fix type suggestions in match arms

rust-lang · bors · Mar 27, 2023 · Jun 29, 2022 · May 29, 2022 · Mar 12, 2023
commit 08f3deb3d5a2164d8a601d37c87f2453b2f09eed
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -1942,7 +1942,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     escaped
                 }
                 let mut err = struct_span_err!(self.tcx.sess, span, E0308, "{}", failure_str);
-                if let Some((expected, found)) = trace.values.ty() {
+                let values = self.resolve_vars_if_possible(trace.values);
+                if let Some((expected, found)) = values.ty() {
                     match (expected.kind(), found.kind()) {
                         (ty::Tuple(_), ty::Tuple(_)) => {}
                         // If a tuple of length one was expected and the found expression has

diff --git a/tests/ui/inference/char-as-str-single.fixed b/tests/ui/inference/char-as-str-single.fixed
@@ -10,3 +10,12 @@ fn main() {
     let _: char = '人'; //~ ERROR mismatched types
     let _: char = '\''; //~ ERROR mismatched types
 }
+
+// regression test for https://github.com/rust-lang/rust/issues/109586
+#[allow(dead_code)]
+fn convert_c_to_str(c: char) {
+    match c {
+        'A' => {} //~ ERROR mismatched types
+        _ => {}
+    }
+}
diff --git a/tests/ui/inference/char-as-str-single.rs b/tests/ui/inference/char-as-str-single.rs
@@ -10,3 +10,12 @@ fn main() {
     let _: char = "人"; //~ ERROR mismatched types
     let _: char = "'"; //~ ERROR mismatched types
 }
+
+// regression test for https://github.com/rust-lang/rust/issues/109586
+#[allow(dead_code)]
+fn convert_c_to_str(c: char) {
+    match c {
+        "A" => {} //~ ERROR mismatched types
+        _ => {}
+    }
+}
diff --git a/tests/ui/inference/char-as-str-single.stderr b/tests/ui/inference/char-as-str-single.stderr
@@ -37,6 +37,19 @@ help: if you meant to write a `char` literal, use single quotes
 LL |     let _: char = '\'';
    |                   ~~~~
 
-error: aborting due to 3 previous errors
+error[E0308]: mismatched types
+  --> $DIR/char-as-str-single.rs:18:9
+   |
+LL |     match c {
+   |           - this expression has type `char`
+LL |         "A" => {}
+   |         ^^^ expected `char`, found `&str`
+   |
+help: if you meant to write a `char` literal, use single quotes
+   |
+LL |         'A' => {}
+   |         ~~~
+
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0308`.