use super::utils::make_iterator_snippet;
-use crate::utils::{is_ok_ctor, is_some_ctor, path_to_local_id, span_lint_and_then};
+use super::MANUAL_FLATTEN;
+use clippy_utils::diagnostics::span_lint_and_then;
+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;
/// Check for unnecessary `if let` usage in a for loop where only the `Some` or `Ok` variant of the
/// iterator element is used.
-pub(super) fn check_manual_flatten<'tcx>(
+pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
pat: &'tcx Pat<'_>,
arg: &'tcx Expr<'_>,
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
- };
-
- 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;
+ 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);
- then {
- // 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);
+ // 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,
- super::MANUAL_FLATTEN,
- span,
- &msg,
- |diag| {
- let sugg = format!("{}.flatten()", arg_snippet);
- 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",
+ );
+ }
+ );
}
}
}