1042 lines
41 KiB
Rust
1042 lines
41 KiB
Rust
use rustc::hir::*;
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use rustc::lint::*;
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use rustc::middle::const_val::ConstVal;
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use rustc::middle::cstore::CrateStore;
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use rustc::ty::subst::{Subst, TypeSpace};
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use rustc::ty;
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use rustc_const_eval::EvalHint::ExprTypeChecked;
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use rustc_const_eval::eval_const_expr_partial;
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use std::borrow::Cow;
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use std::fmt;
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use syntax::codemap::Span;
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use syntax::ptr::P;
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use utils::{get_trait_def_id, implements_trait, in_external_macro, in_macro, match_path, match_trait_method,
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match_type, method_chain_args, return_ty, same_tys, snippet, snippet_opt, span_lint,
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span_lint_and_then, span_note_and_lint, walk_ptrs_ty, walk_ptrs_ty_depth};
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use utils::MethodArgs;
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use utils::paths;
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#[derive(Clone)]
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pub struct MethodsPass;
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/// **What it does:** This lint checks for `.unwrap()` calls on `Option`s.
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///
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/// **Why is this bad?** Usually it is better to handle the `None` case, or to at least call `.expect(_)` with a more helpful message. Still, for a lot of quick-and-dirty code, `unwrap` is a good choice, which is why this lint is `Allow` by default.
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///
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/// **Known problems:** None
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///
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/// **Example:** `x.unwrap()`
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declare_lint! {
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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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}
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/// **What it does:** This lint checks for `.unwrap()` calls on `Result`s.
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///
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/// **Why is this bad?** `result.unwrap()` will let the thread panic on `Err` values. Normally, you want to implement more sophisticated error handling, and propagate errors upwards with `try!`.
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///
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/// Even if you want to panic on errors, not all `Error`s implement good messages on display. Therefore it may be beneficial to look at the places where they may get displayed. Activate this lint to do just that.
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///
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/// **Known problems:** None
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///
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/// **Example:** `x.unwrap()`
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declare_lint! {
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pub RESULT_UNWRAP_USED, Allow,
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"using `Result.unwrap()`, which might be better handled"
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}
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/// **What it does:** This lint checks for methods that should live in a trait implementation of a `std` trait (see [llogiq's blog post](http://llogiq.github.io/2015/07/30/traits.html) for further information) instead of an inherent implementation.
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///
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/// **Why is this bad?** Implementing the traits improve ergonomics for users of the code, often with very little cost. Also people seeing a `mul(..)` method may expect `*` to work equally, so you should have good reason to disappoint them.
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///
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/// **Known problems:** None
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///
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/// **Example:**
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/// ```
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/// struct X;
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/// impl X {
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/// fn add(&self, other: &X) -> X { .. }
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/// }
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/// ```
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declare_lint! {
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pub SHOULD_IMPLEMENT_TRAIT, Warn,
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"defining a method that should be implementing a std trait"
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}
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/// **What it does:** This lint checks for methods with certain name prefixes and which doesn't match how self is taken. The actual rules are:
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///
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/// |Prefix |`self` taken |
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/// |-------|--------------------|
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/// |`as_` |`&self` or &mut self|
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/// |`from_`| none |
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/// |`into_`|`self` |
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/// |`is_` |`&self` or none |
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/// |`to_` |`&self` |
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///
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/// **Why is this bad?** Consistency breeds readability. If you follow the conventions, your users won't be surprised that they e.g. need to supply a mutable reference to a `as_..` function.
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///
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/// **Known problems:** None
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///
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/// **Example**
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///
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/// ```
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/// impl X {
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/// fn as_str(self) -> &str { .. }
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/// }
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/// ```
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declare_lint! {
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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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}
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/// **What it does:** This is the same as [`wrong_self_convention`](#wrong_self_convention), but for public items.
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///
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/// **Why is this bad?** See [`wrong_self_convention`](#wrong_self_convention).
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///
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/// **Known problems:** Actually *renaming* the function may break clients if the function is part of the public interface. In that case, be mindful of the stability guarantees you've given your users.
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///
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/// **Example:**
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/// ```
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/// impl X {
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/// pub fn as_str(self) -> &str { .. }
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/// }
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/// ```
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declare_lint! {
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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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}
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/// **What it does:** This lint checks for usage of `ok().expect(..)`.
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///
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/// **Why is this bad?** Because you usually call `expect()` on the `Result` directly to get a good error message.
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///
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/// **Known problems:** None.
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///
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/// **Example:** `x.ok().expect("why did I do this again?")`
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declare_lint! {
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pub OK_EXPECT, Warn,
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"using `ok().expect()`, which gives worse error messages than \
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calling `expect` directly on the Result"
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}
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/// **What it does:** This lint checks for usage of `_.map(_).unwrap_or(_)`.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as `_.map_or(_, _)`.
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///
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/// **Known problems:** None.
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///
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/// **Example:** `x.map(|a| a + 1).unwrap_or(0)`
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declare_lint! {
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pub OPTION_MAP_UNWRAP_OR, Warn,
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"using `Option.map(f).unwrap_or(a)`, which is more succinctly expressed as \
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`map_or(a, f)`"
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}
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/// **What it does:** This lint `Warn`s on `_.map(_).unwrap_or_else(_)`.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as `_.map_or_else(_, _)`.
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///
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/// **Known problems:** None.
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///
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/// **Example:** `x.map(|a| a + 1).unwrap_or_else(some_function)`
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declare_lint! {
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pub OPTION_MAP_UNWRAP_OR_ELSE, Warn,
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"using `Option.map(f).unwrap_or_else(g)`, which is more succinctly expressed as \
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`map_or_else(g, f)`"
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}
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/// **What it does:** This lint `Warn`s on `_.filter(_).next()`.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as `_.find(_)`.
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///
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/// **Known problems:** None.
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///
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/// **Example:** `iter.filter(|x| x == 0).next()`
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declare_lint! {
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pub FILTER_NEXT, Warn,
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"using `filter(p).next()`, which is more succinctly expressed as `.find(p)`"
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}
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/// **What it does:** This lint `Warn`s on an iterator search (such as `find()`, `position()`, or
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/// `rposition()`) followed by a call to `is_some()`.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as `_.any(_)`.
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///
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/// **Known problems:** None.
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///
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/// **Example:** `iter.find(|x| x == 0).is_some()`
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declare_lint! {
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pub SEARCH_IS_SOME, Warn,
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"using an iterator search followed by `is_some()`, which is more succinctly \
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expressed as a call to `any()`"
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}
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/// **What it does:** This lint `Warn`s on using `.chars().next()` on a `str` to check if it
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/// starts with a given char.
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///
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/// **Why is this bad?** Readability, this can be written more concisely as `_.starts_with(_)`.
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///
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/// **Known problems:** None.
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///
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/// **Example:** `name.chars().next() == Some('_')`
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declare_lint! {
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pub CHARS_NEXT_CMP, Warn,
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"using `.chars().next()` to check if a string starts with a char"
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}
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/// **What it does:** This lint checks for calls to `.or(foo(..))`, `.unwrap_or(foo(..))`, etc., and
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/// suggests to use `or_else`, `unwrap_or_else`, etc., or `unwrap_or_default` instead.
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///
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/// **Why is this bad?** The function will always be called and potentially allocate an object
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/// in expressions such as:
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/// ```rust
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/// foo.unwrap_or(String::new())
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/// ```
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/// this can instead be written:
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/// ```rust
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/// foo.unwrap_or_else(String::new)
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/// ```
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/// or
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/// ```rust
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/// foo.unwrap_or_default()
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/// ```
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///
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/// **Known problems:** If the function as side-effects, not calling it will change the semantic of
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/// the program, but you shouldn't rely on that anyway.
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declare_lint! {
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pub OR_FUN_CALL, Warn,
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"using any `*or` method when the `*or_else` would do"
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}
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/// **What it does:** This lint checks for usage of `.extend(s)` on a `Vec` to extend the vector by a slice.
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///
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/// **Why is this bad?** Since Rust 1.6, the `extend_from_slice(_)` method is stable and at least for now faster.
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///
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/// **Known problems:** None.
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///
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/// **Example:** `my_vec.extend(&xs)`
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declare_lint! {
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pub EXTEND_FROM_SLICE, Warn,
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"`.extend_from_slice(_)` is a faster way to extend a Vec by a slice"
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}
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/// **What it does:** This lint warns on using `.clone()` on a `Copy` type.
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///
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/// **Why is this bad?** The only reason `Copy` types implement `Clone` is for generics, not for
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/// using the `clone` method on a concrete type.
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///
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/// **Known problems:** None.
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///
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/// **Example:** `42u64.clone()`
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declare_lint! {
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pub CLONE_ON_COPY, Warn, "using `clone` on a `Copy` type"
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}
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/// **What it does:** This lint warns on using `.clone()` on an `&&T`
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///
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/// **Why is this bad?** Cloning an `&&T` copies the inner `&T`, instead of cloning the underlying
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/// `T`
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// fn main() {
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/// let x = vec![1];
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/// let y = &&x;
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/// let z = y.clone();
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/// println!("{:p} {:p}",*y, z); // prints out the same pointer
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/// }
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/// ```
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declare_lint! {
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pub CLONE_DOUBLE_REF, Warn, "using `clone` on `&&T`"
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}
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/// **What it does:** This lint warns about `new` not returning `Self`.
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///
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/// **Why is this bad?** As a convention, `new` methods are used to make a new instance of a type.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// impl Foo {
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/// fn new(..) -> NotAFoo {
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/// }
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/// }
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/// ```
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declare_lint! {
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pub NEW_RET_NO_SELF, Warn, "not returning `Self` in a `new` method"
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}
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/// **What it does:** This lint checks for string methods that receive a single-character `str` as an argument, e.g. `_.split("x")`.
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///
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/// **Why is this bad?** Performing these methods using a `char` is faster than using a `str`.
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///
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/// **Known problems:** Does not catch multi-byte unicode characters.
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///
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/// **Example:** `_.split("x")` could be `_.split('x')`
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declare_lint! {
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pub SINGLE_CHAR_PATTERN,
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Warn,
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"using a single-character str where a char could be used, e.g. \
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`_.split(\"x\")`"
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}
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/// **What it does:** This lint checks for getting the inner pointer of a temporary `CString`.
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///
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/// **Why is this bad?** The inner pointer of a `CString` is only valid as long as the `CString` is
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/// alive.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust,ignore
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/// let c_str = CString::new("foo").unwrap().as_ptr();
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/// unsafe {
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/// call_some_ffi_func(c_str);
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/// }
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/// ```
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/// Here `c_str` point to a freed address. The correct use would be:
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/// ```rust,ignore
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/// let c_str = CString::new("foo").unwrap();
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/// unsafe {
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/// call_some_ffi_func(c_str.as_ptr());
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/// }
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/// ```
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declare_lint! {
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pub TEMPORARY_CSTRING_AS_PTR,
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Warn,
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"getting the inner pointer of a temporary `CString`"
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}
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impl LintPass for MethodsPass {
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fn get_lints(&self) -> LintArray {
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lint_array!(EXTEND_FROM_SLICE,
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OPTION_UNWRAP_USED,
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RESULT_UNWRAP_USED,
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SHOULD_IMPLEMENT_TRAIT,
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WRONG_SELF_CONVENTION,
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WRONG_PUB_SELF_CONVENTION,
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OK_EXPECT,
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OPTION_MAP_UNWRAP_OR,
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OPTION_MAP_UNWRAP_OR_ELSE,
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OR_FUN_CALL,
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CHARS_NEXT_CMP,
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CLONE_ON_COPY,
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CLONE_DOUBLE_REF,
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NEW_RET_NO_SELF,
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SINGLE_CHAR_PATTERN,
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SEARCH_IS_SOME,
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TEMPORARY_CSTRING_AS_PTR)
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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 in_macro(cx, expr.span) {
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return;
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}
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match expr.node {
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ExprMethodCall(name, _, ref args) => {
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// Chain calls
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if let Some(arglists) = method_chain_args(expr, &["unwrap"]) {
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lint_unwrap(cx, expr, arglists[0]);
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} else if let Some(arglists) = method_chain_args(expr, &["ok", "expect"]) {
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lint_ok_expect(cx, expr, arglists[0]);
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} else if let Some(arglists) = method_chain_args(expr, &["map", "unwrap_or"]) {
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lint_map_unwrap_or(cx, expr, arglists[0], arglists[1]);
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} else if let Some(arglists) = method_chain_args(expr, &["map", "unwrap_or_else"]) {
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lint_map_unwrap_or_else(cx, expr, arglists[0], arglists[1]);
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} else if let Some(arglists) = method_chain_args(expr, &["filter", "next"]) {
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lint_filter_next(cx, expr, arglists[0]);
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} else if let Some(arglists) = method_chain_args(expr, &["find", "is_some"]) {
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lint_search_is_some(cx, expr, "find", arglists[0], arglists[1]);
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} else if let Some(arglists) = method_chain_args(expr, &["position", "is_some"]) {
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lint_search_is_some(cx, expr, "position", arglists[0], arglists[1]);
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} else if let Some(arglists) = method_chain_args(expr, &["rposition", "is_some"]) {
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lint_search_is_some(cx, expr, "rposition", arglists[0], arglists[1]);
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} else if let Some(arglists) = method_chain_args(expr, &["extend"]) {
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lint_extend(cx, expr, arglists[0]);
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} else if let Some(arglists) = method_chain_args(expr, &["unwrap", "as_ptr"]) {
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lint_cstring_as_ptr(cx, expr, &arglists[0][0], &arglists[1][0]);
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}
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lint_or_fun_call(cx, expr, &name.node.as_str(), &args);
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let self_ty = cx.tcx.expr_ty_adjusted(&args[0]);
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if args.len() == 1 && name.node.as_str() == "clone" {
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lint_clone_on_copy(cx, expr);
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lint_clone_double_ref(cx, expr, &args[0], self_ty);
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}
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match self_ty.sty {
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ty::TyRef(_, ty) if ty.ty.sty == ty::TyStr => {
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for &(method, pos) in &PATTERN_METHODS {
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if name.node.as_str() == method && args.len() > pos {
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lint_single_char_pattern(cx, expr, &args[pos]);
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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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ExprBinary(op, ref lhs, ref rhs) if op.node == BiEq || op.node == BiNe => {
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if !lint_chars_next(cx, expr, lhs, rhs, op.node == BiEq) {
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lint_chars_next(cx, expr, rhs, lhs, op.node == BiEq);
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}
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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 in_external_macro(cx, item.span) {
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return;
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}
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|
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if let ItemImpl(_, _, _, None, _, 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 ty = cx.tcx.lookup_item_type(cx.tcx.map.local_def_id(item.id)).ty;
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let is_copy = is_copy(cx, &ty, &item);
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for &(ref conv, self_kinds) in &CONVENTIONS {
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if conv.check(&name.as_str()) &&
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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,
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lint,
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sig.explicit_self.span,
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&format!("methods called `{}` usually take {}; consider choosing a less \
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ambiguous name",
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conv,
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&self_kinds.iter()
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|
.map(|k| k.description())
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.collect::<Vec<_>>()
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.join(" or ")));
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}
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}
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|
let ret_ty = return_ty(cx, implitem.id);
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if &name.as_str() == &"new" &&
|
|
!ret_ty.map_or(false, |ret_ty| ret_ty.walk().any(|t| same_tys(cx, t, ty, implitem.id))) {
|
|
span_lint(cx,
|
|
NEW_RET_NO_SELF,
|
|
sig.explicit_self.span,
|
|
"methods called `new` usually return `Self`");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Checks for the `OR_FUN_CALL` lint.
|
|
fn lint_or_fun_call(cx: &LateContext, expr: &Expr, name: &str, args: &[P<Expr>]) {
|
|
/// Check for `unwrap_or(T::new())` or `unwrap_or(T::default())`.
|
|
fn check_unwrap_or_default(cx: &LateContext, name: &str, fun: &Expr, self_expr: &Expr, arg: &Expr,
|
|
or_has_args: bool, span: Span)
|
|
-> bool {
|
|
if or_has_args {
|
|
return false;
|
|
}
|
|
|
|
if name == "unwrap_or" {
|
|
if let ExprPath(_, ref path) = fun.node {
|
|
let path: &str = &path.segments
|
|
.last()
|
|
.expect("A path must have at least one segment")
|
|
.identifier
|
|
.name
|
|
.as_str();
|
|
|
|
if ["default", "new"].contains(&path) {
|
|
let arg_ty = cx.tcx.expr_ty(arg);
|
|
let default_trait_id = if let Some(default_trait_id) = get_trait_def_id(cx, &paths::DEFAULT_TRAIT) {
|
|
default_trait_id
|
|
} else {
|
|
return false;
|
|
};
|
|
|
|
if implements_trait(cx, arg_ty, default_trait_id, Vec::new()) {
|
|
span_lint(cx,
|
|
OR_FUN_CALL,
|
|
span,
|
|
&format!("use of `{}` followed by a call to `{}`", name, path))
|
|
.span_suggestion(span,
|
|
"try this",
|
|
format!("{}.unwrap_or_default()", snippet(cx, self_expr.span, "_")));
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
false
|
|
}
|
|
|
|
/// Check for `*or(foo())`.
|
|
fn check_general_case(cx: &LateContext, name: &str, fun: &Expr, self_expr: &Expr, arg: &Expr, or_has_args: bool,
|
|
span: Span) {
|
|
// (path, fn_has_argument, methods)
|
|
let know_types: &[(&[_], _, &[_], _)] = &[(&paths::BTREEMAP_ENTRY, false, &["or_insert"], "with"),
|
|
(&paths::HASHMAP_ENTRY, false, &["or_insert"], "with"),
|
|
(&paths::OPTION,
|
|
false,
|
|
&["map_or", "ok_or", "or", "unwrap_or"],
|
|
"else"),
|
|
(&paths::RESULT, true, &["or", "unwrap_or"], "else")];
|
|
|
|
let self_ty = cx.tcx.expr_ty(self_expr);
|
|
|
|
let (fn_has_arguments, poss, suffix) = if let Some(&(_, fn_has_arguments, poss, suffix)) =
|
|
know_types.iter().find(|&&i| match_type(cx, self_ty, i.0)) {
|
|
(fn_has_arguments, poss, suffix)
|
|
} else {
|
|
return;
|
|
};
|
|
|
|
if !poss.contains(&name) {
|
|
return;
|
|
}
|
|
|
|
let sugg: Cow<_> = match (fn_has_arguments, !or_has_args) {
|
|
(true, _) => format!("|_| {}", snippet(cx, arg.span, "..")).into(),
|
|
(false, false) => format!("|| {}", snippet(cx, arg.span, "..")).into(),
|
|
(false, true) => snippet(cx, fun.span, ".."),
|
|
};
|
|
|
|
span_lint(cx, OR_FUN_CALL, span, &format!("use of `{}` followed by a function call", name))
|
|
.span_suggestion(span,
|
|
"try this",
|
|
format!("{}.{}_{}({})", snippet(cx, self_expr.span, "_"), name, suffix, sugg));
|
|
}
|
|
|
|
if args.len() == 2 {
|
|
if let ExprCall(ref fun, ref or_args) = args[1].node {
|
|
let or_has_args = !or_args.is_empty();
|
|
if !check_unwrap_or_default(cx, name, fun, &args[0], &args[1], or_has_args, expr.span) {
|
|
check_general_case(cx, name, fun, &args[0], &args[1], or_has_args, expr.span);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Checks for the `CLONE_ON_COPY` lint.
|
|
fn lint_clone_on_copy(cx: &LateContext, expr: &Expr) {
|
|
let ty = cx.tcx.expr_ty(expr);
|
|
let parent = cx.tcx.map.get_parent(expr.id);
|
|
let parameter_environment = ty::ParameterEnvironment::for_item(cx.tcx, parent);
|
|
|
|
if !ty.moves_by_default(¶meter_environment, expr.span) {
|
|
span_lint(cx, CLONE_ON_COPY, expr.span, "using `clone` on a `Copy` type");
|
|
}
|
|
}
|
|
|
|
/// Checks for the `CLONE_DOUBLE_REF` lint.
|
|
fn lint_clone_double_ref(cx: &LateContext, expr: &Expr, arg: &Expr, ty: ty::Ty) {
|
|
if let ty::TyRef(_, ty::TypeAndMut { ty: ref inner, .. }) = ty.sty {
|
|
if let ty::TyRef(..) = inner.sty {
|
|
let mut db = span_lint(cx,
|
|
CLONE_DOUBLE_REF,
|
|
expr.span,
|
|
"using `clone` on a double-reference; \
|
|
this will copy the reference instead of cloning \
|
|
the inner type");
|
|
if let Some(snip) = snippet_opt(cx, arg.span) {
|
|
db.span_suggestion(expr.span, "try dereferencing it", format!("(*{}).clone()", snip));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn lint_extend(cx: &LateContext, expr: &Expr, args: &MethodArgs) {
|
|
let (obj_ty, _) = walk_ptrs_ty_depth(cx.tcx.expr_ty(&args[0]));
|
|
if !match_type(cx, obj_ty, &paths::VEC) {
|
|
return;
|
|
}
|
|
let arg_ty = cx.tcx.expr_ty(&args[1]);
|
|
if let Some((span, r)) = derefs_to_slice(cx, &args[1], &arg_ty) {
|
|
span_lint(cx, EXTEND_FROM_SLICE, expr.span, "use of `extend` to extend a Vec by a slice")
|
|
.span_suggestion(expr.span,
|
|
"try this",
|
|
format!("{}.extend_from_slice({}{})",
|
|
snippet(cx, args[0].span, "_"),
|
|
r,
|
|
snippet(cx, span, "_")));
|
|
}
|
|
}
|
|
|
|
fn lint_cstring_as_ptr(cx: &LateContext, expr: &Expr, new: &Expr, unwrap: &Expr) {
|
|
if_let_chain!{[
|
|
let ExprCall(ref fun, ref args) = new.node,
|
|
args.len() == 1,
|
|
let ExprPath(None, ref path) = fun.node,
|
|
match_path(path, &paths::CSTRING_NEW),
|
|
], {
|
|
span_lint_and_then(cx, TEMPORARY_CSTRING_AS_PTR, expr.span,
|
|
"you are getting the inner pointer of a temporary `CString`",
|
|
|db| {
|
|
db.note("that pointer will be invalid outside this expression");
|
|
db.span_help(unwrap.span, "assign the `CString` to a variable to extend its lifetime");
|
|
});
|
|
}}
|
|
}
|
|
|
|
fn derefs_to_slice(cx: &LateContext, expr: &Expr, ty: &ty::Ty) -> Option<(Span, &'static str)> {
|
|
fn may_slice(cx: &LateContext, ty: &ty::Ty) -> bool {
|
|
match ty.sty {
|
|
ty::TySlice(_) => true,
|
|
ty::TyStruct(..) => match_type(cx, ty, &paths::VEC),
|
|
ty::TyArray(_, size) => size < 32,
|
|
ty::TyRef(_, ty::TypeAndMut { ty: ref inner, .. }) |
|
|
ty::TyBox(ref inner) => may_slice(cx, inner),
|
|
_ => false,
|
|
}
|
|
}
|
|
if let ExprMethodCall(name, _, ref args) = expr.node {
|
|
if &name.node.as_str() == &"iter" && may_slice(cx, &cx.tcx.expr_ty(&args[0])) {
|
|
Some((args[0].span, "&"))
|
|
} else {
|
|
None
|
|
}
|
|
} else {
|
|
match ty.sty {
|
|
ty::TySlice(_) => Some((expr.span, "")),
|
|
ty::TyRef(_, ty::TypeAndMut { ty: ref inner, .. }) |
|
|
ty::TyBox(ref inner) => {
|
|
if may_slice(cx, inner) {
|
|
Some((expr.span, ""))
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
_ => None,
|
|
}
|
|
}
|
|
}
|
|
|
|
#[allow(ptr_arg)]
|
|
// Type of MethodArgs is potentially a Vec
|
|
/// lint use of `unwrap()` for `Option`s and `Result`s
|
|
fn lint_unwrap(cx: &LateContext, expr: &Expr, unwrap_args: &MethodArgs) {
|
|
let (obj_ty, _) = walk_ptrs_ty_depth(cx.tcx.expr_ty(&unwrap_args[0]));
|
|
|
|
let mess = if match_type(cx, obj_ty, &paths::OPTION) {
|
|
Some((OPTION_UNWRAP_USED, "an Option", "None"))
|
|
} else if match_type(cx, obj_ty, &paths::RESULT) {
|
|
Some((RESULT_UNWRAP_USED, "a Result", "Err"))
|
|
} else {
|
|
None
|
|
};
|
|
|
|
if let Some((lint, kind, none_value)) = mess {
|
|
span_lint(cx,
|
|
lint,
|
|
expr.span,
|
|
&format!("used unwrap() on {} value. If you don't want to handle the {} case gracefully, consider \
|
|
using expect() to provide a better panic
|
|
message",
|
|
kind,
|
|
none_value));
|
|
}
|
|
}
|
|
|
|
#[allow(ptr_arg)]
|
|
// Type of MethodArgs is potentially a Vec
|
|
/// lint use of `ok().expect()` for `Result`s
|
|
fn lint_ok_expect(cx: &LateContext, expr: &Expr, ok_args: &MethodArgs) {
|
|
// lint if the caller of `ok()` is a `Result`
|
|
if match_type(cx, cx.tcx.expr_ty(&ok_args[0]), &paths::RESULT) {
|
|
let result_type = cx.tcx.expr_ty(&ok_args[0]);
|
|
if let Some(error_type) = get_error_type(cx, result_type) {
|
|
if has_debug_impl(error_type, cx) {
|
|
span_lint(cx,
|
|
OK_EXPECT,
|
|
expr.span,
|
|
"called `ok().expect()` on a Result value. You can call `expect` directly on the `Result`");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
#[allow(ptr_arg)]
|
|
// Type of MethodArgs is potentially a Vec
|
|
/// lint use of `map().unwrap_or()` for `Option`s
|
|
fn lint_map_unwrap_or(cx: &LateContext, expr: &Expr, map_args: &MethodArgs, unwrap_args: &MethodArgs) {
|
|
// lint if the caller of `map()` is an `Option`
|
|
if match_type(cx, cx.tcx.expr_ty(&map_args[0]), &paths::OPTION) {
|
|
// lint message
|
|
let msg = "called `map(f).unwrap_or(a)` on an Option value. This can be done more directly by calling \
|
|
`map_or(a, f)` instead";
|
|
// get snippets for args to map() and unwrap_or()
|
|
let map_snippet = snippet(cx, map_args[1].span, "..");
|
|
let unwrap_snippet = snippet(cx, unwrap_args[1].span, "..");
|
|
// lint, with note if neither arg is > 1 line and both map() and
|
|
// unwrap_or() have the same span
|
|
let multiline = map_snippet.lines().count() > 1 || unwrap_snippet.lines().count() > 1;
|
|
let same_span = map_args[1].span.expn_id == unwrap_args[1].span.expn_id;
|
|
if same_span && !multiline {
|
|
span_note_and_lint(cx,
|
|
OPTION_MAP_UNWRAP_OR,
|
|
expr.span,
|
|
msg,
|
|
expr.span,
|
|
&format!("replace `map({0}).unwrap_or({1})` with `map_or({1}, {0})`",
|
|
map_snippet,
|
|
unwrap_snippet));
|
|
} else if same_span && multiline {
|
|
span_lint(cx, OPTION_MAP_UNWRAP_OR, expr.span, msg);
|
|
};
|
|
}
|
|
}
|
|
|
|
#[allow(ptr_arg)]
|
|
// Type of MethodArgs is potentially a Vec
|
|
/// lint use of `map().unwrap_or_else()` for `Option`s
|
|
fn lint_map_unwrap_or_else(cx: &LateContext, expr: &Expr, map_args: &MethodArgs, unwrap_args: &MethodArgs) {
|
|
// lint if the caller of `map()` is an `Option`
|
|
if match_type(cx, cx.tcx.expr_ty(&map_args[0]), &paths::OPTION) {
|
|
// lint message
|
|
let msg = "called `map(f).unwrap_or_else(g)` on an Option value. This can be done more directly by calling \
|
|
`map_or_else(g, f)` instead";
|
|
// get snippets for args to map() and unwrap_or_else()
|
|
let map_snippet = snippet(cx, map_args[1].span, "..");
|
|
let unwrap_snippet = snippet(cx, unwrap_args[1].span, "..");
|
|
// lint, with note if neither arg is > 1 line and both map() and
|
|
// unwrap_or_else() have the same span
|
|
let multiline = map_snippet.lines().count() > 1 || unwrap_snippet.lines().count() > 1;
|
|
let same_span = map_args[1].span.expn_id == unwrap_args[1].span.expn_id;
|
|
if same_span && !multiline {
|
|
span_note_and_lint(cx,
|
|
OPTION_MAP_UNWRAP_OR_ELSE,
|
|
expr.span,
|
|
msg,
|
|
expr.span,
|
|
&format!("replace `map({0}).unwrap_or_else({1})` with `with map_or_else({1}, {0})`",
|
|
map_snippet,
|
|
unwrap_snippet));
|
|
} else if same_span && multiline {
|
|
span_lint(cx, OPTION_MAP_UNWRAP_OR_ELSE, expr.span, msg);
|
|
};
|
|
}
|
|
}
|
|
|
|
#[allow(ptr_arg)]
|
|
// Type of MethodArgs is potentially a Vec
|
|
/// lint use of `filter().next() for Iterators`
|
|
fn lint_filter_next(cx: &LateContext, expr: &Expr, filter_args: &MethodArgs) {
|
|
// lint if caller of `.filter().next()` is an Iterator
|
|
if match_trait_method(cx, expr, &paths::ITERATOR) {
|
|
let msg = "called `filter(p).next()` on an Iterator. This is more succinctly expressed by calling `.find(p)` \
|
|
instead.";
|
|
let filter_snippet = snippet(cx, filter_args[1].span, "..");
|
|
if filter_snippet.lines().count() <= 1 {
|
|
// add note if not multi-line
|
|
span_note_and_lint(cx,
|
|
FILTER_NEXT,
|
|
expr.span,
|
|
msg,
|
|
expr.span,
|
|
&format!("replace `filter({0}).next()` with `find({0})`", filter_snippet));
|
|
} else {
|
|
span_lint(cx, FILTER_NEXT, expr.span, msg);
|
|
}
|
|
}
|
|
}
|
|
|
|
#[allow(ptr_arg)]
|
|
// Type of MethodArgs is potentially a Vec
|
|
/// lint searching an Iterator followed by `is_some()`
|
|
fn lint_search_is_some(cx: &LateContext, expr: &Expr, search_method: &str, search_args: &MethodArgs,
|
|
is_some_args: &MethodArgs) {
|
|
// lint if caller of search is an Iterator
|
|
if match_trait_method(cx, &*is_some_args[0], &paths::ITERATOR) {
|
|
let msg = format!("called `is_some()` after searching an iterator with {}. This is more succinctly expressed \
|
|
by calling `any()`.",
|
|
search_method);
|
|
let search_snippet = snippet(cx, search_args[1].span, "..");
|
|
if search_snippet.lines().count() <= 1 {
|
|
// add note if not multi-line
|
|
span_note_and_lint(cx,
|
|
SEARCH_IS_SOME,
|
|
expr.span,
|
|
&msg,
|
|
expr.span,
|
|
&format!("replace `{0}({1}).is_some()` with `any({1})`", search_method, search_snippet));
|
|
} else {
|
|
span_lint(cx, SEARCH_IS_SOME, expr.span, &msg);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Checks for the `CHARS_NEXT_CMP` lint.
|
|
fn lint_chars_next(cx: &LateContext, expr: &Expr, chain: &Expr, other: &Expr, eq: bool) -> bool {
|
|
if_let_chain! {[
|
|
let Some(args) = method_chain_args(chain, &["chars", "next"]),
|
|
let ExprCall(ref fun, ref arg_char) = other.node,
|
|
arg_char.len() == 1,
|
|
let ExprPath(None, ref path) = fun.node,
|
|
path.segments.len() == 1 && path.segments[0].identifier.name.as_str() == "Some"
|
|
], {
|
|
let self_ty = walk_ptrs_ty(cx.tcx.expr_ty_adjusted(&args[0][0]));
|
|
|
|
if self_ty.sty != ty::TyStr {
|
|
return false;
|
|
}
|
|
|
|
span_lint_and_then(cx,
|
|
CHARS_NEXT_CMP,
|
|
expr.span,
|
|
"you should use the `starts_with` method",
|
|
|db| {
|
|
let sugg = format!("{}{}.starts_with({})",
|
|
if eq { "" } else { "!" },
|
|
snippet(cx, args[0][0].span, "_"),
|
|
snippet(cx, arg_char[0].span, "_")
|
|
);
|
|
|
|
db.span_suggestion(expr.span, "like this", sugg);
|
|
});
|
|
|
|
return true;
|
|
}}
|
|
|
|
false
|
|
}
|
|
|
|
/// lint for length-1 `str`s for methods in `PATTERN_METHODS`
|
|
fn lint_single_char_pattern(cx: &LateContext, expr: &Expr, arg: &Expr) {
|
|
if let Ok(ConstVal::Str(r)) = eval_const_expr_partial(cx.tcx, arg, ExprTypeChecked, None) {
|
|
if r.len() == 1 {
|
|
let hint = snippet(cx, expr.span, "..").replace(&format!("\"{}\"", r), &format!("'{}'", r));
|
|
span_lint_and_then(cx,
|
|
SINGLE_CHAR_PATTERN,
|
|
arg.span,
|
|
"single-character string constant used as pattern",
|
|
|db| {
|
|
db.span_suggestion(expr.span, "try using a char instead:", hint);
|
|
});
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Given a `Result<T, E>` type, return its error type (`E`).
|
|
fn get_error_type<'a>(cx: &LateContext, ty: ty::Ty<'a>) -> Option<ty::Ty<'a>> {
|
|
if !match_type(cx, ty, &paths::RESULT) {
|
|
return None;
|
|
}
|
|
if let ty::TyEnum(_, substs) = ty.sty {
|
|
if let Some(err_ty) = substs.types.opt_get(TypeSpace, 1) {
|
|
return Some(err_ty);
|
|
}
|
|
}
|
|
None
|
|
}
|
|
|
|
/// This checks whether a given type is known to implement Debug.
|
|
fn has_debug_impl<'a, 'b>(ty: ty::Ty<'a>, cx: &LateContext<'b, 'a>) -> bool {
|
|
match cx.tcx.lang_items.debug_trait() {
|
|
Some(debug) => implements_trait(cx, ty, debug, Vec::new()),
|
|
None => false,
|
|
}
|
|
}
|
|
|
|
enum Convention {
|
|
Eq(&'static str),
|
|
StartsWith(&'static str),
|
|
}
|
|
|
|
#[cfg_attr(rustfmt, rustfmt_skip)]
|
|
const CONVENTIONS: [(Convention, &'static [SelfKind]); 6] = [
|
|
(Convention::Eq("new"), &[SelfKind::No]),
|
|
(Convention::StartsWith("as_"), &[SelfKind::Ref, SelfKind::RefMut]),
|
|
(Convention::StartsWith("from_"), &[SelfKind::No]),
|
|
(Convention::StartsWith("into_"), &[SelfKind::Value]),
|
|
(Convention::StartsWith("is_"), &[SelfKind::Ref, SelfKind::No]),
|
|
(Convention::StartsWith("to_"), &[SelfKind::Ref]),
|
|
];
|
|
|
|
#[cfg_attr(rustfmt, rustfmt_skip)]
|
|
const TRAIT_METHODS: [(&'static str, usize, SelfKind, OutType, &'static str); 30] = [
|
|
("add", 2, SelfKind::Value, OutType::Any, "std::ops::Add"),
|
|
("as_mut", 1, SelfKind::RefMut, OutType::Ref, "std::convert::AsMut"),
|
|
("as_ref", 1, SelfKind::Ref, OutType::Ref, "std::convert::AsRef"),
|
|
("bitand", 2, SelfKind::Value, OutType::Any, "std::ops::BitAnd"),
|
|
("bitor", 2, SelfKind::Value, OutType::Any, "std::ops::BitOr"),
|
|
("bitxor", 2, SelfKind::Value, OutType::Any, "std::ops::BitXor"),
|
|
("borrow", 1, SelfKind::Ref, OutType::Ref, "std::borrow::Borrow"),
|
|
("borrow_mut", 1, SelfKind::RefMut, OutType::Ref, "std::borrow::BorrowMut"),
|
|
("clone", 1, SelfKind::Ref, OutType::Any, "std::clone::Clone"),
|
|
("cmp", 2, SelfKind::Ref, OutType::Any, "std::cmp::Ord"),
|
|
("default", 0, SelfKind::No, OutType::Any, "std::default::Default"),
|
|
("deref", 1, SelfKind::Ref, OutType::Ref, "std::ops::Deref"),
|
|
("deref_mut", 1, SelfKind::RefMut, OutType::Ref, "std::ops::DerefMut"),
|
|
("div", 2, SelfKind::Value, OutType::Any, "std::ops::Div"),
|
|
("drop", 1, SelfKind::RefMut, OutType::Unit, "std::ops::Drop"),
|
|
("eq", 2, SelfKind::Ref, OutType::Bool, "std::cmp::PartialEq"),
|
|
("from_iter", 1, SelfKind::No, OutType::Any, "std::iter::FromIterator"),
|
|
("from_str", 1, SelfKind::No, OutType::Any, "std::str::FromStr"),
|
|
("hash", 2, SelfKind::Ref, OutType::Unit, "std::hash::Hash"),
|
|
("index", 2, SelfKind::Ref, OutType::Ref, "std::ops::Index"),
|
|
("index_mut", 2, SelfKind::RefMut, OutType::Ref, "std::ops::IndexMut"),
|
|
("into_iter", 1, SelfKind::Value, OutType::Any, "std::iter::IntoIterator"),
|
|
("mul", 2, SelfKind::Value, OutType::Any, "std::ops::Mul"),
|
|
("neg", 1, SelfKind::Value, OutType::Any, "std::ops::Neg"),
|
|
("next", 1, SelfKind::RefMut, OutType::Any, "std::iter::Iterator"),
|
|
("not", 1, SelfKind::Value, OutType::Any, "std::ops::Not"),
|
|
("rem", 2, SelfKind::Value, OutType::Any, "std::ops::Rem"),
|
|
("shl", 2, SelfKind::Value, OutType::Any, "std::ops::Shl"),
|
|
("shr", 2, SelfKind::Value, OutType::Any, "std::ops::Shr"),
|
|
("sub", 2, SelfKind::Value, OutType::Any, "std::ops::Sub"),
|
|
];
|
|
|
|
#[cfg_attr(rustfmt, rustfmt_skip)]
|
|
const PATTERN_METHODS: [(&'static str, usize); 17] = [
|
|
("contains", 1),
|
|
("starts_with", 1),
|
|
("ends_with", 1),
|
|
("find", 1),
|
|
("rfind", 1),
|
|
("split", 1),
|
|
("rsplit", 1),
|
|
("split_terminator", 1),
|
|
("rsplit_terminator", 1),
|
|
("splitn", 2),
|
|
("rsplitn", 2),
|
|
("matches", 1),
|
|
("rmatches", 1),
|
|
("match_indices", 1),
|
|
("rmatch_indices", 1),
|
|
("trim_left_matches", 1),
|
|
("trim_right_matches", 1),
|
|
];
|
|
|
|
|
|
#[derive(Clone, Copy)]
|
|
enum SelfKind {
|
|
Value,
|
|
Ref,
|
|
RefMut,
|
|
No,
|
|
}
|
|
|
|
impl SelfKind {
|
|
fn matches(&self, slf: &ExplicitSelf_, allow_value_for_ref: bool) -> bool {
|
|
match (self, slf) {
|
|
(&SelfKind::Value, &SelfValue(_)) |
|
|
(&SelfKind::Ref, &SelfRegion(_, Mutability::MutImmutable, _)) |
|
|
(&SelfKind::RefMut, &SelfRegion(_, Mutability::MutMutable, _)) |
|
|
(&SelfKind::No, &SelfStatic) => true,
|
|
(&SelfKind::Ref, &SelfValue(_)) |
|
|
(&SelfKind::RefMut, &SelfValue(_)) => allow_value_for_ref,
|
|
(_, &SelfExplicit(ref ty, _)) => self.matches_explicit_type(ty, allow_value_for_ref),
|
|
_ => false,
|
|
}
|
|
}
|
|
|
|
fn matches_explicit_type(&self, ty: &Ty, allow_value_for_ref: bool) -> bool {
|
|
match (self, &ty.node) {
|
|
(&SelfKind::Value, &TyPath(..)) |
|
|
(&SelfKind::Ref, &TyRptr(_, MutTy { mutbl: Mutability::MutImmutable, .. })) |
|
|
(&SelfKind::RefMut, &TyRptr(_, MutTy { mutbl: Mutability::MutMutable, .. })) => true,
|
|
(&SelfKind::Ref, &TyPath(..)) |
|
|
(&SelfKind::RefMut, &TyPath(..)) => allow_value_for_ref,
|
|
_ => false,
|
|
}
|
|
}
|
|
|
|
fn description(&self) -> &'static str {
|
|
match *self {
|
|
SelfKind::Value => "self by value",
|
|
SelfKind::Ref => "self by reference",
|
|
SelfKind::RefMut => "self by mutable reference",
|
|
SelfKind::No => "no self",
|
|
}
|
|
}
|
|
}
|
|
|
|
impl Convention {
|
|
fn check(&self, other: &str) -> bool {
|
|
match *self {
|
|
Convention::Eq(this) => this == other,
|
|
Convention::StartsWith(this) => other.starts_with(this),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl fmt::Display for Convention {
|
|
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
|
|
match *self {
|
|
Convention::Eq(this) => this.fmt(f),
|
|
Convention::StartsWith(this) => this.fmt(f).and_then(|_| '*'.fmt(f)),
|
|
}
|
|
}
|
|
}
|
|
|
|
#[derive(Clone, Copy)]
|
|
enum OutType {
|
|
Unit,
|
|
Bool,
|
|
Any,
|
|
Ref,
|
|
}
|
|
|
|
impl OutType {
|
|
fn matches(&self, ty: &FunctionRetTy) -> bool {
|
|
match (self, ty) {
|
|
(&OutType::Unit, &DefaultReturn(_)) => true,
|
|
(&OutType::Unit, &Return(ref ty)) if ty.node == TyTup(vec![].into()) => true,
|
|
(&OutType::Bool, &Return(ref ty)) if is_bool(ty) => true,
|
|
(&OutType::Any, &Return(ref ty)) if ty.node != TyTup(vec![].into()) => true,
|
|
(&OutType::Ref, &Return(ref ty)) => {
|
|
if let TyRptr(_, _) = ty.node {
|
|
true
|
|
} else {
|
|
false
|
|
}
|
|
}
|
|
_ => false,
|
|
}
|
|
}
|
|
}
|
|
|
|
fn is_bool(ty: &Ty) -> bool {
|
|
if let TyPath(None, ref p) = ty.node {
|
|
if match_path(p, &["bool"]) {
|
|
return true;
|
|
}
|
|
}
|
|
false
|
|
}
|
|
|
|
fn is_copy<'a, 'ctx>(cx: &LateContext<'a, 'ctx>, ty: ty::Ty<'ctx>, item: &Item) -> bool {
|
|
let env = ty::ParameterEnvironment::for_item(cx.tcx, item.id);
|
|
!ty.subst(cx.tcx, &env.free_substs).moves_by_default(&env, item.span)
|
|
}
|