rust-clippy/clippy_lints/src/utils/author.rs
2022-01-21 07:48:10 -06:00

735 lines
26 KiB
Rust

//! A group of attributes that can be attached to Rust code in order
//! to generate a clippy lint detecting said code automatically.
use clippy_utils::{get_attr, higher};
use rustc_ast::ast::{LitFloatType, LitKind};
use rustc_ast::LitIntType;
use rustc_data_structures::fx::FxHashMap;
use rustc_hir as hir;
use rustc_hir::{ArrayLen, ExprKind, FnRetTy, HirId, Lit, PatKind, QPath, StmtKind, TyKind};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::symbol::{Ident, Symbol};
use std::fmt::{Display, Formatter, Write as _};
declare_clippy_lint! {
/// ### What it does
/// Generates clippy code that detects the offending pattern
///
/// ### Example
/// ```rust,ignore
/// // ./tests/ui/my_lint.rs
/// fn foo() {
/// // detect the following pattern
/// #[clippy::author]
/// if x == 42 {
/// // but ignore everything from here on
/// #![clippy::author = "ignore"]
/// }
/// ()
/// }
/// ```
///
/// Running `TESTNAME=ui/my_lint cargo uitest` will produce
/// a `./tests/ui/new_lint.stdout` file with the generated code:
///
/// ```rust,ignore
/// // ./tests/ui/new_lint.stdout
/// if_chain! {
/// if let ExprKind::If(ref cond, ref then, None) = item.kind,
/// if let ExprKind::Binary(BinOp::Eq, ref left, ref right) = cond.kind,
/// if let ExprKind::Path(ref path) = left.kind,
/// if let ExprKind::Lit(ref lit) = right.kind,
/// if let LitKind::Int(42, _) = lit.node,
/// then {
/// // report your lint here
/// }
/// }
/// ```
pub LINT_AUTHOR,
internal_warn,
"helper for writing lints"
}
declare_lint_pass!(Author => [LINT_AUTHOR]);
/// Writes a line of output with indentation added
macro_rules! out {
($($t:tt)*) => {
println!(" {}", format_args!($($t)*))
};
}
/// The variables passed in are replaced with `&Binding`s where the `value` field is set
/// to the original value of the variable. The `name` field is set to the name of the variable
/// (using `stringify!`) and is adjusted to avoid duplicate names.
/// Note that the `Binding` may be printed directly to output the `name`.
macro_rules! bind {
($self:ident $(, $name:ident)+) => {
$(let $name = & $self.bind(stringify!($name), $name);)+
};
}
/// Transforms the given `Option<T>` varibles into `OptionPat<Binding<T>>`.
/// This displays as `Some($name)` or `None` when printed. The name of the inner binding
/// is set to the name of the variable passed to the macro.
macro_rules! opt_bind {
($self:ident $(, $name:ident)+) => {
$(let $name = OptionPat::new($name.map(|o| $self.bind(stringify!($name), o)));)+
};
}
/// Creates a `Binding` that accesses the field of an existing `Binding`
macro_rules! field {
($binding:ident.$field:ident) => {
&Binding {
name: $binding.name.to_string() + stringify!(.$field),
value: $binding.value.$field,
}
};
}
fn prelude() {
println!("if_chain! {{");
}
fn done() {
println!(" then {{");
println!(" // report your lint here");
println!(" }}");
println!("}}");
}
impl<'tcx> LateLintPass<'tcx> for Author {
fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) {
check_item(cx, item.hir_id());
}
fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::ImplItem<'_>) {
check_item(cx, item.hir_id());
}
fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::TraitItem<'_>) {
check_item(cx, item.hir_id());
}
fn check_arm(&mut self, cx: &LateContext<'tcx>, arm: &'tcx hir::Arm<'_>) {
check_node(cx, arm.hir_id, |v| {
v.arm(&v.bind("arm", arm));
});
}
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
check_node(cx, expr.hir_id, |v| {
v.expr(&v.bind("expr", expr));
});
}
fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx hir::Stmt<'_>) {
match stmt.kind {
StmtKind::Expr(e) | StmtKind::Semi(e) if has_attr(cx, e.hir_id) => return,
_ => {},
}
check_node(cx, stmt.hir_id, |v| {
v.stmt(&v.bind("stmt", stmt));
});
}
}
fn check_item(cx: &LateContext<'_>, hir_id: HirId) {
let hir = cx.tcx.hir();
if let Some(body_id) = hir.maybe_body_owned_by(hir_id) {
check_node(cx, hir_id, |v| {
v.expr(&v.bind("expr", &hir.body(body_id).value));
});
}
}
fn check_node(cx: &LateContext<'_>, hir_id: HirId, f: impl Fn(&PrintVisitor<'_, '_>)) {
if has_attr(cx, hir_id) {
prelude();
f(&PrintVisitor::new(cx));
done();
}
}
struct Binding<T> {
name: String,
value: T,
}
impl<T> Display for Binding<T> {
fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
f.write_str(&self.name)
}
}
struct OptionPat<T> {
pub opt: Option<T>,
}
impl<T> OptionPat<T> {
fn new(opt: Option<T>) -> Self {
Self { opt }
}
fn if_some(&self, f: impl Fn(&T)) {
if let Some(t) = &self.opt {
f(t);
}
}
}
impl<T: Display> Display for OptionPat<T> {
fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
match &self.opt {
None => f.write_str("None"),
Some(node) => write!(f, "Some({node})"),
}
}
}
struct PrintVisitor<'a, 'tcx> {
cx: &'a LateContext<'tcx>,
/// Fields are the current index that needs to be appended to pattern
/// binding names
ids: std::cell::Cell<FxHashMap<&'static str, u32>>,
}
#[allow(clippy::unused_self)]
impl<'a, 'tcx> PrintVisitor<'a, 'tcx> {
fn new(cx: &'a LateContext<'tcx>) -> Self {
Self {
cx,
ids: std::cell::Cell::default(),
}
}
fn next(&self, s: &'static str) -> String {
let mut ids = self.ids.take();
let out = match *ids.entry(s).and_modify(|n| *n += 1).or_default() {
// first usage of the name, use it as is
0 => s.to_string(),
// append a number starting with 1
n => format!("{s}{n}"),
};
self.ids.set(ids);
out
}
fn bind<T>(&self, name: &'static str, value: T) -> Binding<T> {
let name = self.next(name);
Binding { name, value }
}
fn option<T: Copy>(&self, option: &Binding<Option<T>>, name: &'static str, f: impl Fn(&Binding<T>)) {
match option.value {
None => out!("if {option}.is_none();"),
Some(value) => {
let value = &self.bind(name, value);
out!("if let Some({value}) = {option};");
f(value);
},
}
}
fn slice<T>(&self, slice: &Binding<&[T]>, f: impl Fn(&Binding<&T>)) {
if slice.value.is_empty() {
out!("if {slice}.is_empty();");
} else {
out!("if {slice}.len() == {};", slice.value.len());
for (i, value) in slice.value.iter().enumerate() {
let name = format!("{slice}[{i}]");
f(&Binding { name, value });
}
}
}
fn destination(&self, destination: &Binding<hir::Destination>) {
self.option(field!(destination.label), "label", |label| {
self.ident(field!(label.ident));
});
}
fn ident(&self, ident: &Binding<Ident>) {
out!("if {ident}.as_str() == {:?};", ident.value.as_str());
}
fn symbol(&self, symbol: &Binding<Symbol>) {
out!("if {symbol}.as_str() == {:?};", symbol.value.as_str());
}
fn qpath(&self, qpath: &Binding<&QPath<'_>>) {
if let QPath::LangItem(lang_item, ..) = *qpath.value {
out!("if matches!({qpath}, QPath::LangItem(LangItem::{lang_item:?}, _));");
} else {
out!("if match_qpath({qpath}, &[{}]);", path_to_string(qpath.value));
}
}
fn lit(&self, lit: &Binding<&Lit>) {
let kind = |kind| out!("if let LitKind::{kind} = {lit}.node;");
macro_rules! kind {
($($t:tt)*) => (kind(format_args!($($t)*)));
}
match lit.value.node {
LitKind::Bool(val) => kind!("Bool({val:?})"),
LitKind::Char(c) => kind!("Char({c:?})"),
LitKind::Err(val) => kind!("Err({val})"),
LitKind::Byte(b) => kind!("Byte({b})"),
LitKind::Int(i, suffix) => {
let int_ty = match suffix {
LitIntType::Signed(int_ty) => format!("LitIntType::Signed(IntTy::{int_ty:?})"),
LitIntType::Unsigned(uint_ty) => format!("LitIntType::Unsigned(UintTy::{uint_ty:?})"),
LitIntType::Unsuffixed => String::from("LitIntType::Unsuffixed"),
};
kind!("Int({i}, {int_ty})");
},
LitKind::Float(_, suffix) => {
let float_ty = match suffix {
LitFloatType::Suffixed(suffix_ty) => format!("LitFloatType::Suffixed(FloatTy::{suffix_ty:?})"),
LitFloatType::Unsuffixed => String::from("LitFloatType::Unsuffixed"),
};
kind!("Float(_, {float_ty})");
},
LitKind::ByteStr(ref vec) => {
bind!(self, vec);
kind!("ByteStr(ref {vec})");
out!("if let [{:?}] = **{vec};", vec.value);
},
LitKind::Str(s, _) => {
bind!(self, s);
kind!("Str({s}, _)");
self.symbol(s);
},
}
}
fn arm(&self, arm: &Binding<&hir::Arm<'_>>) {
self.pat(field!(arm.pat));
match arm.value.guard {
None => out!("if {arm}.guard.is_none();"),
Some(hir::Guard::If(expr)) => {
bind!(self, expr);
out!("if let Some(Guard::If({expr})) = {arm}.guard;");
self.expr(expr);
},
Some(hir::Guard::IfLet(pat, expr)) => {
bind!(self, pat, expr);
out!("if let Some(Guard::IfLet({pat}, {expr}) = {arm}.guard;");
self.pat(pat);
self.expr(expr);
},
}
self.expr(field!(arm.body));
}
#[allow(clippy::too_many_lines)]
fn expr(&self, expr: &Binding<&hir::Expr<'_>>) {
if let Some(higher::While { condition, body }) = higher::While::hir(expr.value) {
bind!(self, condition, body);
out!(
"if let Some(higher::While {{ condition: {condition}, body: {body} }}) \
= higher::While::hir({expr});"
);
self.expr(condition);
self.expr(body);
return;
}
if let Some(higher::WhileLet {
let_pat,
let_expr,
if_then,
}) = higher::WhileLet::hir(expr.value)
{
bind!(self, let_pat, let_expr, if_then);
out!(
"if let Some(higher::WhileLet {{ let_pat: {let_pat}, let_expr: {let_expr}, if_then: {if_then} }}) \
= higher::WhileLet::hir({expr});"
);
self.pat(let_pat);
self.expr(let_expr);
self.expr(if_then);
return;
}
if let Some(higher::ForLoop { pat, arg, body, .. }) = higher::ForLoop::hir(expr.value) {
bind!(self, pat, arg, body);
out!(
"if let Some(higher::ForLoop {{ pat: {pat}, arg: {arg}, body: {body}, .. }}) \
= higher::ForLoop::hir({expr});"
);
self.pat(pat);
self.expr(arg);
self.expr(body);
return;
}
let kind = |kind| out!("if let ExprKind::{kind} = {expr}.kind;");
macro_rules! kind {
($($t:tt)*) => (kind(format_args!($($t)*)));
}
match expr.value.kind {
ExprKind::Let(let_expr) => {
bind!(self, let_expr);
kind!("Let({let_expr})");
self.pat(field!(let_expr.pat));
// Does what ExprKind::Cast does, only adds a clause for the type
// if it's a path
if let Some(TyKind::Path(ref qpath)) = let_expr.value.ty.as_ref().map(|ty| &ty.kind) {
bind!(self, qpath);
out!("if let TyKind::Path(ref {qpath}) = {let_expr}.ty.kind;");
self.qpath(qpath);
}
self.expr(field!(let_expr.init));
},
ExprKind::Box(inner) => {
bind!(self, inner);
kind!("Box({inner})");
self.expr(inner);
},
ExprKind::Array(elements) => {
bind!(self, elements);
kind!("Array({elements})");
self.slice(elements, |e| self.expr(e));
},
ExprKind::Call(func, args) => {
bind!(self, func, args);
kind!("Call({func}, {args})");
self.expr(func);
self.slice(args, |e| self.expr(e));
},
ExprKind::MethodCall(method_name, args, _) => {
bind!(self, method_name, args);
kind!("MethodCall({method_name}, {args}, _)");
self.ident(field!(method_name.ident));
self.slice(args, |e| self.expr(e));
},
ExprKind::Tup(elements) => {
bind!(self, elements);
kind!("Tup({elements})");
self.slice(elements, |e| self.expr(e));
},
ExprKind::Binary(op, left, right) => {
bind!(self, op, left, right);
kind!("Binary({op}, {left}, {right})");
out!("if BinOpKind::{:?} == {op}.node;", op.value.node);
self.expr(left);
self.expr(right);
},
ExprKind::Unary(op, inner) => {
bind!(self, inner);
kind!("Unary(UnOp::{op:?}, {inner})");
self.expr(inner);
},
ExprKind::Lit(ref lit) => {
bind!(self, lit);
kind!("Lit(ref {lit})");
self.lit(lit);
},
ExprKind::Cast(expr, cast_ty) => {
bind!(self, expr, cast_ty);
kind!("Cast({expr}, {cast_ty})");
if let TyKind::Path(ref qpath) = cast_ty.value.kind {
bind!(self, qpath);
out!("if let TyKind::Path(ref {qpath}) = {cast_ty}.kind;");
self.qpath(qpath);
}
self.expr(expr);
},
ExprKind::Type(expr, _ty) => {
bind!(self, expr);
kind!("Type({expr}, _)");
self.expr(expr);
},
ExprKind::Loop(body, label, des, _) => {
bind!(self, body);
opt_bind!(self, label);
kind!("Loop({body}, {label}, LoopSource::{des:?}, _)");
self.block(body);
label.if_some(|l| self.ident(field!(l.ident)));
},
ExprKind::If(cond, then, else_expr) => {
bind!(self, cond, then);
opt_bind!(self, else_expr);
kind!("If({cond}, {then}, {else_expr})");
self.expr(cond);
self.expr(then);
else_expr.if_some(|e| self.expr(e));
},
ExprKind::Match(scrutinee, arms, des) => {
bind!(self, scrutinee, arms);
kind!("Match({scrutinee}, {arms}, MatchSource::{des:?})");
self.expr(scrutinee);
self.slice(arms, |arm| self.arm(arm));
},
ExprKind::Closure(capture_by, fn_decl, body_id, _, movability) => {
let movability = OptionPat::new(movability.map(|m| format!("Movability::{m:?}")));
let ret_ty = match fn_decl.output {
FnRetTy::DefaultReturn(_) => "FnRetTy::DefaultReturn(_)",
FnRetTy::Return(_) => "FnRetTy::Return(_ty)",
};
bind!(self, fn_decl, body_id);
kind!("Closure(CaptureBy::{capture_by:?}, {fn_decl}, {body_id}, _, {movability})");
out!("if let {ret_ty} = {fn_decl}.output;");
self.body(body_id);
},
ExprKind::Yield(sub, source) => {
bind!(self, sub);
kind!("Yield(sub, YieldSource::{source:?})");
self.expr(sub);
},
ExprKind::Block(block, label) => {
bind!(self, block);
opt_bind!(self, label);
kind!("Block({block}, {label})");
self.block(block);
label.if_some(|l| self.ident(field!(l.ident)));
},
ExprKind::Assign(target, value, _) => {
bind!(self, target, value);
kind!("Assign({target}, {value}, _span)");
self.expr(target);
self.expr(value);
},
ExprKind::AssignOp(op, target, value) => {
bind!(self, op, target, value);
kind!("AssignOp({op}, {target}, {value})");
out!("if BinOpKind::{:?} == {op}.node;", op.value.node);
self.expr(target);
self.expr(value);
},
ExprKind::Field(object, field_name) => {
bind!(self, object, field_name);
kind!("Field({object}, {field_name})");
self.ident(field_name);
self.expr(object);
},
ExprKind::Index(object, index) => {
bind!(self, object, index);
kind!("Index({object}, {index})");
self.expr(object);
self.expr(index);
},
ExprKind::Path(ref qpath) => {
bind!(self, qpath);
kind!("Path(ref {qpath})");
self.qpath(qpath);
},
ExprKind::AddrOf(kind, mutability, inner) => {
bind!(self, inner);
kind!("AddrOf(BorrowKind::{kind:?}, Mutability::{mutability:?}, {inner})");
self.expr(inner);
},
ExprKind::Break(destination, value) => {
bind!(self, destination);
opt_bind!(self, value);
kind!("Break({destination}, {value})");
self.destination(destination);
value.if_some(|e| self.expr(e));
},
ExprKind::Continue(destination) => {
bind!(self, destination);
kind!("Continue({destination})");
self.destination(destination);
},
ExprKind::Ret(value) => {
opt_bind!(self, value);
kind!("Ret({value})");
value.if_some(|e| self.expr(e));
},
ExprKind::InlineAsm(_) => {
kind!("InlineAsm(_)");
out!("// unimplemented: `ExprKind::InlineAsm` is not further destructured at the moment");
},
ExprKind::Struct(qpath, fields, base) => {
bind!(self, qpath, fields);
opt_bind!(self, base);
kind!("Struct({qpath}, {fields}, {base})");
self.qpath(qpath);
self.slice(fields, |field| {
self.ident(field!(field.ident));
self.expr(field!(field.expr));
});
base.if_some(|e| self.expr(e));
},
ExprKind::ConstBlock(_) => kind!("ConstBlock(_)"),
ExprKind::Repeat(value, length) => {
bind!(self, value, length);
kind!("Repeat({value}, {length})");
self.expr(value);
match length.value {
ArrayLen::Infer(..) => out!("if let ArrayLen::Infer(..) = length;"),
ArrayLen::Body(anon_const) => {
bind!(self, anon_const);
out!("if let ArrayLen::Body({anon_const}) = {length};");
self.body(field!(anon_const.body));
},
}
},
ExprKind::Err => kind!("Err"),
ExprKind::DropTemps(expr) => {
bind!(self, expr);
kind!("DropTemps({expr})");
self.expr(expr);
},
}
}
fn block(&self, block: &Binding<&hir::Block<'_>>) {
self.slice(field!(block.stmts), |stmt| self.stmt(stmt));
self.option(field!(block.expr), "trailing_expr", |expr| {
self.expr(expr);
});
}
fn body(&self, body_id: &Binding<hir::BodyId>) {
let expr = &self.cx.tcx.hir().body(body_id.value).value;
bind!(self, expr);
out!("let {expr} = &cx.tcx.hir().body({body_id}).value;");
self.expr(expr);
}
fn pat(&self, pat: &Binding<&hir::Pat<'_>>) {
let kind = |kind| out!("if let PatKind::{kind} = {pat}.kind;");
macro_rules! kind {
($($t:tt)*) => (kind(format_args!($($t)*)));
}
match pat.value.kind {
PatKind::Wild => kind!("Wild"),
PatKind::Binding(anno, .., name, sub) => {
bind!(self, name);
opt_bind!(self, sub);
kind!("Binding(BindingAnnotation::{anno:?}, _, {name}, {sub})");
self.ident(name);
sub.if_some(|p| self.pat(p));
},
PatKind::Struct(ref qpath, fields, ignore) => {
bind!(self, qpath, fields);
kind!("Struct(ref {qpath}, {fields}, {ignore})");
self.qpath(qpath);
self.slice(fields, |field| {
self.ident(field!(field.ident));
self.pat(field!(field.pat));
});
},
PatKind::Or(fields) => {
bind!(self, fields);
kind!("Or({fields})");
self.slice(fields, |pat| self.pat(pat));
},
PatKind::TupleStruct(ref qpath, fields, skip_pos) => {
bind!(self, qpath, fields);
kind!("TupleStruct(ref {qpath}, {fields}, {skip_pos:?})");
self.qpath(qpath);
self.slice(fields, |pat| self.pat(pat));
},
PatKind::Path(ref qpath) => {
bind!(self, qpath);
kind!("Path(ref {qpath})");
self.qpath(qpath);
},
PatKind::Tuple(fields, skip_pos) => {
bind!(self, fields);
kind!("Tuple({fields}, {skip_pos:?})");
self.slice(fields, |field| self.pat(field));
},
PatKind::Box(pat) => {
bind!(self, pat);
kind!("Box({pat})");
self.pat(pat);
},
PatKind::Ref(pat, muta) => {
bind!(self, pat);
kind!("Ref({pat}, Mutability::{muta:?})");
self.pat(pat);
},
PatKind::Lit(lit_expr) => {
bind!(self, lit_expr);
kind!("Lit({lit_expr})");
self.expr(lit_expr);
},
PatKind::Range(start, end, end_kind) => {
opt_bind!(self, start, end);
kind!("Range({start}, {end}, RangeEnd::{end_kind:?})");
start.if_some(|e| self.expr(e));
end.if_some(|e| self.expr(e));
},
PatKind::Slice(start, middle, end) => {
bind!(self, start, end);
opt_bind!(self, middle);
kind!("Slice({start}, {middle}, {end})");
middle.if_some(|p| self.pat(p));
self.slice(start, |pat| self.pat(pat));
self.slice(end, |pat| self.pat(pat));
},
}
}
fn stmt(&self, stmt: &Binding<&hir::Stmt<'_>>) {
let kind = |kind| out!("if let StmtKind::{kind} = {stmt}.kind;");
macro_rules! kind {
($($t:tt)*) => (kind(format_args!($($t)*)));
}
match stmt.value.kind {
StmtKind::Local(local) => {
bind!(self, local);
kind!("Local({local})");
self.option(field!(local.init), "init", |init| {
self.expr(init);
});
self.pat(field!(local.pat));
},
StmtKind::Item(_) => kind!("Item(item_id)"),
StmtKind::Expr(e) => {
bind!(self, e);
kind!("Expr({e})");
self.expr(e);
},
StmtKind::Semi(e) => {
bind!(self, e);
kind!("Semi({e})");
self.expr(e);
},
}
}
}
fn has_attr(cx: &LateContext<'_>, hir_id: hir::HirId) -> bool {
let attrs = cx.tcx.hir().attrs(hir_id);
get_attr(cx.sess(), attrs, "author").count() > 0
}
fn path_to_string(path: &QPath<'_>) -> String {
fn inner(s: &mut String, path: &QPath<'_>) {
match *path {
QPath::Resolved(_, path) => {
for (i, segment) in path.segments.iter().enumerate() {
if i > 0 {
*s += ", ";
}
write!(s, "{:?}", segment.ident.as_str()).unwrap();
}
},
QPath::TypeRelative(ty, segment) => match &ty.kind {
hir::TyKind::Path(inner_path) => {
inner(s, inner_path);
*s += ", ";
write!(s, "{:?}", segment.ident.as_str()).unwrap();
},
other => write!(s, "/* unimplemented: {:?}*/", other).unwrap(),
},
QPath::LangItem(..) => panic!("path_to_string: called for lang item qpath"),
}
}
let mut s = String::new();
inner(&mut s, path);
s
}