74 lines
2.4 KiB
Rust
74 lines
2.4 KiB
Rust
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use super::USELESS_TRANSMUTE;
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use crate::utils::{span_lint, span_lint_and_then, sugg};
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use rustc_errors::Applicability;
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use rustc_hir::Expr;
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use rustc_lint::LateContext;
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use rustc_middle::ty::{self, Ty};
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/// Checks for `useless_transmute` lint.
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/// Returns `true` if it's triggered, otherwise returns `false`.
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pub(super) fn check<'tcx>(
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cx: &LateContext<'tcx>,
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e: &'tcx Expr<'_>,
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from_ty: Ty<'tcx>,
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to_ty: Ty<'tcx>,
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args: &'tcx [Expr<'_>],
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) -> bool {
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match (&from_ty.kind(), &to_ty.kind()) {
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_ if from_ty == to_ty => {
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span_lint(
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cx,
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USELESS_TRANSMUTE,
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e.span,
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&format!("transmute from a type (`{}`) to itself", from_ty),
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);
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true
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},
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(ty::Ref(_, rty, rty_mutbl), ty::RawPtr(ptr_ty)) => {
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span_lint_and_then(
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cx,
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USELESS_TRANSMUTE,
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e.span,
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"transmute from a reference to a pointer",
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|diag| {
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if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
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let rty_and_mut = ty::TypeAndMut {
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ty: rty,
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mutbl: *rty_mutbl,
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};
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let sugg = if *ptr_ty == rty_and_mut {
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arg.as_ty(to_ty)
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} else {
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arg.as_ty(cx.tcx.mk_ptr(rty_and_mut)).as_ty(to_ty)
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};
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diag.span_suggestion(e.span, "try", sugg.to_string(), Applicability::Unspecified);
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}
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},
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);
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true
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},
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(ty::Int(_) | ty::Uint(_), ty::RawPtr(_)) => {
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span_lint_and_then(
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cx,
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USELESS_TRANSMUTE,
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e.span,
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"transmute from an integer to a pointer",
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|diag| {
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if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
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diag.span_suggestion(
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e.span,
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"try",
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arg.as_ty(&to_ty.to_string()).to_string(),
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Applicability::Unspecified,
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);
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}
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},
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);
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true
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},
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_ => false,
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}
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}
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