diff --git a/compiler/rustc_builtin_macros/src/proc_macro_harness.rs b/compiler/rustc_builtin_macros/src/proc_macro_harness.rs index d6603af101afc..707c36d5046a9 100644 --- a/compiler/rustc_builtin_macros/src/proc_macro_harness.rs +++ b/compiler/rustc_builtin_macros/src/proc_macro_harness.rs @@ -313,14 +313,23 @@ fn mk_decls(cx: &mut ExtCtxt<'_>, macros: &[ProcMacro]) -> P { match m { ProcMacro::Derive(cd) => { cx.resolver.declare_proc_macro(cd.id); - cx.expr_call(span, proc_macro_ty_method_path(cx, custom_derive), thin_vec![ - cx.expr_str(span, cd.trait_name), - cx.expr_array_ref( - span, - cd.attrs.iter().map(|&s| cx.expr_str(span, s)).collect::>(), - ), - local_path(cx, cd.function_name), - ]) + // The call needs to use `harness_span` so that the const stability checker + // accepts it. + cx.expr_call( + harness_span, + proc_macro_ty_method_path(cx, custom_derive), + thin_vec![ + cx.expr_str(span, cd.trait_name), + cx.expr_array_ref( + span, + cd.attrs + .iter() + .map(|&s| cx.expr_str(span, s)) + .collect::>(), + ), + local_path(cx, cd.function_name), + ], + ) } ProcMacro::Attr(ca) | ProcMacro::Bang(ca) => { cx.resolver.declare_proc_macro(ca.id); @@ -330,7 +339,9 @@ fn mk_decls(cx: &mut ExtCtxt<'_>, macros: &[ProcMacro]) -> P { ProcMacro::Derive(_) => unreachable!(), }; - cx.expr_call(span, proc_macro_ty_method_path(cx, ident), thin_vec![ + // The call needs to use `harness_span` so that the const stability checker + // accepts it. + cx.expr_call(harness_span, proc_macro_ty_method_path(cx, ident), thin_vec![ cx.expr_str(span, ca.function_name.name), local_path(cx, ca.function_name), ])