Rollup merge of #98741 - nnethercote:deriving-cleanups, r=Mark-Simula…

…crum

Many small deriving cleanups

These commits remove lots of little unnecessary things, and clarifies other things.

r? `@Mark-Simulacrum`

compiler/rustc_builtin_macros/src/deriving/bounds.rs

@@ -19,7 +19,6 @@ pub fn expand_deriving_copy(
         path: path_std!(marker::Copy),
         additional_bounds: Vec::new(),
         generics: Bounds::empty(),
-        is_unsafe: false,
         supports_unions: true,
         methods: Vec::new(),
         associated_types: Vec::new(),

compiler/rustc_builtin_macros/src/deriving/clone.rs

@@ -15,23 +15,22 @@ pub fn expand_deriving_clone(
     item: &Annotatable,
     push: &mut dyn FnMut(Annotatable),
 ) {
-    // check if we can use a short form
+    // The simple form is `fn clone(&self) -> Self { *self }`, possibly with
+    // some additional `AssertParamIsClone` assertions.
     //
-    // the short form is `fn clone(&self) -> Self { *self }`
-    //
-    // we can use the short form if:
-    // - the item is Copy (unfortunately, all we can check is whether it's also deriving Copy)
-    // - there are no generic parameters (after specialization this limitation can be removed)
-    //      if we used the short form with generics, we'd have to bound the generics with
-    //      Clone + Copy, and then there'd be no Clone impl at all if the user fills in something
-    //      that is Clone but not Copy. and until specialization we can't write both impls.
-    // - the item is a union with Copy fields
-    //      Unions with generic parameters still can derive Clone because they require Copy
-    //      for deriving, Clone alone is not enough.
-    //      Wherever Clone is implemented for fields is irrelevant so we don't assert it.
+    // We can use the simple form if either of the following are true.
+    // - The type derives Copy and there are no generic parameters.  (If we
+    //   used the simple form with generics, we'd have to bound the generics
+    //   with Clone + Copy, and then there'd be no Clone impl at all if the
+    //   user fills in something that is Clone but not Copy. After
+    //   specialization we can remove this no-generics limitation.)
+    // - The item is a union. (Unions with generic parameters still can derive
+    //   Clone because they require Copy for deriving, Clone alone is not
+    //   enough. Whether Clone is implemented for fields is irrelevant so we
+    //   don't assert it.)
     let bounds;
     let substructure;
-    let is_shallow;
+    let is_simple;
     match *item {
         Annotatable::Item(ref annitem) => match annitem.kind {
             ItemKind::Struct(_, Generics { ref params, .. })
@@ -44,30 +43,25 @@ pub fn expand_deriving_clone(
                         .any(|param| matches!(param.kind, ast::GenericParamKind::Type { .. }))
                 {
                     bounds = vec![];
-                    is_shallow = true;
+                    is_simple = true;
                     substructure = combine_substructure(Box::new(|c, s, sub| {
-                        cs_clone_shallow("Clone", c, s, sub, false)
+                        cs_clone_simple("Clone", c, s, sub, false)
                     }));
                 } else {
                     bounds = vec![];
-                    is_shallow = false;
+                    is_simple = false;
                     substructure =
                         combine_substructure(Box::new(|c, s, sub| cs_clone("Clone", c, s, sub)));
                 }
             }
             ItemKind::Union(..) => {
-                bounds = vec![Literal(path_std!(marker::Copy))];
-                is_shallow = true;
+                bounds = vec![Path(path_std!(marker::Copy))];
+                is_simple = true;
                 substructure = combine_substructure(Box::new(|c, s, sub| {
-                    cs_clone_shallow("Clone", c, s, sub, true)
+                    cs_clone_simple("Clone", c, s, sub, true)
                 }));
             }
-            _ => {
-                bounds = vec![];
-                is_shallow = false;
-                substructure =
-                    combine_substructure(Box::new(|c, s, sub| cs_clone("Clone", c, s, sub)));
-            }
+            _ => cx.span_bug(span, "`#[derive(Clone)]` on wrong item kind"),
         },
 
         _ => cx.span_bug(span, "`#[derive(Clone)]` on trait item or impl item"),
@@ -81,26 +75,24 @@ pub fn expand_deriving_clone(
         path: path_std!(clone::Clone),
         additional_bounds: bounds,
         generics: Bounds::empty(),
-        is_unsafe: false,
         supports_unions: true,
         methods: vec![MethodDef {
             name: sym::clone,
             generics: Bounds::empty(),
-            explicit_self: borrowed_explicit_self(),
+            explicit_self: true,
             args: Vec::new(),
             ret_ty: Self_,
             attributes: attrs,
-            is_unsafe: false,
             unify_fieldless_variants: false,
             combine_substructure: substructure,
         }],
         associated_types: Vec::new(),
     };
 
-    trait_def.expand_ext(cx, mitem, item, push, is_shallow)
+    trait_def.expand_ext(cx, mitem, item, push, is_simple)
 }
 
-fn cs_clone_shallow(
+fn cs_clone_simple(
     name: &str,
     cx: &mut ExtCtxt<'_>,
     trait_span: Span,
@@ -143,7 +135,7 @@ fn cs_clone_shallow(
             }
             _ => cx.span_bug(
                 trait_span,
-                &format!("unexpected substructure in shallow `derive({})`", name),
+                &format!("unexpected substructure in simple `derive({})`", name),
             ),
         }
     }

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

@@ -27,16 +27,14 @@ pub fn expand_deriving_eq(
         path: path_std!(cmp::Eq),
         additional_bounds: Vec::new(),
         generics: Bounds::empty(),
-        is_unsafe: false,
         supports_unions: true,
         methods: vec![MethodDef {
             name: sym::assert_receiver_is_total_eq,
             generics: Bounds::empty(),
-            explicit_self: borrowed_explicit_self(),
+            explicit_self: true,
             args: vec![],
-            ret_ty: nil_ty(),
+            ret_ty: Unit,
             attributes: attrs,
-            is_unsafe: false,
             unify_fieldless_variants: true,
             combine_substructure: combine_substructure(Box::new(|a, b, c| {
                 cs_total_eq_assert(a, b, c)

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

@@ -23,16 +23,14 @@ pub fn expand_deriving_ord(
         path: path_std!(cmp::Ord),
         additional_bounds: Vec::new(),
         generics: Bounds::empty(),
-        is_unsafe: false,
         supports_unions: false,
         methods: vec![MethodDef {
             name: sym::cmp,
             generics: Bounds::empty(),
-            explicit_self: borrowed_explicit_self(),
-            args: vec![(borrowed_self(), sym::other)],
-            ret_ty: Literal(path_std!(cmp::Ordering)),
+            explicit_self: true,
+            args: vec![(self_ref(), sym::other)],
+            ret_ty: Path(path_std!(cmp::Ordering)),
             attributes: attrs,
-            is_unsafe: false,
             unify_fieldless_variants: true,
             combine_substructure: combine_substructure(Box::new(|a, b, c| cs_cmp(a, b, c))),
         }],
@@ -99,8 +97,8 @@ pub fn cs_cmp(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> P<
             cx.expr_match(span, new, vec![eq_arm, neq_arm])
         },
         cx.expr_path(equals_path.clone()),
-        Box::new(|cx, span, (self_args, tag_tuple), _non_self_args| {
-            if self_args.len() != 2 {
+        Box::new(|cx, span, tag_tuple| {
+            if tag_tuple.len() != 2 {
                 cx.span_bug(span, "not exactly 2 arguments in `derive(Ord)`")
             } else {
                 ordering_collapsed(cx, span, tag_tuple)

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

@@ -48,7 +48,7 @@ pub fn expand_deriving_partial_eq(
                     None => cx.expr_bool(span, base),
                 }
             },
-            Box::new(|cx, span, _, _| cx.expr_bool(span, !base)),
+            Box::new(|cx, span, _| cx.expr_bool(span, !base)),
             cx,
             span,
             substr,
@@ -69,11 +69,10 @@ pub fn expand_deriving_partial_eq(
             MethodDef {
                 name: $name,
                 generics: Bounds::empty(),
-                explicit_self: borrowed_explicit_self(),
-                args: vec![(borrowed_self(), sym::other)],
-                ret_ty: Literal(path_local!(bool)),
+                explicit_self: true,
+                args: vec![(self_ref(), sym::other)],
+                ret_ty: Path(path_local!(bool)),
                 attributes: attrs,
-                is_unsafe: false,
                 unify_fieldless_variants: true,
                 combine_substructure: combine_substructure(Box::new(|a, b, c| $f(a, b, c))),
             }
@@ -102,7 +101,6 @@ pub fn expand_deriving_partial_eq(
         path: path_std!(cmp::PartialEq),
         additional_bounds: Vec::new(),
         generics: Bounds::empty(),
-        is_unsafe: false,
         supports_unions: false,
         methods,
         associated_types: Vec::new(),

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

@@ -15,25 +15,20 @@ pub fn expand_deriving_partial_ord(
     item: &Annotatable,
     push: &mut dyn FnMut(Annotatable),
 ) {
-    let ordering_ty = Literal(path_std!(cmp::Ordering));
-    let ret_ty = Literal(Path::new_(
-        pathvec_std!(option::Option),
-        None,
-        vec![Box::new(ordering_ty)],
-        PathKind::Std,
-    ));
+    let ordering_ty = Path(path_std!(cmp::Ordering));
+    let ret_ty =
+        Path(Path::new_(pathvec_std!(option::Option), vec![Box::new(ordering_ty)], PathKind::Std));
 
     let inline = cx.meta_word(span, sym::inline);
     let attrs = vec![cx.attribute(inline)];
 
     let partial_cmp_def = MethodDef {
         name: sym::partial_cmp,
         generics: Bounds::empty(),
-        explicit_self: borrowed_explicit_self(),
-        args: vec![(borrowed_self(), sym::other)],
+        explicit_self: true,
+        args: vec![(self_ref(), sym::other)],
         ret_ty,
         attributes: attrs,
-        is_unsafe: false,
         unify_fieldless_variants: true,
         combine_substructure: combine_substructure(Box::new(|cx, span, substr| {
             cs_partial_cmp(cx, span, substr)
@@ -46,7 +41,6 @@ pub fn expand_deriving_partial_ord(
         path: path_std!(cmp::PartialOrd),
         additional_bounds: vec![],
         generics: Bounds::empty(),
-        is_unsafe: false,
         supports_unions: false,
         methods: vec![partial_cmp_def],
         associated_types: Vec::new(),
@@ -102,8 +96,8 @@ pub fn cs_partial_cmp(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_
             cx.expr_match(span, new, vec![eq_arm, neq_arm])
         },
         equals_expr,
-        Box::new(|cx, span, (self_args, tag_tuple), _non_self_args| {
-            if self_args.len() != 2 {
+        Box::new(|cx, span, tag_tuple| {
+            if tag_tuple.len() != 2 {
                 cx.span_bug(span, "not exactly 2 arguments in `derive(PartialOrd)`")
             } else {
                 let lft = cx.expr_addr_of(span, cx.expr_ident(span, tag_tuple[0]));

compiler/rustc_builtin_macros/src/deriving/debug.rs

@@ -16,25 +16,22 @@ pub fn expand_deriving_debug(
     push: &mut dyn FnMut(Annotatable),
 ) {
     // &mut ::std::fmt::Formatter
-    let fmtr =
-        Ptr(Box::new(Literal(path_std!(fmt::Formatter))), Borrowed(None, ast::Mutability::Mut));
+    let fmtr = Ref(Box::new(Path(path_std!(fmt::Formatter))), ast::Mutability::Mut);
 
     let trait_def = TraitDef {
         span,
         attributes: Vec::new(),
         path: path_std!(fmt::Debug),
         additional_bounds: Vec::new(),
         generics: Bounds::empty(),
-        is_unsafe: false,
         supports_unions: false,
         methods: vec![MethodDef {
             name: sym::fmt,
             generics: Bounds::empty(),
-            explicit_self: borrowed_explicit_self(),
+            explicit_self: true,
             args: vec![(fmtr, sym::f)],
-            ret_ty: Literal(path_std!(fmt::Result)),
+            ret_ty: Path(path_std!(fmt::Result)),
             attributes: Vec::new(),
-            is_unsafe: false,
             unify_fieldless_variants: false,
             combine_substructure: combine_substructure(Box::new(|a, b, c| {
                 show_substructure(a, b, c)
@@ -64,8 +61,6 @@ fn show_substructure(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>
     let (is_struct, args_per_field) = match vdata {
         ast::VariantData::Unit(..) => {
             // Special fast path for unit variants.
-            //let fn_path_write_str = cx.std_path(&[sym::fmt, sym::Formatter, sym::write_str]);
-            //return cx.expr_call_global(span, fn_path_write_str, vec![fmt, name]);
             assert!(fields.is_empty());
             (false, 0)
         }

compiler/rustc_builtin_macros/src/deriving/decodable.rs

@@ -23,40 +23,29 @@ pub fn expand_deriving_rustc_decodable(
     let trait_def = TraitDef {
         span,
         attributes: Vec::new(),
-        path: Path::new_(vec![krate, sym::Decodable], None, vec![], PathKind::Global),
+        path: Path::new_(vec![krate, sym::Decodable], vec![], PathKind::Global),
         additional_bounds: Vec::new(),
         generics: Bounds::empty(),
-        is_unsafe: false,
         supports_unions: false,
         methods: vec![MethodDef {
             name: sym::decode,
             generics: Bounds {
                 bounds: vec![(
                     typaram,
-                    vec![Path::new_(vec![krate, sym::Decoder], None, vec![], PathKind::Global)],
+                    vec![Path::new_(vec![krate, sym::Decoder], vec![], PathKind::Global)],
                 )],
             },
-            explicit_self: None,
-            args: vec![(
-                Ptr(Box::new(Literal(Path::new_local(typaram))), Borrowed(None, Mutability::Mut)),
-                sym::d,
-            )],
-            ret_ty: Literal(Path::new_(
+            explicit_self: false,
+            args: vec![(Ref(Box::new(Path(Path::new_local(typaram))), Mutability::Mut), sym::d)],
+            ret_ty: Path(Path::new_(
                 pathvec_std!(result::Result),
-                None,
                 vec![
                     Box::new(Self_),
-                    Box::new(Literal(Path::new_(
-                        vec![typaram, sym::Error],
-                        None,
-                        vec![],
-                        PathKind::Local,
-                    ))),
+                    Box::new(Path(Path::new_(vec![typaram, sym::Error], vec![], PathKind::Local))),
                 ],
                 PathKind::Std,
             )),
             attributes: Vec::new(),
-            is_unsafe: false,
             unify_fieldless_variants: false,
             combine_substructure: combine_substructure(Box::new(|a, b, c| {
                 decodable_substructure(a, b, c, krate)

compiler/rustc_builtin_macros/src/deriving/default.rs

@@ -30,16 +30,14 @@ pub fn expand_deriving_default(
         path: Path::new(vec![kw::Default, sym::Default]),
         additional_bounds: Vec::new(),
         generics: Bounds::empty(),
-        is_unsafe: false,
         supports_unions: false,
         methods: vec![MethodDef {
             name: kw::Default,
             generics: Bounds::empty(),
-            explicit_self: None,
+            explicit_self: false,
             args: Vec::new(),
             ret_ty: Self_,
             attributes: attrs,
-            is_unsafe: false,
             unify_fieldless_variants: false,
             combine_substructure: combine_substructure(Box::new(|cx, trait_span, substr| {
                 match substr.fields {