rust-clippy/clippy_lints/src/utils/internal_lints.rs
xFrednet 637751ff62 Metadata collection lint: Basic lint collection
WIP-2021-02-01

WIP-2021-02-01

WIP-2021-02-13
2021-05-05 18:34:24 +02:00

1235 lines
44 KiB
Rust

use crate::consts::{constant_simple, Constant};
use clippy_utils::diagnostics::{span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then};
use clippy_utils::source::snippet;
use clippy_utils::ty::match_type;
use clippy_utils::{
is_else_clause, is_expn_of, is_expr_path_def_path, match_def_path, method_calls, path_to_res, paths, run_lints,
SpanlessEq,
};
use if_chain::if_chain;
use rustc_ast::ast::{Crate as AstCrate, ItemKind, LitKind, ModKind, NodeId};
use rustc_ast::visit::FnKind;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::DefId;
use rustc_hir::hir_id::CRATE_HIR_ID;
use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
use rustc_hir::{
BinOpKind, Block, Crate, Expr, ExprKind, HirId, Item, Local, MatchSource, MutTy, Mutability, Node, Path, Stmt,
StmtKind, Ty, TyKind, UnOp,
};
use rustc_lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
use rustc_middle::hir::map::Map;
use rustc_middle::mir::interpret::ConstValue;
use rustc_middle::ty;
use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
use rustc_span::source_map::Spanned;
use rustc_span::symbol::{Symbol, SymbolStr};
use rustc_span::{BytePos, Span};
use rustc_typeck::hir_ty_to_ty;
use std::borrow::{Borrow, Cow};
#[cfg(feature = "metadata-collector-lint")]
pub mod metadata_collector;
declare_clippy_lint! {
/// **What it does:** Checks for various things we like to keep tidy in clippy.
///
/// **Why is this bad?** We like to pretend we're an example of tidy code.
///
/// **Known problems:** None.
///
/// **Example:** Wrong ordering of the util::paths constants.
pub CLIPPY_LINTS_INTERNAL,
internal,
"various things that will negatively affect your clippy experience"
}
declare_clippy_lint! {
/// **What it does:** Ensures every lint is associated to a `LintPass`.
///
/// **Why is this bad?** The compiler only knows lints via a `LintPass`. Without
/// putting a lint to a `LintPass::get_lints()`'s return, the compiler will not
/// know the name of the lint.
///
/// **Known problems:** Only checks for lints associated using the
/// `declare_lint_pass!`, `impl_lint_pass!`, and `lint_array!` macros.
///
/// **Example:**
/// ```rust,ignore
/// declare_lint! { pub LINT_1, ... }
/// declare_lint! { pub LINT_2, ... }
/// declare_lint! { pub FORGOTTEN_LINT, ... }
/// // ...
/// declare_lint_pass!(Pass => [LINT_1, LINT_2]);
/// // missing FORGOTTEN_LINT
/// ```
pub LINT_WITHOUT_LINT_PASS,
internal,
"declaring a lint without associating it in a LintPass"
}
declare_clippy_lint! {
/// **What it does:** Checks for calls to `cx.span_lint*` and suggests to use the `utils::*`
/// variant of the function.
///
/// **Why is this bad?** The `utils::*` variants also add a link to the Clippy documentation to the
/// warning/error messages.
///
/// **Known problems:** None.
///
/// **Example:**
/// Bad:
/// ```rust,ignore
/// cx.span_lint(LINT_NAME, "message");
/// ```
///
/// Good:
/// ```rust,ignore
/// utils::span_lint(cx, LINT_NAME, "message");
/// ```
pub COMPILER_LINT_FUNCTIONS,
internal,
"usage of the lint functions of the compiler instead of the utils::* variant"
}
declare_clippy_lint! {
/// **What it does:** Checks for calls to `cx.outer().expn_data()` and suggests to use
/// the `cx.outer_expn_data()`
///
/// **Why is this bad?** `cx.outer_expn_data()` is faster and more concise.
///
/// **Known problems:** None.
///
/// **Example:**
/// Bad:
/// ```rust,ignore
/// expr.span.ctxt().outer().expn_data()
/// ```
///
/// Good:
/// ```rust,ignore
/// expr.span.ctxt().outer_expn_data()
/// ```
pub OUTER_EXPN_EXPN_DATA,
internal,
"using `cx.outer_expn().expn_data()` instead of `cx.outer_expn_data()`"
}
declare_clippy_lint! {
/// **What it does:** Not an actual lint. This lint is only meant for testing our customized internal compiler
/// error message by calling `panic`.
///
/// **Why is this bad?** ICE in large quantities can damage your teeth
///
/// **Known problems:** None
///
/// **Example:**
/// Bad:
/// ```rust,ignore
/// 🍦🍦🍦🍦🍦
/// ```
pub PRODUCE_ICE,
internal,
"this message should not appear anywhere as we ICE before and don't emit the lint"
}
declare_clippy_lint! {
/// **What it does:** Checks for cases of an auto-generated lint without an updated description,
/// i.e. `default lint description`.
///
/// **Why is this bad?** Indicates that the lint is not finished.
///
/// **Known problems:** None
///
/// **Example:**
/// Bad:
/// ```rust,ignore
/// declare_lint! { pub COOL_LINT, nursery, "default lint description" }
/// ```
///
/// Good:
/// ```rust,ignore
/// declare_lint! { pub COOL_LINT, nursery, "a great new lint" }
/// ```
pub DEFAULT_LINT,
internal,
"found 'default lint description' in a lint declaration"
}
declare_clippy_lint! {
/// **What it does:** Lints `span_lint_and_then` function calls, where the
/// closure argument has only one statement and that statement is a method
/// call to `span_suggestion`, `span_help`, `span_note` (using the same
/// span), `help` or `note`.
///
/// These usages of `span_lint_and_then` should be replaced with one of the
/// wrapper functions `span_lint_and_sugg`, span_lint_and_help`, or
/// `span_lint_and_note`.
///
/// **Why is this bad?** Using the wrapper `span_lint_and_*` functions, is more
/// convenient, readable and less error prone.
///
/// **Known problems:** None
///
/// *Example:**
/// Bad:
/// ```rust,ignore
/// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
/// diag.span_suggestion(
/// expr.span,
/// help_msg,
/// sugg.to_string(),
/// Applicability::MachineApplicable,
/// );
/// });
/// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
/// diag.span_help(expr.span, help_msg);
/// });
/// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
/// diag.help(help_msg);
/// });
/// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
/// diag.span_note(expr.span, note_msg);
/// });
/// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
/// diag.note(note_msg);
/// });
/// ```
///
/// Good:
/// ```rust,ignore
/// span_lint_and_sugg(
/// cx,
/// TEST_LINT,
/// expr.span,
/// lint_msg,
/// help_msg,
/// sugg.to_string(),
/// Applicability::MachineApplicable,
/// );
/// span_lint_and_help(cx, TEST_LINT, expr.span, lint_msg, Some(expr.span), help_msg);
/// span_lint_and_help(cx, TEST_LINT, expr.span, lint_msg, None, help_msg);
/// span_lint_and_note(cx, TEST_LINT, expr.span, lint_msg, Some(expr.span), note_msg);
/// span_lint_and_note(cx, TEST_LINT, expr.span, lint_msg, None, note_msg);
/// ```
pub COLLAPSIBLE_SPAN_LINT_CALLS,
internal,
"found collapsible `span_lint_and_then` calls"
}
declare_clippy_lint! {
/// **What it does:** Checks for calls to `utils::match_type()` on a type diagnostic item
/// and suggests to use `utils::is_type_diagnostic_item()` instead.
///
/// **Why is this bad?** `utils::is_type_diagnostic_item()` does not require hardcoded paths.
///
/// **Known problems:** None.
///
/// **Example:**
/// Bad:
/// ```rust,ignore
/// utils::match_type(cx, ty, &paths::VEC)
/// ```
///
/// Good:
/// ```rust,ignore
/// utils::is_type_diagnostic_item(cx, ty, sym::vec_type)
/// ```
pub MATCH_TYPE_ON_DIAGNOSTIC_ITEM,
internal,
"using `utils::match_type()` instead of `utils::is_type_diagnostic_item()`"
}
declare_clippy_lint! {
/// **What it does:**
/// Checks the paths module for invalid paths.
///
/// **Why is this bad?**
/// It indicates a bug in the code.
///
/// **Known problems:** None.
///
/// **Example:** None.
pub INVALID_PATHS,
internal,
"invalid path"
}
declare_clippy_lint! {
/// **What it does:**
/// Checks for interning symbols that have already been pre-interned and defined as constants.
///
/// **Why is this bad?**
/// It's faster and easier to use the symbol constant.
///
/// **Known problems:** None.
///
/// **Example:**
/// Bad:
/// ```rust,ignore
/// let _ = sym!(f32);
/// ```
///
/// Good:
/// ```rust,ignore
/// let _ = sym::f32;
/// ```
pub INTERNING_DEFINED_SYMBOL,
internal,
"interning a symbol that is pre-interned and defined as a constant"
}
declare_clippy_lint! {
/// **What it does:** Checks for unnecessary conversion from Symbol to a string.
///
/// **Why is this bad?** It's faster use symbols directly intead of strings.
///
/// **Known problems:** None.
///
/// **Example:**
/// Bad:
/// ```rust,ignore
/// symbol.as_str() == "clippy";
/// ```
///
/// Good:
/// ```rust,ignore
/// symbol == sym::clippy;
/// ```
pub UNNECESSARY_SYMBOL_STR,
internal,
"unnecessary conversion between Symbol and string"
}
declare_clippy_lint! {
/// Finds unidiomatic usage of `if_chain!`
pub IF_CHAIN_STYLE,
internal,
"non-idiomatic `if_chain!` usage"
}
declare_lint_pass!(ClippyLintsInternal => [CLIPPY_LINTS_INTERNAL]);
impl EarlyLintPass for ClippyLintsInternal {
fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &AstCrate) {
if let Some(utils) = krate.items.iter().find(|item| item.ident.name.as_str() == "utils") {
if let ItemKind::Mod(_, ModKind::Loaded(ref items, ..)) = utils.kind {
if let Some(paths) = items.iter().find(|item| item.ident.name.as_str() == "paths") {
if let ItemKind::Mod(_, ModKind::Loaded(ref items, ..)) = paths.kind {
let mut last_name: Option<SymbolStr> = None;
for item in items {
let name = item.ident.as_str();
if let Some(ref last_name) = last_name {
if **last_name > *name {
span_lint(
cx,
CLIPPY_LINTS_INTERNAL,
item.span,
"this constant should be before the previous constant due to lexical \
ordering",
);
}
}
last_name = Some(name);
}
}
}
}
}
}
}
#[derive(Clone, Debug, Default)]
pub struct LintWithoutLintPass {
declared_lints: FxHashMap<Symbol, Span>,
registered_lints: FxHashSet<Symbol>,
}
impl_lint_pass!(LintWithoutLintPass => [DEFAULT_LINT, LINT_WITHOUT_LINT_PASS]);
impl<'tcx> LateLintPass<'tcx> for LintWithoutLintPass {
fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
if !run_lints(cx, &[DEFAULT_LINT], item.hir_id()) {
return;
}
if let hir::ItemKind::Static(ty, Mutability::Not, body_id) = item.kind {
if is_lint_ref_type(cx, ty) {
let expr = &cx.tcx.hir().body(body_id).value;
if_chain! {
if let ExprKind::AddrOf(_, _, inner_exp) = expr.kind;
if let ExprKind::Struct(_, fields, _) = inner_exp.kind;
let field = fields
.iter()
.find(|f| f.ident.as_str() == "desc")
.expect("lints must have a description field");
if let ExprKind::Lit(Spanned {
node: LitKind::Str(ref sym, _),
..
}) = field.expr.kind;
if sym.as_str() == "default lint description";
then {
span_lint(
cx,
DEFAULT_LINT,
item.span,
&format!("the lint `{}` has the default lint description", item.ident.name),
);
}
}
self.declared_lints.insert(item.ident.name, item.span);
}
} else if is_expn_of(item.span, "impl_lint_pass").is_some()
|| is_expn_of(item.span, "declare_lint_pass").is_some()
{
if let hir::ItemKind::Impl(hir::Impl {
of_trait: None,
items: impl_item_refs,
..
}) = item.kind
{
let mut collector = LintCollector {
output: &mut self.registered_lints,
cx,
};
let body_id = cx.tcx.hir().body_owned_by(
impl_item_refs
.iter()
.find(|iiref| iiref.ident.as_str() == "get_lints")
.expect("LintPass needs to implement get_lints")
.id
.hir_id(),
);
collector.visit_expr(&cx.tcx.hir().body(body_id).value);
}
}
}
fn check_crate_post(&mut self, cx: &LateContext<'tcx>, _: &'tcx Crate<'_>) {
if !run_lints(cx, &[LINT_WITHOUT_LINT_PASS], CRATE_HIR_ID) {
return;
}
for (lint_name, &lint_span) in &self.declared_lints {
// When using the `declare_tool_lint!` macro, the original `lint_span`'s
// file points to "<rustc macros>".
// `compiletest-rs` thinks that's an error in a different file and
// just ignores it. This causes the test in compile-fail/lint_pass
// not able to capture the error.
// Therefore, we need to climb the macro expansion tree and find the
// actual span that invoked `declare_tool_lint!`:
let lint_span = lint_span.ctxt().outer_expn_data().call_site;
if !self.registered_lints.contains(lint_name) {
span_lint(
cx,
LINT_WITHOUT_LINT_PASS,
lint_span,
&format!("the lint `{}` is not added to any `LintPass`", lint_name),
);
}
}
}
}
fn is_lint_ref_type<'tcx>(cx: &LateContext<'tcx>, ty: &Ty<'_>) -> bool {
if let TyKind::Rptr(
_,
MutTy {
ty: inner,
mutbl: Mutability::Not,
},
) = ty.kind
{
if let TyKind::Path(ref path) = inner.kind {
if let Res::Def(DefKind::Struct, def_id) = cx.qpath_res(path, inner.hir_id) {
return match_def_path(cx, def_id, &paths::LINT);
}
}
}
false
}
struct LintCollector<'a, 'tcx> {
output: &'a mut FxHashSet<Symbol>,
cx: &'a LateContext<'tcx>,
}
impl<'a, 'tcx> Visitor<'tcx> for LintCollector<'a, 'tcx> {
type Map = Map<'tcx>;
fn visit_path(&mut self, path: &'tcx Path<'_>, _: HirId) {
if path.segments.len() == 1 {
self.output.insert(path.segments[0].ident.name);
}
}
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::All(self.cx.tcx.hir())
}
}
#[derive(Clone, Default)]
pub struct CompilerLintFunctions {
map: FxHashMap<&'static str, &'static str>,
}
impl CompilerLintFunctions {
#[must_use]
pub fn new() -> Self {
let mut map = FxHashMap::default();
map.insert("span_lint", "utils::span_lint");
map.insert("struct_span_lint", "utils::span_lint");
map.insert("lint", "utils::span_lint");
map.insert("span_lint_note", "utils::span_lint_and_note");
map.insert("span_lint_help", "utils::span_lint_and_help");
Self { map }
}
}
impl_lint_pass!(CompilerLintFunctions => [COMPILER_LINT_FUNCTIONS]);
impl<'tcx> LateLintPass<'tcx> for CompilerLintFunctions {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if !run_lints(cx, &[COMPILER_LINT_FUNCTIONS], expr.hir_id) {
return;
}
if_chain! {
if let ExprKind::MethodCall(path, _, args, _) = expr.kind;
let fn_name = path.ident;
if let Some(sugg) = self.map.get(&*fn_name.as_str());
let ty = cx.typeck_results().expr_ty(&args[0]).peel_refs();
if match_type(cx, ty, &paths::EARLY_CONTEXT)
|| match_type(cx, ty, &paths::LATE_CONTEXT);
then {
span_lint_and_help(
cx,
COMPILER_LINT_FUNCTIONS,
path.ident.span,
"usage of a compiler lint function",
None,
&format!("please use the Clippy variant of this function: `{}`", sugg),
);
}
}
}
}
declare_lint_pass!(OuterExpnDataPass => [OUTER_EXPN_EXPN_DATA]);
impl<'tcx> LateLintPass<'tcx> for OuterExpnDataPass {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
if !run_lints(cx, &[OUTER_EXPN_EXPN_DATA], expr.hir_id) {
return;
}
let (method_names, arg_lists, spans) = method_calls(expr, 2);
let method_names: Vec<SymbolStr> = method_names.iter().map(|s| s.as_str()).collect();
let method_names: Vec<&str> = method_names.iter().map(|s| &**s).collect();
if_chain! {
if let ["expn_data", "outer_expn"] = method_names.as_slice();
let args = arg_lists[1];
if args.len() == 1;
let self_arg = &args[0];
let self_ty = cx.typeck_results().expr_ty(self_arg).peel_refs();
if match_type(cx, self_ty, &paths::SYNTAX_CONTEXT);
then {
span_lint_and_sugg(
cx,
OUTER_EXPN_EXPN_DATA,
spans[1].with_hi(expr.span.hi()),
"usage of `outer_expn().expn_data()`",
"try",
"outer_expn_data()".to_string(),
Applicability::MachineApplicable,
);
}
}
}
}
declare_lint_pass!(ProduceIce => [PRODUCE_ICE]);
impl EarlyLintPass for ProduceIce {
fn check_fn(&mut self, _: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: Span, _: NodeId) {
if is_trigger_fn(fn_kind) {
panic!("Would you like some help with that?");
}
}
}
fn is_trigger_fn(fn_kind: FnKind<'_>) -> bool {
match fn_kind {
FnKind::Fn(_, ident, ..) => ident.name.as_str() == "it_looks_like_you_are_trying_to_kill_clippy",
FnKind::Closure(..) => false,
}
}
declare_lint_pass!(CollapsibleCalls => [COLLAPSIBLE_SPAN_LINT_CALLS]);
impl<'tcx> LateLintPass<'tcx> for CollapsibleCalls {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
if !run_lints(cx, &[COLLAPSIBLE_SPAN_LINT_CALLS], expr.hir_id) {
return;
}
if_chain! {
if let ExprKind::Call(func, and_then_args) = expr.kind;
if is_expr_path_def_path(cx, func, &["clippy_utils", "diagnostics", "span_lint_and_then"]);
if and_then_args.len() == 5;
if let ExprKind::Closure(_, _, body_id, _, _) = &and_then_args[4].kind;
let body = cx.tcx.hir().body(*body_id);
if let ExprKind::Block(block, _) = &body.value.kind;
let stmts = &block.stmts;
if stmts.len() == 1 && block.expr.is_none();
if let StmtKind::Semi(only_expr) = &stmts[0].kind;
if let ExprKind::MethodCall(ps, _, span_call_args, _) = &only_expr.kind;
then {
let and_then_snippets = get_and_then_snippets(cx, and_then_args);
let mut sle = SpanlessEq::new(cx).deny_side_effects();
match &*ps.ident.as_str() {
"span_suggestion" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
suggest_suggestion(cx, expr, &and_then_snippets, &span_suggestion_snippets(cx, span_call_args));
},
"span_help" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
let help_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
suggest_help(cx, expr, &and_then_snippets, help_snippet.borrow(), true);
},
"span_note" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
let note_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
suggest_note(cx, expr, &and_then_snippets, note_snippet.borrow(), true);
},
"help" => {
let help_snippet = snippet(cx, span_call_args[1].span, r#""...""#);
suggest_help(cx, expr, &and_then_snippets, help_snippet.borrow(), false);
}
"note" => {
let note_snippet = snippet(cx, span_call_args[1].span, r#""...""#);
suggest_note(cx, expr, &and_then_snippets, note_snippet.borrow(), false);
}
_ => (),
}
}
}
}
}
struct AndThenSnippets<'a> {
cx: Cow<'a, str>,
lint: Cow<'a, str>,
span: Cow<'a, str>,
msg: Cow<'a, str>,
}
fn get_and_then_snippets<'a, 'hir>(cx: &LateContext<'_>, and_then_snippets: &'hir [Expr<'hir>]) -> AndThenSnippets<'a> {
let cx_snippet = snippet(cx, and_then_snippets[0].span, "cx");
let lint_snippet = snippet(cx, and_then_snippets[1].span, "..");
let span_snippet = snippet(cx, and_then_snippets[2].span, "span");
let msg_snippet = snippet(cx, and_then_snippets[3].span, r#""...""#);
AndThenSnippets {
cx: cx_snippet,
lint: lint_snippet,
span: span_snippet,
msg: msg_snippet,
}
}
struct SpanSuggestionSnippets<'a> {
help: Cow<'a, str>,
sugg: Cow<'a, str>,
applicability: Cow<'a, str>,
}
fn span_suggestion_snippets<'a, 'hir>(
cx: &LateContext<'_>,
span_call_args: &'hir [Expr<'hir>],
) -> SpanSuggestionSnippets<'a> {
let help_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
let sugg_snippet = snippet(cx, span_call_args[3].span, "..");
let applicability_snippet = snippet(cx, span_call_args[4].span, "Applicability::MachineApplicable");
SpanSuggestionSnippets {
help: help_snippet,
sugg: sugg_snippet,
applicability: applicability_snippet,
}
}
fn suggest_suggestion(
cx: &LateContext<'_>,
expr: &Expr<'_>,
and_then_snippets: &AndThenSnippets<'_>,
span_suggestion_snippets: &SpanSuggestionSnippets<'_>,
) {
span_lint_and_sugg(
cx,
COLLAPSIBLE_SPAN_LINT_CALLS,
expr.span,
"this call is collapsible",
"collapse into",
format!(
"span_lint_and_sugg({}, {}, {}, {}, {}, {}, {})",
and_then_snippets.cx,
and_then_snippets.lint,
and_then_snippets.span,
and_then_snippets.msg,
span_suggestion_snippets.help,
span_suggestion_snippets.sugg,
span_suggestion_snippets.applicability
),
Applicability::MachineApplicable,
);
}
fn suggest_help(
cx: &LateContext<'_>,
expr: &Expr<'_>,
and_then_snippets: &AndThenSnippets<'_>,
help: &str,
with_span: bool,
) {
let option_span = if with_span {
format!("Some({})", and_then_snippets.span)
} else {
"None".to_string()
};
span_lint_and_sugg(
cx,
COLLAPSIBLE_SPAN_LINT_CALLS,
expr.span,
"this call is collapsible",
"collapse into",
format!(
"span_lint_and_help({}, {}, {}, {}, {}, {})",
and_then_snippets.cx,
and_then_snippets.lint,
and_then_snippets.span,
and_then_snippets.msg,
&option_span,
help
),
Applicability::MachineApplicable,
);
}
fn suggest_note(
cx: &LateContext<'_>,
expr: &Expr<'_>,
and_then_snippets: &AndThenSnippets<'_>,
note: &str,
with_span: bool,
) {
let note_span = if with_span {
format!("Some({})", and_then_snippets.span)
} else {
"None".to_string()
};
span_lint_and_sugg(
cx,
COLLAPSIBLE_SPAN_LINT_CALLS,
expr.span,
"this call is collspible",
"collapse into",
format!(
"span_lint_and_note({}, {}, {}, {}, {}, {})",
and_then_snippets.cx,
and_then_snippets.lint,
and_then_snippets.span,
and_then_snippets.msg,
note_span,
note
),
Applicability::MachineApplicable,
);
}
declare_lint_pass!(MatchTypeOnDiagItem => [MATCH_TYPE_ON_DIAGNOSTIC_ITEM]);
impl<'tcx> LateLintPass<'tcx> for MatchTypeOnDiagItem {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
if !run_lints(cx, &[MATCH_TYPE_ON_DIAGNOSTIC_ITEM], expr.hir_id) {
return;
}
if_chain! {
// Check if this is a call to utils::match_type()
if let ExprKind::Call(fn_path, [context, ty, ty_path]) = expr.kind;
if is_expr_path_def_path(cx, fn_path, &["clippy_utils", "ty", "match_type"]);
// Extract the path to the matched type
if let Some(segments) = path_to_matched_type(cx, ty_path);
let segments: Vec<&str> = segments.iter().map(|sym| &**sym).collect();
if let Some(ty_did) = path_to_res(cx, &segments[..]).opt_def_id();
// Check if the matched type is a diagnostic item
let diag_items = cx.tcx.diagnostic_items(ty_did.krate);
if let Some(item_name) = diag_items.iter().find_map(|(k, v)| if *v == ty_did { Some(k) } else { None });
then {
// TODO: check paths constants from external crates.
let cx_snippet = snippet(cx, context.span, "_");
let ty_snippet = snippet(cx, ty.span, "_");
span_lint_and_sugg(
cx,
MATCH_TYPE_ON_DIAGNOSTIC_ITEM,
expr.span,
"usage of `clippy_utils::ty::match_type()` on a type diagnostic item",
"try",
format!("clippy_utils::ty::is_type_diagnostic_item({}, {}, sym::{})", cx_snippet, ty_snippet, item_name),
Applicability::MaybeIncorrect,
);
}
}
}
}
fn path_to_matched_type(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<Vec<SymbolStr>> {
use rustc_hir::ItemKind;
match &expr.kind {
ExprKind::AddrOf(.., expr) => return path_to_matched_type(cx, expr),
ExprKind::Path(qpath) => match cx.qpath_res(qpath, expr.hir_id) {
Res::Local(hir_id) => {
let parent_id = cx.tcx.hir().get_parent_node(hir_id);
if let Some(Node::Local(local)) = cx.tcx.hir().find(parent_id) {
if let Some(init) = local.init {
return path_to_matched_type(cx, init);
}
}
},
Res::Def(DefKind::Const | DefKind::Static, def_id) => {
if let Some(Node::Item(item)) = cx.tcx.hir().get_if_local(def_id) {
if let ItemKind::Const(.., body_id) | ItemKind::Static(.., body_id) = item.kind {
let body = cx.tcx.hir().body(body_id);
return path_to_matched_type(cx, &body.value);
}
}
},
_ => {},
},
ExprKind::Array(exprs) => {
let segments: Vec<SymbolStr> = exprs
.iter()
.filter_map(|expr| {
if let ExprKind::Lit(lit) = &expr.kind {
if let LitKind::Str(sym, _) = lit.node {
return Some(sym.as_str());
}
}
None
})
.collect();
if segments.len() == exprs.len() {
return Some(segments);
}
},
_ => {},
}
None
}
// This is not a complete resolver for paths. It works on all the paths currently used in the paths
// module. That's all it does and all it needs to do.
pub fn check_path(cx: &LateContext<'_>, path: &[&str]) -> bool {
if path_to_res(cx, path) != Res::Err {
return true;
}
// Some implementations can't be found by `path_to_res`, particularly inherent
// implementations of native types. Check lang items.
let path_syms: Vec<_> = path.iter().map(|p| Symbol::intern(p)).collect();
let lang_items = cx.tcx.lang_items();
for item_def_id in lang_items.items().iter().flatten() {
let lang_item_path = cx.get_def_path(*item_def_id);
if path_syms.starts_with(&lang_item_path) {
if let [item] = &path_syms[lang_item_path.len()..] {
for child in cx.tcx.item_children(*item_def_id) {
if child.ident.name == *item {
return true;
}
}
}
}
}
false
}
declare_lint_pass!(InvalidPaths => [INVALID_PATHS]);
impl<'tcx> LateLintPass<'tcx> for InvalidPaths {
fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
let local_def_id = &cx.tcx.parent_module(item.hir_id());
let mod_name = &cx.tcx.item_name(local_def_id.to_def_id());
if_chain! {
if mod_name.as_str() == "paths";
if let hir::ItemKind::Const(ty, body_id) = item.kind;
let ty = hir_ty_to_ty(cx.tcx, ty);
if let ty::Array(el_ty, _) = &ty.kind();
if let ty::Ref(_, el_ty, _) = &el_ty.kind();
if el_ty.is_str();
let body = cx.tcx.hir().body(body_id);
let typeck_results = cx.tcx.typeck_body(body_id);
if let Some(Constant::Vec(path)) = constant_simple(cx, typeck_results, &body.value);
let path: Vec<&str> = path.iter().map(|x| {
if let Constant::Str(s) = x {
s.as_str()
} else {
// We checked the type of the constant above
unreachable!()
}
}).collect();
if !check_path(cx, &path[..]);
then {
span_lint(cx, CLIPPY_LINTS_INTERNAL, item.span, "invalid path");
}
}
}
}
#[derive(Default)]
pub struct InterningDefinedSymbol {
// Maps the symbol value to the constant DefId.
symbol_map: FxHashMap<u32, DefId>,
}
impl_lint_pass!(InterningDefinedSymbol => [INTERNING_DEFINED_SYMBOL, UNNECESSARY_SYMBOL_STR]);
impl<'tcx> LateLintPass<'tcx> for InterningDefinedSymbol {
fn check_crate(&mut self, cx: &LateContext<'_>, _: &Crate<'_>) {
if !self.symbol_map.is_empty() {
return;
}
for &module in &[&paths::KW_MODULE, &paths::SYM_MODULE] {
if let Some(def_id) = path_to_res(cx, module).opt_def_id() {
for item in cx.tcx.item_children(def_id).iter() {
if_chain! {
if let Res::Def(DefKind::Const, item_def_id) = item.res;
let ty = cx.tcx.type_of(item_def_id);
if match_type(cx, ty, &paths::SYMBOL);
if let Ok(ConstValue::Scalar(value)) = cx.tcx.const_eval_poly(item_def_id);
if let Ok(value) = value.to_u32();
then {
self.symbol_map.insert(value, item_def_id);
}
}
}
}
}
}
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if_chain! {
if let ExprKind::Call(func, [arg]) = &expr.kind;
if let ty::FnDef(def_id, _) = cx.typeck_results().expr_ty(func).kind();
if match_def_path(cx, *def_id, &paths::SYMBOL_INTERN);
if let Some(Constant::Str(arg)) = constant_simple(cx, cx.typeck_results(), arg);
let value = Symbol::intern(&arg).as_u32();
if let Some(&def_id) = self.symbol_map.get(&value);
then {
span_lint_and_sugg(
cx,
INTERNING_DEFINED_SYMBOL,
is_expn_of(expr.span, "sym").unwrap_or(expr.span),
"interning a defined symbol",
"try",
cx.tcx.def_path_str(def_id),
Applicability::MachineApplicable,
);
}
}
if let ExprKind::Binary(op, left, right) = expr.kind {
if matches!(op.node, BinOpKind::Eq | BinOpKind::Ne) {
let data = [
(left, self.symbol_str_expr(left, cx)),
(right, self.symbol_str_expr(right, cx)),
];
match data {
// both operands are a symbol string
[(_, Some(left)), (_, Some(right))] => {
span_lint_and_sugg(
cx,
UNNECESSARY_SYMBOL_STR,
expr.span,
"unnecessary `Symbol` to string conversion",
"try",
format!(
"{} {} {}",
left.as_symbol_snippet(cx),
op.node.as_str(),
right.as_symbol_snippet(cx),
),
Applicability::MachineApplicable,
);
},
// one of the operands is a symbol string
[(expr, Some(symbol)), _] | [_, (expr, Some(symbol))] => {
// creating an owned string for comparison
if matches!(symbol, SymbolStrExpr::Expr { is_to_owned: true, .. }) {
span_lint_and_sugg(
cx,
UNNECESSARY_SYMBOL_STR,
expr.span,
"unnecessary string allocation",
"try",
format!("{}.as_str()", symbol.as_symbol_snippet(cx)),
Applicability::MachineApplicable,
);
}
},
// nothing found
[(_, None), (_, None)] => {},
}
}
}
}
}
impl InterningDefinedSymbol {
fn symbol_str_expr<'tcx>(&self, expr: &'tcx Expr<'tcx>, cx: &LateContext<'tcx>) -> Option<SymbolStrExpr<'tcx>> {
static IDENT_STR_PATHS: &[&[&str]] = &[&paths::IDENT_AS_STR, &paths::TO_STRING_METHOD];
static SYMBOL_STR_PATHS: &[&[&str]] = &[
&paths::SYMBOL_AS_STR,
&paths::SYMBOL_TO_IDENT_STRING,
&paths::TO_STRING_METHOD,
];
// SymbolStr might be de-referenced: `&*symbol.as_str()`
let call = if_chain! {
if let ExprKind::AddrOf(_, _, e) = expr.kind;
if let ExprKind::Unary(UnOp::Deref, e) = e.kind;
then { e } else { expr }
};
if_chain! {
// is a method call
if let ExprKind::MethodCall(_, _, [item], _) = call.kind;
if let Some(did) = cx.typeck_results().type_dependent_def_id(call.hir_id);
let ty = cx.typeck_results().expr_ty(item);
// ...on either an Ident or a Symbol
if let Some(is_ident) = if match_type(cx, ty, &paths::SYMBOL) {
Some(false)
} else if match_type(cx, ty, &paths::IDENT) {
Some(true)
} else {
None
};
// ...which converts it to a string
let paths = if is_ident { IDENT_STR_PATHS } else { SYMBOL_STR_PATHS };
if let Some(path) = paths.iter().find(|path| match_def_path(cx, did, path));
then {
let is_to_owned = path.last().unwrap().ends_with("string");
return Some(SymbolStrExpr::Expr {
item,
is_ident,
is_to_owned,
});
}
}
// is a string constant
if let Some(Constant::Str(s)) = constant_simple(cx, cx.typeck_results(), expr) {
let value = Symbol::intern(&s).as_u32();
// ...which matches a symbol constant
if let Some(&def_id) = self.symbol_map.get(&value) {
return Some(SymbolStrExpr::Const(def_id));
}
}
None
}
}
enum SymbolStrExpr<'tcx> {
/// a string constant with a corresponding symbol constant
Const(DefId),
/// a "symbol to string" expression like `symbol.as_str()`
Expr {
/// part that evaluates to `Symbol` or `Ident`
item: &'tcx Expr<'tcx>,
is_ident: bool,
/// whether an owned `String` is created like `to_ident_string()`
is_to_owned: bool,
},
}
impl<'tcx> SymbolStrExpr<'tcx> {
/// Returns a snippet that evaluates to a `Symbol` and is const if possible
fn as_symbol_snippet(&self, cx: &LateContext<'_>) -> Cow<'tcx, str> {
match *self {
Self::Const(def_id) => cx.tcx.def_path_str(def_id).into(),
Self::Expr { item, is_ident, .. } => {
let mut snip = snippet(cx, item.span.source_callsite(), "..");
if is_ident {
// get `Ident.name`
snip.to_mut().push_str(".name");
}
snip
},
}
}
}
declare_lint_pass!(IfChainStyle => [IF_CHAIN_STYLE]);
impl<'tcx> LateLintPass<'tcx> for IfChainStyle {
fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx hir::Block<'_>) {
let (local, after, if_chain_span) = if_chain! {
if let [Stmt { kind: StmtKind::Local(local), .. }, after @ ..] = block.stmts;
if let Some(if_chain_span) = is_expn_of(block.span, "if_chain");
then { (local, after, if_chain_span) } else { return }
};
if is_first_if_chain_expr(cx, block.hir_id, if_chain_span) {
span_lint(
cx,
IF_CHAIN_STYLE,
if_chain_local_span(cx, local, if_chain_span),
"`let` expression should be above the `if_chain!`",
);
} else if local.span.ctxt() == block.span.ctxt() && is_if_chain_then(after, block.expr, if_chain_span) {
span_lint(
cx,
IF_CHAIN_STYLE,
if_chain_local_span(cx, local, if_chain_span),
"`let` expression should be inside `then { .. }`",
)
}
}
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
let (cond, then, els) = match expr.kind {
ExprKind::If(cond, then, els) => (Some(cond), then, els.is_some()),
ExprKind::Match(
_,
[arm, ..],
MatchSource::IfLetDesugar {
contains_else_clause: els,
},
) => (None, arm.body, els),
_ => return,
};
let then_block = match then.kind {
ExprKind::Block(block, _) => block,
_ => return,
};
let if_chain_span = is_expn_of(expr.span, "if_chain");
if !els {
check_nested_if_chains(cx, expr, then_block, if_chain_span);
}
let if_chain_span = match if_chain_span {
None => return,
Some(span) => span,
};
// check for `if a && b;`
if_chain! {
if let Some(cond) = cond;
if let ExprKind::Binary(op, _, _) = cond.kind;
if op.node == BinOpKind::And;
if cx.sess().source_map().is_multiline(cond.span);
then {
span_lint(cx, IF_CHAIN_STYLE, cond.span, "`if a && b;` should be `if a; if b;`");
}
}
if is_first_if_chain_expr(cx, expr.hir_id, if_chain_span)
&& is_if_chain_then(then_block.stmts, then_block.expr, if_chain_span)
{
span_lint(cx, IF_CHAIN_STYLE, expr.span, "`if_chain!` only has one `if`")
}
}
}
fn check_nested_if_chains(
cx: &LateContext<'_>,
if_expr: &Expr<'_>,
then_block: &Block<'_>,
if_chain_span: Option<Span>,
) {
#[rustfmt::skip]
let (head, tail) = match *then_block {
Block { stmts, expr: Some(tail), .. } => (stmts, tail),
Block {
stmts: &[
ref head @ ..,
Stmt { kind: StmtKind::Expr(tail) | StmtKind::Semi(tail), .. }
],
..
} => (head, tail),
_ => return,
};
if_chain! {
if matches!(tail.kind,
ExprKind::If(_, _, None)
| ExprKind::Match(.., MatchSource::IfLetDesugar { contains_else_clause: false }));
let sm = cx.sess().source_map();
if head
.iter()
.all(|stmt| matches!(stmt.kind, StmtKind::Local(..)) && !sm.is_multiline(stmt.span));
if if_chain_span.is_some() || !is_else_clause(cx.tcx, if_expr);
then {} else { return }
}
let (span, msg) = match (if_chain_span, is_expn_of(tail.span, "if_chain")) {
(None, Some(_)) => (if_expr.span, "this `if` can be part of the inner `if_chain!`"),
(Some(_), None) => (tail.span, "this `if` can be part of the outer `if_chain!`"),
(Some(a), Some(b)) if a != b => (b, "this `if_chain!` can be merged with the outer `if_chain!`"),
_ => return,
};
span_lint_and_then(cx, IF_CHAIN_STYLE, span, msg, |diag| {
let (span, msg) = match head {
[] => return,
[stmt] => (stmt.span, "this `let` statement can also be in the `if_chain!`"),
[a, .., b] => (
a.span.to(b.span),
"these `let` statements can also be in the `if_chain!`",
),
};
diag.span_help(span, msg);
});
}
fn is_first_if_chain_expr(cx: &LateContext<'_>, hir_id: HirId, if_chain_span: Span) -> bool {
cx.tcx
.hir()
.parent_iter(hir_id)
.find(|(_, node)| {
#[rustfmt::skip]
!matches!(node, Node::Expr(Expr { kind: ExprKind::Block(..), .. }) | Node::Stmt(_))
})
.map_or(false, |(id, _)| {
is_expn_of(cx.tcx.hir().span(id), "if_chain") != Some(if_chain_span)
})
}
/// Checks a trailing slice of statements and expression of a `Block` to see if they are part
/// of the `then {..}` portion of an `if_chain!`
fn is_if_chain_then(stmts: &[Stmt<'_>], expr: Option<&Expr<'_>>, if_chain_span: Span) -> bool {
let span = if let [stmt, ..] = stmts {
stmt.span
} else if let Some(expr) = expr {
expr.span
} else {
// empty `then {}`
return true;
};
is_expn_of(span, "if_chain").map_or(true, |span| span != if_chain_span)
}
/// Creates a `Span` for `let x = ..;` in an `if_chain!` call.
fn if_chain_local_span(cx: &LateContext<'_>, local: &Local<'_>, if_chain_span: Span) -> Span {
let mut span = local.pat.span;
if let Some(init) = local.init {
span = span.to(init.span);
}
span.adjust(if_chain_span.ctxt().outer_expn());
let sm = cx.sess().source_map();
let span = sm.span_extend_to_prev_str(span, "let", false);
let span = sm.span_extend_to_next_char(span, ';', false);
Span::new(span.lo() - BytePos(3), span.hi() + BytePos(1), span.ctxt())
}