Find the correct span in suggesting using clone

Signed-off-by: xizheyin <[email protected]>

Author: xizheyin

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -1297,17 +1297,28 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 )
                 .must_apply_modulo_regions()
         {
-            let suggestion = match self.tcx.hir_maybe_get_struct_pattern_shorthand_field(expr) {
-                Some(ident) => format!(": {ident}.clone()"),
-                None => ".clone()".to_string(),
-            };
+            let (suggestion, shorthand) =
+                match self.tcx.hir_maybe_get_struct_pattern_shorthand_field(expr) {
+                    Some(ident) => (format!(": {ident}.clone()"), Some(ident)),
+                    None => (".clone()".to_string(), None),
+                };
 
-            diag.span_suggestion_verbose(
-                expr.span.shrink_to_hi(),
-                "consider using clone here",
-                suggestion,
-                Applicability::MachineApplicable,
-            );
+            let span = expr.span.find_oldest_ancestor_in_same_ctxt().shrink_to_hi();
+
+            if expr.span.from_expansion()
+                && let Some(ident) = shorthand
+            {
+                let suggestion =
+                    format!("bind the field to a variable: let {ident} = {ident}.clone();");
+                diag.span_help(span, suggestion);
+            } else {
+                diag.span_suggestion_verbose(
+                    span,
+                    "consider using clone here",
+                    suggestion,
+                    Applicability::MachineApplicable,
+                );
+            }
             return true;
         }
         false

tests/ui/typeck/suggestions/suggest-clone-in-macro-issue-139253.rs

@@ -16,4 +16,4 @@ fn test1() {
     let c: S = dbg!(dbg!(field)); //~ ERROR mismatched types [E0308]
 }
 
-fn main() {}
+fn main() {}

tests/ui/typeck/suggestions/suggest-clone-in-macro-issue-139253.stderr

@@ -27,6 +27,10 @@ LL |     let c: S = dbg!(field);
    |                ^^^^^^^^^^^ expected `S`, found `&S`
    |
    = note: this error originates in the macro `dbg` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider using clone here
+   |
+LL |     let c: S = dbg!(field).clone();
+   |                           ++++++++
 
 error[E0308]: mismatched types
   --> $DIR/suggest-clone-in-macro-issue-139253.rs:16:16
@@ -35,6 +39,10 @@ LL |     let c: S = dbg!(dbg!(field));
    |                ^^^^^^^^^^^^^^^^^ expected `S`, found `&S`
    |
    = note: this error originates in the macro `dbg` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider using clone here
+   |
+LL |     let c: S = dbg!(dbg!(field)).clone();
+   |                                 ++++++++
 
 error: aborting due to 4 previous errors