-use crate::utils::{
- match_def_path, match_trait_method, paths, same_tys, snippet, snippet_with_macro_callsite, span_lint_and_sugg,
-};
+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 if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind, HirId, MatchSource};
use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty;
use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::sym;
declare_clippy_lint! {
- /// **What it does:** Checks for `Into`/`From`/`IntoIter` calls that useless converts
- /// to the same type as caller.
+ /// ### What it does
+ /// Checks for `Into`, `TryInto`, `From`, `TryFrom`, or `IntoIter` calls
+ /// which uselessly convert to the same type.
///
- /// **Why is this bad?** Redundant code.
- ///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Why is this bad?
+ /// Redundant code.
///
+ /// ### Example
/// ```rust
/// // Bad
/// // format!() returns a `String`
/// ```
pub USELESS_CONVERSION,
complexity,
- "calls to `Into`/`From`/`IntoIter` that performs useless conversions to the same type"
+ "calls to `Into`, `TryInto`, `From`, `TryFrom`, or `IntoIter` which perform useless conversions to the same type"
}
#[derive(Default)]
impl_lint_pass!(UselessConversion => [USELESS_CONVERSION]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UselessConversion {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr<'_>) {
+#[allow(clippy::too_many_lines)]
+impl<'tcx> LateLintPass<'tcx> for UselessConversion {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
if e.span.from_expansion() {
return;
}
}
match e.kind {
- ExprKind::Match(_, ref arms, MatchSource::TryDesugar) => {
+ ExprKind::Match(_, arms, MatchSource::TryDesugar) => {
let e = match arms[0].body.kind {
- ExprKind::Ret(Some(ref e)) | ExprKind::Break(_, Some(ref e)) => e,
+ ExprKind::Ret(Some(e)) | ExprKind::Break(_, Some(e)) => e,
_ => return,
};
- if let ExprKind::Call(_, ref args) = e.kind {
+ if let ExprKind::Call(_, args) = e.kind {
self.try_desugar_arm.push(args[0].hir_id);
}
},
- ExprKind::MethodCall(ref name, .., ref args) => {
- if match_trait_method(cx, e, &paths::INTO) && &*name.ident.as_str() == "into" {
- let a = cx.tables.expr_ty(e);
- let b = cx.tables.expr_ty(&args[0]);
- if same_tys(cx, a, b) {
+ ExprKind::MethodCall(name, .., args, _) => {
+ if is_trait_method(cx, e, sym::into_trait) && &*name.ident.as_str() == "into" {
+ let a = cx.typeck_results().expr_ty(e);
+ let b = cx.typeck_results().expr_ty(&args[0]);
+ if same_type_and_consts(a, b) {
let sugg = snippet_with_macro_callsite(cx, args[0].span, "<expr>").to_string();
-
span_lint_and_sugg(
cx,
USELESS_CONVERSION,
e.span,
- "useless conversion",
+ &format!("useless conversion to the same type: `{}`", b),
"consider removing `.into()`",
sugg,
Applicability::MachineApplicable, // snippet
);
}
}
- if match_trait_method(cx, e, &paths::INTO_ITERATOR) && &*name.ident.as_str() == "into_iter" {
- let a = cx.tables.expr_ty(e);
- let b = cx.tables.expr_ty(&args[0]);
- if same_tys(cx, a, b) {
+ 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;
+ }
+ }
+ }
+ let a = cx.typeck_results().expr_ty(e);
+ let b = cx.typeck_results().expr_ty(&args[0]);
+ if same_type_and_consts(a, b) {
let sugg = snippet(cx, args[0].span, "<expr>").into_owned();
span_lint_and_sugg(
cx,
USELESS_CONVERSION,
e.span,
- "useless conversion",
+ &format!("useless conversion to the same type: `{}`", b),
"consider removing `.into_iter()`",
sugg,
Applicability::MachineApplicable, // snippet
);
}
}
+ if_chain! {
+ if is_trait_method(cx, e, sym::try_into_trait) && name.ident.name == sym::try_into;
+ let a = cx.typeck_results().expr_ty(e);
+ let b = cx.typeck_results().expr_ty(&args[0]);
+ if is_type_diagnostic_item(cx, a, sym::result_type);
+ if let ty::Adt(_, substs) = a.kind();
+ if let Some(a_type) = substs.types().next();
+ if same_type_and_consts(a_type, b);
+
+ then {
+ span_lint_and_help(
+ cx,
+ USELESS_CONVERSION,
+ e.span,
+ &format!("useless conversion to the same type: `{}`", b),
+ None,
+ "consider removing `.try_into()`",
+ );
+ }
+ }
},
- ExprKind::Call(ref path, ref args) => {
- if let ExprKind::Path(ref qpath) = path.kind {
- if let Some(def_id) = cx.tables.qpath_res(qpath, path.hir_id).opt_def_id() {
- if match_def_path(cx, def_id, &paths::FROM_FROM) {
- let a = cx.tables.expr_ty(e);
- let b = cx.tables.expr_ty(&args[0]);
- if same_tys(cx, a, b) {
- let sugg = snippet(cx, args[0].span.source_callsite(), "<expr>").into_owned();
+ ExprKind::Call(path, args) => {
+ if_chain! {
+ if args.len() == 1;
+ if let ExprKind::Path(ref qpath) = path.kind;
+ if let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id();
+ then {
+ let a = cx.typeck_results().expr_ty(e);
+ let b = cx.typeck_results().expr_ty(&args[0]);
+ if_chain! {
+ if match_def_path(cx, def_id, &paths::TRY_FROM);
+ if is_type_diagnostic_item(cx, a, sym::result_type);
+ if let ty::Adt(_, substs) = a.kind();
+ if let Some(a_type) = substs.types().next();
+ if same_type_and_consts(a_type, b);
+
+ then {
+ let hint = format!("consider removing `{}()`", snippet(cx, path.span, "TryFrom::try_from"));
+ span_lint_and_help(
+ cx,
+ USELESS_CONVERSION,
+ e.span,
+ &format!("useless conversion to the same type: `{}`", b),
+ None,
+ &hint,
+ );
+ }
+ }
+
+ if_chain! {
+ if match_def_path(cx, def_id, &paths::FROM_FROM);
+ if same_type_and_consts(a, b);
+
+ then {
+ let sugg = Sugg::hir_with_macro_callsite(cx, &args[0], "<expr>").maybe_par();
let sugg_msg =
format!("consider removing `{}()`", snippet(cx, path.span, "From::from"));
span_lint_and_sugg(
cx,
USELESS_CONVERSION,
e.span,
- "useless conversion",
+ &format!("useless conversion to the same type: `{}`", b),
&sugg_msg,
- sugg,
+ sugg.to_string(),
Applicability::MachineApplicable, // snippet
);
}
}
}
- fn check_expr_post(&mut self, _: &LateContext<'a, 'tcx>, e: &'tcx Expr<'_>) {
+ fn check_expr_post(&mut self, _: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
if Some(&e.hir_id) == self.try_desugar_arm.last() {
self.try_desugar_arm.pop();
}
projects / rust.git / blobdiff