Pass a TyCtxt directly to Attribute::from_ast

This allows calling `tcx.struct_span_lint_hir` in the next commit. It
also slightly shortens the code.

Author: jyn514

src/librustdoc/clean/inline.rs

@@ -298,8 +298,7 @@ fn merge_attrs(
     // when we render them.
     if let Some(inner) = new_attrs {
         if let Some(new_id) = parent_module {
-            let diag = cx.sess().diagnostic();
-            Attributes::from_ast(diag, old_attrs, Some((inner, new_id)), local)
+            Attributes::from_ast(cx.tcx, old_attrs, Some((inner, new_id)), local)
         } else {
             let mut both = inner.to_vec();
             both.extend_from_slice(old_attrs);

src/librustdoc/clean/mod.rs

@@ -241,7 +241,7 @@ impl Clean<Item> for doctree::Module<'_> {
 }
 
 fn clean_attrs(attrs: &[ast::Attribute], local: bool, cx: &mut DocContext<'_>) -> Attributes {
-    Attributes::from_ast(cx.sess().diagnostic(), attrs, None, local)
+    Attributes::from_ast(cx.tcx, attrs, None, local)
 }
 
 impl Clean<GenericBound> for hir::GenericBound<'_> {

src/librustdoc/clean/types.rs

@@ -739,7 +739,7 @@ impl Attributes {
     }
 
     crate fn from_ast(
-        handler: &::rustc_errors::Handler,
+        tcx: TyCtxt<'_>,
         attrs: &[ast::Attribute],
         additional_attrs: Option<(&[ast::Attribute], DefId)>,
         local: bool,
@@ -801,7 +801,7 @@ impl Attributes {
                             // Extracted #[doc(cfg(...))]
                             match Cfg::parse(cfg_mi) {
                                 Ok(new_cfg) => cfg &= new_cfg,
-                                Err(e) => handler.span_err(e.span, e.msg),
+                                Err(e) => tcx.sess.span_err(e.span, e.msg),
                             }
                         } else if let Some((filename, contents)) = Attributes::extract_include(&mi)
                         {

src/librustdoc/doctest.rs

@@ -1093,7 +1093,7 @@ impl<'a, 'hir, 'tcx> HirCollector<'a, 'hir, 'tcx> {
         nested: F,
     ) {
         let attrs = self.tcx.hir().attrs(hir_id);
-        let mut attrs = Attributes::from_ast(self.sess.diagnostic(), attrs, None, true);
+        let mut attrs = Attributes::from_ast(self.tcx, attrs, None, true);
         if let Some(ref cfg) = attrs.cfg {
             if !cfg.matches(&self.sess.parse_sess, Some(&self.sess.features_untracked())) {
                 return;