+use crate::Lint;
use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
use rustc::ty::adjustment;
use rustc::ty::{self, Ty};
use rustc_ast::ast;
+use rustc_ast::ast::{ExprKind, StmtKind};
use rustc_ast::attr;
use rustc_ast::util::parser;
use rustc_ast_pretty::pprust;
}
}
-declare_lint! {
- pub(super) UNUSED_PARENS,
- Warn,
- "`if`, `match`, `while` and `return` do not need parentheses"
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+enum UnusedDelimsCtx {
+ FunctionArg,
+ MethodArg,
+ AssignedValue,
+ IfCond,
+ WhileCond,
+ ForHeadExpr,
+ MatchHeadExpr,
+ ReturnValue,
+ BlockRetValue,
+ LetHeadExpr,
+ ArrayLenExpr,
+ AnonConst,
}
-declare_lint_pass!(UnusedParens => [UNUSED_PARENS]);
+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::ForHeadExpr => "`for` head expression",
+ UnusedDelimsCtx::MatchHeadExpr => "`match` head expression",
+ UnusedDelimsCtx::ReturnValue => "`return` value",
+ UnusedDelimsCtx::BlockRetValue => "block return value",
+ UnusedDelimsCtx::LetHeadExpr => "`let` head expression",
+ UnusedDelimsCtx::ArrayLenExpr | UnusedDelimsCtx::AnonConst => "const expression",
+ }
+ }
+}
-impl UnusedParens {
- fn is_expr_parens_necessary(inner: &ast::Expr, followed_by_block: bool) -> bool {
+/// Used by both `UnusedParens` and `UnusedBraces` to prevent code duplication.
+trait UnusedDelimLint {
+ const DELIM_STR: &'static str;
+
+ // 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 {
ast::ExprKind::Ret(_) | ast::ExprKind::Break(..) => true,
}
}
- fn check_unused_parens_expr(
+ fn emit_unused_delims_expr(
&self,
cx: &EarlyContext<'_>,
value: &ast::Expr,
- msg: &str,
- followed_by_block: bool,
+ ctx: UnusedDelimsCtx,
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()
- {
- 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);
- }
- }
- 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",
- followed_by_block,
- None,
- None,
- );
- }
- _ => {}
- }
+ 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 check_unused_parens_pat(
+ /// emits a lint
+ fn emit_unused_delims(
&self,
- cx: &EarlyContext<'_>,
- value: &ast::Pat,
- avoid_or: bool,
- avoid_mut: bool,
- ) {
- use ast::{BindingMode, Mutability, PatKind};
-
- if let PatKind::Paren(inner) = &value.kind {
- match inner.kind {
- // The lint visitor will visit each subpattern of `p`. We do not want to lint
- // any range pattern no matter where it occurs in the pattern. For something like
- // `&(a..=b)`, there is a recursive `check_pat` on `a` and `b`, but we will assume
- // that if there are unnecessary parens they serve a purpose of readability.
- PatKind::Range(..) => return,
- // Avoid `p0 | .. | pn` if we should.
- PatKind::Or(..) if avoid_or => return,
- // Avoid `mut x` and `mut x @ p` if we should:
- 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) {
- snippet
- } else {
- pprust::pat_to_string(value)
- };
- Self::remove_outer_parens(cx, value.span, &pattern_text, "pattern", (false, false));
- }
- }
-
- fn remove_outer_parens(
cx: &EarlyContext<'_>,
span: Span,
pattern: &str,
msg: &str,
keep_space: (bool, bool),
) {
- cx.struct_span_lint(UNUSED_PARENS, span, |lint| {
- let span_msg = format!("unnecessary parentheses around {}", msg);
+ 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 {
true
}
}
- ')' => {
+ ')' | '}' => {
if ate_right_paren {
false
} else {
replace
};
- err.span_suggestion_short(
- span,
- "remove these parentheses",
- replace,
- Applicability::MachineApplicable,
- );
+ let suggestion = format!("remove these {}", Self::DELIM_STR);
+
+ err.span_suggestion_short(span, &suggestion, replace, Applicability::MachineApplicable);
err.emit();
});
}
-}
-impl EarlyLintPass for UnusedParens {
fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
use rustc_ast::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;
- }
-
+ let (value, ctx, followed_by_block, left_pos, right_pos) = match e.kind {
If(ref cond, ref block, ..) => {
let left = e.span.lo() + rustc_span::BytePos(2);
let right = block.span.lo();
- (cond, "`if` condition", true, Some(left), Some(right))
+ (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, "`while` condition", true, Some(left), Some(right))
+ (cond, UnusedDelimsCtx::WhileCond, 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()))
+ ForLoop(_, ref cond, ref block, ..) => {
+ (cond, UnusedDelimsCtx::ForHeadExpr, true, None, Some(block.span.lo()))
}
Match(ref head, _) => {
let left = e.span.lo() + rustc_span::BytePos(5);
- (head, "`match` head expression", true, Some(left), None)
+ (head, UnusedDelimsCtx::MatchHeadExpr, true, Some(left), None)
}
Ret(Some(ref value)) => {
let left = e.span.lo() + rustc_span::BytePos(3);
- (value, "`return` value", false, Some(left), None)
+ (value, UnusedDelimsCtx::ReturnValue, false, Some(left), None)
}
- Assign(_, ref value, _) => (value, "assigned value", false, None, None),
- AssignOp(.., ref value) => (value, "assigned value", false, None, 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, 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"),
+ 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;
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);
+ self.check_unused_delims_expr(cx, arg, ctx, false, None, None);
}
return;
}
};
- self.check_unused_parens_expr(cx, &value, msg, followed_by_block, left_pos, right_pos);
+ 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 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,
+ "`if`, `match`, `while` and `return` do not need parentheses"
+}
+
+declare_lint_pass!(UnusedParens => [UNUSED_PARENS]);
+
+impl UnusedDelimLint for UnusedParens {
+ const DELIM_STR: &'static str = "parentheses";
+
+ fn lint(&self) -> &'static Lint {
+ UNUSED_PARENS
+ }
+
+ 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_delims_necessary(inner, followed_by_block)
+ && 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::LetHeadExpr,
+ followed_by_block,
+ None,
+ None,
+ );
+ }
+ _ => {}
+ }
+ }
+}
+
+impl UnusedParens {
+ fn check_unused_parens_pat(
+ &self,
+ cx: &EarlyContext<'_>,
+ value: &ast::Pat,
+ avoid_or: bool,
+ avoid_mut: bool,
+ ) {
+ use ast::{BindingMode, Mutability, PatKind};
+
+ if let PatKind::Paren(inner) = &value.kind {
+ match inner.kind {
+ // The lint visitor will visit each subpattern of `p`. We do not want to lint
+ // any range pattern no matter where it occurs in the pattern. For something like
+ // `&(a..=b)`, there is a recursive `check_pat` on `a` and `b`, but we will assume
+ // that if there are unnecessary parens they serve a purpose of readability.
+ PatKind::Range(..) => return,
+ // Avoid `p0 | .. | pn` if we should.
+ PatKind::Or(..) if avoid_or => return,
+ // Avoid `mut x` and `mut x @ p` if we should:
+ 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) {
+ snippet
+ } else {
+ pprust::pat_to_string(value)
+ };
+ self.emit_unused_delims(cx, value.span, &pattern_text, "pattern", (false, false));
+ }
+ }
+}
+
+impl EarlyLintPass for UnusedParens {
+ fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
+ if let ExprKind::Let(ref pat, ..) | ExprKind::ForLoop(ref pat, ..) = e.kind {
+ self.check_unused_parens_pat(cx, pat, false, false);
+ }
+
+ <Self as UnusedDelimLint>::check_expr(self, cx, e)
}
fn check_pat(&mut self, cx: &EarlyContext<'_>, p: &ast::Pat) {
}
}
- fn check_stmt(&mut self, cx: &EarlyContext<'_>, s: &ast::Stmt) {
- use ast::StmtKind::*;
-
- match s.kind {
- Local(ref local) => {
- self.check_unused_parens_pat(cx, &local.pat, false, false);
+ fn check_anon_const(&mut self, cx: &EarlyContext<'_>, c: &ast::AnonConst) {
+ self.check_unused_delims_expr(cx, &c.value, UnusedDelimsCtx::AnonConst, false, None, None);
+ }
- if let Some(ref value) = local.init {
- self.check_unused_parens_expr(cx, &value, "assigned value", false, None, None);
- }
- }
- Expr(ref expr) => {
- self.check_unused_parens_expr(cx, &expr, "block return value", false, None, None);
- }
- _ => {}
+ fn check_stmt(&mut self, cx: &EarlyContext<'_>, s: &ast::Stmt) {
+ if let StmtKind::Local(ref local) = s.kind {
+ self.check_unused_parens_pat(cx, &local.pat, false, false);
}
+
+ <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) {
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) {
- use ast::ItemKind::*;
+ <Self as UnusedDelimLint>::check_item(self, cx, item)
+ }
+}
- if let Const(.., Some(expr)) | Static(.., Some(expr)) = &item.kind {
- self.check_unused_parens_expr(cx, expr, "assigned value", false, None, None);
+declare_lint! {
+ pub(super) UNUSED_BRACES,
+ Warn,
+ "suggests removing `{` and `}` in case they are not necessary"
+}
+
+declare_lint_pass!(UnusedBraces => [UNUSED_BRACES]);
+
+impl UnusedDelimLint for UnusedBraces {
+ const DELIM_STR: &'static str = "braces";
+
+ 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::LetHeadExpr,
+ 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! {
projects / rust.git / commitdiff