Fix ICE #149821: Handle inconsistent resolution gracefully

Author: Delta17920

compiler/rustc_resolve/src/imports.rs

@@ -1171,7 +1171,16 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         }
                         if let Some(initial_res) = initial_res {
                             if res != initial_res {
-                                span_bug!(import.span, "inconsistent resolution for an import");
+                                // If we already have errors, ignore the inconsistency.
+                                if this.dcx().has_errors().is_some() {
+                                    return;
+                                }
+
+                                this.dcx().span_delayed_bug(
+                                    import.span,
+                                    "inconsistent resolution for an import",
+                                );
+                                return;
                             }
                         } else if this.privacy_errors.is_empty() {
                             this.dcx()

tests/ui/resolve/ice-inconsistent-resolution-149821.rs

@@ -0,0 +1,17 @@
+//@ edition: 2024
+
+mod m {
+    use crate::*;
+    use core;
+}
+
+macro_rules! define_other_core {
+    () => {
+        extern crate std as core;
+        //~^ ERROR macro-expanded `extern crate` items cannot shadow names passed with `--extern`
+    };
+}
+
+define_other_core! {}
+
+fn main() {}

tests/ui/resolve/ice-inconsistent-resolution-149821.stderr

@@ -0,0 +1,13 @@
+error: macro-expanded `extern crate` items cannot shadow names passed with `--extern`
+  --> $DIR/ice-inconsistent-resolution-149821.rs:10:9
+   |
+LL |         extern crate std as core;
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | define_other_core! {}
+   | --------------------- in this macro invocation
+   |
+   = note: this error originates in the macro `define_other_core` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 1 previous error
+