Add the #[derive_const] attribute

Author: fee1-dead

compiler/rustc_builtin_macros/src/cfg_accessible.rs

@@ -34,6 +34,7 @@ impl MultiItemModifier for Expander {
         span: Span,
         meta_item: &ast::MetaItem,
         item: Annotatable,
+        _is_derive_const: bool,
     ) -> ExpandResult<Vec<Annotatable>, Annotatable> {
         let template = AttributeTemplate { list: Some("path"), ..Default::default() };
         let attr = &ecx.attribute(meta_item.clone());

compiler/rustc_builtin_macros/src/derive.rs

@@ -10,7 +10,7 @@ use rustc_session::Session;
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::Span;
 
-pub(crate) struct Expander;
+pub(crate) struct Expander(pub bool);
 
 impl MultiItemModifier for Expander {
     fn expand(
@@ -19,6 +19,7 @@ impl MultiItemModifier for Expander {
         span: Span,
         meta_item: &ast::MetaItem,
         item: Annotatable,
+        _: bool,
     ) -> ExpandResult<Vec<Annotatable>, Annotatable> {
         let sess = ecx.sess;
         if report_bad_target(sess, &item, span) {
@@ -58,20 +59,20 @@ impl MultiItemModifier for Expander {
                         report_path_args(sess, &meta);
                         meta.path
                     })
-                    .map(|path| (path, dummy_annotatable(), None))
+                    .map(|path| (path, dummy_annotatable(), None, self.0))
                     .collect();
 
                 // Do not configure or clone items unless necessary.
                 match &mut resolutions[..] {
                     [] => {}
-                    [(_, first_item, _), others @ ..] => {
+                    [(_, first_item, ..), others @ ..] => {
                         *first_item = cfg_eval(
                             sess,
                             features,
                             item.clone(),
                             ecx.current_expansion.lint_node_id,
                         );
-                        for (_, item, _) in others {
+                        for (_, item, _, _) in others {
                             *item = first_item.clone();
                         }
                     }

compiler/rustc_builtin_macros/src/deriving/bounds.rs

@@ -12,6 +12,7 @@ pub fn expand_deriving_copy(
     mitem: &MetaItem,
     item: &Annotatable,
     push: &mut dyn FnMut(Annotatable),
+    is_const: bool,
 ) {
     let trait_def = TraitDef {
         span,
@@ -21,6 +22,7 @@ pub fn expand_deriving_copy(
         supports_unions: true,
         methods: Vec::new(),
         associated_types: Vec::new(),
+        is_const,
     };
 
     trait_def.expand(cx, mitem, item, push);

compiler/rustc_builtin_macros/src/deriving/clone.rs

@@ -14,6 +14,7 @@ pub fn expand_deriving_clone(
     mitem: &MetaItem,
     item: &Annotatable,
     push: &mut dyn FnMut(Annotatable),
+    is_const: bool,
 ) {
     // The simple form is `fn clone(&self) -> Self { *self }`, possibly with
     // some additional `AssertParamIsClone` assertions.
@@ -86,6 +87,7 @@ pub fn expand_deriving_clone(
             combine_substructure: substructure,
         }],
         associated_types: Vec::new(),
+        is_const,
     };
 
     trait_def.expand_ext(cx, mitem, item, push, is_simple)

compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs

@@ -15,6 +15,7 @@ pub fn expand_deriving_eq(
     mitem: &MetaItem,
     item: &Annotatable,
     push: &mut dyn FnMut(Annotatable),
+    is_const: bool,
 ) {
     let span = cx.with_def_site_ctxt(span);
     let inline = cx.meta_word(span, sym::inline);
@@ -41,6 +42,7 @@ pub fn expand_deriving_eq(
             })),
         }],
         associated_types: Vec::new(),
+        is_const,
     };
 
     super::inject_impl_of_structural_trait(cx, span, item, path_std!(marker::StructuralEq), push);

compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs

@@ -13,6 +13,7 @@ pub fn expand_deriving_ord(
     mitem: &MetaItem,
     item: &Annotatable,
     push: &mut dyn FnMut(Annotatable),
+    is_const: bool,
 ) {
     let inline = cx.meta_word(span, sym::inline);
     let attrs = thin_vec![cx.attribute(inline)];
@@ -33,6 +34,7 @@ pub fn expand_deriving_ord(
             combine_substructure: combine_substructure(Box::new(|a, b, c| cs_cmp(a, b, c))),
         }],
         associated_types: Vec::new(),
+        is_const,
     };
 
     trait_def.expand(cx, mitem, item, push)

compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs

@@ -14,6 +14,7 @@ pub fn expand_deriving_partial_eq(
     mitem: &MetaItem,
     item: &Annotatable,
     push: &mut dyn FnMut(Annotatable),
+    is_const: bool,
 ) {
     fn cs_eq(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> BlockOrExpr {
         let base = true;
@@ -88,6 +89,7 @@ pub fn expand_deriving_partial_eq(
         supports_unions: false,
         methods,
         associated_types: Vec::new(),
+        is_const,
     };
     trait_def.expand(cx, mitem, item, push)
 }

compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs

@@ -13,6 +13,7 @@ pub fn expand_deriving_partial_ord(
     mitem: &MetaItem,
     item: &Annotatable,
     push: &mut dyn FnMut(Annotatable),
+    is_const: bool,
 ) {
     let ordering_ty = Path(path_std!(cmp::Ordering));
     let ret_ty =
@@ -42,6 +43,7 @@ pub fn expand_deriving_partial_ord(
         supports_unions: false,
         methods: vec![partial_cmp_def],
         associated_types: Vec::new(),
+        is_const,
     };
     trait_def.expand(cx, mitem, item, push)
 }

compiler/rustc_builtin_macros/src/deriving/debug.rs

@@ -13,6 +13,7 @@ pub fn expand_deriving_debug(
     mitem: &MetaItem,
     item: &Annotatable,
     push: &mut dyn FnMut(Annotatable),
+    is_const: bool,
 ) {
     // &mut ::std::fmt::Formatter
     let fmtr = Ref(Box::new(Path(path_std!(fmt::Formatter))), ast::Mutability::Mut);
@@ -36,6 +37,7 @@ pub fn expand_deriving_debug(
             })),
         }],
         associated_types: Vec::new(),
+        is_const,
     };
     trait_def.expand(cx, mitem, item, push)
 }

compiler/rustc_builtin_macros/src/deriving/decodable.rs

@@ -16,6 +16,7 @@ pub fn expand_deriving_rustc_decodable(
     mitem: &MetaItem,
     item: &Annotatable,
     push: &mut dyn FnMut(Annotatable),
+    is_const: bool,
 ) {
     let krate = sym::rustc_serialize;
     let typaram = sym::__D;
@@ -54,6 +55,7 @@ pub fn expand_deriving_rustc_decodable(
             })),
         }],
         associated_types: Vec::new(),
+        is_const,
     };
 
     trait_def.expand(cx, mitem, item, push)