Fix and improve internal lint checking for `match_type` usages

* Check for `const`s and `static`s from external crates
* Check for `LangItem`s
* Handle inherent functions which have the same name as a field
* Also check the following functions:
    * `match_trait_method`
    * `match_def_path`
    * `is_expr_path_def_path`
    * `is_qpath_def_path`
* Handle checking for a constructor to a diagnostic item or `LangItem`

2 files changed, 47 insertions, 3 deletions

diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs
index c7cc5d04c85..8f67fa109fc 100644
--- a/clippy_utils/src/lib.rs
+++ b/clippy_utils/src/lib.rs
@@ -261,6 +261,46 @@ pub fn is_res_diagnostic_ctor(cx: &LateContext<'_>, res: Res, diag_item: Symbol)
     }
 }
 
+/// Checks if a `QPath` resolves to a constructor of a diagnostic item.
+pub fn is_diagnostic_ctor(cx: &LateContext<'_>, qpath: &QPath<'_>, diagnostic_item: Symbol) -> bool {
+    if let QPath::Resolved(_, path) = qpath {
+        if let Res::Def(DefKind::Ctor(..), ctor_id) = path.res {
+            return cx.tcx.is_diagnostic_item(diagnostic_item, cx.tcx.parent(ctor_id));
+        }
+    }
+    false
+}
+
+/// Checks if the `DefId` matches the given diagnostic item or it's constructor.
+pub fn is_diagnostic_item_or_ctor(cx: &LateContext<'_>, did: DefId, item: Symbol) -> bool {
+    let did = match cx.tcx.def_kind(did) {
+        DefKind::Ctor(..) => cx.tcx.parent(did),
+        // Constructors for types in external crates seem to have `DefKind::Variant`
+        DefKind::Variant => match cx.tcx.opt_parent(did) {
+            Some(did) if matches!(cx.tcx.def_kind(did), DefKind::Variant) => did,
+            _ => did,
+        },
+        _ => did,
+    };
+
+    cx.tcx.is_diagnostic_item(item, did)
+}
+
+/// Checks if the `DefId` matches the given `LangItem` or it's constructor.
+pub fn is_lang_item_or_ctor(cx: &LateContext<'_>, did: DefId, item: LangItem) -> bool {
+    let did = match cx.tcx.def_kind(did) {
+        DefKind::Ctor(..) => cx.tcx.parent(did),
+        // Constructors for types in external crates seem to have `DefKind::Variant`
+        DefKind::Variant => match cx.tcx.opt_parent(did) {
+            Some(did) if matches!(cx.tcx.def_kind(did), DefKind::Variant) => did,
+            _ => did,
+        },
+        _ => did,
+    };
+
+    cx.tcx.lang_items().require(item).map_or(false, |id| id == did)
+}
+
 pub fn is_unit_expr(expr: &Expr<'_>) -> bool {
     matches!(
         expr.kind,
@@ -496,6 +536,13 @@ pub fn def_path_res(cx: &LateContext<'_>, path: &[&str]) -> Res {
                 .copied()
                 .find(|assoc_def_id| tcx.item_name(*assoc_def_id).as_str() == name)
                 .map(|assoc_def_id| Res::Def(tcx.def_kind(assoc_def_id), assoc_def_id)),
+            DefKind::Struct | DefKind::Union => tcx
+                .adt_def(def_id)
+                .non_enum_variant()
+                .fields
+                .iter()
+                .find(|f| f.name.as_str() == name)
+                .map(|f| Res::Def(DefKind::Field, f.did)),
             _ => None,
         }
     }
diff --git a/clippy_utils/src/paths.rs b/clippy_utils/src/paths.rs
index 07170e2df12..13938645fc3 100644
--- a/clippy_utils/src/paths.rs
+++ b/clippy_utils/src/paths.rs
@@ -34,7 +34,6 @@ pub const DEFAULT_TRAIT_METHOD: [&str; 4] = ["core", "default", "Default", "defa
 pub const DEREF_MUT_TRAIT_METHOD: [&str; 5] = ["core", "ops", "deref", "DerefMut", "deref_mut"];
 /// Preferably use the diagnostic item `sym::deref_method` where possible
 pub const DEREF_TRAIT_METHOD: [&str; 5] = ["core", "ops", "deref", "Deref", "deref"];
-pub const DIR_BUILDER: [&str; 3] = ["std", "fs", "DirBuilder"];
 pub const DISPLAY_TRAIT: [&str; 3] = ["core", "fmt", "Display"];
 #[cfg(feature = "internal")]
 pub const EARLY_CONTEXT: [&str; 2] = ["rustc_lint", "EarlyContext"];
@@ -64,8 +63,6 @@ pub const IDENT_AS_STR: [&str; 4] = ["rustc_span", "symbol", "Ident", "as_str"];
 pub const INDEX: [&str; 3] = ["core", "ops", "Index"];
 pub const INDEX_MUT: [&str; 3] = ["core", "ops", "IndexMut"];
 pub const INSERT_STR: [&str; 4] = ["alloc", "string", "String", "insert_str"];
-pub const IO_READ: [&str; 3] = ["std", "io", "Read"];
-pub const IO_WRITE: [&str; 3] = ["std", "io", "Write"];
 pub const ITER_COUNT: [&str; 6] = ["core", "iter", "traits", "iterator", "Iterator", "count"];
 pub const ITER_EMPTY: [&str; 5] = ["core", "iter", "sources", "empty", "Empty"];
 pub const ITER_REPEAT: [&str; 5] = ["core", "iter", "sources", "repeat", "repeat"];