fix incorrect suggestions in private import diagnostic

compiler/rustc_resolve/src/diagnostics.rs

@@ -2483,6 +2483,11 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 // `tests/ui/imports/issue-55884-2.rs`
                 continue;
             }
+            // In nested imports `dedup_span` is just the inner ident, so a full path
+            // substitution would produce invalid code. See #156060.
+            if single_nested {
+                break;
+            }
             let path = join_path_idents(sugg);
             let sugg = if reexport {
                 errors::ImportIdent::ThroughReExport { span: dedup_span, ident, path }

tests/ui/imports/private-import-nested-suggestion-156060.rs

@@ -0,0 +1,17 @@
+// Regression test for #156060.
+
+mod one {
+    pub struct One();
+}
+
+mod two {
+    use crate::one::One;
+    pub struct Two();
+}
+
+mod test {
+    use crate::two::{One, Two};
+    //~^ ERROR struct import `One` is private [E0603]
+}
+
+fn main() {}

tests/ui/imports/private-import-nested-suggestion-156060.stderr

@@ -0,0 +1,20 @@
+error[E0603]: struct import `One` is private
+  --> $DIR/private-import-nested-suggestion-156060.rs:13:22
+   |
+LL |     use crate::two::{One, Two};
+   |                      ^^^ private struct import
+   |
+note: the struct import `One` is defined here...
+  --> $DIR/private-import-nested-suggestion-156060.rs:8:9
+   |
+LL |     use crate::one::One;
+   |         ^^^^^^^^^^^^^^^
+note: ...and refers to the struct `One` which is defined here
+  --> $DIR/private-import-nested-suggestion-156060.rs:4:5
+   |
+LL |     pub struct One();
+   |     ^^^^^^^^^^^^^^^^^ you could import this directly
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0603`.