| //! Contains utility functions to generate suggestions. |
| #![deny(clippy::missing_docs_in_private_items)] |
| |
| use crate::source::{snippet, snippet_opt, snippet_with_applicability, snippet_with_context}; |
| use crate::ty::expr_sig; |
| use crate::{get_parent_expr_for_hir, higher}; |
| use rustc_ast::util::parser::AssocOp; |
| use rustc_ast::{ast, token}; |
| use rustc_ast_pretty::pprust::token_kind_to_string; |
| use rustc_errors::Applicability; |
| use rustc_hir as hir; |
| use rustc_hir::{Closure, ExprKind, HirId, MutTy, TyKind}; |
| use rustc_hir_typeck::expr_use_visitor::{Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId}; |
| use rustc_infer::infer::TyCtxtInferExt; |
| use rustc_lint::{EarlyContext, LateContext, LintContext}; |
| use rustc_middle::hir::place::ProjectionKind; |
| use rustc_middle::mir::{FakeReadCause, Mutability}; |
| use rustc_middle::ty; |
| use rustc_span::source_map::{BytePos, CharPos, Pos, Span, SyntaxContext}; |
| use std::borrow::Cow; |
| use std::fmt::{self, Display, Write as _}; |
| use std::ops::{Add, Neg, Not, Sub}; |
| |
| /// A helper type to build suggestion correctly handling parentheses. |
| #[derive(Clone, Debug, PartialEq)] |
| pub enum Sugg<'a> { |
| /// An expression that never needs parentheses such as `1337` or `[0; 42]`. |
| NonParen(Cow<'a, str>), |
| /// An expression that does not fit in other variants. |
| MaybeParen(Cow<'a, str>), |
| /// A binary operator expression, including `as`-casts and explicit type |
| /// coercion. |
| BinOp(AssocOp, Cow<'a, str>, Cow<'a, str>), |
| } |
| |
| /// Literal constant `0`, for convenience. |
| pub const ZERO: Sugg<'static> = Sugg::NonParen(Cow::Borrowed("0")); |
| /// Literal constant `1`, for convenience. |
| pub const ONE: Sugg<'static> = Sugg::NonParen(Cow::Borrowed("1")); |
| /// a constant represents an empty string, for convenience. |
| pub const EMPTY: Sugg<'static> = Sugg::NonParen(Cow::Borrowed("")); |
| |
| impl Display for Sugg<'_> { |
| fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> { |
| match *self { |
| Sugg::NonParen(ref s) | Sugg::MaybeParen(ref s) => s.fmt(f), |
| Sugg::BinOp(op, ref lhs, ref rhs) => binop_to_string(op, lhs, rhs).fmt(f), |
| } |
| } |
| } |
| |
| #[expect(clippy::wrong_self_convention)] // ok, because of the function `as_ty` method |
| impl<'a> Sugg<'a> { |
| /// Prepare a suggestion from an expression. |
| pub fn hir_opt(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<Self> { |
| let get_snippet = |span| snippet(cx, span, ""); |
| snippet_opt(cx, expr.span).map(|_| Self::hir_from_snippet(expr, get_snippet)) |
| } |
| |
| /// Convenience function around `hir_opt` for suggestions with a default |
| /// text. |
| pub fn hir(cx: &LateContext<'_>, expr: &hir::Expr<'_>, default: &'a str) -> Self { |
| Self::hir_opt(cx, expr).unwrap_or(Sugg::NonParen(Cow::Borrowed(default))) |
| } |
| |
| /// Same as `hir`, but it adapts the applicability level by following rules: |
| /// |
| /// - Applicability level `Unspecified` will never be changed. |
| /// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`. |
| /// - If the default value is used and the applicability level is `MachineApplicable`, change it |
| /// to |
| /// `HasPlaceholders` |
| pub fn hir_with_applicability( |
| cx: &LateContext<'_>, |
| expr: &hir::Expr<'_>, |
| default: &'a str, |
| applicability: &mut Applicability, |
| ) -> Self { |
| if *applicability != Applicability::Unspecified && expr.span.from_expansion() { |
| *applicability = Applicability::MaybeIncorrect; |
| } |
| Self::hir_opt(cx, expr).unwrap_or_else(|| { |
| if *applicability == Applicability::MachineApplicable { |
| *applicability = Applicability::HasPlaceholders; |
| } |
| Sugg::NonParen(Cow::Borrowed(default)) |
| }) |
| } |
| |
| /// Same as `hir`, but first walks the span up to the given context. This will result in the |
| /// macro call, rather then the expansion, if the span is from a child context. If the span is |
| /// not from a child context, it will be used directly instead. |
| /// |
| /// e.g. Given the expression `&vec![]`, getting a snippet from the span for `vec![]` as a HIR |
| /// node would result in `box []`. If given the context of the address of expression, this |
| /// function will correctly get a snippet of `vec![]`. |
| pub fn hir_with_context( |
| cx: &LateContext<'_>, |
| expr: &hir::Expr<'_>, |
| ctxt: SyntaxContext, |
| default: &'a str, |
| applicability: &mut Applicability, |
| ) -> Self { |
| if expr.span.ctxt() == ctxt { |
| Self::hir_from_snippet(expr, |span| snippet(cx, span, default)) |
| } else { |
| let (snip, _) = snippet_with_context(cx, expr.span, ctxt, default, applicability); |
| Sugg::NonParen(snip) |
| } |
| } |
| |
| /// Generate a suggestion for an expression with the given snippet. This is used by the `hir_*` |
| /// function variants of `Sugg`, since these use different snippet functions. |
| fn hir_from_snippet(expr: &hir::Expr<'_>, get_snippet: impl Fn(Span) -> Cow<'a, str>) -> Self { |
| if let Some(range) = higher::Range::hir(expr) { |
| let op = match range.limits { |
| ast::RangeLimits::HalfOpen => AssocOp::DotDot, |
| ast::RangeLimits::Closed => AssocOp::DotDotEq, |
| }; |
| let start = range.start.map_or("".into(), |expr| get_snippet(expr.span)); |
| let end = range.end.map_or("".into(), |expr| get_snippet(expr.span)); |
| |
| return Sugg::BinOp(op, start, end); |
| } |
| |
| match expr.kind { |
| hir::ExprKind::AddrOf(..) |
| | hir::ExprKind::If(..) |
| | hir::ExprKind::Let(..) |
| | hir::ExprKind::Closure { .. } |
| | hir::ExprKind::Unary(..) |
| | hir::ExprKind::Match(..) => Sugg::MaybeParen(get_snippet(expr.span)), |
| hir::ExprKind::Continue(..) |
| | hir::ExprKind::Yield(..) |
| | hir::ExprKind::Array(..) |
| | hir::ExprKind::Block(..) |
| | hir::ExprKind::Break(..) |
| | hir::ExprKind::Call(..) |
| | hir::ExprKind::Field(..) |
| | hir::ExprKind::Index(..) |
| | hir::ExprKind::InlineAsm(..) |
| | hir::ExprKind::OffsetOf(..) |
| | hir::ExprKind::ConstBlock(..) |
| | hir::ExprKind::Lit(..) |
| | hir::ExprKind::Loop(..) |
| | hir::ExprKind::MethodCall(..) |
| | hir::ExprKind::Path(..) |
| | hir::ExprKind::Repeat(..) |
| | hir::ExprKind::Ret(..) |
| | hir::ExprKind::Become(..) |
| | hir::ExprKind::Struct(..) |
| | hir::ExprKind::Tup(..) |
| | hir::ExprKind::Err(_) => Sugg::NonParen(get_snippet(expr.span)), |
| hir::ExprKind::DropTemps(inner) => Self::hir_from_snippet(inner, get_snippet), |
| hir::ExprKind::Assign(lhs, rhs, _) => { |
| Sugg::BinOp(AssocOp::Assign, get_snippet(lhs.span), get_snippet(rhs.span)) |
| }, |
| hir::ExprKind::AssignOp(op, lhs, rhs) => { |
| Sugg::BinOp(hirbinop2assignop(op), get_snippet(lhs.span), get_snippet(rhs.span)) |
| }, |
| hir::ExprKind::Binary(op, lhs, rhs) => Sugg::BinOp( |
| AssocOp::from_ast_binop(op.node.into()), |
| get_snippet(lhs.span), |
| get_snippet(rhs.span), |
| ), |
| hir::ExprKind::Cast(lhs, ty) | |
| //FIXME(chenyukang), remove this after type ascription is removed from AST |
| hir::ExprKind::Type(lhs, ty) => Sugg::BinOp(AssocOp::As, get_snippet(lhs.span), get_snippet(ty.span)), |
| } |
| } |
| |
| /// Prepare a suggestion from an expression. |
| pub fn ast( |
| cx: &EarlyContext<'_>, |
| expr: &ast::Expr, |
| default: &'a str, |
| ctxt: SyntaxContext, |
| app: &mut Applicability, |
| ) -> Self { |
| use rustc_ast::ast::RangeLimits; |
| |
| match expr.kind { |
| _ if expr.span.ctxt() != ctxt => Sugg::NonParen(snippet_with_context(cx, expr.span, ctxt, default, app).0), |
| ast::ExprKind::AddrOf(..) |
| | ast::ExprKind::Closure { .. } |
| | ast::ExprKind::If(..) |
| | ast::ExprKind::Let(..) |
| | ast::ExprKind::Unary(..) |
| | ast::ExprKind::Match(..) => match snippet_with_context(cx, expr.span, ctxt, default, app) { |
| (snip, false) => Sugg::MaybeParen(snip), |
| (snip, true) => Sugg::NonParen(snip), |
| }, |
| ast::ExprKind::Async(..) |
| | ast::ExprKind::Block(..) |
| | ast::ExprKind::Break(..) |
| | ast::ExprKind::Call(..) |
| | ast::ExprKind::Continue(..) |
| | ast::ExprKind::Yield(..) |
| | ast::ExprKind::Field(..) |
| | ast::ExprKind::ForLoop(..) |
| | ast::ExprKind::Index(..) |
| | ast::ExprKind::InlineAsm(..) |
| | ast::ExprKind::OffsetOf(..) |
| | ast::ExprKind::ConstBlock(..) |
| | ast::ExprKind::Lit(..) |
| | ast::ExprKind::IncludedBytes(..) |
| | ast::ExprKind::Loop(..) |
| | ast::ExprKind::MacCall(..) |
| | ast::ExprKind::MethodCall(..) |
| | ast::ExprKind::Paren(..) |
| | ast::ExprKind::Underscore |
| | ast::ExprKind::Path(..) |
| | ast::ExprKind::Repeat(..) |
| | ast::ExprKind::Ret(..) |
| | ast::ExprKind::Become(..) |
| | ast::ExprKind::Yeet(..) |
| | ast::ExprKind::FormatArgs(..) |
| | ast::ExprKind::Struct(..) |
| | ast::ExprKind::Try(..) |
| | ast::ExprKind::TryBlock(..) |
| | ast::ExprKind::Tup(..) |
| | ast::ExprKind::Array(..) |
| | ast::ExprKind::While(..) |
| | ast::ExprKind::Await(..) |
| | ast::ExprKind::Err => Sugg::NonParen(snippet_with_context(cx, expr.span, ctxt, default, app).0), |
| ast::ExprKind::Range(ref lhs, ref rhs, RangeLimits::HalfOpen) => Sugg::BinOp( |
| AssocOp::DotDot, |
| lhs.as_ref().map_or("".into(), |lhs| { |
| snippet_with_context(cx, lhs.span, ctxt, default, app).0 |
| }), |
| rhs.as_ref().map_or("".into(), |rhs| { |
| snippet_with_context(cx, rhs.span, ctxt, default, app).0 |
| }), |
| ), |
| ast::ExprKind::Range(ref lhs, ref rhs, RangeLimits::Closed) => Sugg::BinOp( |
| AssocOp::DotDotEq, |
| lhs.as_ref().map_or("".into(), |lhs| { |
| snippet_with_context(cx, lhs.span, ctxt, default, app).0 |
| }), |
| rhs.as_ref().map_or("".into(), |rhs| { |
| snippet_with_context(cx, rhs.span, ctxt, default, app).0 |
| }), |
| ), |
| ast::ExprKind::Assign(ref lhs, ref rhs, _) => Sugg::BinOp( |
| AssocOp::Assign, |
| snippet_with_context(cx, lhs.span, ctxt, default, app).0, |
| snippet_with_context(cx, rhs.span, ctxt, default, app).0, |
| ), |
| ast::ExprKind::AssignOp(op, ref lhs, ref rhs) => Sugg::BinOp( |
| astbinop2assignop(op), |
| snippet_with_context(cx, lhs.span, ctxt, default, app).0, |
| snippet_with_context(cx, rhs.span, ctxt, default, app).0, |
| ), |
| ast::ExprKind::Binary(op, ref lhs, ref rhs) => Sugg::BinOp( |
| AssocOp::from_ast_binop(op.node), |
| snippet_with_context(cx, lhs.span, ctxt, default, app).0, |
| snippet_with_context(cx, rhs.span, ctxt, default, app).0, |
| ), |
| ast::ExprKind::Cast(ref lhs, ref ty) | |
| //FIXME(chenyukang), remove this after type ascription is removed from AST |
| ast::ExprKind::Type(ref lhs, ref ty) => Sugg::BinOp( |
| AssocOp::As, |
| snippet_with_context(cx, lhs.span, ctxt, default, app).0, |
| snippet_with_context(cx, ty.span, ctxt, default, app).0, |
| ), |
| } |
| } |
| |
| /// Convenience method to create the `<lhs> && <rhs>` suggestion. |
| pub fn and(self, rhs: &Self) -> Sugg<'static> { |
| make_binop(ast::BinOpKind::And, &self, rhs) |
| } |
| |
| /// Convenience method to create the `<lhs> & <rhs>` suggestion. |
| pub fn bit_and(self, rhs: &Self) -> Sugg<'static> { |
| make_binop(ast::BinOpKind::BitAnd, &self, rhs) |
| } |
| |
| /// Convenience method to create the `<lhs> as <rhs>` suggestion. |
| pub fn as_ty<R: Display>(self, rhs: R) -> Sugg<'static> { |
| make_assoc(AssocOp::As, &self, &Sugg::NonParen(rhs.to_string().into())) |
| } |
| |
| /// Convenience method to create the `&<expr>` suggestion. |
| pub fn addr(self) -> Sugg<'static> { |
| make_unop("&", self) |
| } |
| |
| /// Convenience method to create the `&mut <expr>` suggestion. |
| pub fn mut_addr(self) -> Sugg<'static> { |
| make_unop("&mut ", self) |
| } |
| |
| /// Convenience method to create the `*<expr>` suggestion. |
| pub fn deref(self) -> Sugg<'static> { |
| make_unop("*", self) |
| } |
| |
| /// Convenience method to create the `&*<expr>` suggestion. Currently this |
| /// is needed because `sugg.deref().addr()` produces an unnecessary set of |
| /// parentheses around the deref. |
| pub fn addr_deref(self) -> Sugg<'static> { |
| make_unop("&*", self) |
| } |
| |
| /// Convenience method to create the `&mut *<expr>` suggestion. Currently |
| /// this is needed because `sugg.deref().mut_addr()` produces an unnecessary |
| /// set of parentheses around the deref. |
| pub fn mut_addr_deref(self) -> Sugg<'static> { |
| make_unop("&mut *", self) |
| } |
| |
| /// Convenience method to transform suggestion into a return call |
| pub fn make_return(self) -> Sugg<'static> { |
| Sugg::NonParen(Cow::Owned(format!("return {self}"))) |
| } |
| |
| /// Convenience method to transform suggestion into a block |
| /// where the suggestion is a trailing expression |
| pub fn blockify(self) -> Sugg<'static> { |
| Sugg::NonParen(Cow::Owned(format!("{{ {self} }}"))) |
| } |
| |
| /// Convenience method to prefix the expression with the `async` keyword. |
| /// Can be used after `blockify` to create an async block. |
| pub fn asyncify(self) -> Sugg<'static> { |
| Sugg::NonParen(Cow::Owned(format!("async {self}"))) |
| } |
| |
| /// Convenience method to create the `<lhs>..<rhs>` or `<lhs>...<rhs>` |
| /// suggestion. |
| pub fn range(self, end: &Self, limit: ast::RangeLimits) -> Sugg<'static> { |
| match limit { |
| ast::RangeLimits::HalfOpen => make_assoc(AssocOp::DotDot, &self, end), |
| ast::RangeLimits::Closed => make_assoc(AssocOp::DotDotEq, &self, end), |
| } |
| } |
| |
| /// Adds parentheses to any expression that might need them. Suitable to the |
| /// `self` argument of a method call |
| /// (e.g., to build `bar.foo()` or `(1 + 2).foo()`). |
| #[must_use] |
| pub fn maybe_par(self) -> Self { |
| match self { |
| Sugg::NonParen(..) => self, |
| // `(x)` and `(x).y()` both don't need additional parens. |
| Sugg::MaybeParen(sugg) => { |
| if has_enclosing_paren(&sugg) { |
| Sugg::MaybeParen(sugg) |
| } else { |
| Sugg::NonParen(format!("({sugg})").into()) |
| } |
| }, |
| Sugg::BinOp(op, lhs, rhs) => { |
| let sugg = binop_to_string(op, &lhs, &rhs); |
| Sugg::NonParen(format!("({sugg})").into()) |
| }, |
| } |
| } |
| } |
| |
| /// Generates a string from the operator and both sides. |
| fn binop_to_string(op: AssocOp, lhs: &str, rhs: &str) -> String { |
| match op { |
| AssocOp::Add |
| | AssocOp::Subtract |
| | AssocOp::Multiply |
| | AssocOp::Divide |
| | AssocOp::Modulus |
| | AssocOp::LAnd |
| | AssocOp::LOr |
| | AssocOp::BitXor |
| | AssocOp::BitAnd |
| | AssocOp::BitOr |
| | AssocOp::ShiftLeft |
| | AssocOp::ShiftRight |
| | AssocOp::Equal |
| | AssocOp::Less |
| | AssocOp::LessEqual |
| | AssocOp::NotEqual |
| | AssocOp::Greater |
| | AssocOp::GreaterEqual => { |
| format!( |
| "{lhs} {} {rhs}", |
| op.to_ast_binop().expect("Those are AST ops").to_string() |
| ) |
| }, |
| AssocOp::Assign => format!("{lhs} = {rhs}"), |
| AssocOp::AssignOp(op) => { |
| format!("{lhs} {}= {rhs}", token_kind_to_string(&token::BinOp(op))) |
| }, |
| AssocOp::As => format!("{lhs} as {rhs}"), |
| AssocOp::DotDot => format!("{lhs}..{rhs}"), |
| AssocOp::DotDotEq => format!("{lhs}..={rhs}"), |
| } |
| } |
| |
| /// Returns `true` if `sugg` is enclosed in parenthesis. |
| pub fn has_enclosing_paren(sugg: impl AsRef<str>) -> bool { |
| let mut chars = sugg.as_ref().chars(); |
| if chars.next() == Some('(') { |
| let mut depth = 1; |
| for c in &mut chars { |
| if c == '(' { |
| depth += 1; |
| } else if c == ')' { |
| depth -= 1; |
| } |
| if depth == 0 { |
| break; |
| } |
| } |
| chars.next().is_none() |
| } else { |
| false |
| } |
| } |
| |
| /// Copied from the rust standard library, and then edited |
| macro_rules! forward_binop_impls_to_ref { |
| (impl $imp:ident, $method:ident for $t:ty, type Output = $o:ty) => { |
| impl $imp<$t> for &$t { |
| type Output = $o; |
| |
| fn $method(self, other: $t) -> $o { |
| $imp::$method(self, &other) |
| } |
| } |
| |
| impl $imp<&$t> for $t { |
| type Output = $o; |
| |
| fn $method(self, other: &$t) -> $o { |
| $imp::$method(&self, other) |
| } |
| } |
| |
| impl $imp for $t { |
| type Output = $o; |
| |
| fn $method(self, other: $t) -> $o { |
| $imp::$method(&self, &other) |
| } |
| } |
| }; |
| } |
| |
| impl Add for &Sugg<'_> { |
| type Output = Sugg<'static>; |
| fn add(self, rhs: &Sugg<'_>) -> Sugg<'static> { |
| make_binop(ast::BinOpKind::Add, self, rhs) |
| } |
| } |
| |
| impl Sub for &Sugg<'_> { |
| type Output = Sugg<'static>; |
| fn sub(self, rhs: &Sugg<'_>) -> Sugg<'static> { |
| make_binop(ast::BinOpKind::Sub, self, rhs) |
| } |
| } |
| |
| forward_binop_impls_to_ref!(impl Add, add for Sugg<'_>, type Output = Sugg<'static>); |
| forward_binop_impls_to_ref!(impl Sub, sub for Sugg<'_>, type Output = Sugg<'static>); |
| |
| impl Neg for Sugg<'_> { |
| type Output = Sugg<'static>; |
| fn neg(self) -> Sugg<'static> { |
| make_unop("-", self) |
| } |
| } |
| |
| impl<'a> Not for Sugg<'a> { |
| type Output = Sugg<'a>; |
| fn not(self) -> Sugg<'a> { |
| use AssocOp::{Equal, Greater, GreaterEqual, Less, LessEqual, NotEqual}; |
| |
| if let Sugg::BinOp(op, lhs, rhs) = self { |
| let to_op = match op { |
| Equal => NotEqual, |
| NotEqual => Equal, |
| Less => GreaterEqual, |
| GreaterEqual => Less, |
| Greater => LessEqual, |
| LessEqual => Greater, |
| _ => return make_unop("!", Sugg::BinOp(op, lhs, rhs)), |
| }; |
| Sugg::BinOp(to_op, lhs, rhs) |
| } else { |
| make_unop("!", self) |
| } |
| } |
| } |
| |
| /// Helper type to display either `foo` or `(foo)`. |
| struct ParenHelper<T> { |
| /// `true` if parentheses are needed. |
| paren: bool, |
| /// The main thing to display. |
| wrapped: T, |
| } |
| |
| impl<T> ParenHelper<T> { |
| /// Builds a `ParenHelper`. |
| fn new(paren: bool, wrapped: T) -> Self { |
| Self { paren, wrapped } |
| } |
| } |
| |
| impl<T: Display> Display for ParenHelper<T> { |
| fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> { |
| if self.paren { |
| write!(f, "({})", self.wrapped) |
| } else { |
| self.wrapped.fmt(f) |
| } |
| } |
| } |
| |
| /// Builds the string for `<op><expr>` adding parenthesis when necessary. |
| /// |
| /// For convenience, the operator is taken as a string because all unary |
| /// operators have the same |
| /// precedence. |
| pub fn make_unop(op: &str, expr: Sugg<'_>) -> Sugg<'static> { |
| Sugg::MaybeParen(format!("{op}{}", expr.maybe_par()).into()) |
| } |
| |
| /// Builds the string for `<lhs> <op> <rhs>` adding parenthesis when necessary. |
| /// |
| /// Precedence of shift operator relative to other arithmetic operation is |
| /// often confusing so |
| /// parenthesis will always be added for a mix of these. |
| pub fn make_assoc(op: AssocOp, lhs: &Sugg<'_>, rhs: &Sugg<'_>) -> Sugg<'static> { |
| /// Returns `true` if the operator is a shift operator `<<` or `>>`. |
| fn is_shift(op: AssocOp) -> bool { |
| matches!(op, AssocOp::ShiftLeft | AssocOp::ShiftRight) |
| } |
| |
| /// Returns `true` if the operator is an arithmetic operator |
| /// (i.e., `+`, `-`, `*`, `/`, `%`). |
| fn is_arith(op: AssocOp) -> bool { |
| matches!( |
| op, |
| AssocOp::Add | AssocOp::Subtract | AssocOp::Multiply | AssocOp::Divide | AssocOp::Modulus |
| ) |
| } |
| |
| /// Returns `true` if the operator `op` needs parenthesis with the operator |
| /// `other` in the direction `dir`. |
| fn needs_paren(op: AssocOp, other: AssocOp, dir: Associativity) -> bool { |
| other.precedence() < op.precedence() |
| || (other.precedence() == op.precedence() |
| && ((op != other && associativity(op) != dir) |
| || (op == other && associativity(op) != Associativity::Both))) |
| || is_shift(op) && is_arith(other) |
| || is_shift(other) && is_arith(op) |
| } |
| |
| let lhs_paren = if let Sugg::BinOp(lop, _, _) = *lhs { |
| needs_paren(op, lop, Associativity::Left) |
| } else { |
| false |
| }; |
| |
| let rhs_paren = if let Sugg::BinOp(rop, _, _) = *rhs { |
| needs_paren(op, rop, Associativity::Right) |
| } else { |
| false |
| }; |
| |
| let lhs = ParenHelper::new(lhs_paren, lhs).to_string(); |
| let rhs = ParenHelper::new(rhs_paren, rhs).to_string(); |
| Sugg::BinOp(op, lhs.into(), rhs.into()) |
| } |
| |
| /// Convenience wrapper around `make_assoc` and `AssocOp::from_ast_binop`. |
| pub fn make_binop(op: ast::BinOpKind, lhs: &Sugg<'_>, rhs: &Sugg<'_>) -> Sugg<'static> { |
| make_assoc(AssocOp::from_ast_binop(op), lhs, rhs) |
| } |
| |
| #[derive(PartialEq, Eq, Clone, Copy)] |
| /// Operator associativity. |
| enum Associativity { |
| /// The operator is both left-associative and right-associative. |
| Both, |
| /// The operator is left-associative. |
| Left, |
| /// The operator is not associative. |
| None, |
| /// The operator is right-associative. |
| Right, |
| } |
| |
| /// Returns the associativity/fixity of an operator. The difference with |
| /// `AssocOp::fixity` is that an operator can be both left and right associative |
| /// (such as `+`: `a + b + c == (a + b) + c == a + (b + c)`. |
| /// |
| /// Chained `as` and explicit `:` type coercion never need inner parenthesis so |
| /// they are considered |
| /// associative. |
| #[must_use] |
| fn associativity(op: AssocOp) -> Associativity { |
| use rustc_ast::util::parser::AssocOp::{ |
| Add, As, Assign, AssignOp, BitAnd, BitOr, BitXor, Divide, DotDot, DotDotEq, Equal, Greater, GreaterEqual, LAnd, |
| LOr, Less, LessEqual, Modulus, Multiply, NotEqual, ShiftLeft, ShiftRight, Subtract, |
| }; |
| |
| match op { |
| Assign | AssignOp(_) => Associativity::Right, |
| Add | BitAnd | BitOr | BitXor | LAnd | LOr | Multiply | As => Associativity::Both, |
| Divide | Equal | Greater | GreaterEqual | Less | LessEqual | Modulus | NotEqual | ShiftLeft | ShiftRight |
| | Subtract => Associativity::Left, |
| DotDot | DotDotEq => Associativity::None, |
| } |
| } |
| |
| /// Converts a `hir::BinOp` to the corresponding assigning binary operator. |
| fn hirbinop2assignop(op: hir::BinOp) -> AssocOp { |
| use rustc_ast::token::BinOpToken::{And, Caret, Minus, Or, Percent, Plus, Shl, Shr, Slash, Star}; |
| |
| AssocOp::AssignOp(match op.node { |
| hir::BinOpKind::Add => Plus, |
| hir::BinOpKind::BitAnd => And, |
| hir::BinOpKind::BitOr => Or, |
| hir::BinOpKind::BitXor => Caret, |
| hir::BinOpKind::Div => Slash, |
| hir::BinOpKind::Mul => Star, |
| hir::BinOpKind::Rem => Percent, |
| hir::BinOpKind::Shl => Shl, |
| hir::BinOpKind::Shr => Shr, |
| hir::BinOpKind::Sub => Minus, |
| |
| hir::BinOpKind::And |
| | hir::BinOpKind::Eq |
| | hir::BinOpKind::Ge |
| | hir::BinOpKind::Gt |
| | hir::BinOpKind::Le |
| | hir::BinOpKind::Lt |
| | hir::BinOpKind::Ne |
| | hir::BinOpKind::Or => panic!("This operator does not exist"), |
| }) |
| } |
| |
| /// Converts an `ast::BinOp` to the corresponding assigning binary operator. |
| fn astbinop2assignop(op: ast::BinOp) -> AssocOp { |
| use rustc_ast::ast::BinOpKind::{ |
| Add, And, BitAnd, BitOr, BitXor, Div, Eq, Ge, Gt, Le, Lt, Mul, Ne, Or, Rem, Shl, Shr, Sub, |
| }; |
| use rustc_ast::token::BinOpToken; |
| |
| AssocOp::AssignOp(match op.node { |
| Add => BinOpToken::Plus, |
| BitAnd => BinOpToken::And, |
| BitOr => BinOpToken::Or, |
| BitXor => BinOpToken::Caret, |
| Div => BinOpToken::Slash, |
| Mul => BinOpToken::Star, |
| Rem => BinOpToken::Percent, |
| Shl => BinOpToken::Shl, |
| Shr => BinOpToken::Shr, |
| Sub => BinOpToken::Minus, |
| And | Eq | Ge | Gt | Le | Lt | Ne | Or => panic!("This operator does not exist"), |
| }) |
| } |
| |
| /// Returns the indentation before `span` if there are nothing but `[ \t]` |
| /// before it on its line. |
| fn indentation<T: LintContext>(cx: &T, span: Span) -> Option<String> { |
| let lo = cx.sess().source_map().lookup_char_pos(span.lo()); |
| lo.file |
| .get_line(lo.line - 1 /* line numbers in `Loc` are 1-based */) |
| .and_then(|line| { |
| if let Some((pos, _)) = line.char_indices().find(|&(_, c)| c != ' ' && c != '\t') { |
| // We can mix char and byte positions here because we only consider `[ \t]`. |
| if lo.col == CharPos(pos) { |
| Some(line[..pos].into()) |
| } else { |
| None |
| } |
| } else { |
| None |
| } |
| }) |
| } |
| |
| /// Convenience extension trait for `Diagnostic`. |
| pub trait DiagnosticExt<T: LintContext> { |
| /// Suggests to add an attribute to an item. |
| /// |
| /// Correctly handles indentation of the attribute and item. |
| /// |
| /// # Example |
| /// |
| /// ```rust,ignore |
| /// diag.suggest_item_with_attr(cx, item, "#[derive(Default)]"); |
| /// ``` |
| fn suggest_item_with_attr<D: Display + ?Sized>( |
| &mut self, |
| cx: &T, |
| item: Span, |
| msg: &str, |
| attr: &D, |
| applicability: Applicability, |
| ); |
| |
| /// Suggest to add an item before another. |
| /// |
| /// The item should not be indented (except for inner indentation). |
| /// |
| /// # Example |
| /// |
| /// ```rust,ignore |
| /// diag.suggest_prepend_item(cx, item, |
| /// "fn foo() { |
| /// bar(); |
| /// }"); |
| /// ``` |
| fn suggest_prepend_item(&mut self, cx: &T, item: Span, msg: &str, new_item: &str, applicability: Applicability); |
| |
| /// Suggest to completely remove an item. |
| /// |
| /// This will remove an item and all following whitespace until the next non-whitespace |
| /// character. This should work correctly if item is on the same indentation level as the |
| /// following item. |
| /// |
| /// # Example |
| /// |
| /// ```rust,ignore |
| /// diag.suggest_remove_item(cx, item, "remove this") |
| /// ``` |
| fn suggest_remove_item(&mut self, cx: &T, item: Span, msg: &str, applicability: Applicability); |
| } |
| |
| impl<T: LintContext> DiagnosticExt<T> for rustc_errors::Diagnostic { |
| fn suggest_item_with_attr<D: Display + ?Sized>( |
| &mut self, |
| cx: &T, |
| item: Span, |
| msg: &str, |
| attr: &D, |
| applicability: Applicability, |
| ) { |
| if let Some(indent) = indentation(cx, item) { |
| let span = item.with_hi(item.lo()); |
| |
| self.span_suggestion(span, msg.to_string(), format!("{attr}\n{indent}"), applicability); |
| } |
| } |
| |
| fn suggest_prepend_item(&mut self, cx: &T, item: Span, msg: &str, new_item: &str, applicability: Applicability) { |
| if let Some(indent) = indentation(cx, item) { |
| let span = item.with_hi(item.lo()); |
| |
| let mut first = true; |
| let new_item = new_item |
| .lines() |
| .map(|l| { |
| if first { |
| first = false; |
| format!("{l}\n") |
| } else { |
| format!("{indent}{l}\n") |
| } |
| }) |
| .collect::<String>(); |
| |
| self.span_suggestion(span, msg.to_string(), format!("{new_item}\n{indent}"), applicability); |
| } |
| } |
| |
| fn suggest_remove_item(&mut self, cx: &T, item: Span, msg: &str, applicability: Applicability) { |
| let mut remove_span = item; |
| let fmpos = cx.sess().source_map().lookup_byte_offset(remove_span.hi()); |
| |
| if let Some(ref src) = fmpos.sf.src { |
| let non_whitespace_offset = src[fmpos.pos.to_usize()..].find(|c| c != ' ' && c != '\t' && c != '\n'); |
| |
| if let Some(non_whitespace_offset) = non_whitespace_offset { |
| remove_span = remove_span |
| .with_hi(remove_span.hi() + BytePos(non_whitespace_offset.try_into().expect("offset too large"))); |
| } |
| } |
| |
| self.span_suggestion(remove_span, msg.to_string(), "", applicability); |
| } |
| } |
| |
| /// Suggestion results for handling closure |
| /// args dereferencing and borrowing |
| pub struct DerefClosure { |
| /// confidence on the built suggestion |
| pub applicability: Applicability, |
| /// gradually built suggestion |
| pub suggestion: String, |
| } |
| |
| /// Build suggestion gradually by handling closure arg specific usages, |
| /// such as explicit deref and borrowing cases. |
| /// Returns `None` if no such use cases have been triggered in closure body |
| /// |
| /// note: this only works on single line immutable closures with exactly one input parameter. |
| pub fn deref_closure_args(cx: &LateContext<'_>, closure: &hir::Expr<'_>) -> Option<DerefClosure> { |
| if let hir::ExprKind::Closure(&Closure { |
| fn_decl, def_id, body, .. |
| }) = closure.kind |
| { |
| let closure_body = cx.tcx.hir().body(body); |
| // is closure arg a type annotated double reference (i.e.: `|x: &&i32| ...`) |
| // a type annotation is present if param `kind` is different from `TyKind::Infer` |
| let closure_arg_is_type_annotated_double_ref = if let TyKind::Ref(_, MutTy { ty, .. }) = fn_decl.inputs[0].kind |
| { |
| matches!(ty.kind, TyKind::Ref(_, MutTy { .. })) |
| } else { |
| false |
| }; |
| |
| let mut visitor = DerefDelegate { |
| cx, |
| closure_span: closure.span, |
| closure_arg_is_type_annotated_double_ref, |
| next_pos: closure.span.lo(), |
| suggestion_start: String::new(), |
| applicability: Applicability::MachineApplicable, |
| }; |
| |
| let infcx = cx.tcx.infer_ctxt().build(); |
| ExprUseVisitor::new(&mut visitor, &infcx, def_id, cx.param_env, cx.typeck_results()).consume_body(closure_body); |
| |
| if !visitor.suggestion_start.is_empty() { |
| return Some(DerefClosure { |
| applicability: visitor.applicability, |
| suggestion: visitor.finish(), |
| }); |
| } |
| } |
| None |
| } |
| |
| /// Visitor struct used for tracking down |
| /// dereferencing and borrowing of closure's args |
| struct DerefDelegate<'a, 'tcx> { |
| /// The late context of the lint |
| cx: &'a LateContext<'tcx>, |
| /// The span of the input closure to adapt |
| closure_span: Span, |
| /// Indicates if the arg of the closure is a type annotated double reference |
| closure_arg_is_type_annotated_double_ref: bool, |
| /// last position of the span to gradually build the suggestion |
| next_pos: BytePos, |
| /// starting part of the gradually built suggestion |
| suggestion_start: String, |
| /// confidence on the built suggestion |
| applicability: Applicability, |
| } |
| |
| impl<'tcx> DerefDelegate<'_, 'tcx> { |
| /// build final suggestion: |
| /// - create the ending part of suggestion |
| /// - concatenate starting and ending parts |
| /// - potentially remove needless borrowing |
| pub fn finish(&mut self) -> String { |
| let end_span = Span::new(self.next_pos, self.closure_span.hi(), self.closure_span.ctxt(), None); |
| let end_snip = snippet_with_applicability(self.cx, end_span, "..", &mut self.applicability); |
| let sugg = format!("{}{end_snip}", self.suggestion_start); |
| if self.closure_arg_is_type_annotated_double_ref { |
| sugg.replacen('&', "", 1) |
| } else { |
| sugg |
| } |
| } |
| |
| /// indicates whether the function from `parent_expr` takes its args by double reference |
| fn func_takes_arg_by_double_ref(&self, parent_expr: &'tcx hir::Expr<'_>, cmt_hir_id: HirId) -> bool { |
| let ty = match parent_expr.kind { |
| ExprKind::MethodCall(_, receiver, call_args, _) => { |
| if let Some(sig) = self |
| .cx |
| .typeck_results() |
| .type_dependent_def_id(parent_expr.hir_id) |
| .map(|did| self.cx.tcx.fn_sig(did).instantiate_identity().skip_binder()) |
| { |
| std::iter::once(receiver) |
| .chain(call_args.iter()) |
| .position(|arg| arg.hir_id == cmt_hir_id) |
| .map(|i| sig.inputs()[i]) |
| } else { |
| return false; |
| } |
| }, |
| ExprKind::Call(func, call_args) => { |
| if let Some(sig) = expr_sig(self.cx, func) { |
| call_args |
| .iter() |
| .position(|arg| arg.hir_id == cmt_hir_id) |
| .and_then(|i| sig.input(i)) |
| .map(ty::Binder::skip_binder) |
| } else { |
| return false; |
| } |
| }, |
| _ => return false, |
| }; |
| |
| ty.map_or(false, |ty| matches!(ty.kind(), ty::Ref(_, inner, _) if inner.is_ref())) |
| } |
| } |
| |
| impl<'tcx> Delegate<'tcx> for DerefDelegate<'_, 'tcx> { |
| fn consume(&mut self, _: &PlaceWithHirId<'tcx>, _: HirId) {} |
| |
| fn borrow(&mut self, cmt: &PlaceWithHirId<'tcx>, _: HirId, _: ty::BorrowKind) { |
| if let PlaceBase::Local(id) = cmt.place.base { |
| let map = self.cx.tcx.hir(); |
| let span = map.span(cmt.hir_id); |
| let start_span = Span::new(self.next_pos, span.lo(), span.ctxt(), None); |
| let mut start_snip = snippet_with_applicability(self.cx, start_span, "..", &mut self.applicability); |
| |
| // identifier referring to the variable currently triggered (i.e.: `fp`) |
| let ident_str = map.name(id).to_string(); |
| // full identifier that includes projection (i.e.: `fp.field`) |
| let ident_str_with_proj = snippet(self.cx, span, "..").to_string(); |
| |
| if cmt.place.projections.is_empty() { |
| // handle item without any projection, that needs an explicit borrowing |
| // i.e.: suggest `&x` instead of `x` |
| let _: fmt::Result = write!(self.suggestion_start, "{start_snip}&{ident_str}"); |
| } else { |
| // cases where a parent `Call` or `MethodCall` is using the item |
| // i.e.: suggest `.contains(&x)` for `.find(|x| [1, 2, 3].contains(x)).is_none()` |
| // |
| // Note about method calls: |
| // - compiler automatically dereference references if the target type is a reference (works also for |
| // function call) |
| // - `self` arguments in the case of `x.is_something()` are also automatically (de)referenced, and |
| // no projection should be suggested |
| if let Some(parent_expr) = get_parent_expr_for_hir(self.cx, cmt.hir_id) { |
| match &parent_expr.kind { |
| // given expression is the self argument and will be handled completely by the compiler |
| // i.e.: `|x| x.is_something()` |
| ExprKind::MethodCall(_, self_expr, ..) if self_expr.hir_id == cmt.hir_id => { |
| let _: fmt::Result = write!(self.suggestion_start, "{start_snip}{ident_str_with_proj}"); |
| self.next_pos = span.hi(); |
| return; |
| }, |
| // item is used in a call |
| // i.e.: `Call`: `|x| please(x)` or `MethodCall`: `|x| [1, 2, 3].contains(x)` |
| ExprKind::Call(_, call_args) | ExprKind::MethodCall(_, _, call_args, _) => { |
| let expr = self.cx.tcx.hir().expect_expr(cmt.hir_id); |
| let arg_ty_kind = self.cx.typeck_results().expr_ty(expr).kind(); |
| |
| if matches!(arg_ty_kind, ty::Ref(_, _, Mutability::Not)) { |
| // suggest ampersand if call function is taking args by double reference |
| let takes_arg_by_double_ref = |
| self.func_takes_arg_by_double_ref(parent_expr, cmt.hir_id); |
| |
| // compiler will automatically dereference field or index projection, so no need |
| // to suggest ampersand, but full identifier that includes projection is required |
| let has_field_or_index_projection = |
| cmt.place.projections.iter().any(|proj| { |
| matches!(proj.kind, ProjectionKind::Field(..) | ProjectionKind::Index) |
| }); |
| |
| // no need to bind again if the function doesn't take arg by double ref |
| // and if the item is already a double ref |
| let ident_sugg = if !call_args.is_empty() |
| && !takes_arg_by_double_ref |
| && (self.closure_arg_is_type_annotated_double_ref || has_field_or_index_projection) |
| { |
| let ident = if has_field_or_index_projection { |
| ident_str_with_proj |
| } else { |
| ident_str |
| }; |
| format!("{start_snip}{ident}") |
| } else { |
| format!("{start_snip}&{ident_str}") |
| }; |
| self.suggestion_start.push_str(&ident_sugg); |
| self.next_pos = span.hi(); |
| return; |
| } |
| |
| self.applicability = Applicability::Unspecified; |
| }, |
| _ => (), |
| } |
| } |
| |
| let mut replacement_str = ident_str; |
| let mut projections_handled = false; |
| cmt.place.projections.iter().enumerate().for_each(|(i, proj)| { |
| match proj.kind { |
| // Field projection like `|v| v.foo` |
| // no adjustment needed here, as field projections are handled by the compiler |
| ProjectionKind::Field(..) => match cmt.place.ty_before_projection(i).kind() { |
| ty::Adt(..) | ty::Tuple(_) => { |
| replacement_str = ident_str_with_proj.clone(); |
| projections_handled = true; |
| }, |
| _ => (), |
| }, |
| // Index projection like `|x| foo[x]` |
| // the index is dropped so we can't get it to build the suggestion, |
| // so the span is set-up again to get more code, using `span.hi()` (i.e.: `foo[x]`) |
| // instead of `span.lo()` (i.e.: `foo`) |
| ProjectionKind::Index => { |
| let start_span = Span::new(self.next_pos, span.hi(), span.ctxt(), None); |
| start_snip = snippet_with_applicability(self.cx, start_span, "..", &mut self.applicability); |
| replacement_str.clear(); |
| projections_handled = true; |
| }, |
| // note: unable to trigger `Subslice` kind in tests |
| ProjectionKind::Subslice | |
| // Doesn't have surface syntax. Only occurs in patterns. |
| ProjectionKind::OpaqueCast => (), |
| ProjectionKind::Deref => { |
| // Explicit derefs are typically handled later on, but |
| // some items do not need explicit deref, such as array accesses, |
| // so we mark them as already processed |
| // i.e.: don't suggest `*sub[1..4].len()` for `|sub| sub[1..4].len() == 3` |
| if let ty::Ref(_, inner, _) = cmt.place.ty_before_projection(i).kind() { |
| if matches!(inner.kind(), ty::Ref(_, innermost, _) if innermost.is_array()) { |
| projections_handled = true; |
| } |
| } |
| }, |
| } |
| }); |
| |
| // handle `ProjectionKind::Deref` by removing one explicit deref |
| // if no special case was detected (i.e.: suggest `*x` instead of `**x`) |
| if !projections_handled { |
| let last_deref = cmt |
| .place |
| .projections |
| .iter() |
| .rposition(|proj| proj.kind == ProjectionKind::Deref); |
| |
| if let Some(pos) = last_deref { |
| let mut projections = cmt.place.projections.clone(); |
| projections.truncate(pos); |
| |
| for item in projections { |
| if item.kind == ProjectionKind::Deref { |
| replacement_str = format!("*{replacement_str}"); |
| } |
| } |
| } |
| } |
| |
| let _: fmt::Result = write!(self.suggestion_start, "{start_snip}{replacement_str}"); |
| } |
| self.next_pos = span.hi(); |
| } |
| } |
| |
| fn mutate(&mut self, _: &PlaceWithHirId<'tcx>, _: HirId) {} |
| |
| fn fake_read(&mut self, _: &PlaceWithHirId<'tcx>, _: FakeReadCause, _: HirId) {} |
| } |
| |
| #[cfg(test)] |
| mod test { |
| use super::Sugg; |
| |
| use rustc_ast::util::parser::AssocOp; |
| use std::borrow::Cow; |
| |
| const SUGGESTION: Sugg<'static> = Sugg::NonParen(Cow::Borrowed("function_call()")); |
| |
| #[test] |
| fn make_return_transform_sugg_into_a_return_call() { |
| assert_eq!("return function_call()", SUGGESTION.make_return().to_string()); |
| } |
| |
| #[test] |
| fn blockify_transforms_sugg_into_a_block() { |
| assert_eq!("{ function_call() }", SUGGESTION.blockify().to_string()); |
| } |
| |
| #[test] |
| fn binop_maybe_par() { |
| let sugg = Sugg::BinOp(AssocOp::Add, "1".into(), "1".into()); |
| assert_eq!("(1 + 1)", sugg.maybe_par().to_string()); |
| |
| let sugg = Sugg::BinOp(AssocOp::Add, "(1 + 1)".into(), "(1 + 1)".into()); |
| assert_eq!("((1 + 1) + (1 + 1))", sugg.maybe_par().to_string()); |
| } |
| #[test] |
| fn not_op() { |
| use AssocOp::{Add, Equal, Greater, GreaterEqual, LAnd, LOr, Less, LessEqual, NotEqual}; |
| |
| fn test_not(op: AssocOp, correct: &str) { |
| let sugg = Sugg::BinOp(op, "x".into(), "y".into()); |
| assert_eq!((!sugg).to_string(), correct); |
| } |
| |
| // Invert the comparison operator. |
| test_not(Equal, "x != y"); |
| test_not(NotEqual, "x == y"); |
| test_not(Less, "x >= y"); |
| test_not(LessEqual, "x > y"); |
| test_not(Greater, "x <= y"); |
| test_not(GreaterEqual, "x < y"); |
| |
| // Other operators are inverted like !(..). |
| test_not(Add, "!(x + y)"); |
| test_not(LAnd, "!(x && y)"); |
| test_not(LOr, "!(x || y)"); |
| } |
| } |
