Auto merge of rust-lang#121625 - Urgau:non-local-defs_recover_perf, r=<try>

Recover most of the perf loss of rust-lang#120393

[rust-lang#120393](rust-lang#120393 (comment))

draft for perf

Author: bors

Cargo.lock

@@ -4097,7 +4097,6 @@ dependencies = [
  "rustc_target",
  "rustc_trait_selection",
  "rustc_type_ir",
- "smallvec",
  "tracing",
  "unicode-security",
 ]

compiler/rustc_lint/Cargo.toml

@@ -23,7 +23,6 @@ rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
 rustc_type_ir = { path = "../rustc_type_ir" }
-smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
 tracing = "0.1"
 unicode-security = "0.1.0"
 # tidy-alphabetical-end

compiler/rustc_lint/src/non_local_def.rs

@@ -2,8 +2,6 @@ use rustc_hir::{def::DefKind, Body, Item, ItemKind, Node, Path, QPath, TyKind};
 use rustc_span::def_id::{DefId, LOCAL_CRATE};
 use rustc_span::{sym, symbol::kw, ExpnKind, MacroKind};
 
-use smallvec::{smallvec, SmallVec};
-
 use crate::lints::{NonLocalDefinitionsCargoUpdateNote, NonLocalDefinitionsDiag};
 use crate::{LateContext, LateLintPass, LintContext};
 
@@ -67,24 +65,23 @@ impl<'tcx> LateLintPass<'tcx> for NonLocalDefinitions {
             return;
         }
 
-        let parent = cx.tcx.parent(item.owner_id.def_id.into());
-        let parent_def_kind = cx.tcx.def_kind(parent);
-        let parent_opt_item_name = cx.tcx.opt_item_name(parent);
-
-        // Per RFC we (currently) ignore anon-const (`const _: Ty = ...`) in top-level module.
-        if self.body_depth == 1
-            && parent_def_kind == DefKind::Const
-            && parent_opt_item_name == Some(kw::Underscore)
-        {
-            return;
+        macro_rules! lazy {
+            ($ident:ident = $closure:expr) => {
+                let cache = ::std::cell::RefCell::new(None);
+                let $ident = || *cache.borrow_mut().get_or_insert_with($closure);
+            };
         }
 
+        lazy!(parent = || cx.tcx.parent(item.owner_id.def_id.into()));
+        lazy!(parent_def_kind = || cx.tcx.def_kind(parent()));
+        lazy!(parent_opt_item_name = || cx.tcx.opt_item_name(parent()));
+
         let cargo_update = || {
             let oexpn = item.span.ctxt().outer_expn_data();
             if let Some(def_id) = oexpn.macro_def_id
                 && let ExpnKind::Macro(macro_kind, macro_name) = oexpn.kind
                 && def_id.krate != LOCAL_CRATE
-                && std::env::var_os("CARGO").is_some()
+                && rustc_session::utils::was_invoked_from_cargo()
             {
                 Some(NonLocalDefinitionsCargoUpdateNote {
                     macro_kind: macro_kind.descr(),
@@ -112,26 +109,24 @@ impl<'tcx> LateLintPass<'tcx> for NonLocalDefinitions {
                 // If that's the case this means that this impl block declaration
                 // is using local items and so we don't lint on it.
 
-                // We also ignore anon-const in item by including the anon-const
-                // parent as well; and since it's quite uncommon, we use smallvec
-                // to avoid unnecessary heap allocations.
-                let local_parents: SmallVec<[DefId; 1]> = if parent_def_kind == DefKind::Const
-                    && parent_opt_item_name == Some(kw::Underscore)
-                {
-                    smallvec![parent, cx.tcx.parent(parent)]
-                } else {
-                    smallvec![parent]
-                };
+                lazy!(
+                    parent_is_anon_const = || parent_def_kind() == DefKind::Const
+                        && parent_opt_item_name() == Some(kw::Underscore)
+                );
+                lazy!(
+                    extra_local_parent = || parent_is_anon_const().then(|| cx.tcx.parent(parent()))
+                );
 
                 let self_ty_has_local_parent = match impl_.self_ty.kind {
                     TyKind::Path(QPath::Resolved(_, ty_path)) => {
-                        path_has_local_parent(ty_path, cx, &*local_parents)
+                        path_has_local_parent(ty_path, cx, &parent, &extra_local_parent)
                     }
                     TyKind::TraitObject([principle_poly_trait_ref, ..], _, _) => {
                         path_has_local_parent(
                             principle_poly_trait_ref.trait_ref.path,
                             cx,
-                            &*local_parents,
+                            &parent,
+                            &extra_local_parent,
                         )
                     }
                     TyKind::TraitObject([], _, _)
@@ -151,18 +146,27 @@ impl<'tcx> LateLintPass<'tcx> for NonLocalDefinitions {
                     | TyKind::Err(_) => false,
                 };
 
-                let of_trait_has_local_parent = impl_
-                    .of_trait
-                    .map(|of_trait| path_has_local_parent(of_trait.path, cx, &*local_parents))
-                    .unwrap_or(false);
+                let of_trait_has_local_parent = self_ty_has_local_parent
+                    || impl_
+                        .of_trait
+                        .map(|of_trait| {
+                            path_has_local_parent(of_trait.path, cx, &parent, &extra_local_parent)
+                        })
+                        .unwrap_or(false);
 
                 // If none of them have a local parent (LOGICAL NOR) this means that
                 // this impl definition is a non-local definition and so we lint on it.
                 if !(self_ty_has_local_parent || of_trait_has_local_parent) {
+                    // Per RFC we (currently) ignore anon-const (`const _: Ty = ...`) in
+                    // top-level module.
+                    if self.body_depth == 1 && parent_is_anon_const() {
+                        return;
+                    }
+
                     let const_anon = if self.body_depth == 1
-                        && parent_def_kind == DefKind::Const
-                        && parent_opt_item_name != Some(kw::Underscore)
-                        && let Some(parent) = parent.as_local()
+                        && parent_def_kind() == DefKind::Const
+                        && parent_opt_item_name() != Some(kw::Underscore)
+                        && let Some(parent) = parent().as_local()
                         && let Node::Item(item) = cx.tcx.hir_node_by_def_id(parent)
                         && let ItemKind::Const(ty, _, _) = item.kind
                         && let TyKind::Tup(&[]) = ty.kind
@@ -177,8 +181,8 @@ impl<'tcx> LateLintPass<'tcx> for NonLocalDefinitions {
                         item.span,
                         NonLocalDefinitionsDiag::Impl {
                             depth: self.body_depth,
-                            body_kind_descr: cx.tcx.def_kind_descr(parent_def_kind, parent),
-                            body_name: parent_opt_item_name
+                            body_kind_descr: cx.tcx.def_kind_descr(parent_def_kind(), parent()),
+                            body_name: parent_opt_item_name()
                                 .map(|s| s.to_ident_string())
                                 .unwrap_or_else(|| "<unnameable>".to_string()),
                             cargo_update: cargo_update(),
@@ -195,8 +199,8 @@ impl<'tcx> LateLintPass<'tcx> for NonLocalDefinitions {
                     item.span,
                     NonLocalDefinitionsDiag::MacroRules {
                         depth: self.body_depth,
-                        body_kind_descr: cx.tcx.def_kind_descr(parent_def_kind, parent),
-                        body_name: parent_opt_item_name
+                        body_kind_descr: cx.tcx.def_kind_descr(parent_def_kind(), parent()),
+                        body_name: parent_opt_item_name()
                             .map(|s| s.to_ident_string())
                             .unwrap_or_else(|| "<unnameable>".to_string()),
                         cargo_update: cargo_update(),
@@ -217,6 +221,16 @@ impl<'tcx> LateLintPass<'tcx> for NonLocalDefinitions {
 ///    std::convert::PartialEq<Foo<Bar>>
 ///    ^^^^^^^^^^^^^^^^^^^^^^^
 /// ```
-fn path_has_local_parent(path: &Path<'_>, cx: &LateContext<'_>, local_parents: &[DefId]) -> bool {
-    path.res.opt_def_id().is_some_and(|did| local_parents.contains(&cx.tcx.parent(did)))
+fn path_has_local_parent(
+    path: &Path<'_>,
+    cx: &LateContext<'_>,
+    parent: impl Fn() -> DefId,
+    extra_local_parent: impl Fn() -> Option<DefId>,
+) -> bool {
+    path.res.opt_def_id().is_some_and(|did| {
+        did.is_local() && {
+            let res_parent = cx.tcx.parent(did);
+            res_parent == parent() || Some(res_parent) == extra_local_parent()
+        }
+    })
 }

tests/ui/lint/non_local_definitions.rs

@@ -1,7 +1,7 @@
 //@ check-pass
 //@ edition:2021
 //@ aux-build:non_local_macro.rs
-//@ rustc-env:CARGO=/usr/bin/cargo
+//@ rustc-env:CARGO_CRATE_NAME=non_local_def
 
 #![feature(inline_const)]