diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src')
| -rw-r--r-- | compiler/rustc_mir_transform/src/check_unnecessary_transmutes.rs | 136 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/errors.rs | 20 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/lib.rs | 2 |
3 files changed, 0 insertions, 158 deletions
diff --git a/compiler/rustc_mir_transform/src/check_unnecessary_transmutes.rs b/compiler/rustc_mir_transform/src/check_unnecessary_transmutes.rs deleted file mode 100644 index 1a3715465ad..00000000000 --- a/compiler/rustc_mir_transform/src/check_unnecessary_transmutes.rs +++ /dev/null @@ -1,136 +0,0 @@ -use rustc_middle::mir::visit::Visitor; -use rustc_middle::mir::{Body, Location, Operand, Terminator, TerminatorKind}; -use rustc_middle::ty::*; -use rustc_session::lint::builtin::UNNECESSARY_TRANSMUTES; -use rustc_span::source_map::Spanned; -use rustc_span::{Span, sym}; - -use crate::errors::UnnecessaryTransmute as Error; - -/// Check for transmutes that overlap with stdlib methods. -/// For example, transmuting `[u8; 4]` to `u32`. -/// We chose not to lint u8 -> bool transmutes, see #140431 -pub(super) struct CheckUnnecessaryTransmutes; - -impl<'tcx> crate::MirLint<'tcx> for CheckUnnecessaryTransmutes { - fn run_lint(&self, tcx: TyCtxt<'tcx>, body: &Body<'tcx>) { - let mut checker = UnnecessaryTransmuteChecker { body, tcx }; - checker.visit_body(body); - } -} - -struct UnnecessaryTransmuteChecker<'a, 'tcx> { - body: &'a Body<'tcx>, - tcx: TyCtxt<'tcx>, -} - -impl<'a, 'tcx> UnnecessaryTransmuteChecker<'a, 'tcx> { - fn is_unnecessary_transmute( - &self, - function: &Operand<'tcx>, - arg: String, - span: Span, - is_in_const: bool, - ) -> Option<Error> { - let fn_sig = function.ty(self.body, self.tcx).fn_sig(self.tcx).skip_binder(); - let [input] = fn_sig.inputs() else { return None }; - - let err = |sugg| Error { span, sugg, help: None }; - - Some(match (input.kind(), fn_sig.output().kind()) { - // dont check the length; transmute does that for us. - // [u8; _] => primitive - (Array(t, _), Uint(_) | Float(_) | Int(_)) if *t.kind() == Uint(UintTy::U8) => Error { - sugg: format!("{}::from_ne_bytes({arg})", fn_sig.output()), - help: Some( - "there's also `from_le_bytes` and `from_be_bytes` if you expect a particular byte order", - ), - span, - }, - // primitive => [u8; _] - (Uint(_) | Float(_) | Int(_), Array(t, _)) if *t.kind() == Uint(UintTy::U8) => Error { - sugg: format!("{input}::to_ne_bytes({arg})"), - help: Some( - "there's also `to_le_bytes` and `to_be_bytes` if you expect a particular byte order", - ), - span, - }, - // char → u32 - (Char, Uint(UintTy::U32)) => err(format!("u32::from({arg})")), - // char (→ u32) → i32 - (Char, Int(IntTy::I32)) => err(format!("u32::from({arg}).cast_signed()")), - // u32 → char - (Uint(UintTy::U32), Char) => Error { - sugg: format!("char::from_u32_unchecked({arg})"), - help: Some("consider `char::from_u32(…).unwrap()`"), - span, - }, - // i32 → char - (Int(IntTy::I32), Char) => Error { - sugg: format!("char::from_u32_unchecked(i32::cast_unsigned({arg}))"), - help: Some("consider `char::from_u32(i32::cast_unsigned(…)).unwrap()`"), - span, - }, - // uNN → iNN - (Uint(ty), Int(_)) => err(format!("{}::cast_signed({arg})", ty.name_str())), - // iNN → uNN - (Int(ty), Uint(_)) => err(format!("{}::cast_unsigned({arg})", ty.name_str())), - // fNN → xsize - (Float(ty), Uint(UintTy::Usize)) => { - err(format!("{}::to_bits({arg}) as usize", ty.name_str())) - } - (Float(ty), Int(IntTy::Isize)) => { - err(format!("{}::to_bits({arg}) as isize", ty.name_str())) - } - // fNN (→ uNN) → iNN - (Float(ty), Int(..)) => err(format!("{}::to_bits({arg}).cast_signed()", ty.name_str())), - // fNN → uNN - (Float(ty), Uint(..)) => err(format!("{}::to_bits({arg})", ty.name_str())), - // xsize → fNN - (Uint(UintTy::Usize) | Int(IntTy::Isize), Float(ty)) => { - err(format!("{}::from_bits({arg} as _)", ty.name_str(),)) - } - // iNN (→ uNN) → fNN - (Int(int_ty), Float(ty)) => err(format!( - "{}::from_bits({}::cast_unsigned({arg}))", - ty.name_str(), - int_ty.name_str() - )), - // uNN → fNN - (Uint(_), Float(ty)) => err(format!("{}::from_bits({arg})", ty.name_str())), - // bool → { x8 } in const context since `From::from` is not const yet - // FIXME: is it possible to know when the parentheses arent necessary? - // FIXME(const_traits): Remove this when From::from is constified? - (Bool, Int(..) | Uint(..)) if is_in_const => { - err(format!("({arg}) as {}", fn_sig.output())) - } - // " using `x8::from` - (Bool, Int(..) | Uint(..)) => err(format!("{}::from({arg})", fn_sig.output())), - _ => return None, - }) - } -} - -impl<'tcx> Visitor<'tcx> for UnnecessaryTransmuteChecker<'_, 'tcx> { - // Check each block's terminator for calls to pointer to integer transmutes - // in const functions or associated constants and emit a lint. - fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) { - if let TerminatorKind::Call { func, args, .. } = &terminator.kind - && let [Spanned { span: arg, .. }] = **args - && let Some((func_def_id, _)) = func.const_fn_def() - && self.tcx.is_intrinsic(func_def_id, sym::transmute) - && let span = self.body.source_info(location).span - && let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(arg) - && let def_id = self.body.source.def_id() - && let Some(lint) = self.is_unnecessary_transmute( - func, - snippet, - span, - self.tcx.hir_body_const_context(def_id.expect_local()).is_some(), - ) - && let Some(hir_id) = terminator.source_info.scope.lint_root(&self.body.source_scopes) - { - self.tcx.emit_node_span_lint(UNNECESSARY_TRANSMUTES, hir_id, span, lint); - } - } -} diff --git a/compiler/rustc_mir_transform/src/errors.rs b/compiler/rustc_mir_transform/src/errors.rs index 9777cb56f13..cffa0183fa7 100644 --- a/compiler/rustc_mir_transform/src/errors.rs +++ b/compiler/rustc_mir_transform/src/errors.rs @@ -158,26 +158,6 @@ pub(crate) struct MustNotSuspendReason { pub reason: String, } -pub(crate) struct UnnecessaryTransmute { - pub span: Span, - pub sugg: String, - pub help: Option<&'static str>, -} - -// Needed for def_path_str -impl<'a> LintDiagnostic<'a, ()> for UnnecessaryTransmute { - fn decorate_lint<'b>(self, diag: &'b mut rustc_errors::Diag<'a, ()>) { - diag.primary_message(fluent::mir_transform_unnecessary_transmute); - diag.span_suggestion( - self.span, - "replace this with", - self.sugg, - lint::Applicability::MachineApplicable, - ); - self.help.map(|help| diag.help(help)); - } -} - #[derive(Diagnostic)] #[diag(mir_transform_force_inline)] #[note] diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs index 8d4e9e30f4f..d26e4468715 100644 --- a/compiler/rustc_mir_transform/src/lib.rs +++ b/compiler/rustc_mir_transform/src/lib.rs @@ -123,7 +123,6 @@ declare_passes! { mod check_const_item_mutation : CheckConstItemMutation; mod check_null : CheckNull; mod check_packed_ref : CheckPackedRef; - mod check_unnecessary_transmutes: CheckUnnecessaryTransmutes; // This pass is public to allow external drivers to perform MIR cleanup pub mod cleanup_post_borrowck : CleanupPostBorrowck; @@ -389,7 +388,6 @@ fn mir_built(tcx: TyCtxt<'_>, def: LocalDefId) -> &Steal<Body<'_>> { &Lint(check_packed_ref::CheckPackedRef), &Lint(check_const_item_mutation::CheckConstItemMutation), &Lint(function_item_references::FunctionItemReferences), - &Lint(check_unnecessary_transmutes::CheckUnnecessaryTransmutes), // What we need to do constant evaluation. &simplify::SimplifyCfg::Initial, &Lint(sanity_check::SanityCheck), |