Suppress the error for private fields with non_exhaustive attribute

Author: chenyukang

compiler/rustc_hir_typeck/src/expr.rs

@@ -2331,7 +2331,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
             };
             self.typeck_results.borrow_mut().fru_field_types_mut().insert(expr.hir_id, fru_tys);
-        } else if adt_kind != AdtKind::Union && !remaining_fields.is_empty() {
+        } else if adt_kind != AdtKind::Union
+            && !remaining_fields.is_empty()
+            //~ non_exhaustive already reported, which will only happen for extern modules
+            && !variant.field_list_has_applicable_non_exhaustive()
+        {
             debug!(?remaining_fields);
             let private_fields: Vec<&ty::FieldDef> = variant
                 .fields

tests/ui/privacy/auxiliary/non_exhaustive_with_private.rs

@@ -0,0 +1,13 @@
+// Auxiliary crate for testing non-exhaustive struct with private fields
+
+#[non_exhaustive]
+pub struct Foo {
+    pub my_field: u32,
+    private_field: i32,
+}
+
+#[non_exhaustive]
+pub struct Bar {
+    pub my_field: u32,
+    pub missing_field: i32,
+}

tests/ui/privacy/non-exhaustive-with-private-fields-147513.rs

@@ -0,0 +1,22 @@
+//@ aux-build:non_exhaustive_with_private.rs
+
+// Test that creating a non-exhaustive struct from another crate
+// with private fields produces both errors:
+// 1. E0639: cannot create non-exhaustive struct using struct expression
+// 2. Error about private fields
+
+extern crate non_exhaustive_with_private;
+
+use non_exhaustive_with_private::{Bar, Foo};
+
+fn main() {
+    let foo = Foo {
+        //~^ ERROR cannot create non-exhaustive struct using struct expression
+        my_field: 10,
+    };
+
+    let bar = Bar {
+        //~^ ERROR cannot create non-exhaustive struct using struct expression
+        my_field: 10,
+    };
+}

tests/ui/privacy/non-exhaustive-with-private-fields-147513.stderr

@@ -0,0 +1,23 @@
+error[E0639]: cannot create non-exhaustive struct using struct expression
+  --> $DIR/non-exhaustive-with-private-fields-147513.rs:13:15
+   |
+LL |       let foo = Foo {
+   |  _______________^
+LL | |
+LL | |         my_field: 10,
+LL | |     };
+   | |_____^
+
+error[E0639]: cannot create non-exhaustive struct using struct expression
+  --> $DIR/non-exhaustive-with-private-fields-147513.rs:18:15
+   |
+LL |       let bar = Bar {
+   |  _______________^
+LL | |
+LL | |         my_field: 10,
+LL | |     };
+   | |_____^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0639`.