Add a helper method for extracting spans from AttrArgsEq

Author: oli-obk

Diff for: compiler/rustc_ast/src/ast.rs

@@ -1750,15 +1750,21 @@ pub enum AttrArgsEq {
     Hir(MetaItemLit),
 }
 
+impl AttrArgsEq {
+    pub fn span(&self) -> Span {
+        match self {
+            AttrArgsEq::Ast(p) => p.span,
+            AttrArgsEq::Hir(lit) => lit.span,
+        }
+    }
+}
+
 impl AttrArgs {
     pub fn span(&self) -> Option<Span> {
         match self {
             AttrArgs::Empty => None,
             AttrArgs::Delimited(args) => Some(args.dspan.entire()),
-            AttrArgs::Eq { eq_span, value: AttrArgsEq::Ast(expr) } => Some(eq_span.to(expr.span)),
-            AttrArgs::Eq { value: AttrArgsEq::Hir(lit), .. } => {
-                unreachable!("in literal form when getting span: {:?}", lit);
-            }
+            AttrArgs::Eq { eq_span, value } => Some(eq_span.to(value.span())),
         }
     }
 

Diff for: compiler/rustc_resolve/src/rustdoc.rs

@@ -220,9 +220,9 @@ pub fn attrs_to_doc_fragments<'a>(
 
 fn span_for_value(attr: &ast::Attribute) -> Span {
     if let ast::AttrKind::Normal(normal) = &attr.kind
-        && let ast::AttrArgs::Eq { value: ast::AttrArgsEq::Hir(meta), .. } = &normal.item.args
+        && let ast::AttrArgs::Eq { value, .. } = &normal.item.args
     {
-        meta.span.with_ctxt(attr.span.ctxt())
+        value.span().with_ctxt(attr.span.ctxt())
     } else {
         attr.span
     }

Diff for: compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented.rs

@@ -1,7 +1,7 @@
 use std::iter;
 use std::path::PathBuf;
 
-use rustc_ast::{AttrArgs, AttrArgsEq, AttrKind, Attribute, MetaItemInner};
+use rustc_ast::{AttrArgs, AttrKind, Attribute, MetaItemInner};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::codes::*;
 use rustc_errors::{ErrorGuaranteed, struct_span_code_err};
@@ -639,8 +639,7 @@ impl<'tcx> OnUnimplementedDirective {
                 let report_span = match &item.args {
                     AttrArgs::Empty => item.path.span,
                     AttrArgs::Delimited(args) => args.dspan.entire(),
-                    AttrArgs::Eq { eq_span, value: AttrArgsEq::Ast(expr) } => eq_span.to(expr.span),
-                    AttrArgs::Eq { eq_span, value: AttrArgsEq::Hir(expr) } => eq_span.to(expr.span),
+                    AttrArgs::Eq { eq_span, value } => eq_span.to(value.span()),
                 };
 
                 if let Some(item_def_id) = item_def_id.as_local() {