introduce new lint infra

 lint on duplicates during attribute parsing
To do this we stuff them in the diagnostic context to be emitted after
hir is constructed

2 files changed, 16 insertions, 0 deletions

diff --git a/compiler/rustc_attr_data_structures/src/lib.rs b/compiler/rustc_attr_data_structures/src/lib.rs
index dbfc95b047a..b0fc19d1cd7 100644
--- a/compiler/rustc_attr_data_structures/src/lib.rs
+++ b/compiler/rustc_attr_data_structures/src/lib.rs
@@ -8,6 +8,8 @@ mod attributes;
 mod stability;
 mod version;
 
+pub mod lints;
+
 use std::num::NonZero;
 
 pub use attributes::*;
diff --git a/compiler/rustc_attr_data_structures/src/lints.rs b/compiler/rustc_attr_data_structures/src/lints.rs
new file mode 100644
index 00000000000..7e3664b2263
--- /dev/null
+++ b/compiler/rustc_attr_data_structures/src/lints.rs
@@ -0,0 +1,14 @@
+use rustc_macros::HashStable_Generic;
+use rustc_span::Span;
+
+#[derive(Clone, Debug, HashStable_Generic)]
+pub struct AttributeLint<Id> {
+    pub id: Id,
+    pub span: Span,
+    pub kind: AttributeLintKind,
+}
+
+#[derive(Clone, Debug, HashStable_Generic)]
+pub enum AttributeLintKind {
+    UnusedDuplicate { this: Span, other: Span, warning: bool },
+}