Rollup merge of rust-lang#82090 - notriddle:consider-using-a-semicolon-here, r=estebank

Do not consider using a semicolon inside of a different-crate macro

Fixes rust-lang#81943

Author: Dylan-DPC

compiler/rustc_typeck/src/check/coercion.rs

@@ -42,6 +42,7 @@ use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::{Coercion, InferOk, InferResult};
+use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::adjustment::{
     Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability, PointerCast,
 };
@@ -1448,7 +1449,12 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
                 expected.is_unit(),
                 pointing_at_return_type,
             ) {
-                if cond_expr.span.desugaring_kind().is_none() {
+                // If the block is from an external macro, then do not suggest
+                // adding a semicolon, because there's nowhere to put it.
+                // See issue #81943.
+                if cond_expr.span.desugaring_kind().is_none()
+                    && !in_external_macro(fcx.tcx.sess, cond_expr.span)
+                {
                     err.span_label(cond_expr.span, "expected this to be `()`");
                     if expr.can_have_side_effects() {
                         fcx.suggest_semicolon_at_end(cond_expr.span, &mut err);

src/test/ui/typeck/issue-81943.rs

@@ -0,0 +1,9 @@
+fn f<F: Fn(i32)>(f: F) { f(0); }
+fn main() {
+  f(|x| dbg!(x)); //~ERROR
+  f(|x| match x { tmp => { tmp } }); //~ERROR
+  macro_rules! d {
+    ($e:expr) => { match $e { x => { x } } } //~ERROR
+  }
+  f(|x| d!(x));
+}

src/test/ui/typeck/issue-81943.stderr

@@ -0,0 +1,34 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-81943.rs:3:9
+   |
+LL |   f(|x| dbg!(x));
+   |         ^^^^^^^ expected `()`, found `i32`
+   |
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0308]: mismatched types
+  --> $DIR/issue-81943.rs:4:28
+   |
+LL |   f(|x| match x { tmp => { tmp } });
+   |         -------------------^^^----- help: consider using a semicolon here
+   |         |                  |
+   |         |                  expected `()`, found `i32`
+   |         expected this to be `()`
+
+error[E0308]: mismatched types
+  --> $DIR/issue-81943.rs:6:38
+   |
+LL |     ($e:expr) => { match $e { x => { x } } }
+   |                    ------------------^----- help: consider using a semicolon here
+   |                    |                 |
+   |                    |                 expected `()`, found `i32`
+   |                    expected this to be `()`
+LL |   }
+LL |   f(|x| d!(x));
+   |         ----- in this macro invocation
+   |
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.