Add diagnostic::on_unimplemented for no iterator in repetition

dtolnay · dtolnay · commit c0adb26f414c · 2025-09-28T17:43:04.000-07:00
diff --git a/src/runtime.rs b/src/runtime.rs
@@ -49,6 +49,10 @@ impl BitOr<HasIterator<true>> for HasIterator<true> {
 }
 
 #[doc(hidden)]
+#[diagnostic::on_unimplemented(
+    message = "repetition contains no interpolated value that is an iterator",
+    label = "none of the values interpolated inside this repetition are iterable"
+)]
 pub trait CheckHasIterator: Sized {
     fn check(self) {}
 }
diff --git a/tests/ui/does-not-have-iter-interpolated-dup.stderr b/tests/ui/does-not-have-iter-interpolated-dup.stderr
@@ -1,8 +1,9 @@
-error[E0277]: the trait bound `HasIterator<false>: CheckHasIterator` is not satisfied
+error[E0277]: repetition contains no interpolated value that is an iterator
  --> tests/ui/does-not-have-iter-interpolated-dup.rs:8:5
   |
 8 |     quote!(#(#nonrep #nonrep)*);
-  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `CheckHasIterator` is not implemented for `HasIterator<false>`
+  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ none of the values interpolated inside this repetition are iterable
   |
+  = help: the trait `CheckHasIterator` is not implemented for `HasIterator<false>`
   = help: the trait `CheckHasIterator` is implemented for `HasIterator<true>`
   = note: this error originates in the macro `$crate::quote_token_with_context` which comes from the expansion of the macro `quote` (in Nightly builds, run with -Z macro-backtrace for more info)
diff --git a/tests/ui/does-not-have-iter-interpolated.stderr b/tests/ui/does-not-have-iter-interpolated.stderr
@@ -1,8 +1,9 @@
-error[E0277]: the trait bound `HasIterator<false>: CheckHasIterator` is not satisfied
+error[E0277]: repetition contains no interpolated value that is an iterator
  --> tests/ui/does-not-have-iter-interpolated.rs:8:5
   |
 8 |     quote!(#(#nonrep)*);
-  |     ^^^^^^^^^^^^^^^^^^^ the trait `CheckHasIterator` is not implemented for `HasIterator<false>`
+  |     ^^^^^^^^^^^^^^^^^^^ none of the values interpolated inside this repetition are iterable
   |
+  = help: the trait `CheckHasIterator` is not implemented for `HasIterator<false>`
   = help: the trait `CheckHasIterator` is implemented for `HasIterator<true>`
   = note: this error originates in the macro `$crate::quote_token_with_context` which comes from the expansion of the macro `quote` (in Nightly builds, run with -Z macro-backtrace for more info)
diff --git a/tests/ui/does-not-have-iter-separated.stderr b/tests/ui/does-not-have-iter-separated.stderr
@@ -1,8 +1,9 @@
-error[E0277]: the trait bound `HasIterator<false>: CheckHasIterator` is not satisfied
+error[E0277]: repetition contains no interpolated value that is an iterator
  --> tests/ui/does-not-have-iter-separated.rs:4:5
   |
 4 |     quote!(#(a b),*);
-  |     ^^^^^^^^^^^^^^^^ the trait `CheckHasIterator` is not implemented for `HasIterator<false>`
+  |     ^^^^^^^^^^^^^^^^ none of the values interpolated inside this repetition are iterable
   |
+  = help: the trait `CheckHasIterator` is not implemented for `HasIterator<false>`
   = help: the trait `CheckHasIterator` is implemented for `HasIterator<true>`
   = note: this error originates in the macro `$crate::quote_token_with_context` which comes from the expansion of the macro `quote` (in Nightly builds, run with -Z macro-backtrace for more info)
diff --git a/tests/ui/does-not-have-iter.stderr b/tests/ui/does-not-have-iter.stderr
@@ -1,8 +1,9 @@
-error[E0277]: the trait bound `HasIterator<false>: CheckHasIterator` is not satisfied
+error[E0277]: repetition contains no interpolated value that is an iterator
  --> tests/ui/does-not-have-iter.rs:4:5
   |
 4 |     quote!(#(a b)*);
-  |     ^^^^^^^^^^^^^^^ the trait `CheckHasIterator` is not implemented for `HasIterator<false>`
+  |     ^^^^^^^^^^^^^^^ none of the values interpolated inside this repetition are iterable
   |
+  = help: the trait `CheckHasIterator` is not implemented for `HasIterator<false>`
   = help: the trait `CheckHasIterator` is implemented for `HasIterator<true>`
   = note: this error originates in the macro `$crate::quote_token_with_context` which comes from the expansion of the macro `quote` (in Nightly builds, run with -Z macro-backtrace for more info)

Original file line number	Diff line number	Diff line change
`@@ -49,6 +49,10 @@ impl BitOr<HasIterator<true>> for HasIterator<true> {`
`49`	`49`	`}`
`50`	`50`
`51`	`51`	`#[doc(hidden)]`
	`52`	`+#[diagnostic::on_unimplemented(`
	`53`	`+ message = "repetition contains no interpolated value that is an iterator",`
	`54`	`+ label = "none of the values interpolated inside this repetition are iterable"`
	`55`	`+)]`
`52`	`56`	`pub trait CheckHasIterator: Sized {`
`53`	`57`	`fn check(self) {}`
`54`	`58`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1,8 +1,9 @@`
`1`		-error[E0277]: the trait bound `HasIterator<false>: CheckHasIterator` is not satisfied
	`1`	`+error[E0277]: repetition contains no interpolated value that is an iterator`
`2`	`2`	`--> tests/ui/does-not-have-iter-interpolated-dup.rs:8:5`
`3`	`3`	`\|`
`4`	`4`	`8 \| quote!(#(#nonrep #nonrep)*);`
`5`		- \| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `CheckHasIterator` is not implemented for `HasIterator<false>`
	`5`	`+ \| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ none of the values interpolated inside this repetition are iterable`
`6`	`6`	`\|`
	`7`	+ = help: the trait `CheckHasIterator` is not implemented for `HasIterator<false>`
`7`	`8`	= help: the trait `CheckHasIterator` is implemented for `HasIterator<true>`
`8`	`9`	= note: this error originates in the macro `$crate::quote_token_with_context` which comes from the expansion of the macro `quote` (in Nightly builds, run with -Z macro-backtrace for more info)