From 0e24cee063e7e37d31929faaefaf5ded1732e6e1 Mon Sep 17 00:00:00 2001
From: yukang <moorekang@gmail.com>
Date: Thu, 1 Dec 2022 02:21:48 +0800
Subject: [PATCH] fix #105028, Only suggest removing struct field from
 destructive binding in shorthand scenario

---
 compiler/rustc_passes/src/liveness.rs            |  8 +++++++-
 .../ui/suggestions/try-removing-the-field.rs     | 15 +++++++++++++++
 .../ui/suggestions/try-removing-the-field.stderr | 16 +++++++++++++++-
 3 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/compiler/rustc_passes/src/liveness.rs b/compiler/rustc_passes/src/liveness.rs
index 2234837050bd9..1f65cc8b60967 100644
--- a/compiler/rustc_passes/src/liveness.rs
+++ b/compiler/rustc_passes/src/liveness.rs
@@ -1548,7 +1548,13 @@ impl<'tcx> Liveness<'_, 'tcx> {
                 .or_insert_with(|| (ln, var, vec![id_and_sp]));
         });
 
-        let can_remove = matches!(&pat.kind, hir::PatKind::Struct(_, _, true));
+        let can_remove = match pat.kind {
+            hir::PatKind::Struct(_, fields, true) => {
+                // if all fields are shorthand, remove the struct field, otherwise, mark with _ as prefix
+                fields.iter().all(|f| f.is_shorthand)
+            }
+            _ => false,
+        };
 
         for (_, (ln, var, hir_ids_and_spans)) in vars {
             if self.used_on_entry(ln, var) {
diff --git a/src/test/ui/suggestions/try-removing-the-field.rs b/src/test/ui/suggestions/try-removing-the-field.rs
index 9d0573ca2554d..1b7289b229b5d 100644
--- a/src/test/ui/suggestions/try-removing-the-field.rs
+++ b/src/test/ui/suggestions/try-removing-the-field.rs
@@ -14,4 +14,19 @@ fn use_foo(x: Foo) -> i32 {
     return foo;
 }
 
+// issue #105028, suggest removing the field only for shorthand
+fn use_match(x: Foo) {
+    match x {
+        Foo { foo: unused, .. } => { //~ WARNING unused variable
+                                     //~| help: if this is intentional, prefix it with an underscore
+        }
+    }
+
+    match x {
+        Foo { foo, .. } => { //~ WARNING unused variable
+                             //~| help: try removing the field
+        }
+    }
+}
+
 fn main() {}
diff --git a/src/test/ui/suggestions/try-removing-the-field.stderr b/src/test/ui/suggestions/try-removing-the-field.stderr
index 448a2c3d2ec27..7a6013d4a6eab 100644
--- a/src/test/ui/suggestions/try-removing-the-field.stderr
+++ b/src/test/ui/suggestions/try-removing-the-field.stderr
@@ -8,5 +8,19 @@ LL |     let Foo { foo, bar, .. } = x;
    |
    = note: `#[warn(unused_variables)]` on by default
 
-warning: 1 warning emitted
+warning: unused variable: `unused`
+  --> $DIR/try-removing-the-field.rs:20:20
+   |
+LL |         Foo { foo: unused, .. } => {
+   |                    ^^^^^^ help: if this is intentional, prefix it with an underscore: `_unused`
+
+warning: unused variable: `foo`
+  --> $DIR/try-removing-the-field.rs:26:15
+   |
+LL |         Foo { foo, .. } => {
+   |               ^^^-
+   |               |
+   |               help: try removing the field
+
+warning: 3 warnings emitted