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methods: try to allow value self when type is Copy (fixes #273)

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This commit is contained in:
Georg Brandl 2015-09-01 21:08:49 +02:00
parent 1007864198
commit 5264196538
2 changed files with 34 additions and 10 deletions
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35
src/methods.rs
View file

@ -68,10 +68,10 @@ impl LintPass for MethodsPass {
}
fn check_item(&mut self, cx: &Context, item: &Item) {
if let ItemImpl(_, _, _, None, _, ref items) = item.node {
for item in items {
let name = item.ident.name;
if let MethodImplItem(ref sig, _) = item.node {
if let ItemImpl(_, _, _, None, ref ty, ref items) = item.node {
for implitem in items {
let name = implitem.ident.name;
if let MethodImplItem(ref sig, _) = implitem.node {
// check missing trait implementations
for &(method_name, n_args, self_kind, out_type, trait_name) in &TRAIT_METHODS {
if_let_chain! {
@ -79,9 +79,9 @@ impl LintPass for MethodsPass {
name == method_name,
sig.decl.inputs.len() == n_args,
out_type.matches(&sig.decl.output),
self_kind.matches(&sig.explicit_self.node)
self_kind.matches(&sig.explicit_self.node, false)
], {
span_lint(cx, SHOULD_IMPLEMENT_TRAIT, item.span, &format!(
span_lint(cx, SHOULD_IMPLEMENT_TRAIT, implitem.span, &format!(
"defining a method called `{}` on this type; consider implementing \
the `{}` trait or choosing a less ambiguous name", name, trait_name));
}
@ -89,7 +89,8 @@ impl LintPass for MethodsPass {
}
// check conventions w.r.t. conversion method names and predicates
for &(prefix, self_kind) in &CONVENTIONS {
if name.as_str().starts_with(prefix) && !self_kind.matches(&sig.explicit_self.node) {
if name.as_str().starts_with(prefix) &&
!self_kind.matches(&sig.explicit_self.node, is_copy(cx, &ty, &item)) {
span_lint(cx, WRONG_SELF_CONVENTION, sig.explicit_self.span, &format!(
"methods called `{}*` usually take {}; consider choosing a less \
ambiguous name", prefix, self_kind.description()));
@ -151,22 +152,26 @@ enum SelfKind {
}
impl SelfKind {
fn matches(&self, slf: &ExplicitSelf_) -> bool {
fn matches(&self, slf: &ExplicitSelf_, allow_value_for_ref: bool) -> bool {
match (self, slf) {
(&ValueSelf, &SelfValue(_)) => true,
(&RefSelf, &SelfRegion(_, Mutability::MutImmutable, _)) => true,
(&RefMutSelf, &SelfRegion(_, Mutability::MutMutable, _)) => true,
(&RefSelf, &SelfValue(_)) => allow_value_for_ref,
(&RefMutSelf, &SelfValue(_)) => allow_value_for_ref,
(&NoSelf, &SelfStatic) => true,
(_, &SelfExplicit(ref ty, _)) => self.matches_explicit_type(ty),
(_, &SelfExplicit(ref ty, _)) => self.matches_explicit_type(ty, allow_value_for_ref),
_ => false
}
}
fn matches_explicit_type(&self, ty: &Ty) -> bool {
fn matches_explicit_type(&self, ty: &Ty, allow_value_for_ref: bool) -> bool {
match (self, &ty.node) {
(&ValueSelf, &TyPath(..)) => true,
(&RefSelf, &TyRptr(_, MutTy { mutbl: Mutability::MutImmutable, .. })) => true,
(&RefMutSelf, &TyRptr(_, MutTy { mutbl: Mutability::MutMutable, .. })) => true,
(&RefSelf, &TyPath(..)) => allow_value_for_ref,
(&RefMutSelf, &TyPath(..)) => allow_value_for_ref,
_ => false
}
}
@ -212,3 +217,13 @@ fn is_bool(ty: &Ty) -> bool {
}
false
}
fn is_copy(cx: &Context, ast_ty: &Ty, item: &Item) -> bool {
match cx.tcx.ast_ty_to_ty_cache.borrow().get(&ast_ty.id) {
None => false,
Some(ty) => {
let env = ty::ParameterEnvironment::for_item(cx.tcx, item.id);
!ty.moves_by_default(&env, ast_ty.span)
}
}
}

9
tests/compile-fail/methods.rs
View file

@ -18,6 +18,15 @@ impl T {
fn into_u32(self) -> u32 { 0 } // fine
fn into_u16(&self) -> u16 { 0 } //~ERROR methods called `into_*` usually take self by value
fn to_something(self) -> u32 { 0 } //~ERROR methods called `to_*` usually take self by reference
}
#[derive(Clone,Copy)]
struct U;
impl U {
fn to_something(self) -> u32 { 0 } // ok because U is Copy
}
impl Mul<T> for T {