// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. use crate::rustc::hir; use crate::rustc::hir::def::Def; use crate::rustc::lint::{in_external_macro, LateContext, LateLintPass, Lint, LintArray, LintContext, LintPass}; use crate::rustc::ty::{self, Predicate, Ty}; use crate::rustc::{declare_tool_lint, lint_array}; use crate::rustc_errors::Applicability; use crate::syntax::ast; use crate::syntax::source_map::{BytePos, Span}; use crate::syntax::symbol::LocalInternedString; use crate::utils::paths; use crate::utils::sugg; use crate::utils::{ get_arg_name, get_trait_def_id, implements_trait, in_macro, is_copy, is_expn_of, is_self, is_self_ty, iter_input_pats, last_path_segment, match_def_path, match_path, match_qpath, match_trait_method, match_type, match_var, method_calls, method_chain_args, remove_blocks, return_ty, same_tys, single_segment_path, snippet, snippet_with_applicability, snippet_with_macro_callsite, span_lint, span_lint_and_sugg, span_lint_and_then, span_note_and_lint, walk_ptrs_ty, walk_ptrs_ty_depth, SpanlessEq, }; use if_chain::if_chain; use matches::matches; use std::borrow::Cow; use std::fmt; use std::iter; mod unnecessary_filter_map; #[derive(Clone)] pub struct Pass; /// **What it does:** Checks for `.unwrap()` calls on `Option`s. /// /// **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. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// x.unwrap() /// ``` declare_clippy_lint! { pub OPTION_UNWRAP_USED, restriction, "using `Option.unwrap()`, which should at least get a better message using `expect()`" } /// **What it does:** Checks for `.unwrap()` calls on `Result`s. /// /// **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!`. /// /// 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. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// x.unwrap() /// ``` declare_clippy_lint! { pub RESULT_UNWRAP_USED, restriction, "using `Result.unwrap()`, which might be better handled" } /// **What it does:** 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. /// /// **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. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// struct X; /// impl X { /// fn add(&self, other: &X) -> X { /// .. /// } /// } /// ``` declare_clippy_lint! { pub SHOULD_IMPLEMENT_TRAIT, style, "defining a method that should be implementing a std trait" } /// **What it does:** Checks for methods with certain name prefixes and which /// doesn't match how self is taken. The actual rules are: /// /// |Prefix |`self` taken | /// |-------|----------------------| /// |`as_` |`&self` or `&mut self`| /// |`from_`| none | /// |`into_`|`self` | /// |`is_` |`&self` or none | /// |`to_` |`&self` | /// /// **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. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// impl X { /// fn as_str(self) -> &str { /// .. /// } /// } /// ``` declare_clippy_lint! { pub WRONG_SELF_CONVENTION, style, "defining a method named with an established prefix (like \"into_\") that takes `self` with the wrong convention" } /// **What it does:** This is the same as /// [`wrong_self_convention`](#wrong_self_convention), but for public items. /// /// **Why is this bad?** See [`wrong_self_convention`](#wrong_self_convention). /// /// **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. /// /// **Example:** /// ```rust /// impl X { /// pub fn as_str(self) -> &str { /// .. /// } /// } /// ``` declare_clippy_lint! { pub WRONG_PUB_SELF_CONVENTION, restriction, "defining a public method named with an established prefix (like \"into_\") that takes `self` with the wrong convention" } /// **What it does:** Checks for usage of `ok().expect(..)`. /// /// **Why is this bad?** Because you usually call `expect()` on the `Result` /// directly to get a better error message. /// /// **Known problems:** The error type needs to implement `Debug` /// /// **Example:** /// ```rust /// x.ok().expect("why did I do this again?") /// ``` declare_clippy_lint! { pub OK_EXPECT, style, "using `ok().expect()`, which gives worse error messages than calling `expect` directly on the Result" } /// **What it does:** Checks for usage of `_.map(_).unwrap_or(_)`. /// /// **Why is this bad?** Readability, this can be written more concisely as /// `_.map_or(_, _)`. /// /// **Known problems:** The order of the arguments is not in execution order /// /// **Example:** /// ```rust /// x.map(|a| a + 1).unwrap_or(0) /// ``` declare_clippy_lint! { pub OPTION_MAP_UNWRAP_OR, pedantic, "using `Option.map(f).unwrap_or(a)`, which is more succinctly expressed as \ `map_or(a, f)`" } /// **What it does:** Checks for usage of `_.map(_).unwrap_or_else(_)`. /// /// **Why is this bad?** Readability, this can be written more concisely as /// `_.map_or_else(_, _)`. /// /// **Known problems:** The order of the arguments is not in execution order. /// /// **Example:** /// ```rust /// x.map(|a| a + 1).unwrap_or_else(some_function) /// ``` declare_clippy_lint! { pub OPTION_MAP_UNWRAP_OR_ELSE, pedantic, "using `Option.map(f).unwrap_or_else(g)`, which is more succinctly expressed as `map_or_else(g, f)`" } /// **What it does:** Checks for usage of `result.map(_).unwrap_or_else(_)`. /// /// **Why is this bad?** Readability, this can be written more concisely as /// `result.ok().map_or_else(_, _)`. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// x.map(|a| a + 1).unwrap_or_else(some_function) /// ``` declare_clippy_lint! { pub RESULT_MAP_UNWRAP_OR_ELSE, pedantic, "using `Result.map(f).unwrap_or_else(g)`, which is more succinctly expressed as `.ok().map_or_else(g, f)`" } /// **What it does:** Checks for usage of `_.map_or(None, _)`. /// /// **Why is this bad?** Readability, this can be written more concisely as /// `_.and_then(_)`. /// /// **Known problems:** The order of the arguments is not in execution order. /// /// **Example:** /// ```rust /// opt.map_or(None, |a| a + 1) /// ``` declare_clippy_lint! { pub OPTION_MAP_OR_NONE, style, "using `Option.map_or(None, f)`, which is more succinctly expressed as `and_then(f)`" } /// **What it does:** Checks for usage of `_.filter(_).next()`. /// /// **Why is this bad?** Readability, this can be written more concisely as /// `_.find(_)`. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// iter.filter(|x| x == 0).next() /// ``` declare_clippy_lint! { pub FILTER_NEXT, complexity, "using `filter(p).next()`, which is more succinctly expressed as `.find(p)`" } /// **What it does:** Checks for usage of `_.map(_).flatten(_)`, /// /// **Why is this bad?** Readability, this can be written more concisely as a /// single method call. /// /// **Known problems:** /// /// **Example:** /// ```rust /// iter.map(|x| x.iter()).flatten() /// ``` declare_clippy_lint! { pub MAP_FLATTEN, pedantic, "using combinations of `flatten` and `map` which can usually be written as a single method call" } /// **What it does:** Checks for usage of `_.filter(_).map(_)`, /// `_.filter(_).flat_map(_)`, `_.filter_map(_).flat_map(_)` and similar. /// /// **Why is this bad?** Readability, this can be written more concisely as a /// single method call. /// /// **Known problems:** Often requires a condition + Option/Iterator creation /// inside the closure. /// /// **Example:** /// ```rust /// iter.filter(|x| x == 0).map(|x| x * 2) /// ``` declare_clippy_lint! { pub FILTER_MAP, pedantic, "using combinations of `filter`, `map`, `filter_map` and `flat_map` which can usually be written as a single method call" } /// **What it does:** Checks for an iterator search (such as `find()`, /// `position()`, or `rposition()`) followed by a call to `is_some()`. /// /// **Why is this bad?** Readability, this can be written more concisely as /// `_.any(_)`. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// iter.find(|x| x == 0).is_some() /// ``` declare_clippy_lint! { pub SEARCH_IS_SOME, complexity, "using an iterator search followed by `is_some()`, which is more succinctly expressed as a call to `any()`" } /// **What it does:** Checks for usage of `.chars().next()` on a `str` to check /// if it starts with a given char. /// /// **Why is this bad?** Readability, this can be written more concisely as /// `_.starts_with(_)`. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// name.chars().next() == Some('_') /// ``` declare_clippy_lint! { pub CHARS_NEXT_CMP, complexity, "using `.chars().next()` to check if a string starts with a char" } /// **What it does:** Checks for calls to `.or(foo(..))`, `.unwrap_or(foo(..))`, /// etc., and suggests to use `or_else`, `unwrap_or_else`, etc., or /// `unwrap_or_default` instead. /// /// **Why is this bad?** The function will always be called and potentially /// allocate an object acting as the default. /// /// **Known problems:** If the function has side-effects, not calling it will /// change the semantic of the program, but you shouldn't rely on that anyway. /// /// **Example:** /// ```rust /// foo.unwrap_or(String::new()) /// ``` /// this can instead be written: /// ```rust /// foo.unwrap_or_else(String::new) /// ``` /// or /// ```rust /// foo.unwrap_or_default() /// ``` declare_clippy_lint! { pub OR_FUN_CALL, perf, "using any `*or` method with a function call, which suggests `*or_else`" } /// **What it does:** Checks for calls to `.expect(&format!(...))`, `.expect(foo(..))`, /// etc., and suggests to use `unwrap_or_else` instead /// /// **Why is this bad?** The function will always be called. /// /// **Known problems:** If the function has side-effects, not calling it will /// change the semantic of the program, but you shouldn't rely on that anyway. /// /// **Example:** /// ```rust /// foo.expect(&format!("Err {}: {}", err_code, err_msg)) /// ``` /// or /// ```rust /// foo.expect(format!("Err {}: {}", err_code, err_msg).as_str()) /// ``` /// this can instead be written: /// ```rust /// foo.unwrap_or_else(|_| panic!("Err {}: {}", err_code, err_msg)) /// ``` declare_clippy_lint! { pub EXPECT_FUN_CALL, perf, "using any `expect` method with a function call" } /// **What it does:** Checks for usage of `.clone()` on a `Copy` type. /// /// **Why is this bad?** The only reason `Copy` types implement `Clone` is for /// generics, not for using the `clone` method on a concrete type. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// 42u64.clone() /// ``` declare_clippy_lint! { pub CLONE_ON_COPY, complexity, "using `clone` on a `Copy` type" } /// **What it does:** Checks for usage of `.clone()` on a ref-counted pointer, /// (`Rc`, `Arc`, `rc::Weak`, or `sync::Weak`), and suggests calling Clone via unified /// function syntax instead (e.g. `Rc::clone(foo)`). /// /// **Why is this bad?** Calling '.clone()' on an Rc, Arc, or Weak /// can obscure the fact that only the pointer is being cloned, not the underlying /// data. /// /// **Example:** /// ```rust /// x.clone() /// ``` declare_clippy_lint! { pub CLONE_ON_REF_PTR, restriction, "using 'clone' on a ref-counted pointer" } /// **What it does:** Checks for usage of `.clone()` on an `&&T`. /// /// **Why is this bad?** Cloning an `&&T` copies the inner `&T`, instead of /// cloning the underlying `T`. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// fn main() { /// let x = vec![1]; /// let y = &&x; /// let z = y.clone(); /// println!("{:p} {:p}", *y, z); // prints out the same pointer /// } /// ``` declare_clippy_lint! { pub CLONE_DOUBLE_REF, correctness, "using `clone` on `&&T`" } /// **What it does:** Checks for `new` not returning `Self`. /// /// **Why is this bad?** As a convention, `new` methods are used to make a new /// instance of a type. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// impl Foo { /// fn new(..) -> NotAFoo { /// } /// } /// ``` declare_clippy_lint! { pub NEW_RET_NO_SELF, style, "not returning `Self` in a `new` method" } /// **What it does:** Checks for string methods that receive a single-character /// `str` as an argument, e.g. `_.split("x")`. /// /// **Why is this bad?** Performing these methods using a `char` is faster than /// using a `str`. /// /// **Known problems:** Does not catch multi-byte unicode characters. /// /// **Example:** /// `_.split("x")` could be `_.split('x')` declare_clippy_lint! { pub SINGLE_CHAR_PATTERN, perf, "using a single-character str where a char could be used, e.g. `_.split(\"x\")`" } /// **What it does:** Checks for getting the inner pointer of a temporary /// `CString`. /// /// **Why is this bad?** The inner pointer of a `CString` is only valid as long /// as the `CString` is alive. /// /// **Known problems:** None. /// /// **Example:** /// ```rust,ignore /// let c_str = CString::new("foo").unwrap().as_ptr(); /// unsafe { /// call_some_ffi_func(c_str); /// } /// ``` /// Here `c_str` point to a freed address. The correct use would be: /// ```rust,ignore /// let c_str = CString::new("foo").unwrap(); /// unsafe { /// call_some_ffi_func(c_str.as_ptr()); /// } /// ``` declare_clippy_lint! { pub TEMPORARY_CSTRING_AS_PTR, correctness, "getting the inner pointer of a temporary `CString`" } /// **What it does:** Checks for use of `.iter().nth()` (and the related /// `.iter_mut().nth()`) on standard library types with O(1) element access. /// /// **Why is this bad?** `.get()` and `.get_mut()` are more efficient and more /// readable. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// let some_vec = vec![0, 1, 2, 3]; /// let bad_vec = some_vec.iter().nth(3); /// let bad_slice = &some_vec[..].iter().nth(3); /// ``` /// The correct use would be: /// ```rust /// let some_vec = vec![0, 1, 2, 3]; /// let bad_vec = some_vec.get(3); /// let bad_slice = &some_vec[..].get(3); /// ``` declare_clippy_lint! { pub ITER_NTH, perf, "using `.iter().nth()` on a standard library type with O(1) element access" } /// **What it does:** Checks for use of `.skip(x).next()` on iterators. /// /// **Why is this bad?** `.nth(x)` is cleaner /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// let some_vec = vec![0, 1, 2, 3]; /// let bad_vec = some_vec.iter().skip(3).next(); /// let bad_slice = &some_vec[..].iter().skip(3).next(); /// ``` /// The correct use would be: /// ```rust /// let some_vec = vec![0, 1, 2, 3]; /// let bad_vec = some_vec.iter().nth(3); /// let bad_slice = &some_vec[..].iter().nth(3); /// ``` declare_clippy_lint! { pub ITER_SKIP_NEXT, style, "using `.skip(x).next()` on an iterator" } /// **What it does:** Checks for use of `.get().unwrap()` (or /// `.get_mut().unwrap`) on a standard library type which implements `Index` /// /// **Why is this bad?** Using the Index trait (`[]`) is more clear and more /// concise. /// /// **Known problems:** Not a replacement for error handling: Using either /// `.unwrap()` or the Index trait (`[]`) carries the risk of causing a `panic` /// if the value being accessed is `None`. If the use of `.get().unwrap()` is a /// temporary placeholder for dealing with the `Option` type, then this does /// not mitigate the need for error handling. If there is a chance that `.get()` /// will be `None` in your program, then it is advisable that the `None` case /// is handled in a future refactor instead of using `.unwrap()` or the Index /// trait. /// /// **Example:** /// ```rust /// let some_vec = vec![0, 1, 2, 3]; /// let last = some_vec.get(3).unwrap(); /// *some_vec.get_mut(0).unwrap() = 1; /// ``` /// The correct use would be: /// ```rust /// let some_vec = vec![0, 1, 2, 3]; /// let last = some_vec[3]; /// some_vec[0] = 1; /// ``` declare_clippy_lint! { pub GET_UNWRAP, style, "using `.get().unwrap()` or `.get_mut().unwrap()` when using `[]` would work instead" } /// **What it does:** Checks for the use of `.extend(s.chars())` where s is a /// `&str` or `String`. /// /// **Why is this bad?** `.push_str(s)` is clearer /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// let abc = "abc"; /// let def = String::from("def"); /// let mut s = String::new(); /// s.extend(abc.chars()); /// s.extend(def.chars()); /// ``` /// The correct use would be: /// ```rust /// let abc = "abc"; /// let def = String::from("def"); /// let mut s = String::new(); /// s.push_str(abc); /// s.push_str(&def)); /// ``` declare_clippy_lint! { pub STRING_EXTEND_CHARS, style, "using `x.extend(s.chars())` where s is a `&str` or `String`" } /// **What it does:** Checks for the use of `.cloned().collect()` on slice to /// create a `Vec`. /// /// **Why is this bad?** `.to_vec()` is clearer /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// let s = [1, 2, 3, 4, 5]; /// let s2: Vec = s[..].iter().cloned().collect(); /// ``` /// The better use would be: /// ```rust /// let s = [1, 2, 3, 4, 5]; /// let s2: Vec = s.to_vec(); /// ``` declare_clippy_lint! { pub ITER_CLONED_COLLECT, style, "using `.cloned().collect()` on slice to create a `Vec`" } /// **What it does:** Checks for usage of `.chars().last()` or /// `.chars().next_back()` on a `str` to check if it ends with a given char. /// /// **Why is this bad?** Readability, this can be written more concisely as /// `_.ends_with(_)`. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// name.chars().last() == Some('_') || name.chars().next_back() == Some('-') /// ``` declare_clippy_lint! { pub CHARS_LAST_CMP, style, "using `.chars().last()` or `.chars().next_back()` to check if a string ends with a char" } /// **What it does:** Checks for usage of `.as_ref()` or `.as_mut()` where the /// types before and after the call are the same. /// /// **Why is this bad?** The call is unnecessary. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// let x: &[i32] = &[1, 2, 3, 4, 5]; /// do_stuff(x.as_ref()); /// ``` /// The correct use would be: /// ```rust /// let x: &[i32] = &[1, 2, 3, 4, 5]; /// do_stuff(x); /// ``` declare_clippy_lint! { pub USELESS_ASREF, complexity, "using `as_ref` where the types before and after the call are the same" } /// **What it does:** Checks for using `fold` when a more succinct alternative exists. /// Specifically, this checks for `fold`s which could be replaced by `any`, `all`, /// `sum` or `product`. /// /// **Why is this bad?** Readability. /// /// **Known problems:** False positive in pattern guards. Will be resolved once /// non-lexical lifetimes are stable. /// /// **Example:** /// ```rust /// let _ = (0..3).fold(false, |acc, x| acc || x > 2); /// ``` /// This could be written as: /// ```rust /// let _ = (0..3).any(|x| x > 2); /// ``` declare_clippy_lint! { pub UNNECESSARY_FOLD, style, "using `fold` when a more succinct alternative exists" } /// **What it does:** Checks for `filter_map` calls which could be replaced by `filter` or `map`. /// More specifically it checks if the closure provided is only performing one of the /// filter or map operations and suggests the appropriate option. /// /// **Why is this bad?** Complexity. The intent is also clearer if only a single /// operation is being performed. /// /// **Known problems:** None /// /// **Example:** /// ```rust /// let _ = (0..3).filter_map(|x| if x > 2 { Some(x) } else { None }); /// ``` /// As there is no transformation of the argument this could be written as: /// ```rust /// let _ = (0..3).filter(|&x| x > 2); /// ``` /// /// ```rust /// let _ = (0..4).filter_map(i32::checked_abs); /// ``` /// As there is no conditional check on the argument this could be written as: /// ```rust /// let _ = (0..4).map(i32::checked_abs); /// ``` declare_clippy_lint! { pub UNNECESSARY_FILTER_MAP, complexity, "using `filter_map` when a more succinct alternative exists" } /// **What it does:** Checks for `into_iter` calls on types which should be replaced by `iter` or /// `iter_mut`. /// /// **Why is this bad?** Arrays and `PathBuf` do not yet have an `into_iter` method which move out /// their content into an iterator. Auto-referencing resolves the `into_iter` call to its reference /// instead, like `<&[T; N] as IntoIterator>::into_iter`, which just iterates over item references /// like calling `iter` would. Furthermore, when the standard library actually /// [implements the `into_iter` method][25725] which moves the content out of the array, the /// original use of `into_iter` got inferred with the wrong type and the code will be broken. /// /// **Known problems:** None /// /// **Example:** /// /// ```rust /// let _ = [1, 2, 3].into_iter().map(|x| *x).collect::>(); /// ``` /// /// [25725]: https://github.com/rust-lang/rust/issues/25725 declare_clippy_lint! { pub INTO_ITER_ON_ARRAY, correctness, "using `.into_iter()` on an array" } /// **What it does:** Checks for `into_iter` calls on references which should be replaced by `iter` /// or `iter_mut`. /// /// **Why is this bad?** Readability. Calling `into_iter` on a reference will not move out its /// content into the resulting iterator, which is confusing. It is better just call `iter` or /// `iter_mut` directly. /// /// **Known problems:** None /// /// **Example:** /// /// ```rust /// let _ = (&vec![3, 4, 5]).into_iter(); /// ``` declare_clippy_lint! { pub INTO_ITER_ON_REF, style, "using `.into_iter()` on a reference" } impl LintPass for Pass { fn get_lints(&self) -> LintArray { lint_array!( OPTION_UNWRAP_USED, RESULT_UNWRAP_USED, SHOULD_IMPLEMENT_TRAIT, WRONG_SELF_CONVENTION, WRONG_PUB_SELF_CONVENTION, OK_EXPECT, OPTION_MAP_UNWRAP_OR, OPTION_MAP_UNWRAP_OR_ELSE, RESULT_MAP_UNWRAP_OR_ELSE, OPTION_MAP_OR_NONE, OR_FUN_CALL, EXPECT_FUN_CALL, CHARS_NEXT_CMP, CHARS_LAST_CMP, CLONE_ON_COPY, CLONE_ON_REF_PTR, CLONE_DOUBLE_REF, NEW_RET_NO_SELF, SINGLE_CHAR_PATTERN, SEARCH_IS_SOME, TEMPORARY_CSTRING_AS_PTR, FILTER_NEXT, FILTER_MAP, MAP_FLATTEN, ITER_NTH, ITER_SKIP_NEXT, GET_UNWRAP, STRING_EXTEND_CHARS, ITER_CLONED_COLLECT, USELESS_ASREF, UNNECESSARY_FOLD, UNNECESSARY_FILTER_MAP, INTO_ITER_ON_ARRAY, INTO_ITER_ON_REF, ) } } impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass { #[allow(clippy::cyclomatic_complexity)] fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) { if in_macro(expr.span) { return; } let (method_names, arg_lists) = method_calls(expr, 2); let method_names: Vec = method_names.iter().map(|s| s.as_str()).collect(); let method_names: Vec<&str> = method_names.iter().map(|s| s.as_ref()).collect(); match method_names.as_slice() { ["unwrap", "get"] => lint_get_unwrap(cx, expr, arg_lists[1], false), ["unwrap", "get_mut"] => lint_get_unwrap(cx, expr, arg_lists[1], true), ["unwrap", ..] => lint_unwrap(cx, expr, arg_lists[0]), ["expect", "ok"] => lint_ok_expect(cx, expr, arg_lists[1]), ["unwrap_or", "map"] => lint_map_unwrap_or(cx, expr, arg_lists[1], arg_lists[0]), ["unwrap_or_else", "map"] => lint_map_unwrap_or_else(cx, expr, arg_lists[1], arg_lists[0]), ["map_or", ..] => lint_map_or_none(cx, expr, arg_lists[0]), ["next", "filter"] => lint_filter_next(cx, expr, arg_lists[1]), ["map", "filter"] => lint_filter_map(cx, expr, arg_lists[1], arg_lists[0]), ["map", "filter_map"] => lint_filter_map_map(cx, expr, arg_lists[1], arg_lists[0]), ["flat_map", "filter"] => lint_filter_flat_map(cx, expr, arg_lists[1], arg_lists[0]), ["flat_map", "filter_map"] => lint_filter_map_flat_map(cx, expr, arg_lists[1], arg_lists[0]), ["flatten", "map"] => lint_map_flatten(cx, expr, arg_lists[1]), ["is_some", "find"] => lint_search_is_some(cx, expr, "find", arg_lists[1], arg_lists[0]), ["is_some", "position"] => lint_search_is_some(cx, expr, "position", arg_lists[1], arg_lists[0]), ["is_some", "rposition"] => lint_search_is_some(cx, expr, "rposition", arg_lists[1], arg_lists[0]), ["extend", ..] => lint_extend(cx, expr, arg_lists[0]), ["as_ptr", "unwrap"] => lint_cstring_as_ptr(cx, expr, &arg_lists[1][0], &arg_lists[0][0]), ["nth", "iter"] => lint_iter_nth(cx, expr, arg_lists[1], false), ["nth", "iter_mut"] => lint_iter_nth(cx, expr, arg_lists[1], true), ["next", "skip"] => lint_iter_skip_next(cx, expr), ["collect", "cloned"] => lint_iter_cloned_collect(cx, expr, arg_lists[1]), ["as_ref", ..] => lint_asref(cx, expr, "as_ref", arg_lists[0]), ["as_mut", ..] => lint_asref(cx, expr, "as_mut", arg_lists[0]), ["fold", ..] => lint_unnecessary_fold(cx, expr, arg_lists[0]), ["filter_map", ..] => unnecessary_filter_map::lint(cx, expr, arg_lists[0]), _ => {}, } match expr.node { hir::ExprKind::MethodCall(ref method_call, ref method_span, ref args) => { lint_or_fun_call(cx, expr, *method_span, &method_call.ident.as_str(), args); lint_expect_fun_call(cx, expr, *method_span, &method_call.ident.as_str(), args); let self_ty = cx.tables.expr_ty_adjusted(&args[0]); if args.len() == 1 && method_call.ident.name == "clone" { lint_clone_on_copy(cx, expr, &args[0], self_ty); lint_clone_on_ref_ptr(cx, expr, &args[0]); } match self_ty.sty { ty::Ref(_, ty, _) if ty.sty == ty::Str => { for &(method, pos) in &PATTERN_METHODS { if method_call.ident.name == method && args.len() > pos { lint_single_char_pattern(cx, expr, &args[pos]); } } }, ty::Ref(..) if method_call.ident.name == "into_iter" => { lint_into_iter(cx, expr, self_ty, *method_span); }, _ => (), } }, hir::ExprKind::Binary(op, ref lhs, ref rhs) if op.node == hir::BinOpKind::Eq || op.node == hir::BinOpKind::Ne => { let mut info = BinaryExprInfo { expr, chain: lhs, other: rhs, eq: op.node == hir::BinOpKind::Eq, }; lint_binary_expr_with_method_call(cx, &mut info); } _ => (), } } fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, implitem: &'tcx hir::ImplItem) { if in_external_macro(cx.sess(), implitem.span) { return; } let name = implitem.ident.name; let parent = cx.tcx.hir().get_parent(implitem.id); let item = cx.tcx.hir().expect_item(parent); let def_id = cx.tcx.hir().local_def_id(item.id); let ty = cx.tcx.type_of(def_id); if_chain! { if let hir::ImplItemKind::Method(ref sig, id) = implitem.node; if let Some(first_arg_ty) = sig.decl.inputs.get(0); if let Some(first_arg) = iter_input_pats(&sig.decl, cx.tcx.hir().body(id)).next(); if let hir::ItemKind::Impl(_, _, _, _, None, ref self_ty, _) = item.node; then { if cx.access_levels.is_exported(implitem.id) { // check missing trait implementations for &(method_name, n_args, self_kind, out_type, trait_name) in &TRAIT_METHODS { if name == method_name && sig.decl.inputs.len() == n_args && out_type.matches(cx, &sig.decl.output) && self_kind.matches(cx, first_arg_ty, first_arg, self_ty, false, &implitem.generics) { 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)); } } } // check conventions w.r.t. conversion method names and predicates let is_copy = is_copy(cx, ty); for &(ref conv, self_kinds) in &CONVENTIONS { if conv.check(&name.as_str()) { if !self_kinds .iter() .any(|k| k.matches(cx, first_arg_ty, first_arg, self_ty, is_copy, &implitem.generics)) { let lint = if item.vis.node.is_pub() { WRONG_PUB_SELF_CONVENTION } else { WRONG_SELF_CONVENTION }; span_lint(cx, lint, first_arg.pat.span, &format!("methods called `{}` usually take {}; consider choosing a less \ ambiguous name", conv, &self_kinds.iter() .map(|k| k.description()) .collect::>() .join(" or "))); } // Only check the first convention to match (CONVENTIONS should be listed from most to least // specific) break; } } } } if let hir::ImplItemKind::Method(_, _) = implitem.node { let ret_ty = return_ty(cx, implitem.id); // walk the return type and check for Self (this does not check associated types) for inner_type in ret_ty.walk() { if same_tys(cx, ty, inner_type) { return; } } // if return type is impl trait, check the associated types if let ty::Opaque(def_id, _) = ret_ty.sty { // one of the associated types must be Self for predicate in &cx.tcx.predicates_of(def_id).predicates { match predicate { (Predicate::Projection(poly_projection_predicate), _) => { let binder = poly_projection_predicate.ty(); let associated_type = binder.skip_binder(); let associated_type_is_self_type = same_tys(cx, ty, associated_type); // if the associated type is self, early return and do not trigger lint if associated_type_is_self_type { return; } }, (_, _) => {}, } } } if name == "new" && !same_tys(cx, ret_ty, ty) { span_lint( cx, NEW_RET_NO_SELF, implitem.span, "methods called `new` usually return `Self`", ); } } } } /// Checks for the `OR_FUN_CALL` lint. fn lint_or_fun_call(cx: &LateContext<'_, '_>, expr: &hir::Expr, method_span: Span, name: &str, args: &[hir::Expr]) { /// Check for `unwrap_or(T::new())` or `unwrap_or(T::default())`. fn check_unwrap_or_default( cx: &LateContext<'_, '_>, name: &str, fun: &hir::Expr, self_expr: &hir::Expr, arg: &hir::Expr, or_has_args: bool, span: Span, ) -> bool { if or_has_args { return false; } if name == "unwrap_or" { if let hir::ExprKind::Path(ref qpath) = fun.node { let path = &*last_path_segment(qpath).ident.as_str(); if ["default", "new"].contains(&path) { let arg_ty = cx.tables.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, &[]) { let mut applicability = Applicability::MachineApplicable; span_lint_and_sugg( cx, OR_FUN_CALL, span, &format!("use of `{}` followed by a call to `{}`", name, path), "try this", format!( "{}.unwrap_or_default()", snippet_with_applicability(cx, self_expr.span, "_", &mut applicability) ), applicability, ); return true; } } } } false } /// Check for `*or(foo())`. #[allow(clippy::too_many_arguments)] fn check_general_case( cx: &LateContext<'_, '_>, name: &str, method_span: Span, fun_span: Span, self_expr: &hir::Expr, arg: &hir::Expr, or_has_args: bool, span: Span, ) { // (path, fn_has_argument, methods, suffix) 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"), ]; // early check if the name is one we care about if know_types.iter().all(|k| !k.2.contains(&name)) { return; } // don't lint for constant values let owner_def = cx.tcx.hir().get_parent_did(arg.id); let promotable = cx.tcx.rvalue_promotable_map(owner_def).contains(&arg.hir_id.local_id); if promotable { return; } let self_ty = cx.tables.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_with_macro_callsite(cx, arg.span, "..")).into(), (false, false) => format!("|| {}", snippet_with_macro_callsite(cx, arg.span, "..")).into(), (false, true) => snippet_with_macro_callsite(cx, fun_span, ".."), }; let span_replace_word = method_span.with_hi(span.hi()); span_lint_and_sugg( cx, OR_FUN_CALL, span_replace_word, &format!("use of `{}` followed by a function call", name), "try this", format!("{}_{}({})", name, suffix, sugg), Applicability::HasPlaceholders, ); } if args.len() == 2 { match args[1].node { hir::ExprKind::Call(ref fun, ref or_args) => { 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, method_span, fun.span, &args[0], &args[1], or_has_args, expr.span, ); } }, hir::ExprKind::MethodCall(_, span, ref or_args) => check_general_case( cx, name, method_span, span, &args[0], &args[1], !or_args.is_empty(), expr.span, ), _ => {}, } } } /// Checks for the `EXPECT_FUN_CALL` lint. fn lint_expect_fun_call(cx: &LateContext<'_, '_>, expr: &hir::Expr, method_span: Span, name: &str, args: &[hir::Expr]) { fn extract_format_args(arg: &hir::Expr) -> Option<&hir::HirVec> { let arg = match &arg.node { hir::ExprKind::AddrOf(_, expr) => expr, hir::ExprKind::MethodCall(method_name, _, args) if method_name.ident.name == "as_str" || method_name.ident.name == "as_ref" => { &args[0] }, _ => arg, }; if let hir::ExprKind::Call(ref inner_fun, ref inner_args) = arg.node { if is_expn_of(inner_fun.span, "format").is_some() && inner_args.len() == 1 { if let hir::ExprKind::Call(_, ref format_args) = inner_args[0].node { return Some(format_args); } } } None } fn generate_format_arg_snippet( cx: &LateContext<'_, '_>, a: &hir::Expr, applicability: &mut Applicability, ) -> String { if let hir::ExprKind::AddrOf(_, ref format_arg) = a.node { if let hir::ExprKind::Match(ref format_arg_expr, _, _) = format_arg.node { if let hir::ExprKind::Tup(ref format_arg_expr_tup) = format_arg_expr.node { return snippet_with_applicability(cx, format_arg_expr_tup[0].span, "..", applicability) .into_owned(); } } }; snippet(cx, a.span, "..").into_owned() } fn check_general_case( cx: &LateContext<'_, '_>, name: &str, method_span: Span, self_expr: &hir::Expr, arg: &hir::Expr, span: Span, ) { fn is_call(node: &hir::ExprKind) -> bool { match node { hir::ExprKind::AddrOf(_, expr) => { is_call(&expr.node) }, hir::ExprKind::Call(..) | hir::ExprKind::MethodCall(..) // These variants are debatable or require further examination | hir::ExprKind::If(..) | hir::ExprKind::Match(..) | hir::ExprKind::Block{ .. } => true, _ => false, } } if name != "expect" { return; } let self_type = cx.tables.expr_ty(self_expr); let known_types = &[&paths::OPTION, &paths::RESULT]; // if not a known type, return early if known_types.iter().all(|&k| !match_type(cx, self_type, k)) { return; } if !is_call(&arg.node) { return; } let closure = if match_type(cx, self_type, &paths::OPTION) { "||" } else { "|_|" }; let span_replace_word = method_span.with_hi(span.hi()); if let Some(format_args) = extract_format_args(arg) { let mut applicability = Applicability::MachineApplicable; let args_len = format_args.len(); let args: Vec = format_args .into_iter() .take(args_len - 1) .map(|a| generate_format_arg_snippet(cx, a, &mut applicability)) .collect(); let sugg = args.join(", "); span_lint_and_sugg( cx, EXPECT_FUN_CALL, span_replace_word, &format!("use of `{}` followed by a function call", name), "try this", format!("unwrap_or_else({} panic!({}))", closure, sugg), applicability, ); return; } let mut applicability = Applicability::MachineApplicable; let sugg: Cow<'_, _> = snippet_with_applicability(cx, arg.span, "..", &mut applicability); span_lint_and_sugg( cx, EXPECT_FUN_CALL, span_replace_word, &format!("use of `{}` followed by a function call", name), "try this", format!("unwrap_or_else({} {{ let msg = {}; panic!(msg) }}))", closure, sugg), applicability, ); } if args.len() == 2 { match args[1].node { hir::ExprKind::Lit(_) => {}, _ => check_general_case(cx, name, method_span, &args[0], &args[1], expr.span), } } } /// Checks for the `CLONE_ON_COPY` lint. fn lint_clone_on_copy(cx: &LateContext<'_, '_>, expr: &hir::Expr, arg: &hir::Expr, arg_ty: Ty<'_>) { let ty = cx.tables.expr_ty(expr); if let ty::Ref(_, inner, _) = arg_ty.sty { if let ty::Ref(_, innermost, _) = inner.sty { span_lint_and_then( cx, CLONE_DOUBLE_REF, expr.span, "using `clone` on a double-reference; \ this will copy the reference instead of cloning the inner type", |db| { if let Some(snip) = sugg::Sugg::hir_opt(cx, arg) { let mut ty = innermost; let mut n = 0; while let ty::Ref(_, inner, _) = ty.sty { ty = inner; n += 1; } let refs: String = iter::repeat('&').take(n + 1).collect(); let derefs: String = iter::repeat('*').take(n).collect(); let explicit = format!("{}{}::clone({})", refs, ty, snip); db.span_suggestion_with_applicability( expr.span, "try dereferencing it", format!("{}({}{}).clone()", refs, derefs, snip.deref()), Applicability::MaybeIncorrect, ); db.span_suggestion_with_applicability( expr.span, "or try being explicit about what type to clone", explicit, Applicability::MaybeIncorrect, ); } }, ); return; // don't report clone_on_copy } } if is_copy(cx, ty) { let snip; if let Some(snippet) = sugg::Sugg::hir_opt(cx, arg) { // x.clone() might have dereferenced x, possibly through Deref impls if cx.tables.expr_ty(arg) == ty { snip = Some(("try removing the `clone` call", format!("{}", snippet))); } else { let parent = cx.tcx.hir().get_parent_node(expr.id); match cx.tcx.hir().get(parent) { hir::Node::Expr(parent) => match parent.node { // &*x is a nop, &x.clone() is not hir::ExprKind::AddrOf(..) | // (*x).func() is useless, x.clone().func() can work in case func borrows mutably hir::ExprKind::MethodCall(..) => return, _ => {}, }, hir::Node::Stmt(stmt) => { if let hir::StmtKind::Decl(ref decl, _) = stmt.node { if let hir::DeclKind::Local(ref loc) = decl.node { if let hir::PatKind::Ref(..) = loc.pat.node { // let ref y = *x borrows x, let ref y = x.clone() does not return; } } } }, _ => {}, } let deref_count = cx.tables.expr_adjustments(arg).iter() .filter(|adj| { if let ty::adjustment::Adjust::Deref(_) = adj.kind { true } else { false } }) .count(); let derefs: String = iter::repeat('*').take(deref_count).collect(); snip = Some(("try dereferencing it", format!("{}{}", derefs, snippet))); } } else { snip = None; } span_lint_and_then(cx, CLONE_ON_COPY, expr.span, "using `clone` on a `Copy` type", |db| { if let Some((text, snip)) = snip { db.span_suggestion_with_applicability(expr.span, text, snip, Applicability::Unspecified); } }); } } fn lint_clone_on_ref_ptr(cx: &LateContext<'_, '_>, expr: &hir::Expr, arg: &hir::Expr) { let obj_ty = walk_ptrs_ty(cx.tables.expr_ty(arg)); if let ty::Adt(_, subst) = obj_ty.sty { let caller_type = if match_type(cx, obj_ty, &paths::RC) { "Rc" } else if match_type(cx, obj_ty, &paths::ARC) { "Arc" } else if match_type(cx, obj_ty, &paths::WEAK_RC) || match_type(cx, obj_ty, &paths::WEAK_ARC) { "Weak" } else { return; }; span_lint_and_sugg( cx, CLONE_ON_REF_PTR, expr.span, "using '.clone()' on a ref-counted pointer", "try this", format!( "{}::<{}>::clone(&{})", caller_type, subst.type_at(0), snippet(cx, arg.span, "_") ), Applicability::Unspecified, // Sometimes unnecessary ::<_> after Rc/Arc/Weak ); } } fn lint_string_extend(cx: &LateContext<'_, '_>, expr: &hir::Expr, args: &[hir::Expr]) { let arg = &args[1]; if let Some(arglists) = method_chain_args(arg, &["chars"]) { let target = &arglists[0][0]; let self_ty = walk_ptrs_ty(cx.tables.expr_ty(target)); let ref_str = if self_ty.sty == ty::Str { "" } else if match_type(cx, self_ty, &paths::STRING) { "&" } else { return; }; let mut applicability = Applicability::MachineApplicable; span_lint_and_sugg( cx, STRING_EXTEND_CHARS, expr.span, "calling `.extend(_.chars())`", "try this", format!( "{}.push_str({}{})", snippet_with_applicability(cx, args[0].span, "_", &mut applicability), ref_str, snippet_with_applicability(cx, target.span, "_", &mut applicability) ), applicability, ); } } fn lint_extend(cx: &LateContext<'_, '_>, expr: &hir::Expr, args: &[hir::Expr]) { let obj_ty = walk_ptrs_ty(cx.tables.expr_ty(&args[0])); if match_type(cx, obj_ty, &paths::STRING) { lint_string_extend(cx, expr, args); } } fn lint_cstring_as_ptr(cx: &LateContext<'_, '_>, expr: &hir::Expr, new: &hir::Expr, unwrap: &hir::Expr) { if_chain! { if let hir::ExprKind::Call(ref fun, ref args) = new.node; if args.len() == 1; if let hir::ExprKind::Path(ref path) = fun.node; if let Def::Method(did) = cx.tables.qpath_def(path, fun.hir_id); if match_def_path(cx.tcx, did, &paths::CSTRING_NEW); then { 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 lint_iter_cloned_collect(cx: &LateContext<'_, '_>, expr: &hir::Expr, iter_args: &[hir::Expr]) { if match_type(cx, cx.tables.expr_ty(expr), &paths::VEC) && derefs_to_slice(cx, &iter_args[0], cx.tables.expr_ty(&iter_args[0])).is_some() { span_lint( cx, ITER_CLONED_COLLECT, expr.span, "called `cloned().collect()` on a slice to create a `Vec`. Calling `to_vec()` is both faster and \ more readable", ); } } fn lint_unnecessary_fold(cx: &LateContext<'_, '_>, expr: &hir::Expr, fold_args: &[hir::Expr]) { fn check_fold_with_op( cx: &LateContext<'_, '_>, fold_args: &[hir::Expr], op: hir::BinOpKind, replacement_method_name: &str, replacement_has_args: bool, ) { if_chain! { // Extract the body of the closure passed to fold if let hir::ExprKind::Closure(_, _, body_id, _, _) = fold_args[2].node; let closure_body = cx.tcx.hir().body(body_id); let closure_expr = remove_blocks(&closure_body.value); // Check if the closure body is of the form `acc some_expr(x)` if let hir::ExprKind::Binary(ref bin_op, ref left_expr, ref right_expr) = closure_expr.node; if bin_op.node == op; // Extract the names of the two arguments to the closure if let Some(first_arg_ident) = get_arg_name(&closure_body.arguments[0].pat); if let Some(second_arg_ident) = get_arg_name(&closure_body.arguments[1].pat); if match_var(&*left_expr, first_arg_ident); if replacement_has_args || match_var(&*right_expr, second_arg_ident); then { // Span containing `.fold(...)` let next_point = cx.sess().source_map().next_point(fold_args[0].span); let fold_span = next_point.with_hi(fold_args[2].span.hi() + BytePos(1)); let mut applicability = Applicability::MachineApplicable; let sugg = if replacement_has_args { format!( ".{replacement}(|{s}| {r})", replacement = replacement_method_name, s = second_arg_ident, r = snippet_with_applicability(cx, right_expr.span, "EXPR", &mut applicability), ) } else { format!( ".{replacement}()", replacement = replacement_method_name, ) }; span_lint_and_sugg( cx, UNNECESSARY_FOLD, fold_span, // TODO #2371 don't suggest e.g. .any(|x| f(x)) if we can suggest .any(f) "this `.fold` can be written more succinctly using another method", "try", sugg, applicability, ); } } } // Check that this is a call to Iterator::fold rather than just some function called fold if !match_trait_method(cx, expr, &paths::ITERATOR) { return; } assert!( fold_args.len() == 3, "Expected fold_args to have three entries - the receiver, the initial value and the closure" ); // Check if the first argument to .fold is a suitable literal match fold_args[1].node { hir::ExprKind::Lit(ref lit) => match lit.node { ast::LitKind::Bool(false) => check_fold_with_op(cx, fold_args, hir::BinOpKind::Or, "any", true), ast::LitKind::Bool(true) => check_fold_with_op(cx, fold_args, hir::BinOpKind::And, "all", true), ast::LitKind::Int(0, _) => check_fold_with_op(cx, fold_args, hir::BinOpKind::Add, "sum", false), ast::LitKind::Int(1, _) => check_fold_with_op(cx, fold_args, hir::BinOpKind::Mul, "product", false), _ => return, }, _ => return, }; } fn lint_iter_nth(cx: &LateContext<'_, '_>, expr: &hir::Expr, iter_args: &[hir::Expr], is_mut: bool) { let mut_str = if is_mut { "_mut" } else { "" }; let caller_type = if derefs_to_slice(cx, &iter_args[0], cx.tables.expr_ty(&iter_args[0])).is_some() { "slice" } else if match_type(cx, cx.tables.expr_ty(&iter_args[0]), &paths::VEC) { "Vec" } else if match_type(cx, cx.tables.expr_ty(&iter_args[0]), &paths::VEC_DEQUE) { "VecDeque" } else { return; // caller is not a type that we want to lint }; span_lint( cx, ITER_NTH, expr.span, &format!( "called `.iter{0}().nth()` on a {1}. Calling `.get{0}()` is both faster and more readable", mut_str, caller_type ), ); } fn lint_get_unwrap(cx: &LateContext<'_, '_>, expr: &hir::Expr, get_args: &[hir::Expr], is_mut: bool) { // Note: we don't want to lint `get_mut().unwrap` for HashMap or BTreeMap, // because they do not implement `IndexMut` let mut applicability = Applicability::MachineApplicable; let expr_ty = cx.tables.expr_ty(&get_args[0]); let get_args_str = if get_args.len() > 1 { snippet_with_applicability(cx, get_args[1].span, "_", &mut applicability) } else { return; // not linting on a .get().unwrap() chain or variant }; let needs_ref; let caller_type = if derefs_to_slice(cx, &get_args[0], expr_ty).is_some() { needs_ref = get_args_str.parse::().is_ok(); "slice" } else if match_type(cx, expr_ty, &paths::VEC) { needs_ref = get_args_str.parse::().is_ok(); "Vec" } else if match_type(cx, expr_ty, &paths::VEC_DEQUE) { needs_ref = get_args_str.parse::().is_ok(); "VecDeque" } else if !is_mut && match_type(cx, expr_ty, &paths::HASHMAP) { needs_ref = true; "HashMap" } else if !is_mut && match_type(cx, expr_ty, &paths::BTREEMAP) { needs_ref = true; "BTreeMap" } else { return; // caller is not a type that we want to lint }; let mut_str = if is_mut { "_mut" } else { "" }; let borrow_str = if !needs_ref { "" } else if is_mut { "&mut " } else { "&" }; span_lint_and_sugg( cx, GET_UNWRAP, expr.span, &format!( "called `.get{0}().unwrap()` on a {1}. Using `[]` is more clear and more concise", mut_str, caller_type ), "try this", format!( "{}{}[{}]", borrow_str, snippet_with_applicability(cx, get_args[0].span, "_", &mut applicability), get_args_str ), applicability, ); } fn lint_iter_skip_next(cx: &LateContext<'_, '_>, expr: &hir::Expr) { // lint if caller of skip is an Iterator if match_trait_method(cx, expr, &paths::ITERATOR) { span_lint( cx, ITER_SKIP_NEXT, expr.span, "called `skip(x).next()` on an iterator. This is more succinctly expressed by calling `nth(x)`", ); } } fn derefs_to_slice(cx: &LateContext<'_, '_>, expr: &hir::Expr, ty: Ty<'_>) -> Option> { fn may_slice(cx: &LateContext<'_, '_>, ty: Ty<'_>) -> bool { match ty.sty { ty::Slice(_) => true, ty::Adt(def, _) if def.is_box() => may_slice(cx, ty.boxed_ty()), ty::Adt(..) => match_type(cx, ty, &paths::VEC), ty::Array(_, size) => size.assert_usize(cx.tcx).expect("array length") < 32, ty::Ref(_, inner, _) => may_slice(cx, inner), _ => false, } } if let hir::ExprKind::MethodCall(ref path, _, ref args) = expr.node { if path.ident.name == "iter" && may_slice(cx, cx.tables.expr_ty(&args[0])) { sugg::Sugg::hir_opt(cx, &args[0]).map(|sugg| sugg.addr()) } else { None } } else { match ty.sty { ty::Slice(_) => sugg::Sugg::hir_opt(cx, expr), ty::Adt(def, _) if def.is_box() && may_slice(cx, ty.boxed_ty()) => sugg::Sugg::hir_opt(cx, expr), ty::Ref(_, inner, _) => { if may_slice(cx, inner) { sugg::Sugg::hir_opt(cx, expr) } else { None } }, _ => None, } } } /// lint use of `unwrap()` for `Option`s and `Result`s fn lint_unwrap(cx: &LateContext<'_, '_>, expr: &hir::Expr, unwrap_args: &[hir::Expr]) { let obj_ty = walk_ptrs_ty(cx.tables.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 ), ); } } /// lint use of `ok().expect()` for `Result`s fn lint_ok_expect(cx: &LateContext<'_, '_>, expr: &hir::Expr, ok_args: &[hir::Expr]) { // lint if the caller of `ok()` is a `Result` if match_type(cx, cx.tables.expr_ty(&ok_args[0]), &paths::RESULT) { let result_type = cx.tables.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`", ); } } } } /// lint use of `map().unwrap_or()` for `Option`s fn lint_map_unwrap_or(cx: &LateContext<'_, '_>, expr: &hir::Expr, map_args: &[hir::Expr], unwrap_args: &[hir::Expr]) { // lint if the caller of `map()` is an `Option` if match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::OPTION) { // 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 message // comparing the snippet from source to raw text ("None") below is safe // because we already have checked the type. let arg = if unwrap_snippet == "None" { "None" } else { "a" }; let suggest = if unwrap_snippet == "None" { "and_then(f)" } else { "map_or(a, f)" }; let msg = &format!( "called `map(f).unwrap_or({})` on an Option value. \ This can be done more directly by calling `{}` instead", arg, suggest ); // 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.ctxt() == unwrap_args[1].span.ctxt(); if same_span && !multiline { let suggest = if unwrap_snippet == "None" { format!("and_then({})", map_snippet) } else { format!("map_or({}, {})", unwrap_snippet, map_snippet) }; let note = format!( "replace `map({}).unwrap_or({})` with `{}`", map_snippet, unwrap_snippet, suggest ); span_note_and_lint(cx, OPTION_MAP_UNWRAP_OR, expr.span, msg, expr.span, ¬e); } else if same_span && multiline { span_lint(cx, OPTION_MAP_UNWRAP_OR, expr.span, msg); }; } } /// lint use of `map().flatten()` for `Iterators` fn lint_map_flatten<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, map_args: &'tcx [hir::Expr]) { // lint if caller of `.map().flatten()` is an Iterator if match_trait_method(cx, expr, &paths::ITERATOR) { let msg = "called `map(..).flatten()` on an `Iterator`. \ This is more succinctly expressed by calling `.flat_map(..)`"; let self_snippet = snippet(cx, map_args[0].span, ".."); let func_snippet = snippet(cx, map_args[1].span, ".."); let hint = format!("{0}.flat_map({1})", self_snippet, func_snippet); span_lint_and_then(cx, MAP_FLATTEN, expr.span, msg, |db| { db.span_suggestion_with_applicability( expr.span, "try using flat_map instead", hint, Applicability::MachineApplicable, ); }); } } /// lint use of `map().unwrap_or_else()` for `Option`s and `Result`s fn lint_map_unwrap_or_else<'a, 'tcx>( cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, map_args: &'tcx [hir::Expr], unwrap_args: &'tcx [hir::Expr], ) { // lint if the caller of `map()` is an `Option` let is_option = match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::OPTION); let is_result = match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::RESULT); if is_option || is_result { // lint message let msg = if is_option { "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" } else { "called `map(f).unwrap_or_else(g)` on a Result value. This can be done more directly by calling \ `ok().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.ctxt() == unwrap_args[1].span.ctxt(); if same_span && !multiline { span_note_and_lint( cx, if is_option { OPTION_MAP_UNWRAP_OR_ELSE } else { RESULT_MAP_UNWRAP_OR_ELSE }, expr.span, msg, expr.span, &format!( "replace `map({0}).unwrap_or_else({1})` with `{2}map_or_else({1}, {0})`", map_snippet, unwrap_snippet, if is_result { "ok()." } else { "" } ), ); } else if same_span && multiline { span_lint( cx, if is_option { OPTION_MAP_UNWRAP_OR_ELSE } else { RESULT_MAP_UNWRAP_OR_ELSE }, expr.span, msg, ); }; } } /// lint use of `_.map_or(None, _)` for `Option`s fn lint_map_or_none<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, map_or_args: &'tcx [hir::Expr]) { if match_type(cx, cx.tables.expr_ty(&map_or_args[0]), &paths::OPTION) { // check if the first non-self argument to map_or() is None let map_or_arg_is_none = if let hir::ExprKind::Path(ref qpath) = map_or_args[1].node { match_qpath(qpath, &paths::OPTION_NONE) } else { false }; if map_or_arg_is_none { // lint message let msg = "called `map_or(None, f)` on an Option value. This can be done more directly by calling \ `and_then(f)` instead"; let map_or_self_snippet = snippet(cx, map_or_args[0].span, ".."); let map_or_func_snippet = snippet(cx, map_or_args[2].span, ".."); let hint = format!("{0}.and_then({1})", map_or_self_snippet, map_or_func_snippet); span_lint_and_then(cx, OPTION_MAP_OR_NONE, expr.span, msg, |db| { db.span_suggestion_with_applicability( expr.span, "try using and_then instead", hint, Applicability::MachineApplicable, // snippet ); }); } } } /// lint use of `filter().next()` for `Iterators` fn lint_filter_next<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, filter_args: &'tcx [hir::Expr]) { // 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); } } } /// lint use of `filter().map()` for `Iterators` fn lint_filter_map<'a, 'tcx>( cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, _filter_args: &'tcx [hir::Expr], _map_args: &'tcx [hir::Expr], ) { // lint if caller of `.filter().map()` is an Iterator if match_trait_method(cx, expr, &paths::ITERATOR) { let msg = "called `filter(p).map(q)` on an `Iterator`. \ This is more succinctly expressed by calling `.filter_map(..)` instead."; span_lint(cx, FILTER_MAP, expr.span, msg); } } /// lint use of `filter().map()` for `Iterators` fn lint_filter_map_map<'a, 'tcx>( cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, _filter_args: &'tcx [hir::Expr], _map_args: &'tcx [hir::Expr], ) { // lint if caller of `.filter().map()` is an Iterator if match_trait_method(cx, expr, &paths::ITERATOR) { let msg = "called `filter_map(p).map(q)` on an `Iterator`. \ This is more succinctly expressed by only calling `.filter_map(..)` instead."; span_lint(cx, FILTER_MAP, expr.span, msg); } } /// lint use of `filter().flat_map()` for `Iterators` fn lint_filter_flat_map<'a, 'tcx>( cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, _filter_args: &'tcx [hir::Expr], _map_args: &'tcx [hir::Expr], ) { // lint if caller of `.filter().flat_map()` is an Iterator if match_trait_method(cx, expr, &paths::ITERATOR) { let msg = "called `filter(p).flat_map(q)` on an `Iterator`. \ This is more succinctly expressed by calling `.flat_map(..)` \ and filtering by returning an empty Iterator."; span_lint(cx, FILTER_MAP, expr.span, msg); } } /// lint use of `filter_map().flat_map()` for `Iterators` fn lint_filter_map_flat_map<'a, 'tcx>( cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, _filter_args: &'tcx [hir::Expr], _map_args: &'tcx [hir::Expr], ) { // lint if caller of `.filter_map().flat_map()` is an Iterator if match_trait_method(cx, expr, &paths::ITERATOR) { let msg = "called `filter_map(p).flat_map(q)` on an `Iterator`. \ This is more succinctly expressed by calling `.flat_map(..)` \ and filtering by returning an empty Iterator."; span_lint(cx, FILTER_MAP, expr.span, msg); } } /// lint searching an Iterator followed by `is_some()` fn lint_search_is_some<'a, 'tcx>( cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr, search_method: &str, search_args: &'tcx [hir::Expr], is_some_args: &'tcx [hir::Expr], ) { // 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); } } } /// Used for `lint_binary_expr_with_method_call`. #[derive(Copy, Clone)] struct BinaryExprInfo<'a> { expr: &'a hir::Expr, chain: &'a hir::Expr, other: &'a hir::Expr, eq: bool, } /// Checks for the `CHARS_NEXT_CMP` and `CHARS_LAST_CMP` lints. fn lint_binary_expr_with_method_call(cx: &LateContext<'_, '_>, info: &mut BinaryExprInfo<'_>) { macro_rules! lint_with_both_lhs_and_rhs { ($func:ident, $cx:expr, $info:ident) => { if !$func($cx, $info) { ::std::mem::swap(&mut $info.chain, &mut $info.other); if $func($cx, $info) { return; } } }; } lint_with_both_lhs_and_rhs!(lint_chars_next_cmp, cx, info); lint_with_both_lhs_and_rhs!(lint_chars_last_cmp, cx, info); lint_with_both_lhs_and_rhs!(lint_chars_next_cmp_with_unwrap, cx, info); lint_with_both_lhs_and_rhs!(lint_chars_last_cmp_with_unwrap, cx, info); } /// Wrapper fn for `CHARS_NEXT_CMP` and `CHARS_NEXT_CMP` lints. fn lint_chars_cmp( cx: &LateContext<'_, '_>, info: &BinaryExprInfo<'_>, chain_methods: &[&str], lint: &'static Lint, suggest: &str, ) -> bool { if_chain! { if let Some(args) = method_chain_args(info.chain, chain_methods); if let hir::ExprKind::Call(ref fun, ref arg_char) = info.other.node; if arg_char.len() == 1; if let hir::ExprKind::Path(ref qpath) = fun.node; if let Some(segment) = single_segment_path(qpath); if segment.ident.name == "Some"; then { let mut applicability = Applicability::MachineApplicable; let self_ty = walk_ptrs_ty(cx.tables.expr_ty_adjusted(&args[0][0])); if self_ty.sty != ty::Str { return false; } span_lint_and_sugg( cx, lint, info.expr.span, &format!("you should use the `{}` method", suggest), "like this", format!("{}{}.{}({})", if info.eq { "" } else { "!" }, snippet_with_applicability(cx, args[0][0].span, "_", &mut applicability), suggest, snippet_with_applicability(cx, arg_char[0].span, "_", &mut applicability)), applicability, ); return true; } } false } /// Checks for the `CHARS_NEXT_CMP` lint. fn lint_chars_next_cmp<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, info: &BinaryExprInfo<'_>) -> bool { lint_chars_cmp(cx, info, &["chars", "next"], CHARS_NEXT_CMP, "starts_with") } /// Checks for the `CHARS_LAST_CMP` lint. fn lint_chars_last_cmp<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, info: &BinaryExprInfo<'_>) -> bool { if lint_chars_cmp(cx, info, &["chars", "last"], CHARS_LAST_CMP, "ends_with") { true } else { lint_chars_cmp(cx, info, &["chars", "next_back"], CHARS_LAST_CMP, "ends_with") } } /// Wrapper fn for `CHARS_NEXT_CMP` and `CHARS_LAST_CMP` lints with `unwrap()`. fn lint_chars_cmp_with_unwrap<'a, 'tcx>( cx: &LateContext<'a, 'tcx>, info: &BinaryExprInfo<'_>, chain_methods: &[&str], lint: &'static Lint, suggest: &str, ) -> bool { if_chain! { if let Some(args) = method_chain_args(info.chain, chain_methods); if let hir::ExprKind::Lit(ref lit) = info.other.node; if let ast::LitKind::Char(c) = lit.node; then { let mut applicability = Applicability::MachineApplicable; span_lint_and_sugg( cx, lint, info.expr.span, &format!("you should use the `{}` method", suggest), "like this", format!("{}{}.{}('{}')", if info.eq { "" } else { "!" }, snippet_with_applicability(cx, args[0][0].span, "_", &mut applicability), suggest, c), applicability, ); return true; } } false } /// Checks for the `CHARS_NEXT_CMP` lint with `unwrap()`. fn lint_chars_next_cmp_with_unwrap<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, info: &BinaryExprInfo<'_>) -> bool { lint_chars_cmp_with_unwrap(cx, info, &["chars", "next", "unwrap"], CHARS_NEXT_CMP, "starts_with") } /// Checks for the `CHARS_LAST_CMP` lint with `unwrap()`. fn lint_chars_last_cmp_with_unwrap<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, info: &BinaryExprInfo<'_>) -> bool { if lint_chars_cmp_with_unwrap(cx, info, &["chars", "last", "unwrap"], CHARS_LAST_CMP, "ends_with") { true } else { lint_chars_cmp_with_unwrap(cx, info, &["chars", "next_back", "unwrap"], CHARS_LAST_CMP, "ends_with") } } /// lint for length-1 `str`s for methods in `PATTERN_METHODS` fn lint_single_char_pattern<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, _expr: &'tcx hir::Expr, arg: &'tcx hir::Expr) { if_chain! { if let hir::ExprKind::Lit(lit) = &arg.node; if let ast::LitKind::Str(r, _) = lit.node; if r.as_str().len() == 1; then { let mut applicability = Applicability::MachineApplicable; let snip = snippet_with_applicability(cx, arg.span, "..", &mut applicability); let hint = format!("'{}'", &snip[1..snip.len() - 1]); span_lint_and_sugg( cx, SINGLE_CHAR_PATTERN, arg.span, "single-character string constant used as pattern", "try using a char instead", hint, applicability, ); } } } /// Checks for the `USELESS_ASREF` lint. fn lint_asref(cx: &LateContext<'_, '_>, expr: &hir::Expr, call_name: &str, as_ref_args: &[hir::Expr]) { // when we get here, we've already checked that the call name is "as_ref" or "as_mut" // check if the call is to the actual `AsRef` or `AsMut` trait if match_trait_method(cx, expr, &paths::ASREF_TRAIT) || match_trait_method(cx, expr, &paths::ASMUT_TRAIT) { // check if the type after `as_ref` or `as_mut` is the same as before let recvr = &as_ref_args[0]; let rcv_ty = cx.tables.expr_ty(recvr); let res_ty = cx.tables.expr_ty(expr); let (base_res_ty, res_depth) = walk_ptrs_ty_depth(res_ty); let (base_rcv_ty, rcv_depth) = walk_ptrs_ty_depth(rcv_ty); if base_rcv_ty == base_res_ty && rcv_depth >= res_depth { let mut applicability = Applicability::MachineApplicable; span_lint_and_sugg( cx, USELESS_ASREF, expr.span, &format!("this call to `{}` does nothing", call_name), "try this", snippet_with_applicability(cx, recvr.span, "_", &mut applicability).to_string(), applicability, ); } } } fn ty_has_iter_method( cx: &LateContext<'_, '_>, self_ref_ty: ty::Ty<'_>, ) -> Option<(&'static Lint, &'static str, &'static str)> { // FIXME: instead of this hard-coded list, we should check if `::iter` // exists and has the desired signature. Unfortunately FnCtxt is not exported // so we can't use its `lookup_method` method. static INTO_ITER_COLLECTIONS: [(&Lint, &[&str]); 13] = [ (INTO_ITER_ON_REF, &paths::VEC), (INTO_ITER_ON_REF, &paths::OPTION), (INTO_ITER_ON_REF, &paths::RESULT), (INTO_ITER_ON_REF, &paths::BTREESET), (INTO_ITER_ON_REF, &paths::BTREEMAP), (INTO_ITER_ON_REF, &paths::VEC_DEQUE), (INTO_ITER_ON_REF, &paths::LINKED_LIST), (INTO_ITER_ON_REF, &paths::BINARY_HEAP), (INTO_ITER_ON_REF, &paths::HASHSET), (INTO_ITER_ON_REF, &paths::HASHMAP), (INTO_ITER_ON_ARRAY, &["std", "path", "PathBuf"]), (INTO_ITER_ON_REF, &["std", "path", "Path"]), (INTO_ITER_ON_REF, &["std", "sync", "mpsc", "Receiver"]), ]; let (self_ty, mutbl) = match self_ref_ty.sty { ty::Ref(_, self_ty, mutbl) => (self_ty, mutbl), _ => unreachable!(), }; let method_name = match mutbl { hir::MutImmutable => "iter", hir::MutMutable => "iter_mut", }; let def_id = match self_ty.sty { ty::Array(..) => return Some((INTO_ITER_ON_ARRAY, "array", method_name)), ty::Slice(..) => return Some((INTO_ITER_ON_REF, "slice", method_name)), ty::Adt(adt, _) => adt.did, _ => return None, }; for (lint, path) in &INTO_ITER_COLLECTIONS { if match_def_path(cx.tcx, def_id, path) { return Some((lint, path.last().unwrap(), method_name)); } } None } fn lint_into_iter(cx: &LateContext<'_, '_>, expr: &hir::Expr, self_ref_ty: ty::Ty<'_>, method_span: Span) { if !match_trait_method(cx, expr, &paths::INTO_ITERATOR) { return; } if let Some((lint, kind, method_name)) = ty_has_iter_method(cx, self_ref_ty) { span_lint_and_sugg( cx, lint, method_span, &format!( "this .into_iter() call is equivalent to .{}() and will not move the {}", method_name, kind, ), "call directly", method_name.to_string(), Applicability::MachineApplicable, ); } } /// Given a `Result` type, return its error type (`E`). fn get_error_type<'a>(cx: &LateContext<'_, '_>, ty: Ty<'a>) -> Option> { if let ty::Adt(_, substs) = ty.sty { if match_type(cx, ty, &paths::RESULT) { substs.types().nth(1) } else { None } } else { None } } /// This checks whether a given type is known to implement Debug. fn has_debug_impl<'a, 'b>(ty: Ty<'a>, cx: &LateContext<'b, 'a>) -> bool { match cx.tcx.lang_items().debug_trait() { Some(debug) => implements_trait(cx, ty, debug, &[]), None => false, } } enum Convention { Eq(&'static str), StartsWith(&'static str), } #[rustfmt::skip] const CONVENTIONS: [(Convention, &[SelfKind]); 7] = [ (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::Eq("to_mut"), &[SelfKind::RefMut]), (Convention::StartsWith("to_"), &[SelfKind::Ref]), ]; #[rustfmt::skip] const TRAIT_METHODS: [(&str, usize, SelfKind, OutType, &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"), ]; #[rustfmt::skip] const PATTERN_METHODS: [(&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, PartialEq, Debug)] enum SelfKind { Value, Ref, RefMut, No, } impl SelfKind { fn matches( self, cx: &LateContext<'_, '_>, ty: &hir::Ty, arg: &hir::Arg, self_ty: &hir::Ty, allow_value_for_ref: bool, generics: &hir::Generics, ) -> bool { // Self types in the HIR are desugared to explicit self types. So it will // always be `self: // SomeType`, // where SomeType can be `Self` or an explicit impl self type (e.g. `Foo` if // the impl is on `Foo`) // Thus, we only need to test equality against the impl self type or if it is // an explicit // `Self`. Furthermore, the only possible types for `self: ` are `&Self`, // `Self`, `&mut Self`, // and `Box`, including the equivalent types with `Foo`. let is_actually_self = |ty| is_self_ty(ty) || SpanlessEq::new(cx).eq_ty(ty, self_ty); if is_self(arg) { match self { SelfKind::Value => is_actually_self(ty), SelfKind::Ref | SelfKind::RefMut => { if allow_value_for_ref && is_actually_self(ty) { return true; } match ty.node { hir::TyKind::Rptr(_, ref mt_ty) => { let mutability_match = if self == SelfKind::Ref { mt_ty.mutbl == hir::MutImmutable } else { mt_ty.mutbl == hir::MutMutable }; is_actually_self(&mt_ty.ty) && mutability_match }, _ => false, } }, _ => false, } } else { match self { SelfKind::Value => false, SelfKind::Ref => is_as_ref_or_mut_trait(ty, self_ty, generics, &paths::ASREF_TRAIT), SelfKind::RefMut => is_as_ref_or_mut_trait(ty, self_ty, generics, &paths::ASMUT_TRAIT), SelfKind::No => true, } } } 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", } } } fn is_as_ref_or_mut_trait(ty: &hir::Ty, self_ty: &hir::Ty, generics: &hir::Generics, name: &[&str]) -> bool { single_segment_ty(ty).map_or(false, |seg| { generics.params.iter().any(|param| match param.kind { hir::GenericParamKind::Type { .. } => { param.name.ident().name == seg.ident.name && param.bounds.iter().any(|bound| { if let hir::GenericBound::Trait(ref ptr, ..) = *bound { let path = &ptr.trait_ref.path; match_path(path, name) && path.segments.last().map_or(false, |s| { if let Some(ref params) = s.args { if params.parenthesized { false } else { // FIXME(flip1995): messy, improve if there is a better option // in the compiler let types: Vec<_> = params .args .iter() .filter_map(|arg| match arg { hir::GenericArg::Type(ty) => Some(ty), _ => None, }) .collect(); types.len() == 1 && (is_self_ty(&types[0]) || is_ty(&*types[0], self_ty)) } } else { false } }) } else { false } }) }, _ => false, }) }) } fn is_ty(ty: &hir::Ty, self_ty: &hir::Ty) -> bool { match (&ty.node, &self_ty.node) { ( &hir::TyKind::Path(hir::QPath::Resolved(_, ref ty_path)), &hir::TyKind::Path(hir::QPath::Resolved(_, ref self_ty_path)), ) => ty_path .segments .iter() .map(|seg| seg.ident.name) .eq(self_ty_path.segments.iter().map(|seg| seg.ident.name)), _ => false, } } fn single_segment_ty(ty: &hir::Ty) -> Option<&hir::PathSegment> { if let hir::TyKind::Path(ref path) = ty.node { single_segment_path(path) } else { None } } impl Convention { fn check(&self, other: &str) -> bool { match *self { Convention::Eq(this) => this == other, Convention::StartsWith(this) => other.starts_with(this) && this != other, } } } 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, cx: &LateContext<'_, '_>, ty: &hir::FunctionRetTy) -> bool { let is_unit = |ty: &hir::Ty| SpanlessEq::new(cx).eq_ty_kind(&ty.node, &hir::TyKind::Tup(vec![].into())); match (self, ty) { (OutType::Unit, &hir::DefaultReturn(_)) => true, (OutType::Unit, &hir::Return(ref ty)) if is_unit(ty) => true, (OutType::Bool, &hir::Return(ref ty)) if is_bool(ty) => true, (OutType::Any, &hir::Return(ref ty)) if !is_unit(ty) => true, (OutType::Ref, &hir::Return(ref ty)) => matches!(ty.node, hir::TyKind::Rptr(_, _)), _ => false, } } } fn is_bool(ty: &hir::Ty) -> bool { if let hir::TyKind::Path(ref p) = ty.node { match_qpath(p, &["bool"]) } else { false } }