Move cast_lossless to its own module
This commit is contained in:
Yoshitomo Nakanishi
parent
c2cbcd3229
commit
b12d7515b1
2 changed files with 92 additions and 74 deletions
87
clippy_lints/src/casts/cast_lossless.rs
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87
clippy_lints/src/casts/cast_lossless.rs
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@ -0,0 +1,87 @@
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, ExprKind};
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use rustc_lint::LateContext;
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use rustc_middle::ty::{self, FloatTy, Ty};
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use crate::utils::{in_constant, is_isize_or_usize, snippet_opt, span_lint_and_sugg};
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use super::{utils, CAST_LOSSLESS};
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pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
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if !should_lint(cx, expr, cast_from, cast_to) {
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return;
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}
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// The suggestion is to use a function call, so if the original expression
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// has parens on the outside, they are no longer needed.
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let mut applicability = Applicability::MachineApplicable;
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let opt = snippet_opt(cx, cast_op.span);
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let sugg = opt.as_ref().map_or_else(
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|| {
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applicability = Applicability::HasPlaceholders;
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".."
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},
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|snip| {
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if should_strip_parens(cast_op, snip) {
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&snip[1..snip.len() - 1]
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} else {
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snip.as_str()
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}
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},
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);
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span_lint_and_sugg(
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cx,
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CAST_LOSSLESS,
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expr.span,
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&format!(
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"casting `{}` to `{}` may become silently lossy if you later change the type",
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cast_from, cast_to
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),
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"try",
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format!("{}::from({})", cast_to, sugg),
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applicability,
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);
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}
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fn should_lint(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) -> bool {
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// Do not suggest using From in consts/statics until it is valid to do so (see #2267).
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if in_constant(cx, expr.hir_id) {
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return false;
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}
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match (cast_from.is_integral(), cast_to.is_integral()) {
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(true, true) => {
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let cast_signed_to_unsigned = cast_from.is_signed() && !cast_to.is_signed();
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let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
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let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx);
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!is_isize_or_usize(cast_from)
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&& !is_isize_or_usize(cast_to)
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&& from_nbits < to_nbits
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&& !cast_signed_to_unsigned
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},
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(true, false) => {
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let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
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let to_nbits = if let ty::Float(FloatTy::F32) = cast_to.kind() {
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32
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} else {
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64
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};
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from_nbits < to_nbits
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},
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(_, _) => {
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matches!(cast_from.kind(), ty::Float(FloatTy::F32)) && matches!(cast_to.kind(), ty::Float(FloatTy::F64))
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},
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}
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}
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fn should_strip_parens(cast_expr: &Expr<'_>, snip: &str) -> bool {
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if let ExprKind::Binary(_, _, _) = cast_expr.kind {
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if snip.starts_with('(') && snip.ends_with(')') {
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return true;
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}
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}
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false
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}
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@ -1,3 +1,4 @@
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mod cast_lossless;
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mod cast_precision_loss;
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mod utils;
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@ -18,9 +19,8 @@ use rustc_target::abi::LayoutOf;
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use crate::consts::{constant, Constant};
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use crate::utils::sugg::Sugg;
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use crate::utils::{
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in_constant, is_hir_ty_cfg_dependant, is_isize_or_usize, meets_msrv, method_chain_args,
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numeric_literal::NumericLiteral, sext, snippet_opt, snippet_with_applicability, span_lint, span_lint_and_sugg,
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span_lint_and_then,
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is_hir_ty_cfg_dependant, is_isize_or_usize, meets_msrv, method_chain_args, numeric_literal::NumericLiteral, sext,
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snippet_opt, snippet_with_applicability, span_lint, span_lint_and_sugg, span_lint_and_then,
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};
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use utils::int_ty_to_nbits;
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@ -254,52 +254,6 @@ declare_clippy_lint! {
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"casting a function pointer to a numeric type not wide enough to store the address"
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}
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fn should_strip_parens(op: &Expr<'_>, snip: &str) -> bool {
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if let ExprKind::Binary(_, _, _) = op.kind {
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if snip.starts_with('(') && snip.ends_with(')') {
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return true;
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}
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}
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false
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}
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fn span_lossless_lint(cx: &LateContext<'_>, expr: &Expr<'_>, op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
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// Do not suggest using From in consts/statics until it is valid to do so (see #2267).
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if in_constant(cx, expr.hir_id) {
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return;
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}
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// The suggestion is to use a function call, so if the original expression
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// has parens on the outside, they are no longer needed.
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let mut applicability = Applicability::MachineApplicable;
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let opt = snippet_opt(cx, op.span);
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let sugg = opt.as_ref().map_or_else(
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|| {
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applicability = Applicability::HasPlaceholders;
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".."
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},
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|snip| {
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if should_strip_parens(op, snip) {
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&snip[1..snip.len() - 1]
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} else {
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snip.as_str()
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}
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},
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);
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span_lint_and_sugg(
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cx,
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CAST_LOSSLESS,
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expr.span,
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&format!(
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"casting `{}` to `{}` may become silently lossy if you later change the type",
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cast_from, cast_to
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),
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"try",
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format!("{}::from({})", cast_to, sugg),
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applicability,
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);
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}
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enum ArchSuffix {
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_32,
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_64,
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@ -423,16 +377,6 @@ fn check_truncation_and_wrapping(cx: &LateContext<'_>, expr: &Expr<'_>, cast_fro
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}
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}
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fn check_lossless(cx: &LateContext<'_>, expr: &Expr<'_>, op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) {
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let cast_signed_to_unsigned = cast_from.is_signed() && !cast_to.is_signed();
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let from_nbits = int_ty_to_nbits(cast_from, cx.tcx);
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let to_nbits = int_ty_to_nbits(cast_to, cx.tcx);
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if !is_isize_or_usize(cast_from) && !is_isize_or_usize(cast_to) && from_nbits < to_nbits && !cast_signed_to_unsigned
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{
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span_lossless_lint(cx, expr, op, cast_from, cast_to);
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}
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}
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declare_lint_pass!(Casts => [
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CAST_PRECISION_LOSS,
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CAST_SIGN_LOSS,
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@ -584,18 +528,8 @@ fn lint_numeric_casts<'tcx>(
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cast_to: Ty<'tcx>,
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) {
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cast_precision_loss::check(cx, expr, cast_from, cast_to);
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cast_lossless::check(cx, expr, cast_expr, cast_from, cast_to);
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match (cast_from.is_integral(), cast_to.is_integral()) {
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(true, false) => {
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let from_nbits = int_ty_to_nbits(cast_from, cx.tcx);
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let to_nbits = if let ty::Float(FloatTy::F32) = cast_to.kind() {
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32
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} else {
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64
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};
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if from_nbits < to_nbits {
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span_lossless_lint(cx, expr, cast_expr, cast_from, cast_to);
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}
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},
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(false, true) => {
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span_lint(
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cx,
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@ -618,7 +552,6 @@ fn lint_numeric_casts<'tcx>(
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(true, true) => {
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check_loss_of_sign(cx, expr, cast_expr, cast_from, cast_to);
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check_truncation_and_wrapping(cx, expr, cast_from, cast_to);
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check_lossless(cx, expr, cast_expr, cast_from, cast_to);
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},
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(false, false) => {
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if let (&ty::Float(FloatTy::F64), &ty::Float(FloatTy::F32)) = (&cast_from.kind(), &cast_to.kind()) {
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@ -629,10 +562,8 @@ fn lint_numeric_casts<'tcx>(
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"casting `f64` to `f32` may truncate the value",
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);
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}
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if let (&ty::Float(FloatTy::F32), &ty::Float(FloatTy::F64)) = (&cast_from.kind(), &cast_to.kind()) {
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span_lossless_lint(cx, expr, cast_expr, cast_from, cast_to);
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}
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},
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(_, _) => {},
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}
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}
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