resolve: Relax some asserts in glob overwriting and add tests #150939

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Merged

rust-bors merged 4 commits into rust-lang:main from petrochenkov:impasse

Jan 15, 2026

compiler/rustc_resolve/src/diagnostics.rs

-Original file line number
+Diff line change
@@ Expand Up / @@ -212,12 +212,12 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> { @@
             &mut self,
             ident: Ident,
             ns: Namespace,
-            new_binding: Decl<'ra>,
             old_binding: Decl<'ra>,
+            new_binding: Decl<'ra>,
         ) {
             // Error on the second of two conflicting names
             if old_binding.span.lo() > new_binding.span.lo() {
-                return self.report_conflict(ident, ns, old_binding, new_binding);
+                return self.report_conflict(ident, ns, new_binding, old_binding);
             }
             let container = match old_binding.parent_module.unwrap().kind {
@@ Expand Down @@

compiler/rustc_resolve/src/imports.rs

            
                      Original file line number
                      Diff line number
                      Diff line change
                  
    @@ -300,13 +300,16 @@ fn remove_same_import<'ra>(d1: Decl<'ra>, d2: Decl<'ra>) -> (Decl<'ra>, Decl<'ra
  
        if let DeclKind::Import { import: import1, source_decl: d1_next } = d1.kind

            && let DeclKind::Import { import: import2, source_decl: d2_next } = d2.kind

            && import1 == import2

            && d1.warn_ambiguity.get() == d2.warn_ambiguity.get()

        {

            assert_eq!(d1.ambiguity.get(), d2.ambiguity.get());

            assert!(!d1.warn_ambiguity.get());

            assert_eq!(d1.expansion, d2.expansion);

            assert_eq!(d1.span, d2.span);

            assert_eq!(d1.vis(), d2.vis());

            if d1.ambiguity.get() != d2.ambiguity.get() {

                assert!(d1.ambiguity.get().is_some());

                assert!(d2.ambiguity.get().is_none());

            }

            // Visibility of the new import declaration may be different,

            // because it already incorporates the visibility of the source binding.

            // `warn_ambiguity` of a re-fetched glob can also change in both directions.

            remove_same_import(d1_next, d2_next)

        } else {

            (d1, d2)

    @@ -348,8 +351,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
  
        /// decide which one to keep.

        fn select_glob_decl(

            &self,

            glob_decl: Decl<'ra>,

            old_glob_decl: Decl<'ra>,

            glob_decl: Decl<'ra>,

            warn_ambiguity: bool,

        ) -> Decl<'ra> {

            assert!(glob_decl.is_glob_import());

    @@ -369,14 +372,18 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
  
            // with the re-fetched decls.

            // This is probably incorrect in corner cases, and the outdated decls still get

            // propagated to other places and get stuck there, but that's what we have at the moment.

            let (deep_decl, old_deep_decl) = remove_same_import(glob_decl, old_glob_decl);

            let (old_deep_decl, deep_decl) = remove_same_import(old_glob_decl, glob_decl);

            if deep_decl != glob_decl {

                // Some import layers have been removed, need to overwrite.

                assert_ne!(old_deep_decl, old_glob_decl);

                // FIXME: reenable the asserts when `warn_ambiguity` is removed (#149195).

                // assert_ne!(old_deep_decl, deep_decl);

                // assert!(old_deep_decl.is_glob_import());

                assert!(!deep_decl.is_glob_import());

                if old_glob_decl.ambiguity.get().is_some() && glob_decl.ambiguity.get().is_none() {

                    // Do not lose glob ambiguities when re-fetching the glob.

                    glob_decl.ambiguity.set_unchecked(old_glob_decl.ambiguity.get());

                }

                if glob_decl.is_ambiguity_recursive() {

                    glob_decl.warn_ambiguity.set_unchecked(true);

                }

    @@ -436,7 +443,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
  
                    match (old_decl.is_glob_import(), decl.is_glob_import()) {

                        (true, true) => {

                            resolution.glob_decl =

                                Some(this.select_glob_decl(decl, old_decl, warn_ambiguity));

                                Some(this.select_glob_decl(old_decl, decl, warn_ambiguity));

                        }

                        (old_glob @ true, false) | (old_glob @ false, true) => {

                            let (glob_decl, non_glob_decl) =

    @@ -446,7 +453,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
  
                                && old_glob_decl != glob_decl

                            {

                                resolution.glob_decl =

                                    Some(this.select_glob_decl(glob_decl, old_glob_decl, false));

                                    Some(this.select_glob_decl(old_glob_decl, glob_decl, false));

                            } else {

                                resolution.glob_decl = Some(glob_decl);

                            }

tests/ui/hygiene/cross-crate-redefine.rs

-Original file line number
+Diff line change
@@ Expand Up / @@ -8,7 +8,7 @@ extern crate use_by_macro; @@
     use use_by_macro::*;
     my_struct!(define);
-    //~^ ERROR the name `MyStruct` is defined multiple times
     my_struct!(define);
+    //~^ ERROR the name `MyStruct` is defined multiple times
     fn main() {}

tests/ui/hygiene/cross-crate-redefine.stderr

-Original file line number
+Diff line change
@@ -1,11 +1,10 @@
     error[E0428]: the name `MyStruct` is defined multiple times
-      --> $DIR/cross-crate-redefine.rs:10:1
+      --> $DIR/cross-crate-redefine.rs:11:1
        |
-    LL | my_struct!(define);
-       | ^^^^^^^^^^^^^^^^^^ `MyStruct` redefined here
-    LL |
     LL | my_struct!(define);
        | ------------------ previous definition of the type `MyStruct` here
+    LL | my_struct!(define);
+       | ^^^^^^^^^^^^^^^^^^ `MyStruct` redefined here
        |
        = note: `MyStruct` must be defined only once in the type namespace of this module
        = note: this error originates in the macro `my_struct` (in Nightly builds, run with -Z macro-backtrace for more info)
@@ Expand Down @@

tests/ui/imports/overwrite-deep-glob.rs

-Original file line number
+Diff line change
@@ -0,0 +1,22 @@
+    //@ check-pass
+    mod openssl {
+        pub use self::handwritten::*;
+        mod handwritten {
+            mod m1 {
+                pub struct S {}
+            }
+            mod m2 {
+                #[derive(Default)]
+                pub struct S {}
+            }
+            pub use self::m1::*; //~ WARN ambiguous glob re-exports
+            pub use self::m2::*;
+        }
+    }
+    pub use openssl::*;
+    fn main() {}

tests/ui/imports/overwrite-deep-glob.stderr

-Original file line number
+Diff line change
@@ -0,0 +1,12 @@
+    warning: ambiguous glob re-exports
+      --> $DIR/overwrite-deep-glob.rs:15:17
+       |
+    LL |         pub use self::m1::*;
+       |                 ^^^^^^^^^^^ the name `S` in the type namespace is first re-exported here
+    LL |         pub use self::m2::*;
+       |                 ----------- but the name `S` in the type namespace is also re-exported here
+       |
+       = note: `#[warn(ambiguous_glob_reexports)]` on by default
+    warning: 1 warning emitted

tests/ui/imports/overwrite-different-ambig-2.rs

-Original file line number
+Diff line change
@@ -0,0 +1,24 @@
+    mod m1 {
+        mod inner {
+            pub struct S {}
+        }
+        pub use self::inner::*;
+        #[derive(Debug)]
+        pub struct S {}
+    }
+    mod m2 {
+        pub struct S {}
+    }
+    // First we have a glob ambiguity in this glob (with `m2::*`).
+    // Then we re-fetch `m1::*` because non-glob `m1::S` materializes from derive,
+    // and we need to make sure that the glob ambiguity is not lost during re-fetching.
+    use m1::*;
+    use m2::*;
+    fn main() {
+        let _: m1::S = S {}; //~ ERROR `S` is ambiguous
+                             //~| WARN this was previously accepted
+    }

tests/ui/imports/overwrite-different-ambig-2.stderr

-Original file line number
+Diff line change
@@ -0,0 +1,49 @@
+    error: `S` is ambiguous
+      --> $DIR/overwrite-different-ambig-2.rs:22:20
+       |
+    LL |     let _: m1::S = S {};
+       |                    ^ ambiguous name
+       |
+       = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+       = note: for more information, see issue #114095 <https://github.com/rust-lang/rust/issues/114095>
+       = note: ambiguous because of multiple glob imports of a name in the same module
+    note: `S` could refer to the struct imported here
+      --> $DIR/overwrite-different-ambig-2.rs:18:5
+       |
+    LL | use m1::*;
+       |     ^^^^^
+       = help: consider adding an explicit import of `S` to disambiguate
+    note: `S` could also refer to the struct imported here
+      --> $DIR/overwrite-different-ambig-2.rs:19:5
+       |
+    LL | use m2::*;
+       |     ^^^^^
+       = help: consider adding an explicit import of `S` to disambiguate
+       = note: `#[deny(ambiguous_glob_imports)]` (part of `#[deny(future_incompatible)]`) on by default
+    error: aborting due to 1 previous error
+    Future incompatibility report: Future breakage diagnostic:
+    error: `S` is ambiguous
+      --> $DIR/overwrite-different-ambig-2.rs:22:20
+       |
+    LL |     let _: m1::S = S {};
+       |                    ^ ambiguous name
+       |
+       = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+       = note: for more information, see issue #114095 <https://github.com/rust-lang/rust/issues/114095>
+       = note: ambiguous because of multiple glob imports of a name in the same module
+    note: `S` could refer to the struct imported here
+      --> $DIR/overwrite-different-ambig-2.rs:18:5
+       |
+    LL | use m1::*;
+       |     ^^^^^
+       = help: consider adding an explicit import of `S` to disambiguate
+    note: `S` could also refer to the struct imported here
+      --> $DIR/overwrite-different-ambig-2.rs:19:5
+       |
+    LL | use m2::*;
+       |     ^^^^^
+       = help: consider adding an explicit import of `S` to disambiguate
+       = note: `#[deny(ambiguous_glob_imports)]` (part of `#[deny(future_incompatible)]`) on by default

tests/ui/imports/overwrite-different-ambig.rs

-Original file line number
+Diff line change
@@ -0,0 +1,25 @@
+    //@ check-pass
+    //@ edition:2024
+    mod a {
+        mod b {
+            mod c {
+                pub struct E;
+            }
+            mod d {
+                mod c {
+                    pub struct E;
+                }
+                mod d {
+                    #[derive(Debug)]
+                    pub struct E;
+                }
+                pub use c::*;
+                use d::*;
+            }
+            use c::*;
+            use d::*;
+        }
+    }
+    fn main() {}

tests/ui/imports/overwrite-different-vis.rs

-Original file line number
+Diff line change
@@ -0,0 +1,21 @@
+    //@ check-pass
+    mod b {
+        pub mod http {
+            pub struct HeaderMap;
+        }
+        pub(crate) use self::http::*;
+        #[derive(Debug)]
+        pub struct HeaderMap;
+    }
+    mod a {
+        pub use crate::b::*;
+        fn check_type() {
+            let _: HeaderMap = crate::b::HeaderMap;
+        }
+    }
+    fn main() {}

tests/ui/imports/overwrite-different-warn-ambiguity.rs

-Original file line number
+Diff line change
@@ -0,0 +1,28 @@
+    //@ check-pass
+    //@ edition:2024
+    mod framing {
+        mod public_message_in {
+            mod public_message {
+                mod public_message {
+                    pub struct ConfirmedTranscriptHashInput;
+                }
+                mod public_message_in {
+                    use super::*;
+                    #[derive(Debug)]
+                    pub struct ConfirmedTranscriptHashInput;
+                }
+                pub use public_message::*;
+                use public_message_in::*;
+            }
+            mod public_message_in {
+                #[derive(Debug)]
+                pub struct ConfirmedTranscriptHashInput;
+            }
+            pub use public_message::*;
+            use public_message_in::*;
+        }
+        use public_message_in::*;
+    }
+    fn main() {}

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resolve: Relax some asserts in glob overwriting and add tests #150939

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