Rollup merge of #163080 - cyrgani:builtin-macros-5, r=nnethercote

`rustc_builtin_macros` cleanup, part 5

This PR among other things removes the "mini" version of `Path`, the `nonselflike_args` and most of the usages of `type_ident`. It also comes with some perf gains.
Followup to #162925.

r? @nnethercote

Author: Zalathar

compiler/rustc_builtin_macros/src/deriving/clone.rs

@@ -50,7 +50,7 @@ pub(crate) fn expand_deriving_clone(
             }
         }
         ItemKind::Union(..) => {
-            bounds = smallvec![Path(path_std!(marker::Copy))];
+            bounds = smallvec![path_std!(cx, span, marker::Copy)];
             is_simple = true;
             substructure = combine_substructure(|c, s, sub| cs_clone_simple(c, s, sub, true));
         }
@@ -62,7 +62,7 @@ pub(crate) fn expand_deriving_clone(
     if is_simple {
         let trivial_def = TraitDef {
             span,
-            path: path_std!(clone::TrivialClone),
+            path: path_std!(cx, span, clone::TrivialClone),
             skip_path_as_bound: false,
             needs_copy_as_bound_if_packed: true,
             additional_bounds: bounds.clone(),
@@ -81,7 +81,7 @@ pub(crate) fn expand_deriving_clone(
 
     let trait_def = TraitDef {
         span,
-        path: path_std!(clone::Clone),
+        path: path_std!(cx, span, clone::Clone),
         skip_path_as_bound: false,
         needs_copy_as_bound_if_packed: true,
         additional_bounds: bounds,
@@ -149,7 +149,7 @@ fn cs_clone_simple(
             &[sym::clone, sym::AssertParamIsCopy],
         );
     } else {
-        match substr.fields {
+        match substr {
             StaticStruct(vdata, ..) => {
                 process_variant(vdata);
             }
@@ -171,17 +171,18 @@ fn cs_clone(cx: &ExtCtxt<'_>, trait_span: Span, substr: Substructure<'_>) -> Blo
         cx.expr_call_global(field.span, fn_path.clone(), args)
     };
 
+    let self_ident = Ident::new(kw::SelfUpper, trait_span);
     let ctor_path;
     let all_fields;
     let vdata;
-    match substr.fields {
+    match substr {
         Struct(vdata_, af) => {
-            ctor_path = cx.path(trait_span, vec![substr.type_ident]);
+            ctor_path = cx.path(trait_span, vec![self_ident]);
             all_fields = af;
             vdata = vdata_;
         }
         EnumMatching(.., variant, af) => {
-            ctor_path = cx.path(trait_span, vec![substr.type_ident, variant.ident]);
+            ctor_path = cx.path(trait_span, vec![self_ident, variant.ident]);
             all_fields = af;
             vdata = &variant.data;
         }

compiler/rustc_builtin_macros/src/deriving/const_param_ty.rs

@@ -14,10 +14,10 @@ pub(crate) fn expand_deriving_const_param_ty(
 ) {
     let trait_def = TraitDef {
         span,
-        path: path_std!(marker::ConstParamTy_),
+        path: path_std!(cx, span, marker::ConstParamTy_),
         skip_path_as_bound: false,
         needs_copy_as_bound_if_packed: false,
-        additional_bounds: smallvec![ty::Ty::Path(path_std!(cmp::Eq))],
+        additional_bounds: smallvec![path_std!(cx, span, cmp::Eq)],
         supports_unions: false,
         methods: SmallVec::new(),
         associated_types: SmallVec::new(),

compiler/rustc_builtin_macros/src/deriving/copy.rs

@@ -14,7 +14,7 @@ pub(crate) fn expand_deriving_copy(
 ) {
     let trait_def = TraitDef {
         span,
-        path: path_std!(marker::Copy),
+        path: path_std!(cx, span, marker::Copy),
         skip_path_as_bound: false,
         needs_copy_as_bound_if_packed: false,
         additional_bounds: SmallVec::new(),

compiler/rustc_builtin_macros/src/deriving/debug.rs

@@ -16,11 +16,11 @@ pub(crate) fn expand_deriving_debug(
     is_const: bool,
 ) {
     // &mut ::std::fmt::Formatter
-    let fmtr = Ref(Box::new(Path(path_std!(fmt::Formatter))), ast::Mutability::Mut);
+    let fmtr = Ref(Box::new(Path(path_std!(cx, span, fmt::Formatter))), ast::Mutability::Mut);
 
     let trait_def = TraitDef {
         span,
-        path: path_std!(fmt::Debug),
+        path: path_std!(cx, span, fmt::Debug),
         skip_path_as_bound: false,
         needs_copy_as_bound_if_packed: true,
         additional_bounds: SmallVec::new(),
@@ -30,11 +30,16 @@ pub(crate) fn expand_deriving_debug(
             generics: cx.empty_generics(span),
             explicit_self: true,
             nonself_args: smallvec![(fmtr, sym::character('f'))],
-            ret_ty: Path(path_std!(fmt::Result)),
+            ret_ty: Path(path_std!(cx, span, fmt::Result)),
             attributes: thin_vec![cx.attr_word(sym::inline, span)],
             fieldless_variants_strategy:
                 FieldlessVariantsStrategy::SpecializeIfAllVariantsFieldless,
-            combine_substructure: combine_substructure(show_substructure),
+            combine_substructure: combine_substructure(|cx, span, substr| show_substructure(
+                cx,
+                span,
+                substr,
+                item.kind.ident().unwrap()
+            )),
         }],
         associated_types: SmallVec::new(),
         is_const,
@@ -44,24 +49,30 @@ pub(crate) fn expand_deriving_debug(
     trait_def.expand(cx, item, push)
 }
 
-fn show_substructure(cx: &ExtCtxt<'_>, span: Span, substr: Substructure<'_>) -> BlockOrExpr {
-    // We want to make sure we have the ctxt set so that we can use unstable methods
-    let span = cx.with_def_site_ctxt(span);
+fn formatter_ident(cx: &ExtCtxt<'_>, span: Span) -> Box<ast::Expr> {
+    cx.expr_ident(span, Ident::new(sym::character('f'), span))
+}
 
+fn show_substructure(
+    cx: &ExtCtxt<'_>,
+    span: Span,
+    substr: Substructure<'_>,
+    type_ident: Ident,
+) -> BlockOrExpr {
     let fmt_detail = cx.sess.opts.unstable_opts.fmt_debug;
     if fmt_detail == FmtDebug::None {
         return BlockOrExpr::new_expr(cx.expr_ok(span, cx.expr_tuple(span, ThinVec::new())));
     }
 
-    let (ident, vdata, fields) = match substr.fields {
-        Struct(vdata, fields) => (substr.type_ident, vdata, fields),
+    let (ident, vdata, fields) = match substr {
+        Struct(vdata, fields) => (type_ident, vdata, fields),
         EnumMatching(v, fields) => (v.ident, &v.data, fields),
-        AllFieldlessEnum(enum_def) => return show_fieldless_enum(cx, span, enum_def, substr),
+        AllFieldlessEnum(enum_def) => return show_fieldless_enum(cx, span, enum_def, type_ident),
         _ => cx.dcx().span_bug(span, "unexpected substructure in `derive(Debug)`"),
     };
 
     let name = cx.expr_str(span, ident.name);
-    let fmt = substr.nonselflike_args[0].clone();
+    let fmt = formatter_ident(cx, span);
 
     // Fieldless enums have been special-cased earlier
     if fmt_detail == FmtDebug::Shallow {
@@ -85,13 +96,14 @@ fn show_substructure(cx: &ExtCtxt<'_>, span: Span, substr: Substructure<'_>) ->
     // The number of fields that can be handled without an array.
     const CUTOFF: usize = 5;
 
-    let expr_for_field = |field: &FieldInfo, index: usize| -> Box<ast::Expr> {
-        if index < fields.len() - 1 {
-            field.self_expr.clone()
+    let len = fields.len();
+    let expr_for_field = |field: FieldInfo, index: usize| -> Box<ast::Expr> {
+        if index < len - 1 {
+            field.self_expr
         } else {
             // Unsized types need an extra indirection, but only the last field
             // may be unsized.
-            cx.expr_addr_of(field.span, field.self_expr.clone())
+            cx.expr_addr_of(field.span, field.self_expr)
         }
     };
 
@@ -111,8 +123,7 @@ fn show_substructure(cx: &ExtCtxt<'_>, span: Span, substr: Substructure<'_>) ->
 
         let mut args = ThinVec::with_capacity(2 + fields.len() * args_per_field);
         args.extend([fmt, name]);
-        for i in 0..fields.len() {
-            let field = &fields[i];
+        for (i, field) in fields.into_iter().enumerate() {
             if is_struct {
                 let name = cx.expr_str(field.span, field.name.unwrap().name);
                 args.push(name);
@@ -128,8 +139,7 @@ fn show_substructure(cx: &ExtCtxt<'_>, span: Span, substr: Substructure<'_>) ->
         let mut name_exprs = ThinVec::with_capacity(fields.len());
         let mut value_exprs = ThinVec::with_capacity(fields.len());
 
-        for i in 0..fields.len() {
-            let field = &fields[i];
+        for (i, field) in fields.into_iter().enumerate() {
             if is_struct {
                 name_exprs.push(cx.expr_str(field.span, field.name.unwrap().name));
             }
@@ -216,14 +226,14 @@ fn show_fieldless_enum(
     cx: &ExtCtxt<'_>,
     span: Span,
     def: &EnumDef,
-    substr: Substructure<'_>,
+    type_ident: Ident,
 ) -> BlockOrExpr {
-    let fmt = substr.nonselflike_args[0].clone();
+    let fmt = formatter_ident(cx, span);
     let arms = def
         .variants
         .iter()
         .map(|v| {
-            let variant_path = cx.path(span, vec![substr.type_ident, v.ident]);
+            let variant_path = cx.path(span, vec![type_ident, v.ident]);
             let pat = match &v.data {
                 ast::VariantData::Tuple(fields, _) => {
                     debug_assert!(fields.is_empty());

compiler/rustc_builtin_macros/src/deriving/default.rs

@@ -22,7 +22,7 @@ pub(crate) fn expand_deriving_default(
 
     let trait_def = TraitDef {
         span,
-        path: Path::new(vec![kw::Default, sym::Default]),
+        path: new_path(cx, span, &[kw::Default, sym::Default], &[]),
         skip_path_as_bound: has_a_default_variant(item),
         needs_copy_as_bound_if_packed: false,
         additional_bounds: SmallVec::new(),
@@ -36,9 +36,9 @@ pub(crate) fn expand_deriving_default(
             attributes: thin_vec![cx.attr_word(sym::inline, span)],
             fieldless_variants_strategy: FieldlessVariantsStrategy::Default,
             combine_substructure: combine_substructure(|cx, trait_span, substr| {
-                match substr.fields {
+                match substr {
                     StaticStruct(variant_data) => {
-                        default_struct_substructure(cx, trait_span, substr, variant_data)
+                        default_struct_substructure(cx, trait_span, variant_data)
                     }
                     StaticEnum(enum_def) => {
                         default_enum_substructure(cx, trait_span, enum_def, item.span)
@@ -66,26 +66,23 @@ fn default_call(cx: &ExtCtxt<'_>, span: Span) -> Box<ast::Expr> {
 fn default_struct_substructure(
     cx: &ExtCtxt<'_>,
     trait_span: Span,
-    substr: Substructure<'_>,
     variant_data: &VariantData,
 ) -> BlockOrExpr {
     let expr = match variant_data {
-        VariantData::Unit(_) => cx.expr_ident(trait_span, substr.type_ident),
+        VariantData::Unit(_) => cx.expr_ident(trait_span, Ident::new(kw::SelfUpper, trait_span)),
         VariantData::Tuple(fields, _) => {
             let exprs = fields
                 .iter()
                 .map(|field| default_call(cx, field.span.with_ctxt(trait_span.ctxt())))
                 .collect();
-            cx.expr_call_ident(trait_span, substr.type_ident, exprs)
+            cx.expr_call_ident(trait_span, Ident::new(kw::SelfUpper, trait_span), exprs)
         }
         VariantData::Struct { fields, .. } => {
             let default_fields = fields
                 .iter()
                 .map(|field| {
                     let span = field.span.with_ctxt(trait_span.ctxt());
-                    let value = if let Some(extras) = &field.extras
-                        && let Some(default_val) = &extras.default
-                    {
+                    let value = if let Some(default_val) = field.default_value() {
                         // We use the field default const expression.
                         cx.expr(
                             default_val.value.span,
@@ -98,7 +95,7 @@ fn default_struct_substructure(
                     cx.field_imm(span, field.ident.unwrap(), value)
                 })
                 .collect();
-            cx.expr_struct_ident(trait_span, substr.type_ident, default_fields)
+            cx.expr_struct_ident(trait_span, Ident::new(kw::SelfUpper, trait_span), default_fields)
         }
     };
     BlockOrExpr::new_expr(expr)

compiler/rustc_builtin_macros/src/deriving/eq.rs

@@ -19,7 +19,7 @@ pub(crate) fn expand_deriving_eq(
 
     let trait_def = TraitDef {
         span,
-        path: path_std!(cmp::Eq),
+        path: path_std!(cx, span, cmp::Eq),
         skip_path_as_bound: false,
         needs_copy_as_bound_if_packed: true,
         additional_bounds: SmallVec::new(),
@@ -73,7 +73,7 @@ fn cs_total_eq_assert(cx: &ExtCtxt<'_>, trait_span: Span, substr: Substructure<'
         }
     };
 
-    match substr.fields {
+    match substr {
         StaticStruct(vdata, ..) => {
             process_variant(vdata);
         }

compiler/rustc_builtin_macros/src/deriving/from.rs

@@ -5,7 +5,7 @@ use rustc_expand::base::{DummyResult, ExtCtxt};
 use rustc_span::{Ident, Span, kw, sym};
 use thin_vec::thin_vec;
 
-use crate::deriving::generic::ty::{Path, PathKind, Ty};
+use crate::deriving::generic::ty::*;
 use crate::deriving::generic::*;
 use crate::deriving::pathvec;
 use crate::diagnostics;
@@ -52,8 +52,7 @@ pub(crate) fn expand_deriving_from(
         Err(guar) => cx.ty(span, ast::TyKind::Err(guar)),
     });
 
-    let path =
-        Path::new_(pathvec!(convert::From), vec![Box::new(from_type.clone())], PathKind::Std);
+    let path = new_path(cx, span, pathvec!(convert::From), &[from_type.clone()]);
 
     // Generate code like this:
     //
@@ -89,8 +88,8 @@ pub(crate) fn expand_deriving_from(
                 };
 
                 let self_kw = Ident::new(kw::SelfUpper, span);
-                let expr: Box<ast::Expr> = match substructure.fields {
-                    SubstructureFields::StaticStruct(variant) => match variant {
+                let expr: Box<ast::Expr> = match substructure {
+                    StaticStruct(variant) => match variant {
                         // Self { field: value }
                         VariantData::Struct { .. } => cx.expr_struct_ident(
                             span,