Glob => {},
         UseTreeKind::Nested(ref nested_use_tree) => {
             for (use_tree, _) in nested_use_tree {
                 check_use_tree(use_tree, cx, span);
diff --git a/src/tools/clippy/clippy_utils/src/ast_utils.rs b/src/tools/clippy/clippy_utils/src/ast_utils.rs
index 6bcf0bbd7eb..49e5f283db0 100644
--- a/src/tools/clippy/clippy_utils/src/ast_utils.rs
+++ b/src/tools/clippy/clippy_utils/src/ast_utils.rs
@@ -566,7 +566,7 @@ pub fn eq_use_tree_kind(l: &UseTreeKind, r: &UseTreeKind) -> bool {
     use UseTreeKind::*;
     match (l, r) {
         (Glob, Glob) => true,
-        (Simple(l, _, _), Simple(r, _, _)) => both(l, r, |l, r| eq_id(*l, *r)),
+        (Simple(l), Simple(r)) => both(l, r, |l, r| eq_id(*l, *r)),
         (Nested(l), Nested(r)) => over(l, r, |(l, _), (r, _)| eq_use_tree(l, r)),
         _ => false,
     }
diff --git a/src/tools/clippy/tests/ui/macro_use_imports.stderr b/src/tools/clippy/tests/ui/macro_use_imports.stderr
index bf7b6edd0e3..61843124ccd 100644
--- a/src/tools/clippy/tests/ui/macro_use_imports.stderr
+++ b/src/tools/clippy/tests/ui/macro_use_imports.stderr
@@ -1,8 +1,8 @@
 error: `macro_use` attributes are no longer needed in the Rust 2018 edition
-  --> $DIR/macro_use_imports.rs:23:5
+  --> $DIR/macro_use_imports.rs:25:5
    |
 LL |     #[macro_use]
-   |     ^^^^^^^^^^^^ help: remove the attribute and import the macro directly, try: `use mac::{inner::foofoo, inner::try_err};`
+   |     ^^^^^^^^^^^^ help: remove the attribute and import the macro directly, try: `use mac::inner::nested::string_add;`
    |
    = note: `-D clippy::macro-use-imports` implied by `-D warnings`
 
@@ -13,10 +13,10 @@ LL |     #[macro_use]
    |     ^^^^^^^^^^^^ help: remove the attribute and import the macro directly, try: `use mini_mac::ClippyMiniMacroTest;`
 
 error: `macro_use` attributes are no longer needed in the Rust 2018 edition
-  --> $DIR/macro_use_imports.rs:25:5
+  --> $DIR/macro_use_imports.rs:23:5
    |
 LL |     #[macro_use]
-   |     ^^^^^^^^^^^^ help: remove the attribute and import the macro directly, try: `use mac::inner::nested::string_add;`
+   |     ^^^^^^^^^^^^ help: remove the attribute and import the macro directly, try: `use mac::{inner::foofoo, inner::try_err};`
 
 error: `macro_use` attributes are no longer needed in the Rust 2018 edition
   --> $DIR/macro_use_imports.rs:19:5
diff --git a/src/tools/rustfmt/src/imports.rs b/src/tools/rustfmt/src/imports.rs
index b6530c69243..d9dc8d004af 100644
--- a/src/tools/rustfmt/src/imports.rs
+++ b/src/tools/rustfmt/src/imports.rs
@@ -490,7 +490,7 @@ impl UseTree {
                 );
                 result.path.push(UseSegment { kind, version });
             }
-            UseTreeKind::Simple(ref rename, ..) => {
+            UseTreeKind::Simple(ref rename) => {
                 // If the path has leading double colons and is composed of only 2 segments, then we
                 // bypass the call to path_to_imported_ident which would get only the ident and
                 // lose the path root, e.g., `that` in `::that`.