rust-clippy/clippy_lints/src/methods.rs
Oliver Schneider b13d206a22 run rustfmt
2017-02-13 11:18:03 +01:00

1446 lines
53 KiB
Rust

use rustc::hir;
use rustc::lint::*;
use rustc::middle::const_val::ConstVal;
use rustc::ty;
use rustc::hir::def::Def;
use rustc_const_eval::EvalHint::ExprTypeChecked;
use rustc_const_eval::ConstContext;
use std::borrow::Cow;
use std::fmt;
use syntax::codemap::Span;
use utils::{get_trait_def_id, implements_trait, in_external_macro, in_macro, is_copy, match_path, match_trait_method,
match_type, method_chain_args, return_ty, same_tys, snippet, span_lint, span_lint_and_then,
span_note_and_lint, walk_ptrs_ty, walk_ptrs_ty_depth, last_path_segment, single_segment_path,
match_def_path, is_self, is_self_ty, iter_input_pats};
use utils::paths;
use utils::sugg;
#[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_lint! {
pub OPTION_UNWRAP_USED,
Allow,
"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_lint! {
pub RESULT_UNWRAP_USED,
Allow,
"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_lint! {
pub SHOULD_IMPLEMENT_TRAIT,
Warn,
"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_lint! {
pub WRONG_SELF_CONVENTION,
Warn,
"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_lint! {
pub WRONG_PUB_SELF_CONVENTION,
Allow,
"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:** None.
///
/// **Example:**
/// ```rust
/// x.ok().expect("why did I do this again?")
/// ```
declare_lint! {
pub OK_EXPECT,
Warn,
"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:** None.
///
/// **Example:**
/// ```rust
/// x.map(|a| a + 1).unwrap_or(0)
/// ```
declare_lint! {
pub OPTION_MAP_UNWRAP_OR,
Allow,
"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:** None.
///
/// **Example:**
/// ```rust
/// x.map(|a| a + 1).unwrap_or_else(some_function)
/// ```
declare_lint! {
pub OPTION_MAP_UNWRAP_OR_ELSE,
Allow,
"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 `_.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_lint! {
pub FILTER_NEXT,
Warn,
"using `filter(p).next()`, which is more succinctly expressed as `.find(p)`"
}
/// **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_lint! {
pub FILTER_MAP,
Allow,
"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_lint! {
pub SEARCH_IS_SOME,
Warn,
"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_lint! {
pub CHARS_NEXT_CMP,
Warn,
"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_lint! {
pub OR_FUN_CALL,
Warn,
"using any `*or` method with a function call, which suggests `*or_else`"
}
/// **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_lint! {
pub CLONE_ON_COPY,
Warn,
"using `clone` on a `Copy` type"
}
/// **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_lint! {
pub CLONE_DOUBLE_REF,
Warn,
"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_lint! {
pub NEW_RET_NO_SELF,
Warn,
"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_lint! {
pub SINGLE_CHAR_PATTERN,
Warn,
"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_lint! {
pub TEMPORARY_CSTRING_AS_PTR,
Warn,
"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_lint! {
pub ITER_NTH,
Warn,
"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_lint! {
pub ITER_SKIP_NEXT,
Warn,
"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:** None.
///
/// **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_lint! {
pub GET_UNWRAP,
Warn,
"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_lint! {
pub STRING_EXTEND_CHARS,
Warn,
"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<isize> = s[..].iter().cloned().collect();
/// ```
/// The better use would be:
/// ```rust
/// let s = [1,2,3,4,5];
/// let s2 : Vec<isize> = s.to_vec();
/// ```
declare_lint! {
pub ITER_CLONED_COLLECT,
Warn,
"using `.cloned().collect()` on slice to create a `Vec`"
}
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,
OR_FUN_CALL,
CHARS_NEXT_CMP,
CLONE_ON_COPY,
CLONE_DOUBLE_REF,
NEW_RET_NO_SELF,
SINGLE_CHAR_PATTERN,
SEARCH_IS_SOME,
TEMPORARY_CSTRING_AS_PTR,
FILTER_NEXT,
FILTER_MAP,
ITER_NTH,
ITER_SKIP_NEXT,
GET_UNWRAP,
STRING_EXTEND_CHARS,
ITER_CLONED_COLLECT)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
#[allow(unused_attributes)]
// ^ required because `cyclomatic_complexity` attribute shows up as unused
#[cyclomatic_complexity = "30"]
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) {
if in_macro(cx, expr.span) {
return;
}
match expr.node {
hir::ExprMethodCall(name, _, ref args) => {
// Chain calls
// GET_UNWRAP needs to be checked before general `UNWRAP` lints
if let Some(arglists) = method_chain_args(expr, &["get", "unwrap"]) {
lint_get_unwrap(cx, expr, arglists[0], false);
} else if let Some(arglists) = method_chain_args(expr, &["get_mut", "unwrap"]) {
lint_get_unwrap(cx, expr, arglists[0], true);
} else if let Some(arglists) = method_chain_args(expr, &["unwrap"]) {
lint_unwrap(cx, expr, arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["ok", "expect"]) {
lint_ok_expect(cx, expr, arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["map", "unwrap_or"]) {
lint_map_unwrap_or(cx, expr, arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["map", "unwrap_or_else"]) {
lint_map_unwrap_or_else(cx, expr, arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["filter", "next"]) {
lint_filter_next(cx, expr, arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["filter", "map"]) {
lint_filter_map(cx, expr, arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["filter_map", "map"]) {
lint_filter_map_map(cx, expr, arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["filter", "flat_map"]) {
lint_filter_flat_map(cx, expr, arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["filter_map", "flat_map"]) {
lint_filter_map_flat_map(cx, expr, arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["find", "is_some"]) {
lint_search_is_some(cx, expr, "find", arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["position", "is_some"]) {
lint_search_is_some(cx, expr, "position", arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["rposition", "is_some"]) {
lint_search_is_some(cx, expr, "rposition", arglists[0], arglists[1]);
} else if let Some(arglists) = method_chain_args(expr, &["extend"]) {
lint_extend(cx, expr, arglists[0]);
} else if let Some(arglists) = method_chain_args(expr, &["unwrap", "as_ptr"]) {
lint_cstring_as_ptr(cx, expr, &arglists[0][0], &arglists[1][0]);
} else if let Some(arglists) = method_chain_args(expr, &["iter", "nth"]) {
lint_iter_nth(cx, expr, arglists[0], false);
} else if let Some(arglists) = method_chain_args(expr, &["iter_mut", "nth"]) {
lint_iter_nth(cx, expr, arglists[0], true);
} else if method_chain_args(expr, &["skip", "next"]).is_some() {
lint_iter_skip_next(cx, expr);
} else if let Some(arglists) = method_chain_args(expr, &["cloned", "collect"]) {
lint_iter_cloned_collect(cx, expr, arglists[0]);
}
lint_or_fun_call(cx, expr, &name.node.as_str(), args);
let self_ty = cx.tables.expr_ty_adjusted(&args[0]);
if args.len() == 1 && &*name.node.as_str() == "clone" {
lint_clone_on_copy(cx, expr, &args[0], self_ty);
}
match self_ty.sty {
ty::TyRef(_, ty) if ty.ty.sty == ty::TyStr => {
for &(method, pos) in &PATTERN_METHODS {
if &*name.node.as_str() == method && args.len() > pos {
lint_single_char_pattern(cx, expr, &args[pos]);
}
}
},
_ => (),
}
},
hir::ExprBinary(op, ref lhs, ref rhs) if op.node == hir::BiEq || op.node == hir::BiNe => {
if !lint_chars_next(cx, expr, lhs, rhs, op.node == hir::BiEq) {
lint_chars_next(cx, expr, rhs, lhs, op.node == hir::BiEq);
}
},
_ => (),
}
}
fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, implitem: &'tcx hir::ImplItem) {
if in_external_macro(cx, implitem.span) {
return;
}
let name = implitem.name;
let parent = cx.tcx.hir.get_parent(implitem.id);
let item = cx.tcx.hir.expect_item(parent);
if_let_chain! {[
let hir::ImplItemKind::Method(ref sig, id) = implitem.node,
let Some(first_arg_ty) = sig.decl.inputs.get(0),
let Some(first_arg) = iter_input_pats(&sig.decl, cx.tcx.hir.body(id)).next(),
let hir::ItemImpl(_, _, _, None, ref self_ty, _) = item.node,
], {
// check missing trait implementations
for &(method_name, n_args, self_kind, out_type, trait_name) in &TRAIT_METHODS {
if &*name.as_str() == method_name &&
sig.decl.inputs.len() == n_args &&
out_type.matches(&sig.decl.output) &&
self_kind.matches(&first_arg_ty, &first_arg, &self_ty, false) {
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 ty = cx.tcx.item_type(cx.tcx.hir.local_def_id(item.id));
let is_copy = is_copy(cx, ty, item.id);
for &(ref conv, self_kinds) in &CONVENTIONS {
if_let_chain! {[
conv.check(&name.as_str()),
!self_kinds.iter().any(|k| k.matches(&first_arg_ty, &first_arg, &self_ty, is_copy)),
], {
let lint = if item.vis == hir::Visibility::Public {
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::<Vec<_>>()
.join(" or ")));
}}
}
let ret_ty = return_ty(cx, implitem.id);
if &*name.as_str() == "new" &&
!ret_ty.walk().any(|t| same_tys(cx, t, ty, implitem.id)) {
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, 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::ExprPath(ref qpath) = fun.node {
let path: &str = &*last_path_segment(qpath).name.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, Vec::new()) {
span_lint_and_then(cx,
OR_FUN_CALL,
span,
&format!("use of `{}` followed by a call to `{}`", name, path),
|db| {
db.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_span: Span,
self_expr: &hir::Expr,
arg: &hir::Expr,
or_has_args: bool,
span: Span
) {
// don't lint for constant values
// FIXME: can we `expect` here instead of match?
let promotable = cx.tcx
.rvalue_promotable_to_static
.borrow()
.get(&arg.id)
.cloned()
.unwrap_or(true);
if promotable {
return;
}
// (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")];
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(cx, arg.span, "..")).into(),
(false, false) => format!("|| {}", snippet(cx, arg.span, "..")).into(),
(false, true) => snippet(cx, fun_span, ".."),
};
span_lint_and_then(cx,
OR_FUN_CALL,
span,
&format!("use of `{}` followed by a function call", name),
|db| {
db.span_suggestion(span,
"try this",
format!("{}.{}_{}({})", snippet(cx, self_expr.span, "_"), name, suffix, sugg));
});
}
if args.len() == 2 {
match args[1].node {
hir::ExprCall(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, fun.span, &args[0], &args[1], or_has_args, expr.span);
}
},
hir::ExprMethodCall(fun, _, ref or_args) => {
check_general_case(cx, name, fun.span, &args[0], &args[1], !or_args.is_empty(), 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::Ty) {
let ty = cx.tables.expr_ty(expr);
let parent = cx.tcx.hir.get_parent(expr.id);
let parameter_environment = ty::ParameterEnvironment::for_item(cx.tcx, parent);
if let ty::TyRef(_, ty::TypeAndMut { ty: inner, .. }) = arg_ty.sty {
if let ty::TyRef(..) = 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) {
db.span_suggestion(expr.span,
"try dereferencing it",
format!("({}).clone()", snip.deref()));
});
return; // don't report clone_on_copy
}
}
if !ty.moves_by_default(cx.tcx.global_tcx(), &parameter_environment, expr.span) {
span_lint_and_then(cx,
CLONE_ON_COPY,
expr.span,
"using `clone` on a `Copy` type",
|db| if let Some(snip) = sugg::Sugg::hir_opt(cx, arg) {
if let ty::TyRef(..) = cx.tables.expr_ty(arg).sty {
db.span_suggestion(expr.span, "try dereferencing it", format!("{}", snip.deref()));
} else {
db.span_suggestion(expr.span, "try removing the `clone` call", format!("{}", snip));
}
});
}
}
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_depth(cx.tables.expr_ty(target));
let ref_str = if self_ty.sty == ty::TyStr {
""
} else if match_type(cx, self_ty, &paths::STRING) {
"&"
} else {
return;
};
span_lint_and_then(cx, STRING_EXTEND_CHARS, expr.span, "calling `.extend(_.chars())`", |db| {
db.span_suggestion(expr.span,
"try this",
format!("{}.push_str({}{})",
snippet(cx, args[0].span, "_"),
ref_str,
snippet(cx, target.span, "_")));
});
}
}
fn lint_extend(cx: &LateContext, expr: &hir::Expr, args: &[hir::Expr]) {
let (obj_ty, _) = walk_ptrs_ty_depth(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_let_chain!{[
let hir::ExprCall(ref fun, ref args) = new.node,
args.len() == 1,
let hir::ExprPath(ref path) = fun.node,
let Def::Method(did) = cx.tables.qpath_def(path, fun.id),
match_def_path(cx.tcx, did, &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 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_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 expr_ty = cx.tables.expr_ty(&get_args[0]);
let caller_type = if derefs_to_slice(cx, &get_args[0], expr_ty).is_some() {
"slice"
} else if match_type(cx, expr_ty, &paths::VEC) {
"Vec"
} else if match_type(cx, expr_ty, &paths::VEC_DEQUE) {
"VecDeque"
} else if !is_mut && match_type(cx, expr_ty, &paths::HASHMAP) {
"HashMap"
} else if !is_mut && match_type(cx, expr_ty, &paths::BTREEMAP) {
"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 is_mut { "&mut " } else { "&" };
span_lint_and_then(cx,
GET_UNWRAP,
expr.span,
&format!("called `.get{0}().unwrap()` on a {1}. Using `[]` is more clear and more concise",
mut_str,
caller_type),
|db| {
db.span_suggestion(expr.span,
"try this",
format!("{}{}[{}]",
borrow_str,
snippet(cx, get_args[0].span, "_"),
snippet(cx, get_args[1].span, "_")));
});
}
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::Ty) -> Option<sugg::Sugg<'static>> {
fn may_slice(cx: &LateContext, ty: ty::Ty) -> bool {
match ty.sty {
ty::TySlice(_) => true,
ty::TyAdt(def, _) if def.is_box() => may_slice(cx, ty.boxed_ty()),
ty::TyAdt(..) => match_type(cx, ty, &paths::VEC),
ty::TyArray(_, size) => size < 32,
ty::TyRef(_, ty::TypeAndMut { ty: inner, .. }) => may_slice(cx, inner),
_ => false,
}
}
if let hir::ExprMethodCall(name, _, ref args) = expr.node {
if &*name.node.as_str() == "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::TySlice(_) => sugg::Sugg::hir_opt(cx, expr),
ty::TyAdt(def, _) if def.is_box() && may_slice(cx, ty.boxed_ty()) => sugg::Sugg::hir_opt(cx, expr),
ty::TyRef(_, ty::TypeAndMut { ty: 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_depth(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) {
// 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);
};
}
}
/// lint use of `map().unwrap_or_else()` for `Option`s
fn lint_map_unwrap_or_else(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) {
// 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);
};
}
}
/// lint use of `filter().next()` for `Iterators`
fn lint_filter_next(cx: &LateContext, expr: &hir::Expr, filter_args: &[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(cx: &LateContext, expr: &hir::Expr, _filter_args: &[hir::Expr], _map_args: &[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(cx: &LateContext, expr: &hir::Expr, _filter_args: &[hir::Expr], _map_args: &[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(cx: &LateContext, expr: &hir::Expr, _filter_args: &[hir::Expr], _map_args: &[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(cx: &LateContext, expr: &hir::Expr, _filter_args: &[hir::Expr], _map_args: &[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(
cx: &LateContext,
expr: &hir::Expr,
search_method: &str,
search_args: &[hir::Expr],
is_some_args: &[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);
}
}
}
/// Checks for the `CHARS_NEXT_CMP` lint.
fn lint_chars_next(cx: &LateContext, expr: &hir::Expr, chain: &hir::Expr, other: &hir::Expr, eq: bool) -> bool {
if_let_chain! {[
let Some(args) = method_chain_args(chain, &["chars", "next"]),
let hir::ExprCall(ref fun, ref arg_char) = other.node,
arg_char.len() == 1,
let hir::ExprPath(ref qpath) = fun.node,
let Some(segment) = single_segment_path(qpath),
&*segment.name.as_str() == "Some"
], {
let self_ty = walk_ptrs_ty(cx.tables.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: &hir::Expr, arg: &hir::Expr) {
if let Ok(ConstVal::Str(r)) = ConstContext::with_tables(cx.tcx, cx.tables).eval(arg, ExprTypeChecked) {
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 let ty::TyAdt(_, 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::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, PartialEq, Debug)]
enum SelfKind {
Value,
Ref,
RefMut,
No,
}
impl SelfKind {
fn matches(self, ty: &hir::Ty, arg: &hir::Arg, self_ty: &hir::Ty, allow_value_for_ref: bool) -> 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<Self>`, including the equivalent types with `Foo`.
let is_actually_self = |ty| is_self_ty(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::TyRptr(_, 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 {
self == SelfKind::No
}
}
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) && 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, ty: &hir::FunctionRetTy) -> bool {
match (self, ty) {
(&OutType::Unit, &hir::DefaultReturn(_)) => true,
(&OutType::Unit, &hir::Return(ref ty)) if ty.node == hir::TyTup(vec![].into()) => true,
(&OutType::Bool, &hir::Return(ref ty)) if is_bool(ty) => true,
(&OutType::Any, &hir::Return(ref ty)) if ty.node != hir::TyTup(vec![].into()) => true,
(&OutType::Ref, &hir::Return(ref ty)) => matches!(ty.node, hir::TyRptr(_, _)),
_ => false,
}
}
}
fn is_bool(ty: &hir::Ty) -> bool {
if let hir::TyPath(ref p) = ty.node {
match_path(p, &["bool"])
} else {
false
}
}