Introduce the `#[diagnostic]` attribute namespace

Co-authored-by: est31 <est31@users.noreply.github.com>

Co-authored-by: Esteban Kuber <estebank@users.noreply.github.com>

Co-authored-by: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>

1 files changed, 17 insertions, 3 deletions

diff --git a/compiler/rustc_resolve/src/macros.rs b/compiler/rustc_resolve/src/macros.rs
index 266e37e4cef..d456cc9a9a0 100644
--- a/compiler/rustc_resolve/src/macros.rs
+++ b/compiler/rustc_resolve/src/macros.rs
@@ -24,7 +24,9 @@ use rustc_hir::def_id::{CrateNum, LocalDefId};
 use rustc_middle::middle::stability;
 use rustc_middle::ty::RegisteredTools;
 use rustc_middle::ty::TyCtxt;
-use rustc_session::lint::builtin::{LEGACY_DERIVE_HELPERS, SOFT_UNSTABLE};
+use rustc_session::lint::builtin::{
+    LEGACY_DERIVE_HELPERS, SOFT_UNSTABLE, UNKNOWN_DIAGNOSTIC_ATTRIBUTES,
+};
 use rustc_session::lint::builtin::{UNUSED_MACROS, UNUSED_MACRO_RULES};
 use rustc_session::lint::BuiltinLintDiagnostics;
 use rustc_session::parse::feature_err;
@@ -140,9 +142,9 @@ pub(crate) fn registered_tools(tcx: TyCtxt<'_>, (): ()) -> RegisteredTools {
             }
         }
     }
-    // We implicitly add `rustfmt` and `clippy` to known tools,
+    // We implicitly add `rustfmt`, `clippy`, `diagnostic` to known tools,
     // but it's not an error to register them explicitly.
-    let predefined_tools = [sym::clippy, sym::rustfmt];
+    let predefined_tools = [sym::clippy, sym::rustfmt, sym::diagnostic];
     registered_tools.extend(predefined_tools.iter().cloned().map(Ident::with_dummy_span));
     registered_tools
 }
@@ -595,6 +597,18 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             }
         }
 
+        if res == Res::NonMacroAttr(NonMacroAttrKind::Tool)
+            && path.segments.len() >= 2
+            && path.segments[0].ident.name == sym::diagnostic
+        {
+            self.tcx.sess.parse_sess.buffer_lint(
+                UNKNOWN_DIAGNOSTIC_ATTRIBUTES,
+                path.segments[1].span(),
+                node_id,
+                "unknown diagnostic attribute",
+            );
+        }
+
         Ok((ext, res))
     }