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Add recursive_format_impl lint

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The to_string_in_display lint is renamed to recursive_format_impl
A check is added for the use of self formatted with Display or Debug
inside any format string in the same impl
The to_string_in_display check is kept as is - like in the
format_in_format_args lint

For now only Display and Debug are checked
This could also be extended to other Format traits (Binary, etc.)
This commit is contained in:
James McMurray 2021-12-28 19:27:11 +01:00
parent 4931cab709
commit b162b11abc
17 changed files with 685 additions and 276 deletions
Download patch file Download diff file Expand all files Collapse all files

26
clippy_lints/src/format_args.rs
View file

@ -1,8 +1,8 @@
use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
use clippy_utils::macros::{FormatArgsArg, FormatArgsExpn};
use clippy_utils::is_diag_trait_item;
use clippy_utils::macros::{is_format_macro, FormatArgsArg, FormatArgsExpn};
use clippy_utils::source::snippet_opt;
use clippy_utils::ty::implements_trait;
use clippy_utils::{is_diag_trait_item, match_def_path, paths};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
@ -65,21 +65,6 @@ declare_clippy_lint! {
declare_lint_pass!(FormatArgs => [FORMAT_IN_FORMAT_ARGS, TO_STRING_IN_FORMAT_ARGS]);
const FORMAT_MACRO_PATHS: &[&[&str]] = &[
&paths::FORMAT_ARGS_MACRO,
&paths::ASSERT_EQ_MACRO,
&paths::ASSERT_MACRO,
&paths::ASSERT_NE_MACRO,
&paths::EPRINT_MACRO,
&paths::EPRINTLN_MACRO,
&paths::PRINT_MACRO,
&paths::PRINTLN_MACRO,
&paths::WRITE_MACRO,
&paths::WRITELN_MACRO,
];
const FORMAT_MACRO_DIAG_ITEMS: &[Symbol] = &[sym::format_macro, sym::std_panic_macro];
impl<'tcx> LateLintPass<'tcx> for FormatArgs {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
if_chain! {
@ -87,12 +72,7 @@ impl<'tcx> LateLintPass<'tcx> for FormatArgs {
let expr_expn_data = expr.span.ctxt().outer_expn_data();
let outermost_expn_data = outermost_expn_data(expr_expn_data);
if let Some(macro_def_id) = outermost_expn_data.macro_def_id;
if FORMAT_MACRO_PATHS
.iter()
.any(|path| match_def_path(cx, macro_def_id, path))
|| FORMAT_MACRO_DIAG_ITEMS
.iter()
.any(|diag_item| cx.tcx.is_diagnostic_item(*diag_item, macro_def_id));
if is_format_macro(cx, macro_def_id);
if let ExpnKind::Macro(_, name) = outermost_expn_data.kind;
if let Some(args) = format_args.args();
then {

2
clippy_lints/src/lib.register_all.rs
View file

@ -241,6 +241,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
LintId::of(ranges::MANUAL_RANGE_CONTAINS),
LintId::of(ranges::RANGE_ZIP_WITH_LEN),
LintId::of(ranges::REVERSED_EMPTY_RANGES),
LintId::of(recursive_format_impl::RECURSIVE_FORMAT_IMPL),
LintId::of(redundant_clone::REDUNDANT_CLONE),
LintId::of(redundant_closure_call::REDUNDANT_CLOSURE_CALL),
LintId::of(redundant_field_names::REDUNDANT_FIELD_NAMES),
@ -267,7 +268,6 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
LintId::of(tabs_in_doc_comments::TABS_IN_DOC_COMMENTS),
LintId::of(temporary_assignment::TEMPORARY_ASSIGNMENT),
LintId::of(to_digit_is_some::TO_DIGIT_IS_SOME),
LintId::of(to_string_in_display::TO_STRING_IN_DISPLAY),
LintId::of(transmute::CROSSPOINTER_TRANSMUTE),
LintId::of(transmute::TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS),
LintId::of(transmute::TRANSMUTE_BYTES_TO_STR),

2
clippy_lints/src/lib.register_correctness.rs
View file

@ -52,12 +52,12 @@ store.register_group(true, "clippy::correctness", Some("clippy_correctness"), ve
LintId::of(ptr::INVALID_NULL_PTR_USAGE),
LintId::of(ptr::MUT_FROM_REF),
LintId::of(ranges::REVERSED_EMPTY_RANGES),
LintId::of(recursive_format_impl::RECURSIVE_FORMAT_IMPL),
LintId::of(regex::INVALID_REGEX),
LintId::of(self_assignment::SELF_ASSIGNMENT),
LintId::of(serde_api::SERDE_API_MISUSE),
LintId::of(size_of_in_element_count::SIZE_OF_IN_ELEMENT_COUNT),
LintId::of(swap::ALMOST_SWAPPED),
LintId::of(to_string_in_display::TO_STRING_IN_DISPLAY),
LintId::of(transmute::TRANSMUTE_UNDEFINED_REPR),
LintId::of(transmute::UNSOUND_COLLECTION_TRANSMUTE),
LintId::of(transmute::WRONG_TRANSMUTE),

2
clippy_lints/src/lib.register_lints.rs
View file

@ -416,6 +416,7 @@ store.register_lints(&[
ranges::RANGE_PLUS_ONE,
ranges::RANGE_ZIP_WITH_LEN,
ranges::REVERSED_EMPTY_RANGES,
recursive_format_impl::RECURSIVE_FORMAT_IMPL,
redundant_clone::REDUNDANT_CLONE,
redundant_closure_call::REDUNDANT_CLOSURE_CALL,
redundant_else::REDUNDANT_ELSE,
@ -460,7 +461,6 @@ store.register_lints(&[
tabs_in_doc_comments::TABS_IN_DOC_COMMENTS,
temporary_assignment::TEMPORARY_ASSIGNMENT,
to_digit_is_some::TO_DIGIT_IS_SOME,
to_string_in_display::TO_STRING_IN_DISPLAY,
trailing_empty_array::TRAILING_EMPTY_ARRAY,
trait_bounds::TRAIT_DUPLICATION_IN_BOUNDS,
trait_bounds::TYPE_REPETITION_IN_BOUNDS,

5
clippy_lints/src/lib.rs
View file

@ -332,6 +332,7 @@ mod ptr_eq;
mod ptr_offset_with_cast;
mod question_mark;
mod ranges;
mod recursive_format_impl;
mod redundant_clone;
mod redundant_closure_call;
mod redundant_else;
@ -364,7 +365,6 @@ mod swap;
mod tabs_in_doc_comments;
mod temporary_assignment;
mod to_digit_is_some;
mod to_string_in_display;
mod trailing_empty_array;
mod trait_bounds;
mod transmute;
@ -704,7 +704,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
store.register_late_pass(|| Box::new(modulo_arithmetic::ModuloArithmetic));
store.register_early_pass(|| Box::new(reference::DerefAddrOf));
store.register_early_pass(|| Box::new(double_parens::DoubleParens));
store.register_late_pass(|| Box::new(to_string_in_display::ToStringInDisplay::new()));
store.register_late_pass(|| Box::new(recursive_format_impl::RecursiveFormatImpl::new()));
store.register_early_pass(|| Box::new(unsafe_removed_from_name::UnsafeNameRemoval));
store.register_early_pass(|| Box::new(else_if_without_else::ElseIfWithoutElse));
store.register_early_pass(|| Box::new(int_plus_one::IntPlusOne));
@ -938,6 +938,7 @@ pub fn register_renamed(ls: &mut rustc_lint::LintStore) {
ls.register_renamed("clippy::disallowed_type", "clippy::disallowed_types");
ls.register_renamed("clippy::disallowed_method", "clippy::disallowed_methods");
ls.register_renamed("clippy::ref_in_deref", "clippy::needless_borrow");
ls.register_renamed("clippy::to_string_in_display", "clippy::recursive_format_impl");
// uplifted lints
ls.register_renamed("clippy::invalid_ref", "invalid_value");

190
clippy_lints/src/recursive_format_impl.rs Normal file
View file

@ -0,0 +1,190 @@
use clippy_utils::diagnostics::span_lint;
use clippy_utils::macros::{is_format_macro, root_macro_call_first_node, FormatArgsArg, FormatArgsExpn};
use clippy_utils::{is_diag_trait_item, path_to_local, peel_ref_operators};
use if_chain::if_chain;
use rustc_hir::{Expr, ExprKind, Impl, Item, ItemKind, QPath};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::{sym, symbol::kw, Symbol};
#[derive(Clone, Copy)]
enum FormatTrait {
Debug,
Display,
}
impl FormatTrait {
fn name(self) -> Symbol {
match self {
FormatTrait::Debug => sym::Debug,
FormatTrait::Display => sym::Display,
}
}
}
declare_clippy_lint! {
/// ### What it does
/// Checks for format trait implementations (e.g. `Display`) with a recursive call to itself
/// which uses `self` as a parameter.
/// This is typically done indirectly with the `write!` macro or with `to_string()`.
///
/// ### Why is this bad?
/// This will lead to infinite recursion and a stack overflow.
///
/// ### Example
///
/// ```rust
/// use std::fmt;
///
/// struct Structure(i32);
/// impl fmt::Display for Structure {
/// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
/// write!(f, "{}", self.to_string())
/// }
/// }
///
/// ```
/// Use instead:
/// ```rust
/// use std::fmt;
///
/// struct Structure(i32);
/// impl fmt::Display for Structure {
/// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
/// write!(f, "{}", self.0)
/// }
/// }
/// ```
#[clippy::version = "1.48.0"]
pub RECURSIVE_FORMAT_IMPL,
correctness,
"Format trait method called while implementing the same Format trait"
}
#[derive(Default)]
pub struct RecursiveFormatImpl {
// Whether we are inside Display or Debug trait impl - None for neither
format_trait_impl: Option<FormatTrait>,
}
impl RecursiveFormatImpl {
pub fn new() -> Self {
Self {
format_trait_impl: None,
}
}
}
impl_lint_pass!(RecursiveFormatImpl => [RECURSIVE_FORMAT_IMPL]);
impl<'tcx> LateLintPass<'tcx> for RecursiveFormatImpl {
fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
if let Some(format_trait_impl) = is_format_trait_impl(cx, item) {
self.format_trait_impl = Some(format_trait_impl);
}
}
fn check_item_post(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
// Assume no nested Impl of Debug and Display within eachother
if is_format_trait_impl(cx, item).is_some() {
self.format_trait_impl = None;
}
}
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
match self.format_trait_impl {
Some(FormatTrait::Display) => {
check_to_string_in_display(cx, expr);
check_self_in_format_args(cx, expr, FormatTrait::Display);
},
Some(FormatTrait::Debug) => {
check_self_in_format_args(cx, expr, FormatTrait::Debug);
},
None => {},
}
}
}
fn check_to_string_in_display(cx: &LateContext<'_>, expr: &Expr<'_>) {
if_chain! {
// Get the hir_id of the object we are calling the method on
if let ExprKind::MethodCall(path, [ref self_arg, ..], _) = expr.kind;
// Is the method to_string() ?
if path.ident.name == sym!(to_string);
// Is the method a part of the ToString trait? (i.e. not to_string() implemented
// separately)
if let Some(expr_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
if is_diag_trait_item(cx, expr_def_id, sym::ToString);
// Is the method is called on self
if let ExprKind::Path(QPath::Resolved(_, path)) = self_arg.kind;
if let [segment] = path.segments;
if segment.ident.name == kw::SelfLower;
then {
span_lint(
cx,
RECURSIVE_FORMAT_IMPL,
expr.span,
"using `self.to_string` in `fmt::Display` implementation will cause infinite recursion",
);
}
}
}
fn check_self_in_format_args<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, impl_trait: FormatTrait) {
// Check each arg in format calls - do we ever use Display on self (directly or via deref)?
if_chain! {
if let Some(outer_macro) = root_macro_call_first_node(cx, expr);
if let macro_def_id = outer_macro.def_id;
if let Some(format_args) = FormatArgsExpn::find_nested(cx, expr, outer_macro.expn);
if is_format_macro(cx, macro_def_id);
if let Some(args) = format_args.args();
then {
for arg in args {
if arg.format_trait != impl_trait.name() {
continue;
}
check_format_arg_self(cx, expr, &arg, impl_trait);
}
}
}
}
fn check_format_arg_self(cx: &LateContext<'_>, expr: &Expr<'_>, arg: &FormatArgsArg<'_>, impl_trait: FormatTrait) {
// Handle multiple dereferencing of references e.g. &&self
// Handle dereference of &self -> self that is equivalent (i.e. via *self in fmt() impl)
// Since the argument to fmt is itself a reference: &self
let reference = peel_ref_operators(cx, arg.value);
let map = cx.tcx.hir();
// Is the reference self?
let symbol_ident = impl_trait.name().to_ident_string();
if path_to_local(reference).map(|x| map.name(x)) == Some(kw::SelfLower) {
span_lint(
cx,
RECURSIVE_FORMAT_IMPL,
expr.span,
&format!(
"using `self` as `{}` in `impl {}` will cause infinite recursion",
&symbol_ident, &symbol_ident
),
);
}
}
fn is_format_trait_impl(cx: &LateContext<'_>, item: &Item<'_>) -> Option<FormatTrait> {
if_chain! {
// Are we at an Impl?
if let ItemKind::Impl(Impl { of_trait: Some(trait_ref), .. }) = &item.kind;
if let Some(did) = trait_ref.trait_def_id();
if let Some(name) = cx.tcx.get_diagnostic_name(did);
then {
// Is Impl for Debug or Display?
match name {
sym::Debug => Some(FormatTrait::Debug),
sym::Display => Some(FormatTrait::Display),
_ => None,
}
} else {
None
}
}
}

123
clippy_lints/src/to_string_in_display.rs
View file

@ -1,123 +0,0 @@
use clippy_utils::diagnostics::span_lint;
use clippy_utils::{is_diag_trait_item, match_def_path, path_to_local_id, paths};
use if_chain::if_chain;
use rustc_hir::{Expr, ExprKind, HirId, Impl, ImplItem, ImplItemKind, Item, ItemKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::symbol::sym;
declare_clippy_lint! {
/// ### What it does
/// Checks for uses of `to_string()` in `Display` traits.
///
/// ### Why is this bad?
/// Usually `to_string` is implemented indirectly
/// via `Display`. Hence using it while implementing `Display` would
/// lead to infinite recursion.
///
/// ### Example
///
/// ```rust
/// use std::fmt;
///
/// struct Structure(i32);
/// impl fmt::Display for Structure {
/// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
/// write!(f, "{}", self.to_string())
/// }
/// }
///
/// ```
/// Use instead:
/// ```rust
/// use std::fmt;
///
/// struct Structure(i32);
/// impl fmt::Display for Structure {
/// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
/// write!(f, "{}", self.0)
/// }
/// }
/// ```
#[clippy::version = "1.48.0"]
pub TO_STRING_IN_DISPLAY,
correctness,
"`to_string` method used while implementing `Display` trait"
}
#[derive(Default)]
pub struct ToStringInDisplay {
in_display_impl: bool,
self_hir_id: Option<HirId>,
}
impl ToStringInDisplay {
pub fn new() -> Self {
Self {
in_display_impl: false,
self_hir_id: None,
}
}
}
impl_lint_pass!(ToStringInDisplay => [TO_STRING_IN_DISPLAY]);
impl LateLintPass<'_> for ToStringInDisplay {
fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
if is_display_impl(cx, item) {
self.in_display_impl = true;
}
}
fn check_item_post(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
if is_display_impl(cx, item) {
self.in_display_impl = false;
self.self_hir_id = None;
}
}
fn check_impl_item(&mut self, cx: &LateContext<'_>, impl_item: &ImplItem<'_>) {
if_chain! {
if self.in_display_impl;
if let ImplItemKind::Fn(.., body_id) = &impl_item.kind;
let body = cx.tcx.hir().body(*body_id);
if !body.params.is_empty();
then {
let self_param = &body.params[0];
self.self_hir_id = Some(self_param.pat.hir_id);
}
}
}
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
if_chain! {
if self.in_display_impl;
if let Some(self_hir_id) = self.self_hir_id;
if let ExprKind::MethodCall(path, [ref self_arg, ..], _) = expr.kind;
if path.ident.name == sym!(to_string);
if let Some(expr_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
if is_diag_trait_item(cx, expr_def_id, sym::ToString);
if path_to_local_id(self_arg, self_hir_id);
then {
span_lint(
cx,
TO_STRING_IN_DISPLAY,
expr.span,
"using `to_string` in `fmt::Display` implementation might lead to infinite recursion",
);
}
}
}
}
fn is_display_impl(cx: &LateContext<'_>, item: &Item<'_>) -> bool {
if_chain! {
if let ItemKind::Impl(Impl { of_trait: Some(trait_ref), .. }) = &item.kind;
if let Some(did) = trait_ref.trait_def_id();
then {
match_def_path(cx, did, &paths::DISPLAY_TRAIT)
} else {
false
}
}
}