Auto merge of #10679 - y21:better-const-ctx-check, r=Jarcho

use `is_inside_const_context` for `in_constant` util fn

Fixes #10452.

This PR improves the `in_constant` util function to detect more cases of const contexts. Previously this function would not detect cases like expressions in array length position or expression in an inline const block `const { .. }`.

changelog: [`bool_to_int_with_if`]: recognize array length operand as being in a const context and don't suggest `usize::from` there

1 files changed, 4 insertions, 28 deletions

diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs
index 4b9fa033446..ba4bd6e1769 100644
--- a/clippy_utils/src/lib.rs
+++ b/clippy_utils/src/lib.rs
@@ -86,10 +86,10 @@ use rustc_hir::hir_id::{HirIdMap, HirIdSet};
 use rustc_hir::intravisit::{walk_expr, FnKind, Visitor};
 use rustc_hir::LangItem::{OptionNone, ResultErr, ResultOk};
 use rustc_hir::{
-    self as hir, def, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, Closure, Constness, Destination,
-    Expr, ExprKind, FnDecl, HirId, Impl, ImplItem, ImplItemKind, ImplItemRef, IsAsync, Item, ItemKind, LangItem, Local,
+    self as hir, def, Arm, ArrayLen, BindingAnnotation, Block, BlockCheckMode, Body, Closure, Destination, Expr,
+    ExprKind, FnDecl, HirId, Impl, ImplItem, ImplItemKind, ImplItemRef, IsAsync, Item, ItemKind, LangItem, Local,
     MatchSource, Mutability, Node, OwnerId, Param, Pat, PatKind, Path, PathSegment, PrimTy, QPath, Stmt, StmtKind,
-    TraitItem, TraitItemKind, TraitItemRef, TraitRef, TyKind, UnOp,
+    TraitItem, TraitItemRef, TraitRef, TyKind, UnOp,
 };
 use rustc_lexer::{tokenize, TokenKind};
 use rustc_lint::{LateContext, Level, Lint, LintContext};
@@ -197,31 +197,7 @@ pub fn find_binding_init<'tcx>(cx: &LateContext<'tcx>, hir_id: HirId) -> Option<
 /// }
 /// ```
 pub fn in_constant(cx: &LateContext<'_>, id: HirId) -> bool {
-    let parent_id = cx.tcx.hir().get_parent_item(id).def_id;
-    match cx.tcx.hir().get_by_def_id(parent_id) {
-        Node::Item(&Item {
-            kind: ItemKind::Const(..) | ItemKind::Static(..) | ItemKind::Enum(..),
-            ..
-        })
-        | Node::TraitItem(&TraitItem {
-            kind: TraitItemKind::Const(..),
-            ..
-        })
-        | Node::ImplItem(&ImplItem {
-            kind: ImplItemKind::Const(..),
-            ..
-        })
-        | Node::AnonConst(_) => true,
-        Node::Item(&Item {
-            kind: ItemKind::Fn(ref sig, ..),
-            ..
-        })
-        | Node::ImplItem(&ImplItem {
-            kind: ImplItemKind::Fn(ref sig, _),
-            ..
-        }) => sig.header.constness == Constness::Const,
-        _ => false,
-    }
+    cx.tcx.hir().is_inside_const_context(id)
 }
 
 /// Checks if a `Res` refers to a constructor of a `LangItem`