Remove mk_name_value_item{,_str}.

There are better ways to create the meta items.
- In the rustdoc tests, the commit adds `dummy_meta_item_name_value`,
  which matches the existing `dummy_meta_item_word` function and
  `dummy_meta_item_list` macro.
- In `types.rs` the commit clones the existing meta item and then
  modifies the clone.

compiler/rustc_ast/src/attr/mod.rs

@@ -1,6 +1,5 @@
 //! Functions dealing with attributes and meta items.
 
-use crate::ast;
 use crate::ast::{AttrArgs, AttrArgsEq, AttrId, AttrItem, AttrKind, AttrStyle, AttrVec, Attribute};
 use crate::ast::{DelimArgs, Expr, ExprKind, LitKind, MetaItemLit};
 use crate::ast::{MacDelimiter, MetaItem, MetaItemKind, NestedMetaItem, NormalAttr};
@@ -321,20 +320,6 @@ impl Attribute {
     }
 }
 
-/* Constructors */
-
-pub fn mk_name_value_item_str(ident: Ident, str: Symbol, str_span: Span) -> MetaItem {
-    mk_name_value_item(ident, LitKind::Str(str, ast::StrStyle::Cooked), str_span)
-}
-
-pub fn mk_name_value_item(ident: Ident, kind: LitKind, lit_span: Span) -> MetaItem {
-    let token_lit = kind.synthesize_token_lit();
-    let lit =
-        MetaItemLit { symbol: token_lit.symbol, suffix: token_lit.suffix, kind, span: lit_span };
-    let span = ident.span.to(lit_span);
-    MetaItem { path: Path::from_ident(ident), kind: MetaItemKind::NameValue(lit), span }
-}
-
 pub struct AttrIdGenerator(WorkerLocal<Cell<u32>>);
 
 #[cfg(debug_assertions)]

src/librustdoc/clean/cfg/tests.rs

@@ -1,9 +1,8 @@
 use super::*;
 
-use rustc_ast::attr;
-use rustc_ast::Path;
+use rustc_ast::{LitKind, MetaItemLit, Path, StrStyle};
 use rustc_span::create_default_session_globals_then;
-use rustc_span::symbol::{Ident, Symbol};
+use rustc_span::symbol::{kw, Ident, Symbol};
 use rustc_span::DUMMY_SP;
 
 fn word_cfg(s: &str) -> Cfg {
@@ -22,6 +21,15 @@ fn dummy_meta_item_word(name: &str) -> MetaItem {
     }
 }
 
+fn dummy_meta_item_name_value(name: &str, symbol: Symbol, kind: LitKind) -> MetaItem {
+    let lit = MetaItemLit { symbol, suffix: None, kind, span: DUMMY_SP };
+    MetaItem {
+        path: Path::from_ident(Ident::from_str(name)),
+        kind: MetaItemKind::NameValue(lit),
+        span: DUMMY_SP,
+    }
+}
+
 macro_rules! dummy_meta_item_list {
     ($name:ident, [$($list:ident),* $(,)?]) => {
         MetaItem {
@@ -242,8 +250,8 @@ fn test_parse_ok() {
         let mi = dummy_meta_item_word("all");
         assert_eq!(Cfg::parse(&mi), Ok(word_cfg("all")));
 
-        let mi =
-            attr::mk_name_value_item_str(Ident::from_str("all"), Symbol::intern("done"), DUMMY_SP);
+        let done = Symbol::intern("done");
+        let mi = dummy_meta_item_name_value("all", done, LitKind::Str(done, StrStyle::Cooked));
         assert_eq!(Cfg::parse(&mi), Ok(name_value_cfg("all", "done")));
 
         let mi = dummy_meta_item_list!(all, [a, b]);
@@ -272,7 +280,7 @@ fn test_parse_ok() {
 #[test]
 fn test_parse_err() {
     create_default_session_globals_then(|| {
-        let mi = attr::mk_name_value_item(Ident::from_str("foo"), LitKind::Bool(false), DUMMY_SP);
+        let mi = dummy_meta_item_name_value("foo", kw::False, LitKind::Bool(false));
         assert!(Cfg::parse(&mi).is_err());
 
         let mi = dummy_meta_item_list!(not, [a, b]);

src/librustdoc/clean/types.rs

@@ -10,7 +10,6 @@ use std::{cmp, fmt, iter};
 use arrayvec::ArrayVec;
 use thin_vec::ThinVec;
 
-use rustc_ast::attr;
 use rustc_ast::util::comments::beautify_doc_string;
 use rustc_ast::{self as ast, AttrStyle};
 use rustc_attr::{ConstStability, Deprecation, Stability, StabilityLevel};
@@ -27,7 +26,6 @@ use rustc_middle::ty::fast_reject::SimplifiedType;
 use rustc_middle::ty::{self, DefIdTree, TyCtxt, Visibility};
 use rustc_session::Session;
 use rustc_span::hygiene::MacroKind;
-use rustc_span::source_map::DUMMY_SP;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{self, FileName, Loc};
 use rustc_target::abi::VariantIdx;
@@ -979,12 +977,12 @@ impl AttributesExt for [ast::Attribute] {
         // #[doc(cfg(target_feature = "feat"))] attributes as well
         for attr in self.lists(sym::target_feature) {
             if attr.has_name(sym::enable) {
-                if let Some(feat) = attr.value_str() {
-                    let meta = attr::mk_name_value_item_str(
-                        Ident::with_dummy_span(sym::target_feature),
-                        feat,
-                        DUMMY_SP,
-                    );
+                if attr.value_str().is_some() {
+                    // Clone `enable = "feat"`, change to `target_feature = "feat"`.
+                    // Unwrap is safe because `value_str` succeeded above.
+                    let mut meta = attr.meta_item().unwrap().clone();
+                    meta.path = ast::Path::from_ident(Ident::with_dummy_span(sym::target_feature));
+
                     if let Ok(feat_cfg) = Cfg::parse(&meta) {
                         cfg &= feat_cfg;
                     }