remove invalid suggestion of into_iter for extern macro

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -905,11 +905,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         } else if self.impl_into_iterator_should_be_iterator(rcvr_ty, span, unsatisfied_predicates)
         {
             err.span_label(span, format!("`{rcvr_ty}` is not an iterator"));
-            err.multipart_suggestion_verbose(
-                "call `.into_iter()` first",
-                vec![(span.shrink_to_lo(), format!("into_iter()."))],
-                Applicability::MaybeIncorrect,
-            );
+            if !span.in_external_macro(self.tcx.sess.source_map()) {
+                err.multipart_suggestion_verbose(
+                    "call `.into_iter()` first",
+                    vec![(span.shrink_to_lo(), format!("into_iter()."))],
+                    Applicability::MaybeIncorrect,
+                );
+            }
             return err.emit();
         } else if !unsatisfied_predicates.is_empty() && matches!(rcvr_ty.kind(), ty::Param(_)) {
             // We special case the situation where we are looking for `_` in

tests/ui/proc-macro/auxiliary/quote-issue-137345.rs

@@ -0,0 +1,19 @@
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+fn items() -> impl IntoIterator<Item = i32> {
+    vec![1, 2, 3]
+}
+
+#[macro_export]
+macro_rules! quote {
+    // Rule for any other number of tokens.
+    ($($tt:tt)*) => {{
+        fn items() -> impl IntoIterator<Item = i32> {
+            vec![1, 2, 3]
+        }
+        let _s = TokenStream::new();
+        let other_items = items().map(|i| i + 1);
+        _s
+    }};
+}

tests/ui/proc-macro/valid-sugg-issue-137345.rs

@@ -0,0 +1,17 @@
+//@ aux-crate: quote=quote-issue-137345.rs
+
+extern crate proc_macro;
+extern crate quote;
+
+use proc_macro::TokenStream;
+
+pub fn default_args_fn(_: TokenStream) -> TokenStream {
+    let decl_macro = TokenStream::new();
+
+    quote::quote! {
+        #(#decl_macro)*
+    }
+    .into() //~^^^ ERROR no method named `map` found for opaque type
+}
+
+fn main() {}

tests/ui/proc-macro/valid-sugg-issue-137345.stderr

@@ -0,0 +1,13 @@
+error[E0599]: no method named `map` found for opaque type `impl IntoIterator<Item = i32>` in the current scope
+  --> $DIR/valid-sugg-issue-137345.rs:11:5
+   |
+LL | /     quote::quote! {
+LL | |         #(#decl_macro)*
+LL | |     }
+   | |_____^ `impl IntoIterator<Item = i32>` is not an iterator
+   |
+   = note: this error originates in the macro `quote::quote` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0599`.