Remove duplicate error about raw underscore lifetime

compiler/rustc_resolve/src/late.rs

@@ -2902,7 +2902,16 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                     }
                 }
 
-                if param.ident.name == kw::UnderscoreLifetime {
+                // To avoid emitting two duplicate errors, we need to check if the span is a raw underscore lifetime, see issue #143152
+                let is_raw_underscore = self
+                    .r
+                    .tcx
+                    .sess
+                    .psess
+                    .raw_identifier_spans
+                    .iter()
+                    .any(|span| span == param.span());
+                if param.ident.name == kw::UnderscoreLifetime && !is_raw_underscore {
                     self.r
                         .dcx()
                         .emit_err(errors::UnderscoreLifetimeIsReserved { span: param.ident.span });

tests/ui/underscore-lifetime/raw-underscore-lifetime.rs

@@ -0,0 +1,9 @@
+// This test is to ensure that the raw underscore lifetime won't emit two duplicate errors.
+// See issue #143152
+
+//@ edition: 2021
+
+fn f<'r#_>(){}
+//~^ ERROR `_` cannot be a raw lifetime
+
+fn main() {}

tests/ui/underscore-lifetime/raw-underscore-lifetime.stderr

@@ -0,0 +1,8 @@
+error: `_` cannot be a raw lifetime
+  --> $DIR/raw-underscore-lifetime.rs:6:6
+   |
+LL | fn f<'r#_>(){}
+   |      ^^^^
+
+error: aborting due to 1 previous error
+