Require the constness query to only be invoked on things that can have constness

clippy_lints/src/manual_float_methods.rs

@@ -6,8 +6,11 @@ use clippy_utils::source::SpanRangeExt;
 use clippy_utils::{is_from_proc_macro, path_to_local};
 use rustc_errors::Applicability;
 use rustc_hir::{BinOpKind, Constness, Expr, ExprKind};
+use rustc_hir::def::DefKind;
+use rustc_hir::def_id::DefId;
 use rustc_lint::{LateContext, LateLintPass, Lint, LintContext};
 use rustc_middle::lint::in_external_macro;
+use rustc_middle::ty::TyCtxt;
 use rustc_session::impl_lint_pass;
 
 declare_clippy_lint! {
@@ -94,6 +97,44 @@ impl ManualFloatMethods {
     }
 }
 
+fn is_not_const(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
+    match tcx.def_kind(def_id) {
+        DefKind::Mod
+        | DefKind::Struct
+        | DefKind::Union
+        | DefKind::Enum
+        | DefKind::Variant
+        | DefKind::Trait
+        | DefKind::TyAlias
+        | DefKind::ForeignTy
+        | DefKind::TraitAlias
+        | DefKind::AssocTy
+        | DefKind::Macro(..)
+        | DefKind::Field
+        | DefKind::LifetimeParam
+        | DefKind::ExternCrate
+        | DefKind::Use
+        | DefKind::ForeignMod
+        | DefKind::GlobalAsm
+        | DefKind::Impl { .. }
+        | DefKind::OpaqueTy
+        | DefKind::SyntheticCoroutineBody
+        | DefKind::TyParam => true,
+
+        DefKind::AnonConst
+        | DefKind::InlineConst
+        | DefKind::Const
+        | DefKind::ConstParam
+        | DefKind::Static { .. }
+        | DefKind::Ctor(..)
+        | DefKind::AssocConst => false,
+
+        DefKind::Fn
+        | DefKind::AssocFn
+        | DefKind::Closure => tcx.constness(def_id) == Constness::NotConst,
+    }
+}
+
 impl<'tcx> LateLintPass<'tcx> for ManualFloatMethods {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
         if let ExprKind::Binary(kind, lhs, rhs) = expr.kind
@@ -105,7 +146,7 @@ impl<'tcx> LateLintPass<'tcx> for ManualFloatMethods {
             && exprs.iter_mut().partition_in_place(|i| path_to_local(i).is_some()) == 2
             && !in_external_macro(cx.sess(), expr.span)
             && (
-                matches!(cx.tcx.constness(cx.tcx.hir().enclosing_body_owner(expr.hir_id)), Constness::NotConst)
+                is_not_const(cx.tcx, cx.tcx.hir().enclosing_body_owner(expr.hir_id).into())
                     || self.msrv.meets(msrvs::CONST_FLOAT_CLASSIFY)
             )
             && let [first, second, const_1, const_2] = exprs