diff options
| -rw-r--r-- | clippy_lints/src/casts/cast_lossless.rs | 87 | ||||
| -rw-r--r-- | clippy_lints/src/casts/mod.rs | 79 |
2 files changed, 92 insertions, 74 deletions
diff --git a/clippy_lints/src/casts/cast_lossless.rs b/clippy_lints/src/casts/cast_lossless.rs new file mode 100644 index 00000000000..478832a5164 --- /dev/null +++ b/clippy_lints/src/casts/cast_lossless.rs @@ -0,0 +1,87 @@ +use rustc_errors::Applicability; +use rustc_hir::{Expr, ExprKind}; +use rustc_lint::LateContext; +use rustc_middle::ty::{self, FloatTy, Ty}; + +use crate::utils::{in_constant, is_isize_or_usize, snippet_opt, span_lint_and_sugg}; + +use super::{utils, CAST_LOSSLESS}; + +pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) { + if !should_lint(cx, expr, cast_from, cast_to) { + return; + } + + // The suggestion is to use a function call, so if the original expression + // has parens on the outside, they are no longer needed. + let mut applicability = Applicability::MachineApplicable; + let opt = snippet_opt(cx, cast_op.span); + let sugg = opt.as_ref().map_or_else( + || { + applicability = Applicability::HasPlaceholders; + ".." + }, + |snip| { + if should_strip_parens(cast_op, snip) { + &snip[1..snip.len() - 1] + } else { + snip.as_str() + } + }, + ); + + span_lint_and_sugg( + cx, + CAST_LOSSLESS, + expr.span, + &format!( + "casting `{}` to `{}` may become silently lossy if you later change the type", + cast_from, cast_to + ), + "try", + format!("{}::from({})", cast_to, sugg), + applicability, + ); +} + +fn should_lint(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) -> bool { + // Do not suggest using From in consts/statics until it is valid to do so (see #2267). + if in_constant(cx, expr.hir_id) { + return false; + } + + match (cast_from.is_integral(), cast_to.is_integral()) { + (true, true) => { + let cast_signed_to_unsigned = cast_from.is_signed() && !cast_to.is_signed(); + let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx); + let to_nbits = utils::int_ty_to_nbits(cast_to, cx.tcx); + !is_isize_or_usize(cast_from) + && !is_isize_or_usize(cast_to) + && from_nbits < to_nbits + && !cast_signed_to_unsigned + }, + + (true, false) => { + let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx); + let to_nbits = if let ty::Float(FloatTy::F32) = cast_to.kind() { + 32 + } else { + 64 + }; + from_nbits < to_nbits + }, + + (_, _) => { + matches!(cast_from.kind(), ty::Float(FloatTy::F32)) && matches!(cast_to.kind(), ty::Float(FloatTy::F64)) + }, + } +} + +fn should_strip_parens(cast_expr: &Expr<'_>, snip: &str) -> bool { + if let ExprKind::Binary(_, _, _) = cast_expr.kind { + if snip.starts_with('(') && snip.ends_with(')') { + return true; + } + } + false +} diff --git a/clippy_lints/src/casts/mod.rs b/clippy_lints/src/casts/mod.rs index 7eb35aa8290..6c2464e0090 100644 --- a/clippy_lints/src/casts/mod.rs +++ b/clippy_lints/src/casts/mod.rs @@ -1,3 +1,4 @@ +mod cast_lossless; mod cast_precision_loss; mod utils; @@ -18,9 +19,8 @@ use rustc_target::abi::LayoutOf; use crate::consts::{constant, Constant}; use crate::utils::sugg::Sugg; use crate::utils::{ - in_constant, is_hir_ty_cfg_dependant, is_isize_or_usize, meets_msrv, method_chain_args, - numeric_literal::NumericLiteral, sext, snippet_opt, snippet_with_applicability, span_lint, span_lint_and_sugg, - span_lint_and_then, + is_hir_ty_cfg_dependant, is_isize_or_usize, meets_msrv, method_chain_args, numeric_literal::NumericLiteral, sext, + snippet_opt, snippet_with_applicability, span_lint, span_lint_and_sugg, span_lint_and_then, }; use utils::int_ty_to_nbits; @@ -254,52 +254,6 @@ declare_clippy_lint! { "casting a function pointer to a numeric type not wide enough to store the address" } -fn should_strip_parens(op: &Expr<'_>, snip: &str) -> bool { - if let ExprKind::Binary(_, _, _) = op.kind { - if snip.starts_with('(') && snip.ends_with(')') { - return true; - } - } - false -} - -fn span_lossless_lint(cx: &LateContext<'_>, expr: &Expr<'_>, op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) { - // Do not suggest using From in consts/statics until it is valid to do so (see #2267). - if in_constant(cx, expr.hir_id) { - return; - } - // The suggestion is to use a function call, so if the original expression - // has parens on the outside, they are no longer needed. - let mut applicability = Applicability::MachineApplicable; - let opt = snippet_opt(cx, op.span); - let sugg = opt.as_ref().map_or_else( - || { - applicability = Applicability::HasPlaceholders; - ".." - }, - |snip| { - if should_strip_parens(op, snip) { - &snip[1..snip.len() - 1] - } else { - snip.as_str() - } - }, - ); - - span_lint_and_sugg( - cx, - CAST_LOSSLESS, - expr.span, - &format!( - "casting `{}` to `{}` may become silently lossy if you later change the type", - cast_from, cast_to - ), - "try", - format!("{}::from({})", cast_to, sugg), - applicability, - ); -} - enum ArchSuffix { _32, _64, @@ -423,16 +377,6 @@ fn check_truncation_and_wrapping(cx: &LateContext<'_>, expr: &Expr<'_>, cast_fro } } -fn check_lossless(cx: &LateContext<'_>, expr: &Expr<'_>, op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) { - let cast_signed_to_unsigned = cast_from.is_signed() && !cast_to.is_signed(); - let from_nbits = int_ty_to_nbits(cast_from, cx.tcx); - let to_nbits = int_ty_to_nbits(cast_to, cx.tcx); - if !is_isize_or_usize(cast_from) && !is_isize_or_usize(cast_to) && from_nbits < to_nbits && !cast_signed_to_unsigned - { - span_lossless_lint(cx, expr, op, cast_from, cast_to); - } -} - declare_lint_pass!(Casts => [ CAST_PRECISION_LOSS, CAST_SIGN_LOSS, @@ -584,18 +528,8 @@ fn lint_numeric_casts<'tcx>( cast_to: Ty<'tcx>, ) { cast_precision_loss::check(cx, expr, cast_from, cast_to); + cast_lossless::check(cx, expr, cast_expr, cast_from, cast_to); match (cast_from.is_integral(), cast_to.is_integral()) { - (true, false) => { - let from_nbits = int_ty_to_nbits(cast_from, cx.tcx); - let to_nbits = if let ty::Float(FloatTy::F32) = cast_to.kind() { - 32 - } else { - 64 - }; - if from_nbits < to_nbits { - span_lossless_lint(cx, expr, cast_expr, cast_from, cast_to); - } - }, (false, true) => { span_lint( cx, @@ -618,7 +552,6 @@ fn lint_numeric_casts<'tcx>( (true, true) => { check_loss_of_sign(cx, expr, cast_expr, cast_from, cast_to); check_truncation_and_wrapping(cx, expr, cast_from, cast_to); - check_lossless(cx, expr, cast_expr, cast_from, cast_to); }, (false, false) => { if let (&ty::Float(FloatTy::F64), &ty::Float(FloatTy::F32)) = (&cast_from.kind(), &cast_to.kind()) { @@ -629,10 +562,8 @@ fn lint_numeric_casts<'tcx>( "casting `f64` to `f32` may truncate the value", ); } - if let (&ty::Float(FloatTy::F32), &ty::Float(FloatTy::F64)) = (&cast_from.kind(), &cast_to.kind()) { - span_lossless_lint(cx, expr, cast_expr, cast_from, cast_to); - } }, + (_, _) => {}, } } |