Implement manual flatten lint

clippy_lints/src/utils/higher.rs

@@ -9,6 +9,7 @@ use rustc_ast::ast;
 use rustc_hir as hir;
 use rustc_hir::{BorrowKind, Expr, ExprKind, StmtKind, UnOp};
 use rustc_lint::LateContext;
+use rustc_span::source_map::Span;
 
 /// Converts a hir binary operator to the corresponding `ast` type.
 #[must_use]
@@ -133,11 +134,11 @@ pub fn is_from_for_desugar(local: &hir::Local<'_>) -> bool {
     false
 }
 
-/// Recover the essential nodes of a desugared for loop:
-/// `for pat in arg { body }` becomes `(pat, arg, body)`.
+/// Recover the essential nodes of a desugared for loop as well as the entire span:
+/// `for pat in arg { body }` becomes `(pat, arg, body)`. Return `(pat, arg, body, span)`.
 pub fn for_loop<'tcx>(
     expr: &'tcx hir::Expr<'tcx>,
-) -> Option<(&hir::Pat<'_>, &'tcx hir::Expr<'tcx>, &'tcx hir::Expr<'tcx>)> {
+) -> Option<(&hir::Pat<'_>, &'tcx hir::Expr<'tcx>, &'tcx hir::Expr<'tcx>, Span)> {
     if_chain! {
         if let hir::ExprKind::Match(ref iterexpr, ref arms, hir::MatchSource::ForLoopDesugar) = expr.kind;
         if let hir::ExprKind::Call(_, ref iterargs) = iterexpr.kind;
@@ -148,7 +149,7 @@ pub fn for_loop<'tcx>(
         if let hir::StmtKind::Local(ref local) = let_stmt.kind;
         if let hir::StmtKind::Expr(ref expr) = body.kind;
         then {
-            return Some((&*local.pat, &iterargs[0], expr));
+            return Some((&*local.pat, &iterargs[0], expr, arms[0].span));
         }
     }
     None

clippy_lints/src/utils/internal_lints.rs

@@ -841,15 +841,13 @@ pub fn check_path(cx: &LateContext<'_>, path: &[&str]) -> bool {
     // implementations of native types. Check lang items.
     let path_syms: Vec<_> = path.iter().map(|p| Symbol::intern(p)).collect();
     let lang_items = cx.tcx.lang_items();
-    for lang_item in lang_items.items() {
-        if let Some(def_id) = lang_item {
-            let lang_item_path = cx.get_def_path(*def_id);
-            if path_syms.starts_with(&lang_item_path) {
-                if let [item] = &path_syms[lang_item_path.len()..] {
-                    for child in cx.tcx.item_children(*def_id) {
-                        if child.ident.name == *item {
-                            return true;
-                        }
+    for item_def_id in lang_items.items().iter().flatten() {
+        let lang_item_path = cx.get_def_path(*item_def_id);
+        if path_syms.starts_with(&lang_item_path) {
+            if let [item] = &path_syms[lang_item_path.len()..] {
+                for child in cx.tcx.item_children(*item_def_id) {
+                    if child.ident.name == *item {
+                        return true;
                     }
                 }
             }

clippy_lints/src/utils/mod.rs

@@ -37,7 +37,7 @@ use rustc_ast::ast::{self, Attribute, LitKind};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
-use rustc_hir::def::{DefKind, Res};
+use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::Node;
@@ -50,7 +50,7 @@ use rustc_lint::{LateContext, Level, Lint, LintContext};
 use rustc_middle::hir::exports::Export;
 use rustc_middle::hir::map::Map;
 use rustc_middle::ty::subst::{GenericArg, GenericArgKind};
-use rustc_middle::ty::{self, layout::IntegerExt, Ty, TyCtxt, TypeFoldable};
+use rustc_middle::ty::{self, layout::IntegerExt, DefIdTree, Ty, TyCtxt, TypeFoldable};
 use rustc_semver::RustcVersion;
 use rustc_session::Session;
 use rustc_span::hygiene::{ExpnKind, MacroKind};
@@ -1700,6 +1700,30 @@ pub fn is_hir_ty_cfg_dependant(cx: &LateContext<'_>, ty: &hir::Ty<'_>) -> bool {
     }
 }
 
+/// Check if the resolution of a given path is an `Ok` variant of `Result`.
+pub fn is_ok_ctor(cx: &LateContext<'_>, res: Res) -> bool {
+    if let Some(ok_id) = cx.tcx.lang_items().result_ok_variant() {
+        if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
+            if let Some(variant_id) = cx.tcx.parent(id) {
+                return variant_id == ok_id;
+            }
+        }
+    }
+    false
+}
+
+/// Check if the resolution of a given path is a `Some` variant of `Option`.
+pub fn is_some_ctor(cx: &LateContext<'_>, res: Res) -> bool {
+    if let Some(some_id) = cx.tcx.lang_items().option_some_variant() {
+        if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
+            if let Some(variant_id) = cx.tcx.parent(id) {
+                return variant_id == some_id;
+            }
+        }
+    }
+    false
+}
+
 #[cfg(test)]
 mod test {
     use super::{reindent_multiline, without_block_comments};