243 lines
10 KiB
Rust
243 lines
10 KiB
Rust
use rustc_front::hir::*;
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use rustc::lint::*;
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use rustc::middle::ty;
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use rustc::middle::subst::Subst;
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use std::iter;
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use std::borrow::Cow;
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use utils::{snippet, span_lint, match_path, match_type, walk_ptrs_ty_depth};
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use utils::{OPTION_PATH, RESULT_PATH, STRING_PATH};
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use self::SelfKind::*;
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use self::OutType::*;
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#[derive(Copy,Clone)]
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pub struct MethodsPass;
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declare_lint!(pub OPTION_UNWRAP_USED, Allow,
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"using `Option.unwrap()`, which should at least get a better message using `expect()`");
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declare_lint!(pub RESULT_UNWRAP_USED, Allow,
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"using `Result.unwrap()`, which might be better handled");
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declare_lint!(pub STR_TO_STRING, Warn,
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"using `to_string()` on a str, which should be `to_owned()`");
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declare_lint!(pub STRING_TO_STRING, Warn,
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"calling `String.to_string()` which is a no-op");
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declare_lint!(pub SHOULD_IMPLEMENT_TRAIT, Warn,
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"defining a method that should be implementing a std trait");
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declare_lint!(pub WRONG_SELF_CONVENTION, Warn,
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"defining a method named with an established prefix (like \"into_\") that takes \
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`self` with the wrong convention");
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declare_lint!(pub WRONG_PUB_SELF_CONVENTION, Allow,
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"defining a public method named with an established prefix (like \"into_\") that takes \
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`self` with the wrong convention");
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impl LintPass for MethodsPass {
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fn get_lints(&self) -> LintArray {
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lint_array!(OPTION_UNWRAP_USED, RESULT_UNWRAP_USED, STR_TO_STRING, STRING_TO_STRING,
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SHOULD_IMPLEMENT_TRAIT, WRONG_SELF_CONVENTION)
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}
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}
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impl LateLintPass for MethodsPass {
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fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
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if let ExprMethodCall(ref name, _, ref args) = expr.node {
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let (obj_ty, ptr_depth) = walk_ptrs_ty_depth(cx.tcx.expr_ty(&args[0]));
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if name.node.as_str() == "unwrap" {
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if match_type(cx, obj_ty, &OPTION_PATH) {
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span_lint(cx, OPTION_UNWRAP_USED, expr.span,
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"used unwrap() on an Option value. If you don't want \
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to handle the None case gracefully, consider using \
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expect() to provide a better panic message");
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} else if match_type(cx, obj_ty, &RESULT_PATH) {
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span_lint(cx, RESULT_UNWRAP_USED, expr.span,
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"used unwrap() on a Result value. Graceful handling \
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of Err values is preferred");
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}
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}
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else if name.node.as_str() == "to_string" {
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if obj_ty.sty == ty::TyStr {
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let mut arg_str = snippet(cx, args[0].span, "_");
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if ptr_depth > 1 {
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arg_str = Cow::Owned(format!(
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"({}{})",
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iter::repeat('*').take(ptr_depth - 1).collect::<String>(),
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arg_str));
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}
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span_lint(cx, STR_TO_STRING, expr.span, &format!(
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"`{}.to_owned()` is faster", arg_str));
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} else if match_type(cx, obj_ty, &STRING_PATH) {
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span_lint(cx, STRING_TO_STRING, expr.span, "`String.to_string()` is a no-op; use \
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`clone()` to make a copy");
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}
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}
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}
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}
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fn check_item(&mut self, cx: &LateContext, item: &Item) {
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if let ItemImpl(_, _, _, None, ref ty, ref items) = item.node {
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for implitem in items {
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let name = implitem.name;
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if let ImplItemKind::Method(ref sig, _) = implitem.node {
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// check missing trait implementations
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for &(method_name, n_args, self_kind, out_type, trait_name) in &TRAIT_METHODS {
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if_let_chain! {
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[
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name.as_str() == method_name,
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sig.decl.inputs.len() == n_args,
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out_type.matches(&sig.decl.output),
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self_kind.matches(&sig.explicit_self.node, false)
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], {
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span_lint(cx, SHOULD_IMPLEMENT_TRAIT, implitem.span, &format!(
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"defining a method called `{}` on this type; consider implementing \
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the `{}` trait or choosing a less ambiguous name", name, trait_name));
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}
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}
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}
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// check conventions w.r.t. conversion method names and predicates
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let is_copy = is_copy(cx, &ty, &item);
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for &(prefix, self_kinds) in &CONVENTIONS {
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if name.as_str().starts_with(prefix) &&
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!self_kinds.iter().any(|k| k.matches(&sig.explicit_self.node, is_copy)) {
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let lint = if item.vis == Visibility::Public {
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WRONG_PUB_SELF_CONVENTION
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} else {
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WRONG_SELF_CONVENTION
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};
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span_lint(cx, lint, sig.explicit_self.span, &format!(
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"methods called `{}*` usually take {}; consider choosing a less \
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ambiguous name", prefix,
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&self_kinds.iter().map(|k| k.description()).collect::<Vec<_>>().join(" or ")));
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}
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}
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}
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}
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}
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}
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}
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const CONVENTIONS: [(&'static str, &'static [SelfKind]); 5] = [
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("into_", &[ValueSelf]),
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("to_", &[RefSelf]),
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("as_", &[RefSelf, RefMutSelf]),
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("is_", &[RefSelf, NoSelf]),
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("from_", &[NoSelf]),
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];
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const TRAIT_METHODS: [(&'static str, usize, SelfKind, OutType, &'static str); 30] = [
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("add", 2, ValueSelf, AnyType, "std::ops::Add"),
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("sub", 2, ValueSelf, AnyType, "std::ops::Sub"),
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("mul", 2, ValueSelf, AnyType, "std::ops::Mul"),
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("div", 2, ValueSelf, AnyType, "std::ops::Div"),
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("rem", 2, ValueSelf, AnyType, "std::ops::Rem"),
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("shl", 2, ValueSelf, AnyType, "std::ops::Shl"),
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("shr", 2, ValueSelf, AnyType, "std::ops::Shr"),
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("bitand", 2, ValueSelf, AnyType, "std::ops::BitAnd"),
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("bitor", 2, ValueSelf, AnyType, "std::ops::BitOr"),
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("bitxor", 2, ValueSelf, AnyType, "std::ops::BitXor"),
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("neg", 1, ValueSelf, AnyType, "std::ops::Neg"),
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("not", 1, ValueSelf, AnyType, "std::ops::Not"),
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("drop", 1, RefMutSelf, UnitType, "std::ops::Drop"),
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("index", 2, RefSelf, RefType, "std::ops::Index"),
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("index_mut", 2, RefMutSelf, RefType, "std::ops::IndexMut"),
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("deref", 1, RefSelf, RefType, "std::ops::Deref"),
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("deref_mut", 1, RefMutSelf, RefType, "std::ops::DerefMut"),
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("clone", 1, RefSelf, AnyType, "std::clone::Clone"),
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("borrow", 1, RefSelf, RefType, "std::borrow::Borrow"),
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("borrow_mut", 1, RefMutSelf, RefType, "std::borrow::BorrowMut"),
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("as_ref", 1, RefSelf, RefType, "std::convert::AsRef"),
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("as_mut", 1, RefMutSelf, RefType, "std::convert::AsMut"),
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("eq", 2, RefSelf, BoolType, "std::cmp::PartialEq"),
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("cmp", 2, RefSelf, AnyType, "std::cmp::Ord"),
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("default", 0, NoSelf, AnyType, "std::default::Default"),
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("hash", 2, RefSelf, UnitType, "std::hash::Hash"),
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("next", 1, RefMutSelf, AnyType, "std::iter::Iterator"),
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("into_iter", 1, ValueSelf, AnyType, "std::iter::IntoIterator"),
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("from_iter", 1, NoSelf, AnyType, "std::iter::FromIterator"),
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("from_str", 1, NoSelf, AnyType, "std::str::FromStr"),
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];
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#[derive(Clone, Copy)]
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enum SelfKind {
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ValueSelf,
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RefSelf,
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RefMutSelf,
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NoSelf,
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}
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impl SelfKind {
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fn matches(&self, slf: &ExplicitSelf_, allow_value_for_ref: bool) -> bool {
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match (self, slf) {
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(&ValueSelf, &SelfValue(_)) => true,
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(&RefSelf, &SelfRegion(_, Mutability::MutImmutable, _)) => true,
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(&RefMutSelf, &SelfRegion(_, Mutability::MutMutable, _)) => true,
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(&RefSelf, &SelfValue(_)) => allow_value_for_ref,
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(&RefMutSelf, &SelfValue(_)) => allow_value_for_ref,
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(&NoSelf, &SelfStatic) => true,
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(_, &SelfExplicit(ref ty, _)) => self.matches_explicit_type(ty, allow_value_for_ref),
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_ => false
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}
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}
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fn matches_explicit_type(&self, ty: &Ty, allow_value_for_ref: bool) -> bool {
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match (self, &ty.node) {
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(&ValueSelf, &TyPath(..)) => true,
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(&RefSelf, &TyRptr(_, MutTy { mutbl: Mutability::MutImmutable, .. })) => true,
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(&RefMutSelf, &TyRptr(_, MutTy { mutbl: Mutability::MutMutable, .. })) => true,
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(&RefSelf, &TyPath(..)) => allow_value_for_ref,
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(&RefMutSelf, &TyPath(..)) => allow_value_for_ref,
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_ => false
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}
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}
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fn description(&self) -> &'static str {
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match *self {
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ValueSelf => "self by value",
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RefSelf => "self by reference",
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RefMutSelf => "self by mutable reference",
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NoSelf => "no self",
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}
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}
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}
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#[derive(Clone, Copy)]
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enum OutType {
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UnitType,
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BoolType,
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AnyType,
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RefType,
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}
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impl OutType {
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fn matches(&self, ty: &FunctionRetTy) -> bool {
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match (self, ty) {
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(&UnitType, &DefaultReturn(_)) => true,
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(&UnitType, &Return(ref ty)) if ty.node == TyTup(vec![]) => true,
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(&BoolType, &Return(ref ty)) if is_bool(ty) => true,
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(&AnyType, &Return(ref ty)) if ty.node != TyTup(vec![]) => true,
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(&RefType, &Return(ref ty)) => {
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if let TyRptr(_, _) = ty.node { true } else { false }
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}
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_ => false
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}
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}
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}
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fn is_bool(ty: &Ty) -> bool {
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if let TyPath(None, ref p) = ty.node {
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if match_path(p, &["bool"]) {
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return true;
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}
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}
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false
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}
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fn is_copy(cx: &LateContext, ast_ty: &Ty, item: &Item) -> bool {
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match cx.tcx.ast_ty_to_ty_cache.borrow().get(&ast_ty.id) {
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None => false,
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Some(ty) => {
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let env = ty::ParameterEnvironment::for_item(cx.tcx, item.id);
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!ty.subst(cx.tcx, &env.free_substs).moves_by_default(&env, ast_ty.span)
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}
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}
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}
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