use rustc::hir;
use rustc::lint::*;
use rustc::middle::const_val::ConstVal;
use rustc::ty::{self, Ty};
use rustc::hir::def::Def;
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_lint_and_sugg, 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, match_path_old};
use utils::paths;
use utils::sugg;
#[derive(Clone)]
pub struct Pass;
declare_lint! {
pub OPTION_UNWRAP_USED,
Allow,
"using `Option.unwrap()`, which should at least get a better message using `expect()`"
}
declare_lint! {
pub RESULT_UNWRAP_USED,
Allow,
"using `Result.unwrap()`, which might be better handled"
}
declare_lint! {
pub SHOULD_IMPLEMENT_TRAIT,
Warn,
"defining a method that should be implementing a std trait"
}
declare_lint! {
pub WRONG_SELF_CONVENTION,
Warn,
"defining a method named with an established prefix (like \"into_\") that takes \
`self` with the wrong convention"
}
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"
}
declare_lint! {
pub OK_EXPECT,
Warn,
"using `ok().expect()`, which gives worse error messages than \
calling `expect` directly on the Result"
}
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)`"
}
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)`"
}
declare_lint! {
pub FILTER_NEXT,
Warn,
"using `filter(p).next()`, which is more succinctly expressed as `.find(p)`"
}
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"
}
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()`"
}
declare_lint! {
pub CHARS_NEXT_CMP,
Warn,
"using `.chars().next()` to check if a string starts with a char"
}
declare_lint! {
pub OR_FUN_CALL,
Warn,
"using any `*or` method with a function call, which suggests `*or_else`"
}
declare_lint! {
pub CLONE_ON_COPY,
Warn,
"using `clone` on a `Copy` type"
}
declare_lint! {
pub CLONE_DOUBLE_REF,
Warn,
"using `clone` on `&&T`"
}
declare_lint! {
pub NEW_RET_NO_SELF,
Warn,
"not returning `Self` in a `new` method"
}
declare_lint! {
pub SINGLE_CHAR_PATTERN,
Warn,
"using a single-character str where a char could be used, e.g. \
`_.split(\"x\")`"
}
declare_lint! {
pub TEMPORARY_CSTRING_AS_PTR,
Warn,
"getting the inner pointer of a temporary `CString`"
}
declare_lint! {
pub ITER_NTH,
Warn,
"using `.iter().nth()` on a standard library type with O(1) element access"
}
declare_lint! {
pub ITER_SKIP_NEXT,
Warn,
"using `.skip(x).next()` on an iterator"
}
declare_lint! {
pub GET_UNWRAP,
Warn,
"using `.get().unwrap()` or `.get_mut().unwrap()` when using `[]` would work instead"
}
declare_lint! {
pub STRING_EXTEND_CHARS,
Warn,
"using `x.extend(s.chars())` where s is a `&str` or `String`"
}
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)]
#[cyclomatic_complexity = "30"]
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) {
if in_macro(expr.span) {
return;
}
match expr.node {
hir::ExprMethodCall(name, _, ref args) => {
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 == "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 == 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,
], {
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(&sig.decl.output) &&
self_kind.matches(first_arg_ty, first_arg, self_ty, false, &sig.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));
}
}
let def_id = cx.tcx.hir.local_def_id(item.id);
let ty = cx.tcx.type_of(def_id);
let is_copy = is_copy(cx, ty);
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, &sig.generics)),
], {
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 == "new" &&
!ret_ty.walk().any(|t| same_tys(cx, t, ty)) {
span_lint(cx,
NEW_RET_NO_SELF,
implitem.span,
"methods called `new` usually return `Self`");
}
}}
}
}
fn lint_or_fun_call(cx: &LateContext, expr: &hir::Expr, name: &str, args: &[hir::Expr]) {
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 = &*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, &[]) {
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(cx, self_expr.span, "_")));
return true;
}
}
}
}
false
}
fn check_general_case(
cx: &LateContext,
name: &str,
fun_span: Span,
self_expr: &hir::Expr,
arg: &hir::Expr,
or_has_args: bool,
span: Span
) {
let promotable = cx.tcx
.rvalue_promotable_to_static
.borrow()
.get(&arg.id)
.cloned()
.unwrap_or(true);
if promotable {
return;
}
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_sugg(cx,
OR_FUN_CALL,
span,
&format!("use of `{}` followed by a function call", name),
"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)
},
_ => {},
}
}
}
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::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; }
}
if is_copy(cx, ty) {
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_sugg(cx,
STRING_EXTEND_CHARS,
expr.span,
"calling `.extend(_.chars())`",
"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; };
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) {
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; };
let mut_str = if is_mut { "_mut" } else { "" };
let borrow_str = 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(cx, get_args[0].span, "_"),
snippet(cx, get_args[1].span, "_")));
}
fn lint_iter_skip_next(cx: &LateContext, expr: &hir::Expr) {
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<sugg::Sugg<'static>> {
fn may_slice(cx: &LateContext, 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 == "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,
}
}
}
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));
}
}
fn lint_ok_expect(cx: &LateContext, expr: &hir::Expr, ok_args: &[hir::Expr]) {
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`");
}
}
}
}
fn lint_map_unwrap_or(cx: &LateContext, expr: &hir::Expr, map_args: &[hir::Expr], unwrap_args: &[hir::Expr]) {
if match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::OPTION) {
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";
let map_snippet = snippet(cx, map_args[1].span, "..");
let unwrap_snippet = snippet(cx, unwrap_args[1].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,
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);
};
}
}
fn lint_map_unwrap_or_else(cx: &LateContext, expr: &hir::Expr, map_args: &[hir::Expr], unwrap_args: &[hir::Expr]) {
if match_type(cx, cx.tables.expr_ty(&map_args[0]), &paths::OPTION) {
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";
let map_snippet = snippet(cx, map_args[1].span, "..");
let unwrap_snippet = snippet(cx, unwrap_args[1].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,
OPTION_MAP_UNWRAP_OR_ELSE,
expr.span,
msg,
expr.span,
&format!("replace `map({0}).unwrap_or_else({1})` 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);
};
}
}
fn lint_filter_next(cx: &LateContext, expr: &hir::Expr, filter_args: &[hir::Expr]) {
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 {
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);
}
}
}
fn lint_filter_map(cx: &LateContext, expr: &hir::Expr, _filter_args: &[hir::Expr], _map_args: &[hir::Expr]) {
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);
}
}
fn lint_filter_map_map(cx: &LateContext, expr: &hir::Expr, _filter_args: &[hir::Expr], _map_args: &[hir::Expr]) {
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);
}
}
fn lint_filter_flat_map(cx: &LateContext, expr: &hir::Expr, _filter_args: &[hir::Expr], _map_args: &[hir::Expr]) {
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);
}
}
fn lint_filter_map_flat_map(cx: &LateContext, expr: &hir::Expr, _filter_args: &[hir::Expr], _map_args: &[hir::Expr]) {
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);
}
}
fn lint_search_is_some(
cx: &LateContext,
expr: &hir::Expr,
search_method: &str,
search_args: &[hir::Expr],
is_some_args: &[hir::Expr]
) {
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 {
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);
}
}
}
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 == "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_sugg(cx,
CHARS_NEXT_CMP,
expr.span,
"you should use the `starts_with` method",
"like this",
format!("{}{}.starts_with({})",
if eq { "" } else { "!" },
snippet(cx, args[0][0].span, "_"),
snippet(cx, arg_char[0].span, "_")));
return true;
}}
false
}
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) {
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); });
}
}
}
fn get_error_type<'a>(cx: &LateContext, ty: Ty<'a>) -> Option<Ty<'a>> {
if let ty::TyAdt(_, substs) = ty.sty {
if match_type(cx, ty, &paths::RESULT) {
substs.types().nth(1)
} else {
None
}
} else {
None
}
}
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),
}
#[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,
generics: &hir::Generics
) -> bool {
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 {
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.ty_params.iter().any(|param| {
param.name == seg.name &&
param.bounds.iter().any(|bound| if let hir::TyParamBound::TraitTyParamBound(ref ptr, ..) = *bound {
let path = &ptr.trait_ref.path;
match_path_old(path, name) &&
path.segments.last().map_or(false, |s| if let hir::PathParameters::AngleBracketedParameters(ref data) =
s.parameters {
data.types.len() == 1 && (is_self_ty(&data.types[0]) || is_ty(&*data.types[0], self_ty))
} else {
false
})
} else {
false
})
})
})
}
fn is_ty(ty: &hir::Ty, self_ty: &hir::Ty) -> bool {
match (&ty.node, &self_ty.node) {
(&hir::TyPath(hir::QPath::Resolved(_, ref ty_path)),
&hir::TyPath(hir::QPath::Resolved(_, ref self_ty_path))) => {
ty_path.segments.iter().map(|seg| seg.name).eq(self_ty_path.segments.iter().map(|seg| seg.name))
},
_ => false,
}
}
fn single_segment_ty(ty: &hir::Ty) -> Option<&hir::PathSegment> {
if let hir::TyPath(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, 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
}
}