macros: make unhandled_panic bails with multi_thread runtime

tests-build/tests/fail/macros_invalid_input.rs

@@ -41,6 +41,9 @@ async fn test_crate_not_path_int() {}
 #[tokio::test(crate = "456")]
 async fn test_crate_not_path_invalid() {}
 
+#[tokio::test(flavor = "multi_thread", unhandled_panic = "shutdown_runtime")]
+async fn test_worker_threads_not_int() {}
+
 #[tokio::test]
 #[test]
 async fn test_has_second_test_attr() {}

tests-build/tests/fail/macros_invalid_input.stderr

@@ -76,40 +76,46 @@ error: Failed to parse value of `crate` as path: "456"
 41 | #[tokio::test(crate = "456")]
    |                       ^^^^^
 
+error: The `unhandled_panic` option requires the `current_thread` runtime flavor. Use `#[tokio::test(flavor = "current_thread")]`
+  --> tests/fail/macros_invalid_input.rs:44:58
+   |
+44 | #[tokio::test(flavor = "multi_thread", unhandled_panic = "shutdown_runtime")]
+   |                                                          ^^^^^^^^^^^^^^^^^^
+
 error: second test attribute is supplied, consider removing or changing the order of your test attributes
-  --> tests/fail/macros_invalid_input.rs:45:1
+  --> tests/fail/macros_invalid_input.rs:48:1
    |
-45 | #[test]
+48 | #[test]
    | ^^^^^^^
 
 error: second test attribute is supplied, consider removing or changing the order of your test attributes
-  --> tests/fail/macros_invalid_input.rs:49:1
+  --> tests/fail/macros_invalid_input.rs:52:1
    |
-49 | #[::core::prelude::v1::test]
+52 | #[::core::prelude::v1::test]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: second test attribute is supplied, consider removing or changing the order of your test attributes
-  --> tests/fail/macros_invalid_input.rs:53:1
+  --> tests/fail/macros_invalid_input.rs:56:1
    |
-53 | #[core::prelude::rust_2015::test]
+56 | #[core::prelude::rust_2015::test]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: second test attribute is supplied, consider removing or changing the order of your test attributes
-  --> tests/fail/macros_invalid_input.rs:57:1
+  --> tests/fail/macros_invalid_input.rs:60:1
    |
-57 | #[::std::prelude::rust_2018::test]
+60 | #[::std::prelude::rust_2018::test]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: second test attribute is supplied, consider removing or changing the order of your test attributes
-  --> tests/fail/macros_invalid_input.rs:61:1
+  --> tests/fail/macros_invalid_input.rs:64:1
    |
-61 | #[std::prelude::rust_2021::test]
+64 | #[std::prelude::rust_2021::test]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: second test attribute is supplied, consider removing or changing the order of your test attributes
-  --> tests/fail/macros_invalid_input.rs:64:1
+  --> tests/fail/macros_invalid_input.rs:67:1
    |
-64 | #[tokio::test]
+67 | #[tokio::test]
    | ^^^^^^^^^^^^^^
    |
    = note: this error originates in the attribute macro `tokio::test` (in Nightly builds, run with -Z macro-backtrace for more info)

tokio-macros/src/entry.rs

@@ -75,7 +75,7 @@ struct Configuration {
     start_paused: Option<(bool, Span)>,
     is_test: bool,
     crate_name: Option<Path>,
-    unhandled_panic: Option<UnhandledPanic>,
+    unhandled_panic: Option<(UnhandledPanic, Span)>,
 }
 
 impl Configuration {
@@ -161,7 +161,7 @@ impl Configuration {
         let unhandled_panic = parse_string(unhandled_panic, span, "unhandled_panic")?;
         let unhandled_panic =
             UnhandledPanic::from_str(&unhandled_panic).map_err(|err| syn::Error::new(span, err))?;
-        self.unhandled_panic = Some(unhandled_panic);
+        self.unhandled_panic = Some((unhandled_panic, span));
         Ok(())
     }
 
@@ -211,12 +211,24 @@ impl Configuration {
             (_, None) => None,
         };
 
+        let unhandled_panic = match (flavor, self.unhandled_panic) {
+            (F::Threaded, Some((_, unhandled_panic_span))) => {
+                let msg = format!(
+                    "The `unhandled_panic` option requires the `current_thread` runtime flavor. Use `#[{}(flavor = \"current_thread\")]`",
+                    self.macro_name(),
+                );
+                return Err(syn::Error::new(unhandled_panic_span, msg));
+            }
+            (F::CurrentThread, Some((unhandled_panic, _))) => Some(unhandled_panic),
+            (_, None) => None,
+        };
+
         Ok(FinalConfig {
             crate_name: self.crate_name.clone(),
-            unhandled_panic: self.unhandled_panic,
             flavor,
             worker_threads,
             start_paused,
+            unhandled_panic,
         })
     }
 }

tokio-macros/src/lib.rs

@@ -208,6 +208,8 @@ use proc_macro::TokenStream;
 /// Available options are `shutdown_runtime` and `ignore`. For more details, see
 /// [`Builder::unhandled_panic`].
 ///
+/// This option is only compatible with the `current_thread` runtime.
+///
 /// ```ignore
 /// #[tokio::main(flavor = "current_thread", unhandled_panic = "shutdown_runtime")]
 /// async fn main() {
@@ -467,6 +469,8 @@ pub fn main_rt(args: TokenStream, item: TokenStream) -> TokenStream {
 /// Available options are `shutdown_runtime` and `ignore`. For more details, see
 /// [`Builder::unhandled_panic`].
 ///
+/// This option is only compatible with the `current_thread` runtime.
+///
 /// ```ignore
 /// #[tokio::test(flavor = "current_thread", unhandled_panic = "shutdown_runtime")]
 /// async fn my_test() {