Set correct `ParamEnv` for `derive_partial_eq_without_eq`

[rust.git] / clippy_lints / src / derive.rs

diff --git a/clippy_lints/src/derive.rs b/clippy_lints/src/derive.rs
index fe99f4a8d55d1e359473da38289fb397400cd490..99347ebadc60277e7249796cd1048e1cafa388ff 100644 (file)
--- a/clippy_lints/src/derive.rs
+++ b/clippy_lints/src/derive.rs
@@ -1,16 +1,17 @@
 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note, span_lint_and_sugg, span_lint_and_then};
 use clippy_utils::paths;
-use clippy_utils::ty::{implements_trait, is_copy};
+use clippy_utils::ty::{implements_trait, implements_trait_with_env, is_copy};
 use clippy_utils::{is_lint_allowed, match_def_path};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::{walk_expr, walk_fn, walk_item, FnKind, Visitor};
 use rustc_hir::{
-    BlockCheckMode, BodyId, Expr, ExprKind, FnDecl, HirId, Impl, Item, ItemKind, TraitRef, UnsafeSource, Unsafety,
+    self as hir, BlockCheckMode, BodyId, Expr, ExprKind, FnDecl, HirId, Impl, Item, ItemKind, UnsafeSource, Unsafety,
 };
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::hir::nested_filter;
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::ty::subst::GenericArg;
+use rustc_middle::ty::{self, BoundConstness, ImplPolarity, ParamEnv, PredicateKind, TraitPredicate, TraitRef, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
 use rustc_span::sym;
@@ -224,7 +225,7 @@ fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
 fn check_hash_peq<'tcx>(
     cx: &LateContext<'tcx>,
     span: Span,
-    trait_ref: &TraitRef<'_>,
+    trait_ref: &hir::TraitRef<'_>,
     ty: Ty<'tcx>,
     hash_is_automatically_derived: bool,
 ) {
@@ -277,7 +278,7 @@ fn check_hash_peq<'tcx>(
 fn check_ord_partial_ord<'tcx>(
     cx: &LateContext<'tcx>,
     span: Span,
-    trait_ref: &TraitRef<'_>,
+    trait_ref: &hir::TraitRef<'_>,
     ty: Ty<'tcx>,
     ord_is_automatically_derived: bool,
 ) {
@@ -328,7 +329,7 @@ fn check_ord_partial_ord<'tcx>(
 }
 
 /// Implementation of the `EXPL_IMPL_CLONE_ON_COPY` lint.
-fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &TraitRef<'_>, ty: Ty<'tcx>) {
+fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &hir::TraitRef<'_>, ty: Ty<'tcx>) {
     let clone_id = match cx.tcx.lang_items().clone_trait() {
         Some(id) if trait_ref.trait_def_id() == Some(id) => id,
         _ => return,
@@ -378,7 +379,7 @@ fn check_copy_clone<'tcx>(cx: &LateContext<'tcx>, item: &Item<'_>, trait_ref: &T
 fn check_unsafe_derive_deserialize<'tcx>(
     cx: &LateContext<'tcx>,
     item: &Item<'_>,
-    trait_ref: &TraitRef<'_>,
+    trait_ref: &hir::TraitRef<'_>,
     ty: Ty<'tcx>,
 ) {
     fn has_unsafe<'tcx>(cx: &LateContext<'tcx>, item: &'tcx Item<'_>) -> bool {
@@ -455,13 +456,41 @@ fn nested_visit_map(&mut self) -> Self::Map {
 }
 
 /// Implementation of the `DERIVE_PARTIAL_EQ_WITHOUT_EQ` lint.
-fn check_partial_eq_without_eq<'tcx>(cx: &LateContext<'tcx>, span: Span, trait_ref: &TraitRef<'_>, ty: Ty<'tcx>) {
+fn check_partial_eq_without_eq<'tcx>(cx: &LateContext<'tcx>, span: Span, trait_ref: &hir::TraitRef<'_>, ty: Ty<'tcx>) {
     if_chain! {
         if let ty::Adt(adt, substs) = ty.kind();
         if let Some(eq_trait_def_id) = cx.tcx.get_diagnostic_item(sym::Eq);
+        if let Some(peq_trait_def_id) = cx.tcx.get_diagnostic_item(sym::PartialEq);
         if let Some(def_id) = trait_ref.trait_def_id();
         if cx.tcx.is_diagnostic_item(sym::PartialEq, def_id);
-        if !implements_trait(cx, ty, eq_trait_def_id, substs);
+        // New `ParamEnv` replacing `T: PartialEq` with `T: Eq`
+        let param_env = ParamEnv::new(
+            cx.tcx.mk_predicates(cx.param_env.caller_bounds().iter().map(|p| {
+                let kind = p.kind();
+                match kind.skip_binder() {
+                    PredicateKind::Trait(p)
+                        if p.trait_ref.def_id == peq_trait_def_id
+                            && p.trait_ref.substs.get(0) == p.trait_ref.substs.get(1)
+                            && matches!(p.trait_ref.self_ty().kind(), ty::Param(_))
+                            && p.constness == BoundConstness::NotConst
+                            && p.polarity == ImplPolarity::Positive =>
+                    {
+                        cx.tcx.mk_predicate(kind.rebind(PredicateKind::Trait(TraitPredicate {
+                            trait_ref: TraitRef::new(
+                                eq_trait_def_id,
+                                cx.tcx.mk_substs([GenericArg::from(p.trait_ref.self_ty())].into_iter()),
+                            ),
+                            constness: BoundConstness::NotConst,
+                            polarity: ImplPolarity::Positive,
+                        })))
+                    },
+                    _ => p,
+                }
+            })),
+            cx.param_env.reveal(),
+            cx.param_env.constness(),
+        );
+        if !implements_trait_with_env(cx.tcx, param_env, ty, eq_trait_def_id, substs);
         then {
             // If all of our fields implement `Eq`, we can implement `Eq` too
             for variant in adt.variants() {