-use rustc::hir;
-use rustc::hir::def::{Res, DefKind};
-use rustc::hir::def_id::DefId;
-use rustc::lint;
-use rustc::lint::builtin::UNUSED_ATTRIBUTES;
-use rustc::ty::{self, Ty};
-use rustc::ty::adjustment;
+use crate::Lint;
+use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
+use rustc_ast::ast;
+use rustc_ast::ast::{ExprKind, StmtKind};
+use rustc_ast::attr;
+use rustc_ast::util::parser;
+use rustc_ast_pretty::pprust;
use rustc_data_structures::fx::FxHashMap;
-use lint::{LateContext, EarlyContext, LintContext, LintArray};
-use lint::{LintPass, EarlyLintPass, LateLintPass};
+use rustc_errors::{pluralize, Applicability};
use rustc_feature::{AttributeType, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
-
-use syntax::ast;
-use syntax::attr;
-use syntax::errors::{Applicability, pluralize};
-use syntax::print::pprust;
-use syntax::symbol::{kw, sym};
-use syntax::symbol::Symbol;
-use syntax::util::parser;
-use syntax_pos::{Span, BytePos};
+use rustc_hir as hir;
+use rustc_hir::def::{DefKind, Res};
+use rustc_hir::def_id::DefId;
+use rustc_middle::ty::adjustment;
+use rustc_middle::ty::{self, Ty};
+use rustc_session::lint::builtin::UNUSED_ATTRIBUTES;
+use rustc_span::symbol::Symbol;
+use rustc_span::symbol::{kw, sym};
+use rustc_span::{BytePos, Span, DUMMY_SP};
use log::debug;
declare_lint_pass!(UnusedResults => [UNUSED_MUST_USE, UNUSED_RESULTS]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
- fn check_stmt(&mut self, cx: &LateContext<'_, '_>, s: &hir::Stmt) {
+ fn check_stmt(&mut self, cx: &LateContext<'_, '_>, s: &hir::Stmt<'_>) {
let expr = match s.kind {
hir::StmtKind::Semi(ref expr) => &**expr,
_ => return,
match callee.kind {
hir::ExprKind::Path(ref qpath) => {
match cx.tables.qpath_res(qpath, callee.hir_id) {
- Res::Def(DefKind::Fn, def_id)
- | Res::Def(DefKind::Method, def_id) => Some(def_id),
+ Res::Def(DefKind::Fn | DefKind::AssocFn, def_id) => Some(def_id),
// `Res::Local` if it was a closure, for which we
// do not currently support must-use linting
- _ => None
+ _ => None,
}
- },
- _ => None
+ }
+ _ => None,
}
- },
- hir::ExprKind::MethodCall(..) => {
- cx.tables.type_dependent_def_id(expr.hir_id)
- },
- _ => None
+ }
+ hir::ExprKind::MethodCall(..) => cx.tables.type_dependent_def_id(expr.hir_id),
+ _ => None,
};
if let Some(def_id) = maybe_def_id {
fn_warned = check_must_use_def(cx, def_id, s.span, "return value of ", "");
// Hardcoding operators here seemed more expedient than the
// refactoring that would be needed to look up the `#[must_use]`
// attribute which does exist on the comparison trait methods
- hir::ExprKind::Binary(bin_op, ..) => {
- match bin_op.node {
- hir::BinOpKind::Eq |
- hir::BinOpKind::Lt |
- hir::BinOpKind::Le |
- hir::BinOpKind::Ne |
- hir::BinOpKind::Ge |
- hir::BinOpKind::Gt => {
- Some("comparison")
- },
- hir::BinOpKind::Add |
- hir::BinOpKind::Sub |
- hir::BinOpKind::Div |
- hir::BinOpKind::Mul |
- hir::BinOpKind::Rem => {
- Some("arithmetic operation")
- },
- hir::BinOpKind::And | hir::BinOpKind::Or => {
- Some("logical operation")
- },
- hir::BinOpKind::BitXor |
- hir::BinOpKind::BitAnd |
- hir::BinOpKind::BitOr |
- hir::BinOpKind::Shl |
- hir::BinOpKind::Shr => {
- Some("bitwise operation")
- },
- }
+ hir::ExprKind::Binary(bin_op, ..) => match bin_op.node {
+ hir::BinOpKind::Eq
+ | hir::BinOpKind::Lt
+ | hir::BinOpKind::Le
+ | hir::BinOpKind::Ne
+ | hir::BinOpKind::Ge
+ | hir::BinOpKind::Gt => Some("comparison"),
+ hir::BinOpKind::Add
+ | hir::BinOpKind::Sub
+ | hir::BinOpKind::Div
+ | hir::BinOpKind::Mul
+ | hir::BinOpKind::Rem => Some("arithmetic operation"),
+ hir::BinOpKind::And | hir::BinOpKind::Or => Some("logical operation"),
+ hir::BinOpKind::BitXor
+ | hir::BinOpKind::BitAnd
+ | hir::BinOpKind::BitOr
+ | hir::BinOpKind::Shl
+ | hir::BinOpKind::Shr => Some("bitwise operation"),
},
hir::ExprKind::Unary(..) => Some("unary operation"),
- _ => None
+ _ => None,
};
if let Some(must_use_op) = must_use_op {
- cx.span_lint(UNUSED_MUST_USE, expr.span,
- &format!("unused {} that must be used", must_use_op));
+ cx.struct_span_lint(UNUSED_MUST_USE, expr.span, |lint| {
+ lint.build(&format!("unused {} that must be used", must_use_op)).emit()
+ });
op_warned = true;
}
if !(type_permits_lack_of_use || fn_warned || op_warned) {
- cx.span_lint(UNUSED_RESULTS, s.span, "unused result");
+ cx.struct_span_lint(UNUSED_RESULTS, s.span, |lint| lint.build("unused result").emit());
}
// Returns whether an error has been emitted (and thus another does not need to be later).
fn check_must_use_ty<'tcx>(
cx: &LateContext<'_, 'tcx>,
ty: Ty<'tcx>,
- expr: &hir::Expr,
+ expr: &hir::Expr<'_>,
span: Span,
descr_pre: &str,
descr_post: &str,
plural_len: usize,
) -> bool {
- if ty.is_unit() || cx.tcx.is_ty_uninhabited_from(
- cx.tcx.hir().get_module_parent(expr.hir_id), ty)
+ if ty.is_unit()
+ || cx.tcx.is_ty_uninhabited_from(
+ cx.tcx.parent_module(expr.hir_id).to_def_id(),
+ ty,
+ cx.param_env,
+ )
{
return true;
}
let descr_pre = &format!("{}boxed ", descr_pre);
check_must_use_ty(cx, boxed_ty, expr, span, descr_pre, descr_post, plural_len)
}
- ty::Adt(def, _) => {
- check_must_use_def(cx, def.did, span, descr_pre, descr_post)
- }
+ ty::Adt(def, _) => check_must_use_def(cx, def.did, span, descr_pre, descr_post),
ty::Opaque(def, _) => {
let mut has_emitted = false;
for (predicate, _) in cx.tcx.predicates_of(def).predicates {
- if let ty::Predicate::Trait(ref poly_trait_predicate) = predicate {
+ if let ty::Predicate::Trait(ref poly_trait_predicate, _) = predicate {
let trait_ref = poly_trait_predicate.skip_binder().trait_ref;
let def_id = trait_ref.def_id;
- let descr_pre = &format!(
- "{}implementer{} of ",
- descr_pre,
- plural_suffix,
- );
+ let descr_pre =
+ &format!("{}implementer{} of ", descr_pre, plural_suffix,);
if check_must_use_def(cx, def_id, span, descr_pre, descr_post) {
has_emitted = true;
break;
for predicate in binder.skip_binder().iter() {
if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate {
let def_id = trait_ref.def_id;
- let descr_post = &format!(
- " trait object{}{}",
- plural_suffix,
- descr_post,
- );
+ let descr_post =
+ &format!(" trait object{}{}", plural_suffix, descr_post,);
if check_must_use_def(cx, def_id, span, descr_pre, descr_post) {
has_emitted = true;
break;
for (i, ty) in tys.iter().map(|k| k.expect_ty()).enumerate() {
let descr_post = &format!(" in tuple element {}", i);
let span = *spans.get(i).unwrap_or(&span);
- if check_must_use_ty(
- cx,
- ty,
- expr,
- span,
- descr_pre,
- descr_post,
- plural_len
- ) {
+ if check_must_use_ty(cx, ty, expr, span, descr_pre, descr_post, plural_len)
+ {
has_emitted = true;
}
}
ty::Array(ty, len) => match len.try_eval_usize(cx.tcx, cx.param_env) {
// If the array is definitely non-empty, we can do `#[must_use]` checking.
Some(n) if n != 0 => {
- let descr_pre = &format!(
- "{}array{} of ",
- descr_pre,
- plural_suffix,
- );
+ let descr_pre = &format!("{}array{} of ", descr_pre, plural_suffix,);
check_must_use_ty(cx, ty, expr, span, descr_pre, descr_post, n as usize + 1)
}
// Otherwise, we don't lint, to avoid false positives.
_ => false,
- }
+ },
_ => false,
}
}
// Returns whether an error has been emitted (and thus another does not need to be later).
+ // FIXME: Args desc_{pre,post}_path could be made lazy by taking Fn() -> &str, but this
+ // would make calling it a big awkward. Could also take String (so args are moved), but
+ // this would still require a copy into the format string, which would only be executed
+ // when needed.
fn check_must_use_def(
cx: &LateContext<'_, '_>,
def_id: DefId,
) -> bool {
for attr in cx.tcx.get_attrs(def_id).iter() {
if attr.check_name(sym::must_use) {
- let msg = format!("unused {}`{}`{} that must be used",
- descr_pre_path, cx.tcx.def_path_str(def_id), descr_post_path);
- let mut err = cx.struct_span_lint(UNUSED_MUST_USE, span, &msg);
- // check for #[must_use = "..."]
- if let Some(note) = attr.value_str() {
- err.note(¬e.as_str());
- }
- err.emit();
+ cx.struct_span_lint(UNUSED_MUST_USE, span, |lint| {
+ let msg = format!(
+ "unused {}`{}`{} that must be used",
+ descr_pre_path,
+ cx.tcx.def_path_str(def_id),
+ descr_post_path
+ );
+ let mut err = lint.build(&msg);
+ // check for #[must_use = "..."]
+ if let Some(note) = attr.value_str() {
+ err.note(¬e.as_str());
+ }
+ err.emit();
+ });
return true;
}
}
declare_lint_pass!(PathStatements => [PATH_STATEMENTS]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PathStatements {
- fn check_stmt(&mut self, cx: &LateContext<'_, '_>, s: &hir::Stmt) {
+ fn check_stmt(&mut self, cx: &LateContext<'_, '_>, s: &hir::Stmt<'_>) {
if let hir::StmtKind::Semi(ref expr) = s.kind {
if let hir::ExprKind::Path(_) = expr.kind {
- cx.span_lint(PATH_STATEMENTS, s.span, "path statement with no effect");
+ cx.struct_span_lint(PATH_STATEMENTS, s.span, |lint| {
+ lint.build("path statement with no effect").emit()
+ });
}
}
}
impl UnusedAttributes {
pub fn new() -> Self {
- UnusedAttributes {
- builtin_attributes: &*BUILTIN_ATTRIBUTE_MAP,
- }
+ UnusedAttributes { builtin_attributes: &*BUILTIN_ATTRIBUTE_MAP }
}
}
fn check_attribute(&mut self, cx: &LateContext<'_, '_>, attr: &ast::Attribute) {
debug!("checking attribute: {:?}", attr);
+ if attr.is_doc_comment() {
+ return;
+ }
+
let attr_info = attr.ident().and_then(|ident| self.builtin_attributes.get(&ident.name));
if let Some(&&(name, ty, ..)) = attr_info {
- match ty {
- AttributeType::Whitelisted => {
- debug!("{:?} is Whitelisted", name);
- return;
- }
- _ => (),
+ if let AttributeType::Whitelisted = ty {
+ debug!("{:?} is Whitelisted", name);
+ return;
}
}
if !attr::is_used(attr) {
debug!("emitting warning for: {:?}", attr);
- cx.span_lint(UNUSED_ATTRIBUTES, attr.span, "unused attribute");
+ cx.struct_span_lint(UNUSED_ATTRIBUTES, attr.span, |lint| {
+ lint.build("unused attribute").emit()
+ });
// Is it a builtin attribute that must be used at the crate level?
if attr_info.map_or(false, |(_, ty, ..)| ty == &AttributeType::CrateLevel) {
- let msg = match attr.style {
- ast::AttrStyle::Outer => {
- "crate-level attribute should be an inner attribute: add an exclamation \
- mark: `#![foo]`"
- }
- ast::AttrStyle::Inner => "crate-level attribute should be in the root module",
- };
- cx.span_lint(UNUSED_ATTRIBUTES, attr.span, msg);
+ cx.struct_span_lint(UNUSED_ATTRIBUTES, attr.span, |lint| {
+ let msg = match attr.style {
+ ast::AttrStyle::Outer => {
+ "crate-level attribute should be an inner attribute: add an exclamation \
+ mark: `#![foo]`"
+ }
+ ast::AttrStyle::Inner => "crate-level attribute should be in the root module",
+ };
+ lint.build(msg).emit()
+ });
}
} else {
debug!("Attr was used: {:?}", attr);
}
}
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+enum UnusedDelimsCtx {
+ FunctionArg,
+ MethodArg,
+ AssignedValue,
+ IfCond,
+ WhileCond,
+ ForIterExpr,
+ MatchScrutineeExpr,
+ ReturnValue,
+ BlockRetValue,
+ LetScrutineeExpr,
+ ArrayLenExpr,
+ AnonConst,
+}
+
+impl From<UnusedDelimsCtx> for &'static str {
+ fn from(ctx: UnusedDelimsCtx) -> &'static str {
+ match ctx {
+ UnusedDelimsCtx::FunctionArg => "function argument",
+ UnusedDelimsCtx::MethodArg => "method argument",
+ UnusedDelimsCtx::AssignedValue => "assigned value",
+ UnusedDelimsCtx::IfCond => "`if` condition",
+ UnusedDelimsCtx::WhileCond => "`while` condition",
+ UnusedDelimsCtx::ForIterExpr => "`for` iterator expression",
+ UnusedDelimsCtx::MatchScrutineeExpr => "`match` scrutinee expression",
+ UnusedDelimsCtx::ReturnValue => "`return` value",
+ UnusedDelimsCtx::BlockRetValue => "block return value",
+ UnusedDelimsCtx::LetScrutineeExpr => "`let` scrutinee expression",
+ UnusedDelimsCtx::ArrayLenExpr | UnusedDelimsCtx::AnonConst => "const expression",
+ }
+ }
+}
+
+/// Used by both `UnusedParens` and `UnusedBraces` to prevent code duplication.
+trait UnusedDelimLint {
+ const DELIM_STR: &'static str;
+
+ /// Due to `ref` pattern, there can be a difference between using
+ /// `{ expr }` and `expr` in pattern-matching contexts. This means
+ /// that we should only lint `unused_parens` and not `unused_braces`
+ /// in this case.
+ ///
+ /// ```rust
+ /// let mut a = 7;
+ /// let ref b = { a }; // We actually borrow a copy of `a` here.
+ /// a += 1; // By mutating `a` we invalidate any borrows of `a`.
+ /// assert_eq!(b + 1, a); // `b` does not borrow `a`, so we can still use it here.
+ /// ```
+ const LINT_EXPR_IN_PATTERN_MATCHING_CTX: bool;
+
+ // this cannot be a constant is it refers to a static.
+ fn lint(&self) -> &'static Lint;
+
+ fn check_unused_delims_expr(
+ &self,
+ cx: &EarlyContext<'_>,
+ value: &ast::Expr,
+ ctx: UnusedDelimsCtx,
+ followed_by_block: bool,
+ left_pos: Option<BytePos>,
+ right_pos: Option<BytePos>,
+ );
+
+ fn is_expr_delims_necessary(inner: &ast::Expr, followed_by_block: bool) -> bool {
+ followed_by_block
+ && match inner.kind {
+ ExprKind::Ret(_) | ExprKind::Break(..) => true,
+ _ => parser::contains_exterior_struct_lit(&inner),
+ }
+ }
+
+ fn emit_unused_delims_expr(
+ &self,
+ cx: &EarlyContext<'_>,
+ value: &ast::Expr,
+ ctx: UnusedDelimsCtx,
+ left_pos: Option<BytePos>,
+ right_pos: Option<BytePos>,
+ ) {
+ let expr_text = if let Ok(snippet) = cx.sess().source_map().span_to_snippet(value.span) {
+ snippet
+ } else {
+ pprust::expr_to_string(value)
+ };
+ let keep_space = (
+ left_pos.map(|s| s >= value.span.lo()).unwrap_or(false),
+ right_pos.map(|s| s <= value.span.hi()).unwrap_or(false),
+ );
+ self.emit_unused_delims(cx, value.span, &expr_text, ctx.into(), keep_space);
+ }
+
+ fn emit_unused_delims(
+ &self,
+ cx: &EarlyContext<'_>,
+ span: Span,
+ pattern: &str,
+ msg: &str,
+ keep_space: (bool, bool),
+ ) {
+ // FIXME(flip1995): Quick and dirty fix for #70814. This should be fixed in rustdoc
+ // properly.
+ if span == DUMMY_SP {
+ return;
+ }
+
+ cx.struct_span_lint(self.lint(), span, |lint| {
+ let span_msg = format!("unnecessary {} around {}", Self::DELIM_STR, msg);
+ let mut err = lint.build(&span_msg);
+ let mut ate_left_paren = false;
+ let mut ate_right_paren = false;
+ let parens_removed = pattern.trim_matches(|c| match c {
+ '(' | '{' => {
+ if ate_left_paren {
+ false
+ } else {
+ ate_left_paren = true;
+ true
+ }
+ }
+ ')' | '}' => {
+ if ate_right_paren {
+ false
+ } else {
+ ate_right_paren = true;
+ true
+ }
+ }
+ _ => false,
+ });
+
+ let replace = {
+ let mut replace = if keep_space.0 {
+ let mut s = String::from(" ");
+ s.push_str(parens_removed);
+ s
+ } else {
+ String::from(parens_removed)
+ };
+
+ if keep_space.1 {
+ replace.push(' ');
+ }
+ replace
+ };
+
+ let suggestion = format!("remove these {}", Self::DELIM_STR);
+
+ err.span_suggestion_short(span, &suggestion, replace, Applicability::MachineApplicable);
+ err.emit();
+ });
+ }
+
+ fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
+ use rustc_ast::ast::ExprKind::*;
+ let (value, ctx, followed_by_block, left_pos, right_pos) = match e.kind {
+ // Do not lint `unused_braces` in `if let` expressions.
+ If(ref cond, ref block, ..)
+ if !matches!(cond.kind, Let(_, _)) || Self::LINT_EXPR_IN_PATTERN_MATCHING_CTX =>
+ {
+ let left = e.span.lo() + rustc_span::BytePos(2);
+ let right = block.span.lo();
+ (cond, UnusedDelimsCtx::IfCond, true, Some(left), Some(right))
+ }
+
+ While(ref cond, ref block, ..) => {
+ let left = e.span.lo() + rustc_span::BytePos(5);
+ let right = block.span.lo();
+ (cond, UnusedDelimsCtx::WhileCond, true, Some(left), Some(right))
+ }
+
+ ForLoop(_, ref cond, ref block, ..) => {
+ (cond, UnusedDelimsCtx::ForIterExpr, true, None, Some(block.span.lo()))
+ }
+
+ Match(ref head, _) if Self::LINT_EXPR_IN_PATTERN_MATCHING_CTX => {
+ let left = e.span.lo() + rustc_span::BytePos(5);
+ (head, UnusedDelimsCtx::MatchScrutineeExpr, true, Some(left), None)
+ }
+
+ Ret(Some(ref value)) => {
+ let left = e.span.lo() + rustc_span::BytePos(3);
+ (value, UnusedDelimsCtx::ReturnValue, false, Some(left), None)
+ }
+
+ Assign(_, ref value, _) | AssignOp(.., ref value) => {
+ (value, UnusedDelimsCtx::AssignedValue, false, None, None)
+ }
+ // either function/method call, or something this lint doesn't care about
+ ref call_or_other => {
+ let (args_to_check, ctx) = match *call_or_other {
+ Call(_, ref args) => (&args[..], UnusedDelimsCtx::FunctionArg),
+ // first "argument" is self (which sometimes needs delims)
+ MethodCall(_, ref args) => (&args[1..], UnusedDelimsCtx::MethodArg),
+ // actual catch-all arm
+ _ => {
+ return;
+ }
+ };
+ // Don't lint if this is a nested macro expansion: otherwise, the lint could
+ // trigger in situations that macro authors shouldn't have to care about, e.g.,
+ // when a parenthesized token tree matched in one macro expansion is matched as
+ // an expression in another and used as a fn/method argument (Issue #47775)
+ if e.span.ctxt().outer_expn_data().call_site.from_expansion() {
+ return;
+ }
+ for arg in args_to_check {
+ self.check_unused_delims_expr(cx, arg, ctx, false, None, None);
+ }
+ return;
+ }
+ };
+ self.check_unused_delims_expr(cx, &value, ctx, followed_by_block, left_pos, right_pos);
+ }
+
+ fn check_stmt(&mut self, cx: &EarlyContext<'_>, s: &ast::Stmt) {
+ match s.kind {
+ StmtKind::Local(ref local) if Self::LINT_EXPR_IN_PATTERN_MATCHING_CTX => {
+ if let Some(ref value) = local.init {
+ self.check_unused_delims_expr(
+ cx,
+ &value,
+ UnusedDelimsCtx::AssignedValue,
+ false,
+ None,
+ None,
+ );
+ }
+ }
+ StmtKind::Expr(ref expr) => {
+ self.check_unused_delims_expr(
+ cx,
+ &expr,
+ UnusedDelimsCtx::BlockRetValue,
+ false,
+ None,
+ None,
+ );
+ }
+ _ => {}
+ }
+ }
+
+ fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
+ use ast::ItemKind::*;
+
+ if let Const(.., Some(expr)) | Static(.., Some(expr)) = &item.kind {
+ self.check_unused_delims_expr(
+ cx,
+ expr,
+ UnusedDelimsCtx::AssignedValue,
+ false,
+ None,
+ None,
+ );
+ }
+ }
+}
+
declare_lint! {
pub(super) UNUSED_PARENS,
Warn,
declare_lint_pass!(UnusedParens => [UNUSED_PARENS]);
-impl UnusedParens {
+impl UnusedDelimLint for UnusedParens {
+ const DELIM_STR: &'static str = "parentheses";
- fn is_expr_parens_necessary(inner: &ast::Expr, followed_by_block: bool) -> bool {
- followed_by_block && match inner.kind {
- ast::ExprKind::Ret(_) | ast::ExprKind::Break(..) => true,
- _ => parser::contains_exterior_struct_lit(&inner),
- }
+ const LINT_EXPR_IN_PATTERN_MATCHING_CTX: bool = true;
+
+ fn lint(&self) -> &'static Lint {
+ UNUSED_PARENS
}
- fn check_unused_parens_expr(&self,
- cx: &EarlyContext<'_>,
- value: &ast::Expr,
- msg: &str,
- followed_by_block: bool,
- left_pos: Option<BytePos>,
- right_pos: Option<BytePos>) {
+ fn check_unused_delims_expr(
+ &self,
+ cx: &EarlyContext<'_>,
+ value: &ast::Expr,
+ ctx: UnusedDelimsCtx,
+ followed_by_block: bool,
+ left_pos: Option<BytePos>,
+ right_pos: Option<BytePos>,
+ ) {
match value.kind {
ast::ExprKind::Paren(ref inner) => {
- if !Self::is_expr_parens_necessary(inner, followed_by_block) &&
- value.attrs.is_empty() &&
- !value.span.from_expansion()
+ if !Self::is_expr_delims_necessary(inner, followed_by_block)
+ && value.attrs.is_empty()
+ && !value.span.from_expansion()
{
- let expr_text = if let Ok(snippet) = cx.sess().source_map()
- .span_to_snippet(value.span) {
- snippet
- } else {
- pprust::expr_to_string(value)
- };
- let keep_space = (
- left_pos.map(|s| s >= value.span.lo()).unwrap_or(false),
- right_pos.map(|s| s <= value.span.hi()).unwrap_or(false),
- );
- Self::remove_outer_parens(cx, value.span, &expr_text, msg, keep_space);
+ self.emit_unused_delims_expr(cx, value, ctx, left_pos, right_pos)
}
}
ast::ExprKind::Let(_, ref expr) => {
// FIXME(#60336): Properly handle `let true = (false && true)`
// actually needing the parenthesis.
- self.check_unused_parens_expr(
- cx, expr,
- "`let` head expression",
+ self.check_unused_delims_expr(
+ cx,
+ expr,
+ UnusedDelimsCtx::LetScrutineeExpr,
followed_by_block,
- None, None
+ None,
+ None,
);
}
_ => {}
}
}
+}
+impl UnusedParens {
fn check_unused_parens_pat(
&self,
cx: &EarlyContext<'_>,
avoid_or: bool,
avoid_mut: bool,
) {
- use ast::{PatKind, BindingMode::ByValue, Mutability::Mutable};
+ use ast::{BindingMode, Mutability, PatKind};
if let PatKind::Paren(inner) = &value.kind {
match inner.kind {
// Avoid `p0 | .. | pn` if we should.
PatKind::Or(..) if avoid_or => return,
// Avoid `mut x` and `mut x @ p` if we should:
- PatKind::Ident(ByValue(Mutable), ..) if avoid_mut => return,
+ PatKind::Ident(BindingMode::ByValue(Mutability::Mut), ..) if avoid_mut => return,
// Otherwise proceed with linting.
_ => {}
}
- let pattern_text = if let Ok(snippet) = cx.sess().source_map()
- .span_to_snippet(value.span) {
+ let pattern_text =
+ if let Ok(snippet) = cx.sess().source_map().span_to_snippet(value.span) {
snippet
} else {
pprust::pat_to_string(value)
};
- Self::remove_outer_parens(cx, value.span, &pattern_text, "pattern", (false, false));
+ self.emit_unused_delims(cx, value.span, &pattern_text, "pattern", (false, false));
}
}
-
- fn remove_outer_parens(cx: &EarlyContext<'_>,
- span: Span,
- pattern: &str,
- msg: &str,
- keep_space: (bool, bool)) {
- let span_msg = format!("unnecessary parentheses around {}", msg);
- let mut err = cx.struct_span_lint(UNUSED_PARENS, span, &span_msg);
- let mut ate_left_paren = false;
- let mut ate_right_paren = false;
- let parens_removed = pattern
- .trim_matches(|c| {
- match c {
- '(' => {
- if ate_left_paren {
- false
- } else {
- ate_left_paren = true;
- true
- }
- },
- ')' => {
- if ate_right_paren {
- false
- } else {
- ate_right_paren = true;
- true
- }
- },
- _ => false,
- }
- });
-
- let replace = {
- let mut replace = if keep_space.0 {
- let mut s = String::from(" ");
- s.push_str(parens_removed);
- s
- } else {
- String::from(parens_removed)
- };
-
- if keep_space.1 {
- replace.push(' ');
- }
- replace
- };
-
- err.span_suggestion_short(
- span,
- "remove these parentheses",
- replace,
- Applicability::MachineApplicable,
- );
- err.emit();
- }
}
impl EarlyLintPass for UnusedParens {
fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
- use syntax::ast::ExprKind::*;
- let (value, msg, followed_by_block, left_pos, right_pos) = match e.kind {
- Let(ref pat, ..) => {
- self.check_unused_parens_pat(cx, pat, false, false);
- return;
- }
-
- If(ref cond, ref block, ..) => {
- let left = e.span.lo() + syntax_pos::BytePos(2);
- let right = block.span.lo();
- (cond, "`if` condition", true, Some(left), Some(right))
- }
-
- While(ref cond, ref block, ..) => {
- let left = e.span.lo() + syntax_pos::BytePos(5);
- let right = block.span.lo();
- (cond, "`while` condition", true, Some(left), Some(right))
- },
-
- ForLoop(ref pat, ref cond, ref block, ..) => {
- self.check_unused_parens_pat(cx, pat, false, false);
- (cond, "`for` head expression", true, None, Some(block.span.lo()))
- }
-
- Match(ref head, _) => {
- let left = e.span.lo() + syntax_pos::BytePos(5);
- (head, "`match` head expression", true, Some(left), None)
- }
-
- Ret(Some(ref value)) => {
- let left = e.span.lo() + syntax_pos::BytePos(3);
- (value, "`return` value", false, Some(left), None)
- }
+ if let ExprKind::Let(ref pat, ..) | ExprKind::ForLoop(ref pat, ..) = e.kind {
+ self.check_unused_parens_pat(cx, pat, false, false);
+ }
- Assign(_, ref value) => (value, "assigned value", false, None, None),
- AssignOp(.., ref value) => (value, "assigned value", false, None, None),
- // either function/method call, or something this lint doesn't care about
- ref call_or_other => {
- let (args_to_check, call_kind) = match *call_or_other {
- Call(_, ref args) => (&args[..], "function"),
- // first "argument" is self (which sometimes needs parens)
- MethodCall(_, ref args) => (&args[1..], "method"),
- // actual catch-all arm
- _ => {
- return;
- }
- };
- // Don't lint if this is a nested macro expansion: otherwise, the lint could
- // trigger in situations that macro authors shouldn't have to care about, e.g.,
- // when a parenthesized token tree matched in one macro expansion is matched as
- // an expression in another and used as a fn/method argument (Issue #47775)
- if e.span.ctxt().outer_expn_data().call_site.from_expansion() {
- return;
- }
- let msg = format!("{} argument", call_kind);
- for arg in args_to_check {
- self.check_unused_parens_expr(cx, arg, &msg, false, None, None);
- }
- return;
- }
- };
- self.check_unused_parens_expr(cx, &value, msg, followed_by_block, left_pos, right_pos);
+ <Self as UnusedDelimLint>::check_expr(self, cx, e)
}
fn check_pat(&mut self, cx: &EarlyContext<'_>, p: &ast::Pat) {
- use ast::{PatKind::*, Mutability};
+ use ast::{Mutability, PatKind::*};
match &p.kind {
// Do not lint on `(..)` as that will result in the other arms being useless.
Paren(_)
// The other cases do not contain sub-patterns.
- | Wild | Rest | Lit(..) | Mac(..) | Range(..) | Ident(.., None) | Path(..) => return,
+ | Wild | Rest | Lit(..) | MacCall(..) | Range(..) | Ident(.., None) | Path(..) => {},
// These are list-like patterns; parens can always be removed.
TupleStruct(_, ps) | Tuple(ps) | Slice(ps) | Or(ps) => for p in ps {
self.check_unused_parens_pat(cx, p, false, false);
Ident(.., Some(p)) | Box(p) => self.check_unused_parens_pat(cx, p, true, false),
// Avoid linting on `&(mut x)` as `&mut x` has a different meaning, #55342.
// Also avoid linting on `& mut? (p0 | .. | pn)`, #64106.
- Ref(p, m) => self.check_unused_parens_pat(cx, p, true, *m == Mutability::Immutable),
+ Ref(p, m) => self.check_unused_parens_pat(cx, p, true, *m == Mutability::Not),
}
}
+ fn check_anon_const(&mut self, cx: &EarlyContext<'_>, c: &ast::AnonConst) {
+ self.check_unused_delims_expr(cx, &c.value, UnusedDelimsCtx::AnonConst, false, None, None);
+ }
+
fn check_stmt(&mut self, cx: &EarlyContext<'_>, s: &ast::Stmt) {
- if let ast::StmtKind::Local(ref local) = s.kind {
+ if let StmtKind::Local(ref local) = s.kind {
self.check_unused_parens_pat(cx, &local.pat, false, false);
-
- if let Some(ref value) = local.init {
- self.check_unused_parens_expr(cx, &value, "assigned value", false, None, None);
- }
}
+
+ <Self as UnusedDelimLint>::check_stmt(self, cx, s)
}
fn check_param(&mut self, cx: &EarlyContext<'_>, param: &ast::Param) {
match &r.kind {
&ast::TyKind::TraitObject(..) => {}
&ast::TyKind::ImplTrait(_, ref bounds) if bounds.len() > 1 => {}
+ &ast::TyKind::Array(_, ref len) => {
+ self.check_unused_delims_expr(
+ cx,
+ &len.value,
+ UnusedDelimsCtx::ArrayLenExpr,
+ false,
+ None,
+ None,
+ );
+ }
_ => {
- let pattern_text = if let Ok(snippet) = cx.sess().source_map()
- .span_to_snippet(ty.span) {
+ let pattern_text =
+ if let Ok(snippet) = cx.sess().source_map().span_to_snippet(ty.span) {
snippet
} else {
pprust::ty_to_string(ty)
};
- Self::remove_outer_parens(cx, ty.span, &pattern_text, "type", (false, false));
+ self.emit_unused_delims(cx, ty.span, &pattern_text, "type", (false, false));
+ }
+ }
+ }
+ }
+
+ fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
+ <Self as UnusedDelimLint>::check_item(self, cx, item)
+ }
+}
+
+declare_lint! {
+ pub(super) UNUSED_BRACES,
+ Warn,
+ "unnecessary braces around an expression"
+}
+
+declare_lint_pass!(UnusedBraces => [UNUSED_BRACES]);
+
+impl UnusedDelimLint for UnusedBraces {
+ const DELIM_STR: &'static str = "braces";
+
+ const LINT_EXPR_IN_PATTERN_MATCHING_CTX: bool = false;
+
+ fn lint(&self) -> &'static Lint {
+ UNUSED_BRACES
+ }
+
+ fn check_unused_delims_expr(
+ &self,
+ cx: &EarlyContext<'_>,
+ value: &ast::Expr,
+ ctx: UnusedDelimsCtx,
+ followed_by_block: bool,
+ left_pos: Option<BytePos>,
+ right_pos: Option<BytePos>,
+ ) {
+ match value.kind {
+ ast::ExprKind::Block(ref inner, None)
+ if inner.rules == ast::BlockCheckMode::Default =>
+ {
+ // emit a warning under the following conditions:
+ //
+ // - the block does not have a label
+ // - the block is not `unsafe`
+ // - the block contains exactly one expression (do not lint `{ expr; }`)
+ // - `followed_by_block` is true and the internal expr may contain a `{`
+ // - the block is not multiline (do not lint multiline match arms)
+ // ```
+ // match expr {
+ // Pattern => {
+ // somewhat_long_expression
+ // }
+ // // ...
+ // }
+ // ```
+ // - the block has no attribute and was not created inside a macro
+ // - if the block is an `anon_const`, the inner expr must be a literal
+ // (do not lint `struct A<const N: usize>; let _: A<{ 2 + 3 }>;`)
+ //
+ // FIXME(const_generics): handle paths when #67075 is fixed.
+ if let [stmt] = inner.stmts.as_slice() {
+ if let ast::StmtKind::Expr(ref expr) = stmt.kind {
+ if !Self::is_expr_delims_necessary(expr, followed_by_block)
+ && (ctx != UnusedDelimsCtx::AnonConst
+ || matches!(expr.kind, ast::ExprKind::Lit(_)))
+ // array length expressions are checked during `check_anon_const` and `check_ty`,
+ // once as `ArrayLenExpr` and once as `AnonConst`.
+ //
+ // As we do not want to lint this twice, we do not emit an error for
+ // `ArrayLenExpr` if `AnonConst` would do the same.
+ && (ctx != UnusedDelimsCtx::ArrayLenExpr
+ || !matches!(expr.kind, ast::ExprKind::Lit(_)))
+ && !cx.sess().source_map().is_multiline(value.span)
+ && value.attrs.is_empty()
+ && !value.span.from_expansion()
+ {
+ self.emit_unused_delims_expr(cx, value, ctx, left_pos, right_pos)
+ }
+ }
}
}
+ ast::ExprKind::Let(_, ref expr) => {
+ // FIXME(#60336): Properly handle `let true = (false && true)`
+ // actually needing the parenthesis.
+ self.check_unused_delims_expr(
+ cx,
+ expr,
+ UnusedDelimsCtx::LetScrutineeExpr,
+ followed_by_block,
+ None,
+ None,
+ );
+ }
+ _ => {}
}
}
}
+impl EarlyLintPass for UnusedBraces {
+ fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
+ <Self as UnusedDelimLint>::check_expr(self, cx, e)
+ }
+
+ fn check_anon_const(&mut self, cx: &EarlyContext<'_>, c: &ast::AnonConst) {
+ self.check_unused_delims_expr(cx, &c.value, UnusedDelimsCtx::AnonConst, false, None, None);
+ }
+
+ fn check_stmt(&mut self, cx: &EarlyContext<'_>, s: &ast::Stmt) {
+ <Self as UnusedDelimLint>::check_stmt(self, cx, s)
+ }
+
+ fn check_ty(&mut self, cx: &EarlyContext<'_>, ty: &ast::Ty) {
+ if let &ast::TyKind::Paren(ref r) = &ty.kind {
+ if let ast::TyKind::Array(_, ref len) = r.kind {
+ self.check_unused_delims_expr(
+ cx,
+ &len.value,
+ UnusedDelimsCtx::ArrayLenExpr,
+ false,
+ None,
+ None,
+ );
+ }
+ }
+ }
+
+ fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
+ <Self as UnusedDelimLint>::check_item(self, cx, item)
+ }
+}
+
declare_lint! {
UNUSED_IMPORT_BRACES,
Allow,
ast::UseTreeKind::Nested(_) => return,
};
- let msg = format!("braces around {} is unnecessary", node_name);
- cx.span_lint(UNUSED_IMPORT_BRACES, item.span, &msg);
+ cx.struct_span_lint(UNUSED_IMPORT_BRACES, item.span, |lint| {
+ lint.build(&format!("braces around {} is unnecessary", node_name)).emit()
+ });
}
}
}
declare_lint_pass!(UnusedAllocation => [UNUSED_ALLOCATION]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedAllocation {
- fn check_expr(&mut self, cx: &LateContext<'_, '_>, e: &hir::Expr) {
+ fn check_expr(&mut self, cx: &LateContext<'_, '_>, e: &hir::Expr<'_>) {
match e.kind {
hir::ExprKind::Box(_) => {}
_ => return,
for adj in cx.tables.expr_adjustments(e) {
if let adjustment::Adjust::Borrow(adjustment::AutoBorrow::Ref(_, m)) = adj.kind {
- let msg = match m {
- adjustment::AutoBorrowMutability::Immutable =>
- "unnecessary allocation, use `&` instead",
- adjustment::AutoBorrowMutability::Mutable { .. }=>
- "unnecessary allocation, use `&mut` instead"
- };
- cx.span_lint(UNUSED_ALLOCATION, e.span, msg);
+ cx.struct_span_lint(UNUSED_ALLOCATION, e.span, |lint| {
+ let msg = match m {
+ adjustment::AutoBorrowMutability::Not => {
+ "unnecessary allocation, use `&` instead"
+ }
+ adjustment::AutoBorrowMutability::Mut { .. } => {
+ "unnecessary allocation, use `&mut` instead"
+ }
+ };
+ lint.build(msg).emit()
+ });
}
}
}
projects / rustc.git / blobdiff