1116 lines
43 KiB
Rust
1116 lines
43 KiB
Rust
//! Contains utility functions to generate suggestions.
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#![deny(clippy::missing_docs_in_private_items)]
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use crate::source::{snippet, snippet_opt, snippet_with_applicability, snippet_with_macro_callsite};
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use crate::ty::expr_sig;
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use crate::{get_parent_expr_for_hir, higher};
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use rustc_ast::util::parser::AssocOp;
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use rustc_ast::{ast, token};
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use rustc_ast_pretty::pprust::token_kind_to_string;
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_hir::{Closure, ExprKind, HirId, MutTy, TyKind};
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use rustc_hir_analysis::expr_use_visitor::{Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId};
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use rustc_infer::infer::TyCtxtInferExt;
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use rustc_lint::{EarlyContext, LateContext, LintContext};
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use rustc_middle::hir::place::ProjectionKind;
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use rustc_middle::mir::{FakeReadCause, Mutability};
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use rustc_middle::ty;
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use rustc_span::source_map::{BytePos, CharPos, Pos, Span, SyntaxContext};
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use std::borrow::Cow;
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use std::fmt::{Display, Write as _};
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use std::ops::{Add, Neg, Not, Sub};
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/// A helper type to build suggestion correctly handling parentheses.
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#[derive(Clone, Debug, PartialEq)]
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pub enum Sugg<'a> {
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/// An expression that never needs parentheses such as `1337` or `[0; 42]`.
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NonParen(Cow<'a, str>),
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/// An expression that does not fit in other variants.
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MaybeParen(Cow<'a, str>),
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/// A binary operator expression, including `as`-casts and explicit type
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/// coercion.
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BinOp(AssocOp, Cow<'a, str>, Cow<'a, str>),
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}
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/// Literal constant `0`, for convenience.
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pub const ZERO: Sugg<'static> = Sugg::NonParen(Cow::Borrowed("0"));
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/// Literal constant `1`, for convenience.
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pub const ONE: Sugg<'static> = Sugg::NonParen(Cow::Borrowed("1"));
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/// a constant represents an empty string, for convenience.
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pub const EMPTY: Sugg<'static> = Sugg::NonParen(Cow::Borrowed(""));
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impl Display for Sugg<'_> {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
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match *self {
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Sugg::NonParen(ref s) | Sugg::MaybeParen(ref s) => s.fmt(f),
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Sugg::BinOp(op, ref lhs, ref rhs) => binop_to_string(op, lhs, rhs).fmt(f),
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}
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}
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}
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#[expect(clippy::wrong_self_convention)] // ok, because of the function `as_ty` method
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impl<'a> Sugg<'a> {
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/// Prepare a suggestion from an expression.
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pub fn hir_opt(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<Self> {
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let get_snippet = |span| snippet(cx, span, "");
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snippet_opt(cx, expr.span).map(|_| Self::hir_from_snippet(expr, get_snippet))
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}
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/// Convenience function around `hir_opt` for suggestions with a default
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/// text.
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pub fn hir(cx: &LateContext<'_>, expr: &hir::Expr<'_>, default: &'a str) -> Self {
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Self::hir_opt(cx, expr).unwrap_or(Sugg::NonParen(Cow::Borrowed(default)))
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}
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/// Same as `hir`, but it adapts the applicability level by following rules:
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///
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/// - Applicability level `Unspecified` will never be changed.
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/// - If the span is inside a macro, change the applicability level to `MaybeIncorrect`.
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/// - If the default value is used and the applicability level is `MachineApplicable`, change it
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/// to
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/// `HasPlaceholders`
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pub fn hir_with_applicability(
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cx: &LateContext<'_>,
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expr: &hir::Expr<'_>,
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default: &'a str,
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applicability: &mut Applicability,
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) -> Self {
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if *applicability != Applicability::Unspecified && expr.span.from_expansion() {
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*applicability = Applicability::MaybeIncorrect;
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}
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Self::hir_opt(cx, expr).unwrap_or_else(|| {
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if *applicability == Applicability::MachineApplicable {
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*applicability = Applicability::HasPlaceholders;
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}
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Sugg::NonParen(Cow::Borrowed(default))
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})
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}
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/// Same as `hir`, but will use the pre expansion span if the `expr` was in a macro.
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pub fn hir_with_macro_callsite(cx: &LateContext<'_>, expr: &hir::Expr<'_>, default: &'a str) -> Self {
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let get_snippet = |span| snippet_with_macro_callsite(cx, span, default);
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Self::hir_from_snippet(expr, get_snippet)
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}
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/// Same as `hir`, but first walks the span up to the given context. This will result in the
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/// macro call, rather then the expansion, if the span is from a child context. If the span is
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/// not from a child context, it will be used directly instead.
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///
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/// e.g. Given the expression `&vec![]`, getting a snippet from the span for `vec![]` as a HIR
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/// node would result in `box []`. If given the context of the address of expression, this
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/// function will correctly get a snippet of `vec![]`.
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pub fn hir_with_context(
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cx: &LateContext<'_>,
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expr: &hir::Expr<'_>,
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ctxt: SyntaxContext,
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default: &'a str,
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applicability: &mut Applicability,
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) -> Self {
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if expr.span.ctxt() == ctxt {
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Self::hir_from_snippet(expr, |span| snippet(cx, span, default))
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} else {
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let snip = snippet_with_applicability(cx, expr.span, default, applicability);
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Sugg::NonParen(snip)
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}
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}
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/// Generate a suggestion for an expression with the given snippet. This is used by the `hir_*`
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/// function variants of `Sugg`, since these use different snippet functions.
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fn hir_from_snippet(expr: &hir::Expr<'_>, get_snippet: impl Fn(Span) -> Cow<'a, str>) -> Self {
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if let Some(range) = higher::Range::hir(expr) {
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let op = match range.limits {
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ast::RangeLimits::HalfOpen => AssocOp::DotDot,
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ast::RangeLimits::Closed => AssocOp::DotDotEq,
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};
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let start = range.start.map_or("".into(), |expr| get_snippet(expr.span));
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let end = range.end.map_or("".into(), |expr| get_snippet(expr.span));
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return Sugg::BinOp(op, start, end);
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}
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match expr.kind {
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hir::ExprKind::AddrOf(..)
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| hir::ExprKind::Box(..)
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| hir::ExprKind::If(..)
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| hir::ExprKind::Let(..)
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| hir::ExprKind::Closure { .. }
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| hir::ExprKind::Unary(..)
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| hir::ExprKind::Match(..) => Sugg::MaybeParen(get_snippet(expr.span)),
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hir::ExprKind::Continue(..)
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| hir::ExprKind::Yield(..)
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| hir::ExprKind::Array(..)
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| hir::ExprKind::Block(..)
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| hir::ExprKind::Break(..)
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| hir::ExprKind::Call(..)
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| hir::ExprKind::Field(..)
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| hir::ExprKind::Index(..)
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| hir::ExprKind::InlineAsm(..)
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| hir::ExprKind::ConstBlock(..)
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| hir::ExprKind::Lit(..)
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| hir::ExprKind::Loop(..)
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| hir::ExprKind::MethodCall(..)
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| hir::ExprKind::Path(..)
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| hir::ExprKind::Repeat(..)
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| hir::ExprKind::Ret(..)
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| hir::ExprKind::Struct(..)
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| hir::ExprKind::Tup(..)
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| hir::ExprKind::Err => Sugg::NonParen(get_snippet(expr.span)),
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hir::ExprKind::DropTemps(inner) => Self::hir_from_snippet(inner, get_snippet),
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hir::ExprKind::Assign(lhs, rhs, _) => {
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Sugg::BinOp(AssocOp::Assign, get_snippet(lhs.span), get_snippet(rhs.span))
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},
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hir::ExprKind::AssignOp(op, lhs, rhs) => {
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Sugg::BinOp(hirbinop2assignop(op), get_snippet(lhs.span), get_snippet(rhs.span))
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},
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hir::ExprKind::Binary(op, lhs, rhs) => Sugg::BinOp(
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AssocOp::from_ast_binop(op.node.into()),
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get_snippet(lhs.span),
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get_snippet(rhs.span),
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),
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hir::ExprKind::Cast(lhs, ty) => Sugg::BinOp(AssocOp::As, get_snippet(lhs.span), get_snippet(ty.span)),
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hir::ExprKind::Type(lhs, ty) => Sugg::BinOp(AssocOp::Colon, get_snippet(lhs.span), get_snippet(ty.span)),
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}
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}
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/// Prepare a suggestion from an expression.
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pub fn ast(cx: &EarlyContext<'_>, expr: &ast::Expr, default: &'a str) -> Self {
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use rustc_ast::ast::RangeLimits;
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let snippet_without_expansion = |cx, span: Span, default| {
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if span.from_expansion() {
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snippet_with_macro_callsite(cx, span, default)
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} else {
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snippet(cx, span, default)
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}
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};
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match expr.kind {
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ast::ExprKind::AddrOf(..)
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| ast::ExprKind::Box(..)
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| ast::ExprKind::Closure { .. }
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| ast::ExprKind::If(..)
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| ast::ExprKind::Let(..)
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| ast::ExprKind::Unary(..)
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| ast::ExprKind::Match(..) => Sugg::MaybeParen(snippet_without_expansion(cx, expr.span, default)),
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ast::ExprKind::Async(..)
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| ast::ExprKind::Block(..)
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| ast::ExprKind::Break(..)
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| ast::ExprKind::Call(..)
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| ast::ExprKind::Continue(..)
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| ast::ExprKind::Yield(..)
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| ast::ExprKind::Field(..)
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| ast::ExprKind::ForLoop(..)
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| ast::ExprKind::Index(..)
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| ast::ExprKind::InlineAsm(..)
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| ast::ExprKind::ConstBlock(..)
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| ast::ExprKind::Lit(..)
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| ast::ExprKind::Loop(..)
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| ast::ExprKind::MacCall(..)
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| ast::ExprKind::MethodCall(..)
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| ast::ExprKind::Paren(..)
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| ast::ExprKind::Underscore
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| ast::ExprKind::Path(..)
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| ast::ExprKind::Repeat(..)
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| ast::ExprKind::Ret(..)
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| ast::ExprKind::Yeet(..)
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| ast::ExprKind::Struct(..)
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| ast::ExprKind::Try(..)
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| ast::ExprKind::TryBlock(..)
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| ast::ExprKind::Tup(..)
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| ast::ExprKind::Array(..)
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| ast::ExprKind::While(..)
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| ast::ExprKind::Await(..)
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| ast::ExprKind::Err => Sugg::NonParen(snippet_without_expansion(cx, expr.span, default)),
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ast::ExprKind::Range(ref lhs, ref rhs, RangeLimits::HalfOpen) => Sugg::BinOp(
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AssocOp::DotDot,
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lhs.as_ref()
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.map_or("".into(), |lhs| snippet_without_expansion(cx, lhs.span, default)),
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rhs.as_ref()
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.map_or("".into(), |rhs| snippet_without_expansion(cx, rhs.span, default)),
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),
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ast::ExprKind::Range(ref lhs, ref rhs, RangeLimits::Closed) => Sugg::BinOp(
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AssocOp::DotDotEq,
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lhs.as_ref()
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.map_or("".into(), |lhs| snippet_without_expansion(cx, lhs.span, default)),
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rhs.as_ref()
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.map_or("".into(), |rhs| snippet_without_expansion(cx, rhs.span, default)),
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),
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ast::ExprKind::Assign(ref lhs, ref rhs, _) => Sugg::BinOp(
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AssocOp::Assign,
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snippet_without_expansion(cx, lhs.span, default),
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snippet_without_expansion(cx, rhs.span, default),
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),
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ast::ExprKind::AssignOp(op, ref lhs, ref rhs) => Sugg::BinOp(
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astbinop2assignop(op),
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snippet_without_expansion(cx, lhs.span, default),
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snippet_without_expansion(cx, rhs.span, default),
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),
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ast::ExprKind::Binary(op, ref lhs, ref rhs) => Sugg::BinOp(
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AssocOp::from_ast_binop(op.node),
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snippet_without_expansion(cx, lhs.span, default),
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snippet_without_expansion(cx, rhs.span, default),
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),
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ast::ExprKind::Cast(ref lhs, ref ty) => Sugg::BinOp(
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AssocOp::As,
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snippet_without_expansion(cx, lhs.span, default),
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snippet_without_expansion(cx, ty.span, default),
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),
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ast::ExprKind::Type(ref lhs, ref ty) => Sugg::BinOp(
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AssocOp::Colon,
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snippet_without_expansion(cx, lhs.span, default),
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snippet_without_expansion(cx, ty.span, default),
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),
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}
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}
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/// Convenience method to create the `<lhs> && <rhs>` suggestion.
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pub fn and(self, rhs: &Self) -> Sugg<'static> {
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make_binop(ast::BinOpKind::And, &self, rhs)
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}
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/// Convenience method to create the `<lhs> & <rhs>` suggestion.
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pub fn bit_and(self, rhs: &Self) -> Sugg<'static> {
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make_binop(ast::BinOpKind::BitAnd, &self, rhs)
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}
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/// Convenience method to create the `<lhs> as <rhs>` suggestion.
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pub fn as_ty<R: Display>(self, rhs: R) -> Sugg<'static> {
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make_assoc(AssocOp::As, &self, &Sugg::NonParen(rhs.to_string().into()))
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}
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/// Convenience method to create the `&<expr>` suggestion.
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pub fn addr(self) -> Sugg<'static> {
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make_unop("&", self)
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}
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/// Convenience method to create the `&mut <expr>` suggestion.
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pub fn mut_addr(self) -> Sugg<'static> {
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make_unop("&mut ", self)
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}
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/// Convenience method to create the `*<expr>` suggestion.
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pub fn deref(self) -> Sugg<'static> {
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make_unop("*", self)
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}
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/// Convenience method to create the `&*<expr>` suggestion. Currently this
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/// is needed because `sugg.deref().addr()` produces an unnecessary set of
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/// parentheses around the deref.
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pub fn addr_deref(self) -> Sugg<'static> {
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make_unop("&*", self)
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}
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/// Convenience method to create the `&mut *<expr>` suggestion. Currently
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/// this is needed because `sugg.deref().mut_addr()` produces an unnecessary
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/// set of parentheses around the deref.
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pub fn mut_addr_deref(self) -> Sugg<'static> {
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make_unop("&mut *", self)
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}
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/// Convenience method to transform suggestion into a return call
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pub fn make_return(self) -> Sugg<'static> {
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Sugg::NonParen(Cow::Owned(format!("return {self}")))
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}
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/// Convenience method to transform suggestion into a block
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/// where the suggestion is a trailing expression
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pub fn blockify(self) -> Sugg<'static> {
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Sugg::NonParen(Cow::Owned(format!("{{ {self} }}")))
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}
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/// Convenience method to prefix the expression with the `async` keyword.
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/// Can be used after `blockify` to create an async block.
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pub fn asyncify(self) -> Sugg<'static> {
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Sugg::NonParen(Cow::Owned(format!("async {self}")))
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}
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/// Convenience method to create the `<lhs>..<rhs>` or `<lhs>...<rhs>`
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/// suggestion.
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pub fn range(self, end: &Self, limit: ast::RangeLimits) -> Sugg<'static> {
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match limit {
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ast::RangeLimits::HalfOpen => make_assoc(AssocOp::DotDot, &self, end),
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ast::RangeLimits::Closed => make_assoc(AssocOp::DotDotEq, &self, end),
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}
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}
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/// Adds parentheses to any expression that might need them. Suitable to the
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/// `self` argument of a method call
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/// (e.g., to build `bar.foo()` or `(1 + 2).foo()`).
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#[must_use]
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pub fn maybe_par(self) -> Self {
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match self {
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Sugg::NonParen(..) => self,
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// `(x)` and `(x).y()` both don't need additional parens.
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Sugg::MaybeParen(sugg) => {
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if has_enclosing_paren(&sugg) {
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Sugg::MaybeParen(sugg)
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} else {
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Sugg::NonParen(format!("({sugg})").into())
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}
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},
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Sugg::BinOp(op, lhs, rhs) => {
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let sugg = binop_to_string(op, &lhs, &rhs);
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Sugg::NonParen(format!("({sugg})").into())
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},
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}
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}
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}
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/// Generates a string from the operator and both sides.
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fn binop_to_string(op: AssocOp, lhs: &str, rhs: &str) -> String {
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match op {
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AssocOp::Add
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| AssocOp::Subtract
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| AssocOp::Multiply
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| AssocOp::Divide
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| AssocOp::Modulus
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| AssocOp::LAnd
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| AssocOp::LOr
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| AssocOp::BitXor
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| AssocOp::BitAnd
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| AssocOp::BitOr
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| AssocOp::ShiftLeft
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| AssocOp::ShiftRight
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| AssocOp::Equal
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| AssocOp::Less
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| AssocOp::LessEqual
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| AssocOp::NotEqual
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| AssocOp::Greater
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| AssocOp::GreaterEqual => {
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format!(
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"{lhs} {} {rhs}",
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op.to_ast_binop().expect("Those are AST ops").to_string()
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)
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},
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AssocOp::Assign => format!("{lhs} = {rhs}"),
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AssocOp::AssignOp(op) => {
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format!("{lhs} {}= {rhs}", token_kind_to_string(&token::BinOp(op)))
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},
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AssocOp::As => format!("{lhs} as {rhs}"),
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AssocOp::DotDot => format!("{lhs}..{rhs}"),
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AssocOp::DotDotEq => format!("{lhs}..={rhs}"),
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AssocOp::Colon => format!("{lhs}: {rhs}"),
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}
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}
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/// Return `true` if `sugg` is enclosed in parenthesis.
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pub fn has_enclosing_paren(sugg: impl AsRef<str>) -> bool {
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let mut chars = sugg.as_ref().chars();
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if chars.next() == Some('(') {
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let mut depth = 1;
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for c in &mut chars {
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if c == '(' {
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depth += 1;
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} else if c == ')' {
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depth -= 1;
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}
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if depth == 0 {
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break;
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}
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}
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chars.next().is_none()
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} else {
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false
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}
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}
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/// Copied from the rust standard library, and then edited
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macro_rules! forward_binop_impls_to_ref {
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(impl $imp:ident, $method:ident for $t:ty, type Output = $o:ty) => {
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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, Colon, 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 | Colon => 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, 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, 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 hi = cx.sess().source_map().next_point(remove_span).hi();
|
|
let fmpos = cx.sess().source_map().lookup_byte_offset(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, "", 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<'tcx>(cx: &LateContext<'_>, closure: &'tcx hir::Expr<'_>) -> Option<DerefClosure> {
|
|
if let hir::ExprKind::Closure(&Closure { fn_decl, 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::Rptr(_, MutTy { ty, .. }) = fn_decl.inputs[0].kind
|
|
{
|
|
matches!(ty.kind, TyKind::Rptr(_, 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 fn_def_id = cx.tcx.hir().local_def_id(closure.hir_id);
|
|
cx.tcx.infer_ctxt().enter(|infcx| {
|
|
ExprUseVisitor::new(&mut visitor, &infcx, fn_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).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 _ = 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 _ = 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 => (),
|
|
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 _ = 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,
|
|
_: &rustc_hir_analysis::expr_use_visitor::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)");
|
|
}
|
|
}
|