Avoid some unnecessary symbol interning.

- `Ident::from_str_and_span` -> `Ident::new` when the string is
  pre-interned.
- `Ident::from_str` -> `Ident::with_dummy_span` when the string is
  pre-interned.
- `_d` and `_e` are unused.

2 files changed, 6 insertions, 4 deletions

diff --git a/compiler/rustc_builtin_macros/src/alloc_error_handler.rs b/compiler/rustc_builtin_macros/src/alloc_error_handler.rs
index ea406e70666..e75bc944d7e 100644
--- a/compiler/rustc_builtin_macros/src/alloc_error_handler.rs
+++ b/compiler/rustc_builtin_macros/src/alloc_error_handler.rs
@@ -62,8 +62,8 @@ pub(crate) fn expand(
 fn generate_handler(cx: &ExtCtxt<'_>, handler: Ident, span: Span, sig_span: Span) -> Stmt {
     let usize = cx.path_ident(span, Ident::new(sym::usize, span));
     let ty_usize = cx.ty_path(usize);
-    let size = Ident::from_str_and_span("size", span);
-    let align = Ident::from_str_and_span("align", span);
+    let size = Ident::new(sym::size, span);
+    let align = Ident::new(sym::align, span);
 
     let layout_new = cx.std_path(&[sym::alloc, sym::Layout, sym::from_size_align_unchecked]);
     let layout_new = cx.expr_path(cx.path(span, layout_new));
diff --git a/compiler/rustc_builtin_macros/src/autodiff.rs b/compiler/rustc_builtin_macros/src/autodiff.rs
index dc3bb8ab52a..df1b1eb60e1 100644
--- a/compiler/rustc_builtin_macros/src/autodiff.rs
+++ b/compiler/rustc_builtin_macros/src/autodiff.rs
@@ -652,8 +652,10 @@ mod llvm_enzyme {
                 exprs = ecx.expr_call(new_decl_span, bb_call_expr, thin_vec![exprs]);
             } else {
                 let q = QSelf { ty: d_ret_ty, path_span: span, position: 0 };
-                let y =
-                    ExprKind::Path(Some(P(q)), ecx.path_ident(span, Ident::from_str("default")));
+                let y = ExprKind::Path(
+                    Some(P(q)),
+                    ecx.path_ident(span, Ident::with_dummy_span(kw::Default)),
+                );
                 let default_call_expr = ecx.expr(span, y);
                 let default_call_expr =
                     ecx.expr_call(new_decl_span, default_call_expr, thin_vec![]);