Port #[export_name] to the new attribute parsing infrastructure

Signed-off-by: Jonathan Brouwer <jonathantbrouwer@gmail.com>

compiler/rustc_attr_data_structures/src/attributes.rs

@@ -231,6 +231,14 @@ pub enum AttributeKind {
     /// Represents [`#[doc]`](https://doc.rust-lang.org/stable/rustdoc/write-documentation/the-doc-attribute.html).
     DocComment { style: AttrStyle, kind: CommentKind, span: Span, comment: Symbol },
 
+    /// Represents [`#[export_name]`](https://doc.rust-lang.org/reference/abi.html#the-export_name-attribute).
+    ExportName {
+        /// The name to export this item with.
+        /// It may not contain \0 bytes as it will be converted to a null-terminated string.
+        name: Symbol,
+        span: Span,
+    },
+
     /// Represents `#[inline]` and `#[rustc_force_inline]`.
     Inline(InlineAttr, Span),
 

compiler/rustc_attr_data_structures/src/encode_cross_crate.rs

@@ -22,6 +22,7 @@ impl AttributeKind {
             ConstStabilityIndirect => No,
             Deprecation { .. } => Yes,
             DocComment { .. } => Yes,
+            ExportName { .. } => Yes,
             Inline(..) => No,
             MacroTransparency(..) => Yes,
             Repr(..) => No,