diff options
Diffstat (limited to 'src/tools/clippy/clippy_lints/src/useless_conversion.rs')
-rw-r--r-- | src/tools/clippy/clippy_lints/src/useless_conversion.rs | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/src/tools/clippy/clippy_lints/src/useless_conversion.rs b/src/tools/clippy/clippy_lints/src/useless_conversion.rs index 3743d5d97..a95e7b613 100644 --- a/src/tools/clippy/clippy_lints/src/useless_conversion.rs +++ b/src/tools/clippy/clippy_lints/src/useless_conversion.rs @@ -1,11 +1,11 @@ use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_sugg}; use clippy_utils::source::{snippet, snippet_with_macro_callsite}; use clippy_utils::sugg::Sugg; -use clippy_utils::ty::{is_type_diagnostic_item, same_type_and_consts}; -use clippy_utils::{get_parent_expr, is_trait_method, match_def_path, paths}; +use clippy_utils::ty::{is_copy, is_type_diagnostic_item, same_type_and_consts}; +use clippy_utils::{get_parent_expr, is_trait_method, match_def_path, path_to_local, paths}; use if_chain::if_chain; use rustc_errors::Applicability; -use rustc_hir::{Expr, ExprKind, HirId, MatchSource}; +use rustc_hir::{BindingAnnotation, Expr, ExprKind, HirId, MatchSource, Node, PatKind}; use rustc_lint::{LateContext, LateLintPass}; use rustc_middle::ty; use rustc_session::{declare_tool_lint, impl_lint_pass}; @@ -81,16 +81,24 @@ impl<'tcx> LateLintPass<'tcx> for UselessConversion { } } if is_trait_method(cx, e, sym::IntoIterator) && name.ident.name == sym::into_iter { - if let Some(parent_expr) = get_parent_expr(cx, e) { - if let ExprKind::MethodCall(parent_name, ..) = parent_expr.kind { - if parent_name.ident.name != sym::into_iter { - return; - } - } + if get_parent_expr(cx, e).is_some() && + let Some(id) = path_to_local(recv) && + let Node::Pat(pat) = cx.tcx.hir().get(id) && + let PatKind::Binding(ann, ..) = pat.kind && + ann != BindingAnnotation::MUT + { + // Do not remove .into_iter() applied to a non-mutable local variable used in + // a larger expression context as it would differ in mutability. + return; } + let a = cx.typeck_results().expr_ty(e); let b = cx.typeck_results().expr_ty(recv); - if same_type_and_consts(a, b) { + + // If the types are identical then .into_iter() can be removed, unless the type + // implements Copy, in which case .into_iter() returns a copy of the receiver and + // cannot be safely omitted. + if same_type_and_consts(a, b) && !is_copy(cx, b) { let sugg = snippet(cx, recv.span, "<expr>").into_owned(); span_lint_and_sugg( cx, |