-use rustc::hir::intravisit::FnKind;
use rustc::hir::def_id::DefId;
use rustc::hir;
use rustc::lint::*;
-use rustc::ty;
-use syntax::ast;
+use rustc::{declare_lint, lint_array};
+use if_chain::if_chain;
+use rustc::ty::{self, Ty};
use syntax::codemap::Span;
-use utils::paths;
-use utils::{get_trait_def_id, implements_trait, in_external_macro, return_ty, same_tys, span_lint_and_then};
-use utils::sugg::DiagnosticBuilderExt;
+use crate::utils::paths;
+use crate::utils::{get_trait_def_id, implements_trait, in_external_macro, return_ty, same_tys, span_lint_and_then};
+use crate::utils::sugg::DiagnosticBuilderExt;
-/// **What it does:** This lints about type with a `fn new() -> Self` method
-/// and no implementation of
-/// [`Default`](https://doc.rust-lang.org/std/default/trait.Default.html)
+/// **What it does:** Checks for types with a `fn new() -> Self` method and no
+/// implementation of
+/// [`Default`](https://doc.rust-lang.org/std/default/trait.Default.html).
///
-/// **Why is this bad?** User might expect to be able to use
-/// [`Default`](https://doc.rust-lang.org/std/default/trait.Default.html)
-/// as the type can be constructed without arguments.
+/// **Why is this bad?** The user might expect to be able to use
+/// [`Default`](https://doc.rust-lang.org/std/default/trait.Default.html) as the
+/// type can be constructed without arguments.
///
/// **Known problems:** Hopefully none.
///
/// }
/// ```
///
-/// You can also have `new()` call `Default::default()`
-declare_lint! {
+/// You can also have `new()` call `Default::default()`.
+declare_clippy_lint! {
pub NEW_WITHOUT_DEFAULT,
- Warn,
+ style,
"`fn new() -> Self` method without `Default` implementation"
}
-/// **What it does:** This lints about type with a `fn new() -> Self` method
+/// **What it does:** Checks for types with a `fn new() -> Self` method
/// and no implementation of
-/// [`Default`](https://doc.rust-lang.org/std/default/trait.Default.html)
+/// [`Default`](https://doc.rust-lang.org/std/default/trait.Default.html),
+/// where the `Default` can be derived by `#[derive(Default)]`.
///
-/// **Why is this bad?** User might expect to be able to use
-/// [`Default`](https://doc.rust-lang.org/std/default/trait.Default.html)
-/// as the type can be
-/// constructed without arguments.
+/// **Why is this bad?** The user might expect to be able to use
+/// [`Default`](https://doc.rust-lang.org/std/default/trait.Default.html) as the
+/// type can be constructed without arguments.
///
/// **Known problems:** Hopefully none.
///
/// }
/// ```
///
-/// Just prepend `#[derive(Default)]` before the `struct` definition
-declare_lint! {
+/// Just prepend `#[derive(Default)]` before the `struct` definition.
+declare_clippy_lint! {
pub NEW_WITHOUT_DEFAULT_DERIVE,
- Warn,
+ style,
"`fn new() -> Self` without `#[derive]`able `Default` implementation"
}
-#[derive(Copy,Clone)]
+#[derive(Copy, Clone)]
pub struct NewWithoutDefault;
impl LintPass for NewWithoutDefault {
}
}
-impl LateLintPass for NewWithoutDefault {
- fn check_fn(&mut self, cx: &LateContext, kind: FnKind, decl: &hir::FnDecl, _: &hir::Block, span: Span, id: ast::NodeId) {
- if in_external_macro(cx, span) {
- return;
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NewWithoutDefault {
+ fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
+ if let hir::ItemKind::Impl(_, _, _, _, None, _, ref items) = item.node {
+ for assoc_item in items {
+ if let hir::AssociatedItemKind::Method { has_self: false } = assoc_item.kind {
+ let impl_item = cx.tcx.hir.impl_item(assoc_item.id);
+ if in_external_macro(cx, impl_item.span) {
+ return;
+ }
+ if let hir::ImplItemKind::Method(ref sig, _) = impl_item.node {
+ let name = impl_item.ident.name;
+ let id = impl_item.id;
+ if sig.header.constness == hir::Constness::Const {
+ // can't be implemented by default
+ return;
+ }
+ if impl_item.generics.params.iter().any(|gen| match gen.kind {
+ hir::GenericParamKind::Type { .. } => true,
+ _ => false
+ }) {
+ // when the result of `new()` depends on a type parameter we should not require
+ // an
+ // impl of `Default`
+ return;
+ }
+ if sig.decl.inputs.is_empty() && name == "new" && cx.access_levels.is_reachable(id) {
+ let self_ty = cx.tcx
+ .type_of(cx.tcx.hir.local_def_id(cx.tcx.hir.get_parent(id)));
+ if_chain! {
+ if same_tys(cx, self_ty, return_ty(cx, id));
+ if let Some(default_trait_id) = get_trait_def_id(cx, &paths::DEFAULT_TRAIT);
+ if !implements_trait(cx, self_ty, default_trait_id, &[]);
+ then {
+ if let Some(sp) = can_derive_default(self_ty, cx, default_trait_id) {
+ span_lint_and_then(
+ cx,
+ NEW_WITHOUT_DEFAULT_DERIVE,
+ impl_item.span,
+ &format!("you should consider deriving a `Default` implementation for `{}`", self_ty),
+ |db| {
+ db.suggest_item_with_attr(cx, sp, "try this", "#[derive(Default)]");
+ });
+ } else {
+ span_lint_and_then(
+ cx,
+ NEW_WITHOUT_DEFAULT,
+ impl_item.span,
+ &format!("you should consider adding a `Default` implementation for `{}`", self_ty),
+ |db| {
+ db.suggest_prepend_item(
+ cx,
+ item.span,
+ "try this",
+ &create_new_without_default_suggest_msg(self_ty),
+ );
+ },
+ );
+ }
+ }
+ }
+ }
+ }
+ }
+ }
}
+ }
+}
- if let FnKind::Method(name, sig, _, _) = kind {
- if sig.constness == hir::Constness::Const {
- // can't be implemented by default
- return;
- }
- if decl.inputs.is_empty() && name.as_str() == "new" && cx.access_levels.is_reachable(id) {
- let self_ty = cx.tcx
- .lookup_item_type(cx.tcx.map.local_def_id(cx.tcx.map.get_parent(id)))
- .ty;
- if_let_chain!{[
- self_ty.walk_shallow().next().is_none(), // implements_trait does not work with generics
- let Some(ret_ty) = return_ty(cx, id),
- same_tys(cx, self_ty, ret_ty, id),
- let Some(default_trait_id) = get_trait_def_id(cx, &paths::DEFAULT_TRAIT),
- !implements_trait(cx, self_ty, default_trait_id, Vec::new())
- ], {
- if can_derive_default(self_ty, cx, default_trait_id) {
- span_lint_and_then(cx,
- NEW_WITHOUT_DEFAULT_DERIVE, span,
- &format!("you should consider deriving a \
- `Default` implementation for `{}`",
- self_ty),
- |db| {
- db.suggest_item_with_attr(cx, span, "try this", "#[derive(Default)]");
- });
- } else {
- span_lint_and_then(cx,
- NEW_WITHOUT_DEFAULT, span,
- &format!("you should consider adding a \
- `Default` implementation for `{}`",
- self_ty),
- |db| {
- db.suggest_prepend_item(cx,
- span,
- "try this",
- &format!(
+fn create_new_without_default_suggest_msg(ty: Ty) -> String {
+ #[cfg_attr(rustfmt, rustfmt_skip)]
+ format!(
"impl Default for {} {{
fn default() -> Self {{
Self::new()
}}
-}}",
- self_ty));
- });
- }
- }}
- }
- }
- }
+}}", ty)
}
-fn can_derive_default<'t, 'c>(ty: ty::Ty<'t>, cx: &LateContext<'c, 't>, default_trait_id: DefId) -> bool {
+fn can_derive_default<'t, 'c>(ty: Ty<'t>, cx: &LateContext<'c, 't>, default_trait_id: DefId) -> Option<Span> {
match ty.sty {
- ty::TyStruct(adt_def, substs) => {
+ ty::TyAdt(adt_def, substs) if adt_def.is_struct() => {
for field in adt_def.all_fields() {
let f_ty = field.ty(cx.tcx, substs);
- if !implements_trait(cx, f_ty, default_trait_id, Vec::new()) {
- return false;
+ if !implements_trait(cx, f_ty, default_trait_id, &[]) {
+ return None;
}
}
- true
- }
- _ => false,
+ Some(cx.tcx.def_span(adt_def.did))
+ },
+ _ => None,
}
}
projects / rust.git / blobdiff