Diagnostic args are still args if they're documented

2 files changed, 90 insertions, 0 deletions

diff --git a/tests/ui-fulldeps/session-diagnostic/diagnostic-derive-doc-comment-field.rs b/tests/ui-fulldeps/session-diagnostic/diagnostic-derive-doc-comment-field.rs
new file mode 100644
index 00000000000..7e1f7b1c5c1
--- /dev/null
+++ b/tests/ui-fulldeps/session-diagnostic/diagnostic-derive-doc-comment-field.rs
@@ -0,0 +1,47 @@
+// check-fail
+// Tests that a doc comment will not preclude a field from being considered a diagnostic argument
+
+// The proc_macro2 crate handles spans differently when on beta/stable release rather than nightly,
+// changing the output of this test. Since Subdiagnostic is strictly internal to the compiler
+// the test is just ignored on stable and beta:
+// ignore-stage1
+// ignore-beta
+// ignore-stable
+
+#![feature(rustc_private)]
+#![crate_type = "lib"]
+
+extern crate rustc_errors;
+extern crate rustc_fluent_macro;
+extern crate rustc_macros;
+extern crate rustc_session;
+extern crate rustc_span;
+
+use rustc_errors::{Applicability, DiagnosticMessage, SubdiagnosticMessage};
+use rustc_fluent_macro::fluent_messages;
+use rustc_macros::{Diagnostic, Subdiagnostic};
+use rustc_span::Span;
+
+fluent_messages! { "./example.ftl" }
+
+struct NotIntoDiagnosticArg;
+
+#[derive(Diagnostic)]
+//~^ ERROR the trait bound `NotIntoDiagnosticArg: IntoDiagnosticArg` is not satisfied
+#[diag(no_crate_example)]
+struct Test {
+    #[primary_span]
+    span: Span,
+    /// A doc comment
+    arg: NotIntoDiagnosticArg,
+}
+
+#[derive(Subdiagnostic)]
+//~^ ERROR the trait bound `NotIntoDiagnosticArg: IntoDiagnosticArg` is not satisfied
+#[label(no_crate_example)]
+struct SubTest {
+    #[primary_span]
+    span: Span,
+    /// A doc comment
+    arg: NotIntoDiagnosticArg,
+}
diff --git a/tests/ui-fulldeps/session-diagnostic/diagnostic-derive-doc-comment-field.stderr b/tests/ui-fulldeps/session-diagnostic/diagnostic-derive-doc-comment-field.stderr
new file mode 100644
index 00000000000..27044748d08
--- /dev/null
+++ b/tests/ui-fulldeps/session-diagnostic/diagnostic-derive-doc-comment-field.stderr
@@ -0,0 +1,43 @@
+error[E0277]: the trait bound `NotIntoDiagnosticArg: IntoDiagnosticArg` is not satisfied
+  --> $DIR/diagnostic-derive-doc-comment-field.rs:29:10
+   |
+LL | #[derive(Diagnostic)]
+   |          ^^^^^^^^^^ the trait `IntoDiagnosticArg` is not implemented for `NotIntoDiagnosticArg`
+   |
+   = help: the following other types implement trait `IntoDiagnosticArg`:
+             &'a T
+             &'a std::path::Path
+             &'a str
+             &rustc_target::spec::TargetTriple
+             Box<(dyn std::error::Error + 'static)>
+             CString
+             CguReuse
+             Cow<'a, str>
+           and 42 others
+note: required by a bound in `DiagnosticBuilder::<'a, G>::set_arg`
+  --> $COMPILER_DIR/rustc_errors/src/diagnostic_builder.rs:747:5
+   = note: this error originates in the derive macro `Diagnostic` which comes from the expansion of the macro `forward` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the trait bound `NotIntoDiagnosticArg: IntoDiagnosticArg` is not satisfied
+  --> $DIR/diagnostic-derive-doc-comment-field.rs:39:10
+   |
+LL | #[derive(Subdiagnostic)]
+   |          ^^^^^^^^^^^^^ the trait `IntoDiagnosticArg` is not implemented for `NotIntoDiagnosticArg`
+   |
+   = help: the following other types implement trait `IntoDiagnosticArg`:
+             &'a T
+             &'a std::path::Path
+             &'a str
+             &rustc_target::spec::TargetTriple
+             Box<(dyn std::error::Error + 'static)>
+             CString
+             CguReuse
+             Cow<'a, str>
+           and 42 others
+note: required by a bound in `Diagnostic::set_arg`
+  --> $COMPILER_DIR/rustc_errors/src/diagnostic.rs:964:5
+   = note: this error originates in the derive macro `Subdiagnostic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.