Fix #107113, avoid suggest for macro attributes

compiler/rustc_hir_typeck/src/demand.rs

@@ -880,6 +880,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected: Ty<'tcx>,
         expr_ty: Ty<'tcx>,
     ) -> bool {
+        if in_external_macro(self.tcx.sess, expr.span) {
+            return false;
+        }
         if let ty::Adt(expected_adt, args) = expected.kind() {
             if let hir::ExprKind::Field(base, ident) = expr.kind {
                 let base_ty = self.typeck_results.borrow().expr_ty(base);

compiler/rustc_middle/src/lint.rs

@@ -449,7 +449,11 @@ pub fn in_external_macro(sess: &Session, span: Span) -> bool {
     match expn_data.kind {
         ExpnKind::Root
         | ExpnKind::Desugaring(
-            DesugaringKind::ForLoop | DesugaringKind::WhileLoop | DesugaringKind::OpaqueTy,
+            DesugaringKind::ForLoop
+            | DesugaringKind::WhileLoop
+            | DesugaringKind::OpaqueTy
+            | DesugaringKind::Async
+            | DesugaringKind::Await,
         ) => false,
         ExpnKind::AstPass(_) | ExpnKind::Desugaring(_) => true, // well, it's "external"
         ExpnKind::Macro(MacroKind::Bang, _) => {

tests/ui/coercion/coerce-block-tail-83783.fixed

@@ -0,0 +1,13 @@
+// run-rustfix
+// edition:2018
+fn _consume_reference<T: ?Sized>(_: &T) {}
+
+async fn _foo() {
+    _consume_reference::<i32>(&Box::new(7_i32));
+    _consume_reference::<i32>(&*async { Box::new(7_i32) }.await);
+    //~^ ERROR mismatched types
+    _consume_reference::<[i32]>(&vec![7_i32]);
+    _consume_reference::<[i32]>(&async { vec![7_i32] }.await);
+}
+
+fn main() { }

tests/ui/coercion/coerce-block-tail-83783.rs

@@ -1,4 +1,4 @@
-// check-fail
+// run-rustfix
 // edition:2018
 fn _consume_reference<T: ?Sized>(_: &T) {}
 

tests/ui/coercion/coerce-block-tail-83783.stderr

@@ -6,6 +6,10 @@ LL |     _consume_reference::<i32>(&async { Box::new(7_i32) }.await);
    |
    = note: expected type `i32`
             found struct `Box<i32>`
+help: consider unboxing the value
+   |
+LL |     _consume_reference::<i32>(&*async { Box::new(7_i32) }.await);
+   |                                +
 
 error: aborting due to previous error
 

tests/ui/proc-macro/auxiliary/issue-107113.rs

@@ -0,0 +1,13 @@
+// force-host
+// no-prefer-dynamic
+
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+
+#[proc_macro_attribute]
+pub fn main(_: TokenStream, item: TokenStream) -> TokenStream {
+    "fn main() -> std::io::Result<()> { () } ".parse().unwrap()
+}

tests/ui/proc-macro/issue-107113-wrap.rs

@@ -0,0 +1,8 @@
+// edition:2021
+// aux-build:issue-107113.rs
+
+#[macro_use]
+extern crate issue_107113;
+
+#[issue_107113::main] //~ ERROR mismatched types [E0308]
+async fn main() -> std::io::Result<()> {}

tests/ui/proc-macro/issue-107113-wrap.stderr

@@ -0,0 +1,16 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-107113-wrap.rs:7:1
+   |
+LL | #[issue_107113::main]
+   | ^^^^^^^^^^^^^^^^^^^^^
+   | |
+   | expected `Result<(), Error>`, found `()`
+   | expected `Result<(), std::io::Error>` because of return type
+   |
+   = note:   expected enum `Result<(), std::io::Error>`
+           found unit type `()`
+   = note: this error originates in the attribute macro `issue_107113::main` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.