From 10ed08f5b644e1bd521eaf7d64474a837b17a7ae Mon Sep 17 00:00:00 2001
From: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>
Date: Sun, 7 Mar 2021 00:18:51 +0300
Subject: [PATCH] cfg_eval: Configure everything through mutable visitor
 methods

This is simpler and mirrors what invocation collector does
---
 compiler/rustc_builtin_macros/src/cfg_eval.rs | 97 ++++++-------------
 1 file changed, 27 insertions(+), 70 deletions(-)

diff --git a/compiler/rustc_builtin_macros/src/cfg_eval.rs b/compiler/rustc_builtin_macros/src/cfg_eval.rs
index 8cf3be33e20..efc5f5af877 100644
--- a/compiler/rustc_builtin_macros/src/cfg_eval.rs
+++ b/compiler/rustc_builtin_macros/src/cfg_eval.rs
@@ -3,7 +3,6 @@ use crate::util::check_builtin_macro_attribute;
 use rustc_ast::mut_visit::{self, MutVisitor};
 use rustc_ast::ptr::P;
 use rustc_ast::{self as ast, AstLike};
-use rustc_data_structures::map_in_place::MapInPlace;
 use rustc_expand::base::{Annotatable, ExtCtxt};
 use rustc_expand::config::StripUnconfigured;
 use rustc_expand::configure;
@@ -43,57 +42,6 @@ impl CfgEval<'_> {
         self.cfg.configure(node)
     }
 
-    fn configure_foreign_mod(&mut self, foreign_mod: &mut ast::ForeignMod) {
-        let ast::ForeignMod { unsafety: _, abi: _, items } = foreign_mod;
-        items.flat_map_in_place(|item| self.configure(item));
-    }
-
-    fn configure_variant_data(&mut self, vdata: &mut ast::VariantData) {
-        match vdata {
-            ast::VariantData::Struct(fields, ..) | ast::VariantData::Tuple(fields, _) => {
-                fields.flat_map_in_place(|field| self.configure(field))
-            }
-            ast::VariantData::Unit(_) => {}
-        }
-    }
-
-    fn configure_item_kind(&mut self, item: &mut ast::ItemKind) {
-        match item {
-            ast::ItemKind::Struct(def, _generics) | ast::ItemKind::Union(def, _generics) => {
-                self.configure_variant_data(def)
-            }
-            ast::ItemKind::Enum(ast::EnumDef { variants }, _generics) => {
-                variants.flat_map_in_place(|variant| self.configure(variant));
-                for variant in variants {
-                    self.configure_variant_data(&mut variant.data);
-                }
-            }
-            _ => {}
-        }
-    }
-
-    fn configure_expr_kind(&mut self, expr_kind: &mut ast::ExprKind) {
-        match expr_kind {
-            ast::ExprKind::Match(_m, arms) => {
-                arms.flat_map_in_place(|arm| self.configure(arm));
-            }
-            ast::ExprKind::Struct(_path, fields, _base) => {
-                fields.flat_map_in_place(|field| self.configure(field));
-            }
-            _ => {}
-        }
-    }
-
-    fn configure_pat(&mut self, pat: &mut P<ast::Pat>) {
-        if let ast::PatKind::Struct(_path, fields, _etc) = &mut pat.kind {
-            fields.flat_map_in_place(|field| self.configure(field));
-        }
-    }
-
-    fn configure_fn_decl(&mut self, fn_decl: &mut ast::FnDecl) {
-        fn_decl.inputs.flat_map_in_place(|arg| self.configure(arg));
-    }
-
     crate fn fully_configure(&mut self, item: Annotatable) -> Annotatable {
         // Since the item itself has already been configured by the InvocationCollector,
         // we know that fold result vector will contain exactly one element
@@ -139,25 +87,13 @@ impl CfgEval<'_> {
 }
 
 impl MutVisitor for CfgEval<'_> {
-    fn visit_foreign_mod(&mut self, foreign_mod: &mut ast::ForeignMod) {
-        self.configure_foreign_mod(foreign_mod);
-        mut_visit::noop_visit_foreign_mod(foreign_mod, self);
-    }
-
-    fn visit_item_kind(&mut self, item: &mut ast::ItemKind) {
-        self.configure_item_kind(item);
-        mut_visit::noop_visit_item_kind(item, self);
-    }
-
     fn visit_expr(&mut self, expr: &mut P<ast::Expr>) {
         self.cfg.configure_expr(expr);
-        self.configure_expr_kind(&mut expr.kind);
         mut_visit::noop_visit_expr(expr, self);
     }
 
     fn filter_map_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
         let mut expr = configure!(self, expr);
-        self.configure_expr_kind(&mut expr.kind);
         mut_visit::noop_visit_expr(&mut expr, self);
         Some(expr)
     }
@@ -185,13 +121,34 @@ impl MutVisitor for CfgEval<'_> {
         mut_visit::noop_flat_map_assoc_item(configure!(self, item), self)
     }
 
-    fn visit_pat(&mut self, pat: &mut P<ast::Pat>) {
-        self.configure_pat(pat);
-        mut_visit::noop_visit_pat(pat, self)
+    fn flat_map_foreign_item(
+        &mut self,
+        foreign_item: P<ast::ForeignItem>,
+    ) -> SmallVec<[P<ast::ForeignItem>; 1]> {
+        mut_visit::noop_flat_map_foreign_item(configure!(self, foreign_item), self)
     }
 
-    fn visit_fn_decl(&mut self, mut fn_decl: &mut P<ast::FnDecl>) {
-        self.configure_fn_decl(&mut fn_decl);
-        mut_visit::noop_visit_fn_decl(fn_decl, self);
+    fn flat_map_arm(&mut self, arm: ast::Arm) -> SmallVec<[ast::Arm; 1]> {
+        mut_visit::noop_flat_map_arm(configure!(self, arm), self)
+    }
+
+    fn flat_map_field(&mut self, field: ast::Field) -> SmallVec<[ast::Field; 1]> {
+        mut_visit::noop_flat_map_field(configure!(self, field), self)
+    }
+
+    fn flat_map_field_pattern(&mut self, fp: ast::FieldPat) -> SmallVec<[ast::FieldPat; 1]> {
+        mut_visit::noop_flat_map_field_pattern(configure!(self, fp), self)
+    }
+
+    fn flat_map_param(&mut self, p: ast::Param) -> SmallVec<[ast::Param; 1]> {
+        mut_visit::noop_flat_map_param(configure!(self, p), self)
+    }
+
+    fn flat_map_struct_field(&mut self, sf: ast::StructField) -> SmallVec<[ast::StructField; 1]> {
+        mut_visit::noop_flat_map_struct_field(configure!(self, sf), self)
+    }
+
+    fn flat_map_variant(&mut self, variant: ast::Variant) -> SmallVec<[ast::Variant; 1]> {
+        mut_visit::noop_flat_map_variant(configure!(self, variant), self)
     }
 }