use crate::utils::{
- attr_by_name, attrs::is_proc_macro, is_must_use_ty, is_trait_impl_item, iter_input_pats, match_def_path,
- must_use_attr, qpath_res, return_ty, snippet, snippet_opt, span_lint, span_lint_and_help, span_lint_and_then,
- trait_ref_of_method, type_is_unsafe_function,
+ attr_by_name, attrs::is_proc_macro, is_must_use_ty, is_trait_impl_item, is_type_diagnostic_item, iter_input_pats,
+ match_def_path, must_use_attr, path_to_local, return_ty, snippet, snippet_opt, span_lint, span_lint_and_help,
+ span_lint_and_then, trait_ref_of_method, type_is_unsafe_function,
};
+use if_chain::if_chain;
use rustc_ast::ast::Attribute;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_hir::intravisit;
-use rustc_hir::{def::Res, def_id::DefId};
+use rustc_hir::{def::Res, def_id::DefId, QPath};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::hir::map::Map;
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::{self, Ty};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::source_map::Span;
+use rustc_span::sym;
use rustc_target::spec::abi::Abi;
+use rustc_typeck::hir_ty_to_ty;
declare_clippy_lint! {
/// **What it does:** Checks for functions with too many parameters.
"function or method that could take a `#[must_use]` attribute"
}
+declare_clippy_lint! {
+ /// **What it does:** Checks for public functions that return a `Result`
+ /// with an `Err` type of `()`. It suggests using a custom type that
+ /// implements [`std::error::Error`].
+ ///
+ /// **Why is this bad?** Unit does not implement `Error` and carries no
+ /// further information about what went wrong.
+ ///
+ /// **Known problems:** Of course, this lint assumes that `Result` is used
+ /// for a fallible operation (which is after all the intended use). However
+ /// code may opt to (mis)use it as a basic two-variant-enum. In that case,
+ /// the suggestion is misguided, and the code should use a custom enum
+ /// instead.
+ ///
+ /// **Examples:**
+ /// ```rust
+ /// pub fn read_u8() -> Result<u8, ()> { Err(()) }
+ /// ```
+ /// should become
+ /// ```rust,should_panic
+ /// use std::fmt;
+ ///
+ /// #[derive(Debug)]
+ /// pub struct EndOfStream;
+ ///
+ /// impl fmt::Display for EndOfStream {
+ /// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ /// write!(f, "End of Stream")
+ /// }
+ /// }
+ ///
+ /// impl std::error::Error for EndOfStream { }
+ ///
+ /// pub fn read_u8() -> Result<u8, EndOfStream> { Err(EndOfStream) }
+ ///# fn main() {
+ ///# read_u8().unwrap();
+ ///# }
+ /// ```
+ ///
+ /// Note that there are crates that simplify creating the error type, e.g.
+ /// [`thiserror`](https://docs.rs/thiserror).
+ pub RESULT_UNIT_ERR,
+ style,
+ "public function returning `Result` with an `Err` type of `()`"
+}
+
#[derive(Copy, Clone)]
pub struct Functions {
threshold: u64,
MUST_USE_UNIT,
DOUBLE_MUST_USE,
MUST_USE_CANDIDATE,
+ RESULT_UNIT_ERR,
]);
impl<'tcx> LateLintPass<'tcx> for Functions {
hir_id: hir::HirId,
) {
let unsafety = match kind {
- intravisit::FnKind::ItemFn(_, _, hir::FnHeader { unsafety, .. }, _, _) => unsafety,
- intravisit::FnKind::Method(_, sig, _, _) => sig.header.unsafety,
- intravisit::FnKind::Closure(_) => return,
+ intravisit::FnKind::ItemFn(_, _, hir::FnHeader { unsafety, .. }, _) => unsafety,
+ intravisit::FnKind::Method(_, sig, _) => sig.header.unsafety,
+ intravisit::FnKind::Closure => return,
};
// don't warn for implementations, it's not their fault
..
},
_,
- _,
)
- | intravisit::FnKind::ItemFn(_, _, hir::FnHeader { abi: Abi::Rust, .. }, _, _) => {
+ | intravisit::FnKind::ItemFn(_, _, hir::FnHeader { abi: Abi::Rust, .. }, _) => {
self.check_arg_number(cx, decl, span.with_hi(decl.output.span().hi()))
},
_ => {},
}
fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
- let attr = must_use_attr(&item.attrs);
+ let attrs = cx.tcx.hir().attrs(item.hir_id());
+ let attr = must_use_attr(attrs);
if let hir::ItemKind::Fn(ref sig, ref _generics, ref body_id) = item.kind {
+ let is_public = cx.access_levels.is_exported(item.hir_id());
+ let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
+ if is_public {
+ check_result_unit_err(cx, &sig.decl, item.span, fn_header_span);
+ }
if let Some(attr) = attr {
- let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
- check_needless_must_use(cx, &sig.decl, item.hir_id, item.span, fn_header_span, attr);
+ check_needless_must_use(cx, &sig.decl, item.hir_id(), item.span, fn_header_span, attr);
return;
}
- if cx.access_levels.is_exported(item.hir_id)
- && !is_proc_macro(cx.sess(), &item.attrs)
- && attr_by_name(&item.attrs, "no_mangle").is_none()
- {
+ if is_public && !is_proc_macro(cx.sess(), attrs) && attr_by_name(attrs, "no_mangle").is_none() {
check_must_use_candidate(
cx,
&sig.decl,
cx.tcx.hir().body(*body_id),
item.span,
- item.hir_id,
+ item.hir_id(),
item.span.with_hi(sig.decl.output.span().hi()),
"this function could have a `#[must_use]` attribute",
);
fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::ImplItem<'_>) {
if let hir::ImplItemKind::Fn(ref sig, ref body_id) = item.kind {
- let attr = must_use_attr(&item.attrs);
+ let is_public = cx.access_levels.is_exported(item.hir_id());
+ let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
+ if is_public && trait_ref_of_method(cx, item.hir_id()).is_none() {
+ check_result_unit_err(cx, &sig.decl, item.span, fn_header_span);
+ }
+ let attrs = cx.tcx.hir().attrs(item.hir_id());
+ let attr = must_use_attr(attrs);
if let Some(attr) = attr {
- let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
- check_needless_must_use(cx, &sig.decl, item.hir_id, item.span, fn_header_span, attr);
- } else if cx.access_levels.is_exported(item.hir_id)
- && !is_proc_macro(cx.sess(), &item.attrs)
- && trait_ref_of_method(cx, item.hir_id).is_none()
+ check_needless_must_use(cx, &sig.decl, item.hir_id(), item.span, fn_header_span, attr);
+ } else if is_public && !is_proc_macro(cx.sess(), attrs) && trait_ref_of_method(cx, item.hir_id()).is_none()
{
check_must_use_candidate(
cx,
&sig.decl,
cx.tcx.hir().body(*body_id),
item.span,
- item.hir_id,
+ item.hir_id(),
item.span.with_hi(sig.decl.output.span().hi()),
"this method could have a `#[must_use]` attribute",
);
if sig.header.abi == Abi::Rust {
self.check_arg_number(cx, &sig.decl, item.span.with_hi(sig.decl.output.span().hi()));
}
+ let is_public = cx.access_levels.is_exported(item.hir_id());
+ let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
+ if is_public {
+ check_result_unit_err(cx, &sig.decl, item.span, fn_header_span);
+ }
- let attr = must_use_attr(&item.attrs);
+ let attrs = cx.tcx.hir().attrs(item.hir_id());
+ let attr = must_use_attr(attrs);
if let Some(attr) = attr {
- let fn_header_span = item.span.with_hi(sig.decl.output.span().hi());
- check_needless_must_use(cx, &sig.decl, item.hir_id, item.span, fn_header_span, attr);
+ check_needless_must_use(cx, &sig.decl, item.hir_id(), item.span, fn_header_span, attr);
}
if let hir::TraitFn::Provided(eid) = *eid {
let body = cx.tcx.hir().body(eid);
- Self::check_raw_ptr(cx, sig.header.unsafety, &sig.decl, body, item.hir_id);
+ Self::check_raw_ptr(cx, sig.header.unsafety, &sig.decl, body, item.hir_id());
- if attr.is_none() && cx.access_levels.is_exported(item.hir_id) && !is_proc_macro(cx.sess(), &item.attrs)
- {
+ if attr.is_none() && is_public && !is_proc_macro(cx.sess(), attrs) {
check_must_use_candidate(
cx,
&sig.decl,
body,
item.span,
- item.hir_id,
+ item.hir_id(),
item.span.with_hi(sig.decl.output.span().hi()),
"this method could have a `#[must_use]` attribute",
);
break;
}
if in_comment {
- match line.find("*/") {
- Some(i) => {
- line = &line[i + 2..];
- in_comment = false;
- continue;
- },
- None => break,
+ if let Some(i) = line.find("*/") {
+ line = &line[i + 2..];
+ in_comment = false;
+ continue;
}
} else {
let multi_idx = line.find("/*").unwrap_or_else(|| line.len());
in_comment = true;
continue;
}
- break;
}
+ break;
}
if code_in_line {
line_count += 1;
}
if line_count > self.max_lines {
- span_lint(cx, TOO_MANY_LINES, span, "this function has a large number of lines")
+ span_lint(
+ cx,
+ TOO_MANY_LINES,
+ span,
+ &format!("this function has too many lines ({}/{})", line_count, self.max_lines),
+ )
}
}
}
}
+fn check_result_unit_err(cx: &LateContext<'_>, decl: &hir::FnDecl<'_>, item_span: Span, fn_header_span: Span) {
+ if_chain! {
+ if !in_external_macro(cx.sess(), item_span);
+ if let hir::FnRetTy::Return(ref ty) = decl.output;
+ let ty = hir_ty_to_ty(cx.tcx, ty);
+ if is_type_diagnostic_item(cx, ty, sym::result_type);
+ if let ty::Adt(_, substs) = ty.kind();
+ let err_ty = substs.type_at(1);
+ if err_ty.is_unit();
+ then {
+ span_lint_and_help(
+ cx,
+ RESULT_UNIT_ERR,
+ fn_header_span,
+ "this returns a `Result<_, ()>",
+ None,
+ "use a custom Error type instead",
+ );
+ }
+ }
+}
+
fn check_needless_must_use(
cx: &LateContext<'_>,
decl: &hir::FnDecl<'_>,
if let hir::PatKind::Wild = pat.kind {
return false; // ignore `_` patterns
}
- let def_id = pat.hir_id.owner.to_def_id();
- if cx.tcx.has_typeck_results(def_id) {
- is_mutable_ty(cx, &cx.tcx.typeck(def_id.expect_local()).pat_ty(pat), pat.span, tys)
+ if cx.tcx.has_typeck_results(pat.hir_id.owner.to_def_id()) {
+ is_mutable_ty(cx, &cx.tcx.typeck(pat.hir_id.owner).pat_ty(pat), pat.span, tys)
} else {
false
}
static KNOWN_WRAPPER_TYS: &[&[&str]] = &[&["alloc", "rc", "Rc"], &["std", "sync", "Arc"]];
fn is_mutable_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, span: Span, tys: &mut FxHashSet<DefId>) -> bool {
- match ty.kind {
+ match *ty.kind() {
// primitive types are never mutable
ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str => false,
ty::Adt(ref adt, ref substs) => {
}
}
},
- hir::ExprKind::Unary(hir::UnOp::UnDeref, ref ptr) => self.check_arg(ptr),
+ hir::ExprKind::Unary(hir::UnOp::Deref, ref ptr) => self.check_arg(ptr),
_ => (),
}
impl<'a, 'tcx> DerefVisitor<'a, 'tcx> {
fn check_arg(&self, ptr: &hir::Expr<'_>) {
- if let hir::ExprKind::Path(ref qpath) = ptr.kind {
- if let Res::Local(id) = qpath_res(self.cx, qpath, ptr.hir_id) {
- if self.ptrs.contains(&id) {
- span_lint(
- self.cx,
- NOT_UNSAFE_PTR_ARG_DEREF,
- ptr.span,
- "this public function dereferences a raw pointer but is not marked `unsafe`",
- );
- }
+ if let Some(id) = path_to_local(ptr) {
+ if self.ptrs.contains(&id) {
+ span_lint(
+ self.cx,
+ NOT_UNSAFE_PTR_ARG_DEREF,
+ ptr.span,
+ "this public function dereferences a raw pointer but is not marked `unsafe`",
+ );
}
}
}
Call(_, args) | MethodCall(_, _, args, _) => {
let mut tys = FxHashSet::default();
for arg in args {
- let def_id = arg.hir_id.owner.to_def_id();
- if self.cx.tcx.has_typeck_results(def_id)
+ if self.cx.tcx.has_typeck_results(arg.hir_id.owner.to_def_id())
&& is_mutable_ty(
self.cx,
- self.cx.tcx.typeck(def_id.expect_local()).expr_ty(arg),
+ self.cx.tcx.typeck(arg.hir_id.owner).expr_ty(arg),
arg.span,
&mut tys,
)
- && is_mutated_static(self.cx, arg)
+ && is_mutated_static(arg)
{
self.mutates_static = true;
return;
}
},
Assign(ref target, ..) | AssignOp(_, ref target, _) | AddrOf(_, hir::Mutability::Mut, ref target) => {
- self.mutates_static |= is_mutated_static(self.cx, target)
+ self.mutates_static |= is_mutated_static(target)
},
_ => {},
}
}
}
-fn is_mutated_static(cx: &LateContext<'_>, e: &hir::Expr<'_>) -> bool {
+fn is_mutated_static(e: &hir::Expr<'_>) -> bool {
use hir::ExprKind::{Field, Index, Path};
match e.kind {
- Path(ref qpath) => !matches!(qpath_res(cx, qpath, e.hir_id), Res::Local(_)),
- Field(ref inner, _) | Index(ref inner, _) => is_mutated_static(cx, inner),
+ Path(QPath::Resolved(_, path)) => !matches!(path.res, Res::Local(_)),
+ Path(_) => true,
+ Field(ref inner, _) | Index(ref inner, _) => is_mutated_static(inner),
_ => false,
}
}
projects / rust.git / blobdiff