From c41b2089c7a059a7ce86107b8f3528c05ca11254 Mon Sep 17 00:00:00 2001
From: bohan <bohan-zhang@foxmail.com>
Date: Fri, 19 May 2023 21:12:08 +0800
Subject: [PATCH] fix(resolve): not defined `extern crate shadow_name`

---
 compiler/rustc_resolve/src/build_reduced_graph.rs |  5 +++++
 compiler/rustc_resolve/src/lib.rs                 |  2 +-
 tests/ui/imports/issue-109148.rs                  | 15 +++++++++++++++
 tests/ui/imports/issue-109148.stderr              | 13 +++++++++++++
 4 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 tests/ui/imports/issue-109148.rs
 create mode 100644 tests/ui/imports/issue-109148.stderr

diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
index 08b73ebb69470..b3d0e4ba25894 100644
--- a/compiler/rustc_resolve/src/build_reduced_graph.rs
+++ b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -873,6 +873,11 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
                     let msg = "macro-expanded `extern crate` items cannot \
                                        shadow names passed with `--extern`";
                     self.r.tcx.sess.span_err(item.span, msg);
+                    // `return` is intended to discard this binding because it's an
+                    // unregistered ambiguity error which would result in a panic
+                    // caused by inconsistency `path_res`
+                    // more details: https://github.com/rust-lang/rust/pull/111761
+                    return;
                 }
             }
             let entry = self.r.extern_prelude.entry(ident.normalize_to_macros_2_0()).or_insert(
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 3cdc3f0ecf892..1e31a0ff27824 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -106,7 +106,7 @@ impl Determinacy {
 /// A specific scope in which a name can be looked up.
 /// This enum is currently used only for early resolution (imports and macros),
 /// but not for late resolution yet.
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Debug)]
 enum Scope<'a> {
     DeriveHelpers(LocalExpnId),
     DeriveHelpersCompat,
diff --git a/tests/ui/imports/issue-109148.rs b/tests/ui/imports/issue-109148.rs
new file mode 100644
index 0000000000000..694cb494a15dc
--- /dev/null
+++ b/tests/ui/imports/issue-109148.rs
@@ -0,0 +1,15 @@
+// edition: 2021
+
+// https://github.com/rust-lang/rust/pull/111761#issuecomment-1557777314
+macro_rules! m {
+    () => {
+        extern crate core as std;
+        //~^ ERROR macro-expanded `extern crate` items cannot shadow names passed with `--extern`
+    }
+}
+
+m!();
+
+use std::mem;
+
+fn main() {}
diff --git a/tests/ui/imports/issue-109148.stderr b/tests/ui/imports/issue-109148.stderr
new file mode 100644
index 0000000000000..6cc1221cfe993
--- /dev/null
+++ b/tests/ui/imports/issue-109148.stderr
@@ -0,0 +1,13 @@
+error: macro-expanded `extern crate` items cannot shadow names passed with `--extern`
+  --> $DIR/issue-109148.rs:6:9
+   |
+LL |         extern crate core as std;
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | m!();
+   | ---- in this macro invocation
+   |
+   = note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to previous error
+