Suppress suggest swapping the equality in extern macro

Signed-off-by: xizheyin <xizheyin@smail.nju.edu.cn>

Author: xizheyin

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -3636,7 +3636,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 .must_apply_modulo_regions()
         {
             let sm = self.tcx.sess.source_map();
-            if let Ok(rhs_snippet) = sm.span_to_snippet(rhs_expr.span)
+            // If the span of rhs_expr or lhs_expr is in an external macro,
+            // we just suppress the suggestion. See issue #139050
+            if !rhs_expr.span.in_external_macro(sm)
+                && !lhs_expr.span.in_external_macro(sm)
+                && let Ok(rhs_snippet) = sm.span_to_snippet(rhs_expr.span)
                 && let Ok(lhs_snippet) = sm.span_to_snippet(lhs_expr.span)
             {
                 err.note(format!("`{rhs_ty}` implements `PartialEq<{lhs_ty}>`"));

tests/ui/typeck/sugg-swap-equality-in-macro-issue-139050.stderr

@@ -12,14 +12,7 @@ LL |     ext::eq!(assert iter.next(), Some(value));
    |
    = note: expected enum `Option<_>`
               found enum `Option<&_>`
-   = note: `Option<&<I as Iterator>::Item>` implements `PartialEq<Option<<I as Iterator>::Item>>`
    = note: this error originates in the macro `ext::eq` (in Nightly builds, run with -Z macro-backtrace for more info)
-help: consider swapping the equality
-  --> $DIR/auxiliary/extern-macro-issue-139050.rs:6:22
-   |
-LL -                 if !(*left_val == *right_val) {
-LL +                 if !(*right_val == *left_val) {
-   |
 
 error[E0308]: mismatched types
   --> $DIR/sugg-swap-equality-in-macro-issue-139050.rs:15:35