Auto merge of #8030 - WaffleLapkin:ignore_trait_assoc_types_type_complexity, r=llogiq

[rust.git] / clippy_lints / src / loops / manual_flatten.rs

diff --git a/clippy_lints/src/loops/manual_flatten.rs b/clippy_lints/src/loops/manual_flatten.rs
index 574ad8c0f29dd905bab9f6590c956ee140487e63..d276c901059974a54c38d51601f26c3a6d070638 100644 (file)
--- a/clippy_lints/src/loops/manual_flatten.rs
+++ b/clippy_lints/src/loops/manual_flatten.rs
@@ -1,10 +1,13 @@
 use super::utils::make_iterator_snippet;
 use super::MANUAL_FLATTEN;
 use clippy_utils::diagnostics::span_lint_and_then;
-use clippy_utils::{is_ok_ctor, is_some_ctor, path_to_local_id};
+use clippy_utils::higher;
+use clippy_utils::visitors::is_local_used;
+use clippy_utils::{is_lang_ctor, path_to_local_id, peel_blocks_with_stmt};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::{Expr, ExprKind, MatchSource, Pat, PatKind, QPath, StmtKind};
+use rustc_hir::LangItem::{OptionSome, ResultOk};
+use rustc_hir::{Expr, Pat, PatKind};
 use rustc_lint::LateContext;
 use rustc_middle::ty;
 use rustc_span::source_map::Span;
@@ -18,70 +21,55 @@ pub(super) fn check<'tcx>(
     body: &'tcx Expr<'_>,
     span: Span,
 ) {
-    if let ExprKind::Block(ref block, _) = body.kind {
-        // Ensure the `if let` statement is the only expression or statement in the for-loop
-        let inner_expr = if block.stmts.len() == 1 && block.expr.is_none() {
-            let match_stmt = &block.stmts[0];
-            if let StmtKind::Semi(inner_expr) = match_stmt.kind {
-                Some(inner_expr)
-            } else {
-                None
-            }
-        } else if block.stmts.is_empty() {
-            block.expr
-        } else {
-            None
-        };
+    let inner_expr = peel_blocks_with_stmt(body);
+    if_chain! {
+        if let Some(higher::IfLet { let_pat, let_expr, if_then, if_else: None })
+            = higher::IfLet::hir(cx, inner_expr);
+        // Ensure match_expr in `if let` statement is the same as the pat from the for-loop
+        if let PatKind::Binding(_, pat_hir_id, _, _) = pat.kind;
+        if path_to_local_id(let_expr, pat_hir_id);
+        // Ensure the `if let` statement is for the `Some` variant of `Option` or the `Ok` variant of `Result`
+        if let PatKind::TupleStruct(ref qpath, _, _) = let_pat.kind;
+        let some_ctor = is_lang_ctor(cx, qpath, OptionSome);
+        let ok_ctor = is_lang_ctor(cx, qpath, ResultOk);
+        if some_ctor || ok_ctor;
+        // Ensure expr in `if let` is not used afterwards
+        if !is_local_used(cx, if_then, pat_hir_id);
+        then {
+            let if_let_type = if some_ctor { "Some" } else { "Ok" };
+            // Prepare the error message
+            let msg = format!("unnecessary `if let` since only the `{}` variant of the iterator element is used", if_let_type);
 
-        if_chain! {
-            if let Some(inner_expr) = inner_expr;
-            if let ExprKind::Match(
-                ref match_expr, ref match_arms, MatchSource::IfLetDesugar{ contains_else_clause: false }
-            ) = inner_expr.kind;
-            // Ensure match_expr in `if let` statement is the same as the pat from the for-loop
-            if let PatKind::Binding(_, pat_hir_id, _, _) = pat.kind;
-            if path_to_local_id(match_expr, pat_hir_id);
-            // Ensure the `if let` statement is for the `Some` variant of `Option` or the `Ok` variant of `Result`
-            if let PatKind::TupleStruct(QPath::Resolved(None, path), _, _) = match_arms[0].pat.kind;
-            let some_ctor = is_some_ctor(cx, path.res);
-            let ok_ctor = is_ok_ctor(cx, path.res);
-            if some_ctor || ok_ctor;
-            then {
-                let if_let_type = if some_ctor { "Some" } else { "Ok" };
-                // Prepare the error message
-                let msg = format!("unnecessary `if let` since only the `{}` variant of the iterator element is used", if_let_type);
-
-                // Prepare the help message
-                let mut applicability = Applicability::MaybeIncorrect;
-                let arg_snippet = make_iterator_snippet(cx, arg, &mut applicability);
-                let copied = match cx.typeck_results().expr_ty(match_expr).kind() {
-                    ty::Ref(_, inner, _) => match inner.kind() {
-                        ty::Ref(..) => ".copied()",
-                        _ => ""
-                    }
+            // Prepare the help message
+            let mut applicability = Applicability::MaybeIncorrect;
+            let arg_snippet = make_iterator_snippet(cx, arg, &mut applicability);
+            let copied = match cx.typeck_results().expr_ty(let_expr).kind() {
+                ty::Ref(_, inner, _) => match inner.kind() {
+                    ty::Ref(..) => ".copied()",
                     _ => ""
-                };
+                }
+                _ => ""
+            };
 
-                span_lint_and_then(
-                    cx,
-                    MANUAL_FLATTEN,
-                    span,
-                    &msg,
-                    |diag| {
-                        let sugg = format!("{}{}.flatten()", arg_snippet, copied);
-                        diag.span_suggestion(
-                            arg.span,
-                            "try",
-                            sugg,
-                            Applicability::MaybeIncorrect,
-                        );
-                        diag.span_help(
-                            inner_expr.span,
-                            "...and remove the `if let` statement in the for loop",
-                        );
-                    }
-                );
-            }
+            span_lint_and_then(
+                cx,
+                MANUAL_FLATTEN,
+                span,
+                &msg,
+                |diag| {
+                    let sugg = format!("{}{}.flatten()", arg_snippet, copied);
+                    diag.span_suggestion(
+                        arg.span,
+                        "try",
+                        sugg,
+                        Applicability::MaybeIncorrect,
+                    );
+                    diag.span_help(
+                        inner_expr.span,
+                        "...and remove the `if let` statement in the for loop",
+                    );
+                }
+            );
         }
     }
 }