|
| 1 | +use clippy_utils::diagnostics::span_lint_and_then; |
| 2 | +use clippy_utils::msrvs::{self, Msrv}; |
| 3 | +use clippy_utils::source::SpanRangeExt; |
| 4 | +use clippy_utils::sym; |
| 5 | +use rustc_ast::LitKind; |
| 6 | +use rustc_errors::Applicability; |
| 7 | +use rustc_hir::{Expr, ExprKind, Lit, UnOp}; |
| 8 | +use rustc_lint::LateContext; |
| 9 | +use std::cmp::Ordering; |
| 10 | +use std::fmt; |
| 11 | + |
| 12 | +use super::PTR_OFFSET_BY_LITERAL; |
| 13 | + |
| 14 | +pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, msrv: Msrv) { |
| 15 | + // `pointer::add` and `pointer::wrapping_add` are only stable since 1.26.0. These functions |
| 16 | + // became const-stable in 1.61.0, the same version that `pointer::offset` became const-stable. |
| 17 | + if !msrv.meets(cx, msrvs::POINTER_ADD_SUB_METHODS) { |
| 18 | + return; |
| 19 | + } |
| 20 | + |
| 21 | + let ExprKind::MethodCall(method_name, recv, [arg_expr], _) = expr.kind else { |
| 22 | + return; |
| 23 | + }; |
| 24 | + |
| 25 | + let method = match method_name.ident.name { |
| 26 | + sym::offset => Method::Offset, |
| 27 | + sym::wrapping_offset => Method::WrappingOffset, |
| 28 | + _ => return, |
| 29 | + }; |
| 30 | + |
| 31 | + if !cx.typeck_results().expr_ty_adjusted(recv).is_raw_ptr() { |
| 32 | + return; |
| 33 | + } |
| 34 | + |
| 35 | + // Check if the argument to the method call is a (negated) literal. |
| 36 | + let Some((literal, literal_text)) = expr_as_literal(cx, arg_expr) else { |
| 37 | + return; |
| 38 | + }; |
| 39 | + |
| 40 | + match method.suggestion(literal) { |
| 41 | + None => { |
| 42 | + let msg = format!("use of `{method}` with zero"); |
| 43 | + span_lint_and_then(cx, PTR_OFFSET_BY_LITERAL, expr.span, msg, |diag| { |
| 44 | + diag.span_suggestion( |
| 45 | + expr.span.with_lo(recv.span.hi()), |
| 46 | + format!("remove the call to `{method}`"), |
| 47 | + String::new(), |
| 48 | + Applicability::MachineApplicable, |
| 49 | + ); |
| 50 | + }); |
| 51 | + }, |
| 52 | + Some(method_suggestion) => { |
| 53 | + let msg = format!("use of `{method}` with a literal"); |
| 54 | + span_lint_and_then(cx, PTR_OFFSET_BY_LITERAL, expr.span, msg, |diag| { |
| 55 | + diag.multipart_suggestion( |
| 56 | + format!("use `{method_suggestion}` instead"), |
| 57 | + vec![ |
| 58 | + (method_name.ident.span, method_suggestion.to_string()), |
| 59 | + (arg_expr.span, literal_text), |
| 60 | + ], |
| 61 | + Applicability::MachineApplicable, |
| 62 | + ); |
| 63 | + }); |
| 64 | + }, |
| 65 | + } |
| 66 | +} |
| 67 | + |
| 68 | +fn get_literal_bits<'tcx>(expr: &'tcx Expr<'tcx>) -> Option<u128> { |
| 69 | + match expr.kind { |
| 70 | + ExprKind::Lit(Lit { |
| 71 | + node: LitKind::Int(packed_u128, _), |
| 72 | + .. |
| 73 | + }) => Some(packed_u128.get()), |
| 74 | + _ => None, |
| 75 | + } |
| 76 | +} |
| 77 | + |
| 78 | +// If the given expression is a (negated) literal, return its value. |
| 79 | +fn expr_as_literal<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> Option<(i128, String)> { |
| 80 | + if let Some(literal_bits) = get_literal_bits(expr) { |
| 81 | + // The value must fit in a isize, so we can't have overflow here. |
| 82 | + return Some((literal_bits.cast_signed(), format_isize_literal(cx, expr)?)); |
| 83 | + } |
| 84 | + |
| 85 | + if let ExprKind::Unary(UnOp::Neg, inner) = expr.kind |
| 86 | + && let Some(literal_bits) = get_literal_bits(inner) |
| 87 | + { |
| 88 | + return Some((-(literal_bits.cast_signed()), format_isize_literal(cx, inner)?)); |
| 89 | + } |
| 90 | + |
| 91 | + None |
| 92 | +} |
| 93 | + |
| 94 | +fn format_isize_literal<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> Option<String> { |
| 95 | + let text = expr.span.get_source_text(cx)?; |
| 96 | + let text = peel_parens_str(&text); |
| 97 | + Some(text.trim_end_matches("isize").trim_end_matches('_').to_string()) |
| 98 | +} |
| 99 | + |
| 100 | +fn peel_parens_str(snippet: &str) -> &str { |
| 101 | + let mut s = snippet.trim(); |
| 102 | + while let Some(next) = s.strip_prefix("(").and_then(|suf| suf.strip_suffix(")")) { |
| 103 | + s = next.trim(); |
| 104 | + } |
| 105 | + s |
| 106 | +} |
| 107 | + |
| 108 | +#[derive(Copy, Clone)] |
| 109 | +enum Method { |
| 110 | + Offset, |
| 111 | + WrappingOffset, |
| 112 | +} |
| 113 | + |
| 114 | +impl Method { |
| 115 | + fn suggestion(self, literal: i128) -> Option<&'static str> { |
| 116 | + match Ord::cmp(&literal, &0) { |
| 117 | + Ordering::Greater => match self { |
| 118 | + Method::Offset => Some("add"), |
| 119 | + Method::WrappingOffset => Some("wrapping_add"), |
| 120 | + }, |
| 121 | + // `ptr.offset(0)` is equivalent to `ptr`, so no adjustment is needed |
| 122 | + Ordering::Equal => None, |
| 123 | + Ordering::Less => match self { |
| 124 | + Method::Offset => Some("sub"), |
| 125 | + Method::WrappingOffset => Some("wrapping_sub"), |
| 126 | + }, |
| 127 | + } |
| 128 | + } |
| 129 | +} |
| 130 | + |
| 131 | +impl fmt::Display for Method { |
| 132 | + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| 133 | + match self { |
| 134 | + Self::Offset => write!(f, "offset"), |
| 135 | + Self::WrappingOffset => write!(f, "wrapping_offset"), |
| 136 | + } |
| 137 | + } |
| 138 | +} |
0 commit comments