use rustc::ty;
use rustc_const_eval::ConstContext;
use rustc_const_math::ConstFloat;
-use syntax::codemap::{Span, Spanned, ExpnFormat};
+use syntax::codemap::{Span, ExpnFormat};
use utils::{get_item_name, get_parent_expr, implements_trait, in_macro, is_integer_literal, match_path, snippet,
- span_lint, span_lint_and_then, walk_ptrs_ty, last_path_segment, iter_input_pats, in_constant};
+ span_lint, span_lint_and_then, walk_ptrs_ty, last_path_segment, iter_input_pats, in_constant,
+ match_trait_method, paths};
use utils::sugg::Sugg;
-use syntax::ast::LitKind;
+use syntax::ast::{LitKind, CRATE_NODE_ID};
/// **What it does:** Checks for function arguments and let bindings denoted as `ref`.
///
if let ExprPath(QPath::Resolved(_, ref path)) = right.node {
check_nan(cx, path, expr);
}
- check_to_owned(cx, left, right, true, cmp.span);
- check_to_owned(cx, right, left, false, cmp.span)
+ check_to_owned(cx, left, right);
+ check_to_owned(cx, right, left);
}
if (op == BiEq || op == BiNe) && (is_float(cx, left) || is_float(cx, right)) {
if is_allowed(cx, left) || is_allowed(cx, right) {
matches!(walk_ptrs_ty(cx.tables.expr_ty(expr)).sty, ty::TyFloat(_))
}
-fn check_to_owned(cx: &LateContext, expr: &Expr, other: &Expr, left: bool, op: Span) {
+fn check_to_owned(cx: &LateContext, expr: &Expr, other: &Expr) {
let (arg_ty, snip) = match expr.node {
- ExprMethodCall(Spanned { node: ref name, .. }, _, ref args) if args.len() == 1 => {
- let name = name.as_str();
- if name == "to_string" || name == "to_owned" && is_str_arg(cx, args) {
- (cx.tables.expr_ty(&args[0]), snippet(cx, args[0].span, ".."))
+ ExprMethodCall(.., ref args) if args.len() == 1 => {
+ if match_trait_method(cx, expr, &paths::TO_STRING) || match_trait_method(cx, expr, &paths::TO_OWNED) {
+ (cx.tables.expr_ty_adjusted(&args[0]), snippet(cx, args[0].span, ".."))
} else {
return;
}
ExprCall(ref path, ref v) if v.len() == 1 => {
if let ExprPath(ref path) = path.node {
if match_path(path, &["String", "from_str"]) || match_path(path, &["String", "from"]) {
- (cx.tables.expr_ty(&v[0]), snippet(cx, v[0].span, ".."))
+ (cx.tables.expr_ty_adjusted(&v[0]), snippet(cx, v[0].span, ".."))
} else {
return;
}
_ => return,
};
- let other_ty = cx.tables.expr_ty(other);
+ let other_ty = cx.tables.expr_ty_adjusted(other);
let partial_eq_trait_id = match cx.tcx.lang_items.eq_trait() {
Some(id) => id,
None => return,
};
- if !implements_trait(cx, arg_ty, partial_eq_trait_id, &[other_ty], None) {
+ // *arg impls PartialEq<other>
+ if !arg_ty
+ .builtin_deref(true, ty::LvaluePreference::NoPreference)
+ .map_or(false, |tam| implements_trait(cx, tam.ty, partial_eq_trait_id, &[other_ty]))
+ // arg impls PartialEq<*other>
+ && !other_ty
+ .builtin_deref(true, ty::LvaluePreference::NoPreference)
+ .map_or(false, |tam| implements_trait(cx, arg_ty, partial_eq_trait_id, &[tam.ty]))
+ // arg impls PartialEq<other>
+ && !implements_trait(cx, arg_ty, partial_eq_trait_id, &[other_ty]) {
return;
}
- if left {
- span_lint(cx,
- CMP_OWNED,
- expr.span,
- &format!("this creates an owned instance just for comparison. Consider using `{} {} {}` to \
- compare without allocation",
- snip,
- snippet(cx, op, "=="),
- snippet(cx, other.span, "..")));
- } else {
- span_lint(cx,
- CMP_OWNED,
- expr.span,
- &format!("this creates an owned instance just for comparison. Consider using `{} {} {}` to \
- compare without allocation",
- snippet(cx, other.span, ".."),
- snippet(cx, op, "=="),
- snip));
- }
-
-}
-
-fn is_str_arg(cx: &LateContext, args: &[Expr]) -> bool {
- args.len() == 1 && matches!(walk_ptrs_ty(cx.tables.expr_ty(&args[0])).sty, ty::TyStr)
+ span_lint_and_then(cx,
+ CMP_OWNED,
+ expr.span,
+ "this creates an owned instance just for comparison",
+ |db| {
+ // this is as good as our recursion check can get, we can't prove that the current function is
+ // called by
+ // PartialEq::eq, but we can at least ensure that this code is not part of it
+ let parent_fn = cx.tcx.hir.get_parent(expr.id);
+ let parent_impl = cx.tcx.hir.get_parent(parent_fn);
+ if parent_impl != CRATE_NODE_ID {
+ if let map::NodeItem(item) = cx.tcx.hir.get(parent_impl) {
+ if let ItemImpl(.., Some(ref trait_ref), _, _) = item.node {
+ if trait_ref.path.def.def_id() == partial_eq_trait_id {
+ // we are implementing PartialEq, don't suggest not doing `to_owned`, otherwise we go into
+ // recursion
+ db.span_label(expr.span, "try calling implementing the comparison without allocating");
+ return;
+ }
+ }
+ }
+ }
+ db.span_suggestion(expr.span, "try", snip.to_string());
+ });
}
/// Heuristic to see if an expression is used. Should be compatible with `unused_variables`'s idea
/// Test whether an expression is in a macro expansion (e.g. something generated by
/// `#[derive(...)`] or the like).
fn in_attributes_expansion(expr: &Expr) -> bool {
- expr.span.ctxt.outer().expn_info().map(|info| {
- matches!(info.callee.format, ExpnFormat::MacroAttribute(_))
- }).unwrap_or(false)
+ expr.span.ctxt.outer().expn_info().map_or(false, |info| matches!(info.callee.format, ExpnFormat::MacroAttribute(_)))
}
/// Test whether `def` is a variable defined outside a macro.
projects / rust.git / blobdiff