Fix invalid suggestion from type error for derive macro

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -23,7 +23,7 @@ use rustc_middle::ty::{
 };
 use rustc_session::errors::ExprParenthesesNeeded;
 use rustc_span::source_map::Spanned;
-use rustc_span::{Ident, Span, Symbol, sym};
+use rustc_span::{ExpnKind, Ident, MacroKind, Span, Symbol, sym};
 use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
 use rustc_trait_selection::error_reporting::traits::DefIdOrName;
 use rustc_trait_selection::infer::InferCtxtExt;
@@ -1365,6 +1365,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 self.param_env,
                 ty::TraitRef::new(self.tcx, into_def_id, [expr_ty, expected_ty]),
             ))
+            && !expr
+                .span
+                .macro_backtrace()
+                .any(|x| matches!(x.kind, ExpnKind::Macro(MacroKind::Attr | MacroKind::Derive, ..)))
         {
             let span = expr.span.find_oldest_ancestor_in_same_ctxt();
 
@@ -1380,10 +1384,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 sugg.insert(0, (expr.span.shrink_to_lo(), format!("{}: ", name)));
             }
             diag.multipart_suggestion(
-                format!("call `Into::into` on this expression to convert `{expr_ty}` into `{expected_ty}`"),
-                sugg,
-                Applicability::MaybeIncorrect
-            );
+                    format!("call `Into::into` on this expression to convert `{expr_ty}` into `{expected_ty}`"),
+                    sugg,
+                    Applicability::MaybeIncorrect
+                );
             return true;
         }
 

tests/ui/typeck/auxiliary/derive-demo-issue-136343.rs

@@ -0,0 +1,7 @@
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro_derive(Sample)]
+pub fn sample(_: TokenStream) -> TokenStream {
+    "fn bad<T: Into<U>, U>(a: T) -> U { a }".parse().unwrap()
+}

tests/ui/typeck/invalid-sugg-for-derive-macro-issue-136343.rs

@@ -0,0 +1,9 @@
+//@ proc-macro: derive-demo-issue-136343.rs
+
+#[macro_use]
+extern crate derive_demo_issue_136343;
+
+#[derive(Sample)] //~ ERROR mismatched types
+struct Test;
+
+fn main() {}

tests/ui/typeck/invalid-sugg-for-derive-macro-issue-136343.stderr

@@ -0,0 +1,19 @@
+error[E0308]: mismatched types
+  --> $DIR/invalid-sugg-for-derive-macro-issue-136343.rs:6:10
+   |
+LL | #[derive(Sample)]
+   |          ^^^^^^
+   |          |
+   |          expected type parameter `U`, found type parameter `T`
+   |          expected `U` because of return type
+   |
+   = note: expected type parameter `U`
+              found type parameter `T`
+   = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
+   = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
+   = note: the caller chooses a type for `U` which can be different from `T`
+   = note: this error originates in the derive macro `Sample` (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 E0308`.