Rollup merge of #130764 - compiler-errors:inherent, r=estebank

Separate collection of crate-local inherent impls from error tracking

#119895 changed the return type of the `crate_inherent_impls` query from `CrateInherentImpls` to `Result<CrateInherentImpls, ErrorGuaranteed>` to avoid needing to use the non-parallel-friendly `track_errors()` to track if an error was reporting from within the query... This was mostly fine until #121113, which stopped halting compilation when we hit an `Err(ErrorGuaranteed)` in the `crate_inherent_impls` query.

Thus we proceed onwards to typeck, and since a return type of `Result<CrateInherentImpls, ErrorGuaranteed>` means that the query can *either* return one of "the list inherent impls" or "error has been reported", later on when we want to assemble method or associated item candidates for inherent impls, we were just treating any `Err(ErrorGuaranteed)` return value as if Rust had no inherent impls defined anywhere at all! This leads to basically every inherent method call failing with an error, lol, which was reported in #127798.

This PR changes the `crate_inherent_impls` query to return `(CrateInherentImpls, Result<(), ErrorGuaranteed>)`, i.e. returning the inherent impls collected *and* whether an error was reported in the query itself. It firewalls the latter part of that query into a new `crate_inherent_impls_validity_check` just for the `ensure()` call.

This fixes #127798.

6 files changed, 5 insertions, 14 deletions

diff --git a/clippy_lints/src/derive.rs b/clippy_lints/src/derive.rs
index 636698e96f6..649c480fb92 100644
--- a/clippy_lints/src/derive.rs
+++ b/clippy_lints/src/derive.rs
@@ -386,7 +386,6 @@ fn check_unsafe_derive_deserialize<'tcx>(
             .tcx
             .inherent_impls(def.did())
             .into_iter()
-            .flatten()
             .map(|imp_did| cx.tcx.hir().expect_item(imp_did.expect_local()))
             .any(|imp| has_unsafe(cx, imp))
     {
diff --git a/clippy_lints/src/inherent_impl.rs b/clippy_lints/src/inherent_impl.rs
index d39f910f993..309d2dfb28b 100644
--- a/clippy_lints/src/inherent_impl.rs
+++ b/clippy_lints/src/inherent_impl.rs
@@ -51,9 +51,7 @@ impl<'tcx> LateLintPass<'tcx> for MultipleInherentImpl {
         // List of spans to lint. (lint_span, first_span)
         let mut lint_spans = Vec::new();
 
-        let Ok(impls) = cx.tcx.crate_inherent_impls(()) else {
-            return;
-        };
+        let (impls, _) = cx.tcx.crate_inherent_impls(());
 
         for (&id, impl_ids) in &impls.inherent_impls {
             if impl_ids.len() < 2
diff --git a/clippy_lints/src/len_zero.rs b/clippy_lints/src/len_zero.rs
index 0bc7fc2dd9d..16f86b18e2e 100644
--- a/clippy_lints/src/len_zero.rs
+++ b/clippy_lints/src/len_zero.rs
@@ -448,7 +448,6 @@ fn check_for_is_empty(
         .tcx
         .inherent_impls(impl_ty)
         .into_iter()
-        .flatten()
         .flat_map(|&id| cx.tcx.associated_items(id).filter_by_name_unhygienic(is_empty))
         .find(|item| item.kind == AssocKind::Fn);
 
@@ -616,7 +615,7 @@ fn has_is_empty(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
     /// Checks the inherent impl's items for an `is_empty(self)` method.
     fn has_is_empty_impl(cx: &LateContext<'_>, id: DefId) -> bool {
         let is_empty = sym!(is_empty);
-        cx.tcx.inherent_impls(id).into_iter().flatten().any(|imp| {
+        cx.tcx.inherent_impls(id).into_iter().any(|imp| {
             cx.tcx
                 .associated_items(*imp)
                 .filter_by_name_unhygienic(is_empty)
diff --git a/clippy_lints/src/methods/or_fun_call.rs b/clippy_lints/src/methods/or_fun_call.rs
index e4326cb958e..af71799f0a7 100644
--- a/clippy_lints/src/methods/or_fun_call.rs
+++ b/clippy_lints/src/methods/or_fun_call.rs
@@ -78,7 +78,6 @@ pub(super) fn check<'tcx>(
             cx.tcx
                 .inherent_impls(adt_def.did())
                 .into_iter()
-                .flatten()
                 .flat_map(|impl_id| cx.tcx.associated_items(impl_id).filter_by_name_unhygienic(sugg))
                 .find_map(|assoc| {
                     if assoc.fn_has_self_parameter
diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs
index 0d0d6219c5e..aed0bc565d8 100644
--- a/clippy_utils/src/lib.rs
+++ b/clippy_utils/src/lib.rs
@@ -589,14 +589,11 @@ fn find_primitive_impls<'tcx>(tcx: TyCtxt<'tcx>, name: &str) -> impl Iterator<It
         "f32" => SimplifiedType::Float(FloatTy::F32),
         "f64" => SimplifiedType::Float(FloatTy::F64),
         _ => {
-            return Result::<&[_], rustc_errors::ErrorGuaranteed>::Ok(&[])
-                .into_iter()
-                .flatten()
-                .copied();
+            return [].iter().copied();
         },
     };
 
-    tcx.incoherent_impls(ty).into_iter().flatten().copied()
+    tcx.incoherent_impls(ty).into_iter().copied()
 }
 
 fn non_local_item_children_by_name(tcx: TyCtxt<'_>, def_id: DefId, name: Symbol) -> Vec<Res> {
@@ -721,7 +718,6 @@ pub fn def_path_res(tcx: TyCtxt<'_>, path: &[&str]) -> Vec<Res> {
                 let inherent_impl_children = tcx
                     .inherent_impls(def_id)
                     .into_iter()
-                    .flatten()
                     .flat_map(|&impl_def_id| item_children_by_name(tcx, impl_def_id, segment));
 
                 let direct_children = item_children_by_name(tcx, def_id, segment);
diff --git a/clippy_utils/src/ty.rs b/clippy_utils/src/ty.rs
index 585134209ca..22aaaa1b734 100644
--- a/clippy_utils/src/ty.rs
+++ b/clippy_utils/src/ty.rs
@@ -1316,7 +1316,7 @@ pub fn deref_chain<'cx, 'tcx>(cx: &'cx LateContext<'tcx>, ty: Ty<'tcx>) -> impl
 /// If you need this, you should wrap this call in `clippy_utils::ty::deref_chain().any(...)`.
 pub fn get_adt_inherent_method<'a>(cx: &'a LateContext<'_>, ty: Ty<'_>, method_name: Symbol) -> Option<&'a AssocItem> {
     if let Some(ty_did) = ty.ty_adt_def().map(AdtDef::did) {
-        cx.tcx.inherent_impls(ty_did).into_iter().flatten().find_map(|&did| {
+        cx.tcx.inherent_impls(ty_did).into_iter().find_map(|&did| {
             cx.tcx
                 .associated_items(did)
                 .filter_by_name_unhygienic(method_name)