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Allow closure to unsafe fn coercion
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taiki-e committed Mar 31, 2019
1 parent cee58fd commit 07021e0
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Showing 19 changed files with 50 additions and 27 deletions.
2 changes: 1 addition & 1 deletion src/librustc/middle/expr_use_visitor.rs
Expand Up @@ -707,7 +707,7 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
adjustment::Adjust::NeverToAny |
adjustment::Adjust::ReifyFnPointer |
adjustment::Adjust::UnsafeFnPointer |
adjustment::Adjust::ClosureFnPointer |
adjustment::Adjust::ClosureFnPointer(_) |
adjustment::Adjust::MutToConstPointer |
adjustment::Adjust::Unsize => {
// Creating a closure/fn-pointer or unsizing consumes
Expand Down
2 changes: 1 addition & 1 deletion src/librustc/middle/mem_categorization.rs
Expand Up @@ -621,7 +621,7 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
adjustment::Adjust::NeverToAny |
adjustment::Adjust::ReifyFnPointer |
adjustment::Adjust::UnsafeFnPointer |
adjustment::Adjust::ClosureFnPointer |
adjustment::Adjust::ClosureFnPointer(_) |
adjustment::Adjust::MutToConstPointer |
adjustment::Adjust::Borrow(_) |
adjustment::Adjust::Unsize => {
Expand Down
5 changes: 3 additions & 2 deletions src/librustc/mir/mod.rs
Expand Up @@ -2247,8 +2247,9 @@ pub enum CastKind {
/// Converts unique, zero-sized type for a fn to fn()
ReifyFnPointer,

/// Converts non capturing closure to fn()
ClosureFnPointer,
/// Converts non capturing closure to fn() or unsafe fn().
/// It cannot convert a closure that requires unsafe.
ClosureFnPointer(hir::Unsafety),

/// Converts safe fn() to unsafe fn()
UnsafeFnPointer,
Expand Down
5 changes: 3 additions & 2 deletions src/librustc/ty/adjustment.rs
Expand Up @@ -62,8 +62,9 @@ pub enum Adjust<'tcx> {
/// Go from a safe fn pointer to an unsafe fn pointer.
UnsafeFnPointer,

/// Go from a non-capturing closure to an fn pointer.
ClosureFnPointer,
/// Go from a non-capturing closure to an fn pointer or an unsafe fn pointer.
/// It cannot convert a closure that requires unsafe.
ClosureFnPointer(hir::Unsafety),

/// Go from a mut raw pointer to a const raw pointer.
MutToConstPointer,
Expand Down
8 changes: 6 additions & 2 deletions src/librustc/ty/context.rs
Expand Up @@ -2441,7 +2441,11 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
/// type with the same signature. Detuples and so forth -- so
/// e.g., if we have a sig with `Fn<(u32, i32)>` then you would get
/// a `fn(u32, i32)`.
pub fn coerce_closure_fn_ty(self, sig: PolyFnSig<'tcx>) -> Ty<'tcx> {
/// `unsafety` determines the unsafety of the `fn` type. If you pass
/// `hir::Unsafety::Unsafe` in the previous example, then you would get
/// an `unsafe fn (u32, i32)`.
/// It cannot convert a closure that requires unsafe.
pub fn coerce_closure_fn_ty(self, sig: PolyFnSig<'tcx>, unsafety: hir::Unsafety) -> Ty<'tcx> {
let converted_sig = sig.map_bound(|s| {
let params_iter = match s.inputs()[0].sty {
ty::Tuple(params) => {
Expand All @@ -2453,7 +2457,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
params_iter,
s.output(),
s.c_variadic,
hir::Unsafety::Normal,
unsafety,
abi::Abi::Rust,
)
});
Expand Down
6 changes: 3 additions & 3 deletions src/librustc/ty/structural_impls.rs
Expand Up @@ -630,8 +630,8 @@ impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
Some(ty::adjustment::Adjust::ReifyFnPointer),
ty::adjustment::Adjust::UnsafeFnPointer =>
Some(ty::adjustment::Adjust::UnsafeFnPointer),
ty::adjustment::Adjust::ClosureFnPointer =>
Some(ty::adjustment::Adjust::ClosureFnPointer),
ty::adjustment::Adjust::ClosureFnPointer(unsafety) =>
Some(ty::adjustment::Adjust::ClosureFnPointer(unsafety)),
ty::adjustment::Adjust::MutToConstPointer =>
Some(ty::adjustment::Adjust::MutToConstPointer),
ty::adjustment::Adjust::Unsize =>
Expand Down Expand Up @@ -1187,7 +1187,7 @@ EnumTypeFoldableImpl! {
(ty::adjustment::Adjust::NeverToAny),
(ty::adjustment::Adjust::ReifyFnPointer),
(ty::adjustment::Adjust::UnsafeFnPointer),
(ty::adjustment::Adjust::ClosureFnPointer),
(ty::adjustment::Adjust::ClosureFnPointer)(a),
(ty::adjustment::Adjust::MutToConstPointer),
(ty::adjustment::Adjust::Unsize),
(ty::adjustment::Adjust::Deref)(a),
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_codegen_ssa/mir/rvalue.rs
Expand Up @@ -193,7 +193,7 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
}
}
}
mir::CastKind::ClosureFnPointer => {
mir::CastKind::ClosureFnPointer(_) => {
match operand.layout.ty.sty {
ty::Closure(def_id, substs) => {
let instance = monomorphize::resolve_closure(
Expand Down
4 changes: 2 additions & 2 deletions src/librustc_mir/borrow_check/nll/type_check/mod.rs
Expand Up @@ -1999,14 +1999,14 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
}
}

CastKind::ClosureFnPointer => {
CastKind::ClosureFnPointer(unsafety) => {
let sig = match op.ty(mir, tcx).sty {
ty::Closure(def_id, substs) => {
substs.closure_sig_ty(def_id, tcx).fn_sig(tcx)
}
_ => bug!(),
};
let ty_fn_ptr_from = tcx.coerce_closure_fn_ty(sig);
let ty_fn_ptr_from = tcx.coerce_closure_fn_ty(sig, *unsafety);

if let Err(terr) = self.eq_types(
ty_fn_ptr_from,
Expand Down
4 changes: 2 additions & 2 deletions src/librustc_mir/build/expr/as_rvalue.rs
Expand Up @@ -162,9 +162,9 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
let source = unpack!(block = this.as_operand(block, scope, source));
block.and(Rvalue::Cast(CastKind::UnsafeFnPointer, source, expr.ty))
}
ExprKind::ClosureFnPointer { source } => {
ExprKind::ClosureFnPointer { source, unsafety } => {
let source = unpack!(block = this.as_operand(block, scope, source));
block.and(Rvalue::Cast(CastKind::ClosureFnPointer, source, expr.ty))
block.and(Rvalue::Cast(CastKind::ClosureFnPointer(unsafety), source, expr.ty))
}
ExprKind::MutToConstPointer { source } => {
let source = unpack!(block = this.as_operand(block, scope, source));
Expand Down
4 changes: 2 additions & 2 deletions src/librustc_mir/hair/cx/expr.rs
Expand Up @@ -81,8 +81,8 @@ fn apply_adjustment<'a, 'gcx, 'tcx>(cx: &mut Cx<'a, 'gcx, 'tcx>,
Adjust::UnsafeFnPointer => {
ExprKind::UnsafeFnPointer { source: expr.to_ref() }
}
Adjust::ClosureFnPointer => {
ExprKind::ClosureFnPointer { source: expr.to_ref() }
Adjust::ClosureFnPointer(unsafety) => {
ExprKind::ClosureFnPointer { source: expr.to_ref(), unsafety }
}
Adjust::NeverToAny => {
ExprKind::NeverToAny { source: expr.to_ref() }
Expand Down
1 change: 1 addition & 0 deletions src/librustc_mir/hair/mod.rs
Expand Up @@ -185,6 +185,7 @@ pub enum ExprKind<'tcx> {
},
ClosureFnPointer {
source: ExprRef<'tcx>,
unsafety: hir::Unsafety,
},
UnsafeFnPointer {
source: ExprRef<'tcx>,
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_mir/interpret/cast.rs
Expand Up @@ -105,7 +105,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> InterpretCx<'a, 'mir, 'tcx, M>
}
}

ClosureFnPointer => {
ClosureFnPointer(_) => {
// The src operand does not matter, just its type
match src.layout.ty.sty {
ty::Closure(def_id, substs) => {
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_mir/monomorphize/collector.rs
Expand Up @@ -563,7 +563,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirNeighborCollector<'a, 'tcx> {
);
visit_fn_use(self.tcx, fn_ty, false, &mut self.output);
}
mir::Rvalue::Cast(mir::CastKind::ClosureFnPointer, ref operand, _) => {
mir::Rvalue::Cast(mir::CastKind::ClosureFnPointer(_), ref operand, _) => {
let source_ty = operand.ty(self.mir, self.tcx);
let source_ty = self.tcx.subst_and_normalize_erasing_regions(
self.param_substs,
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_mir/transform/qualify_consts.rs
Expand Up @@ -1105,7 +1105,7 @@ impl<'a, 'tcx> Visitor<'tcx> for Checker<'a, 'tcx> {
Rvalue::CheckedBinaryOp(..) |
Rvalue::Cast(CastKind::ReifyFnPointer, ..) |
Rvalue::Cast(CastKind::UnsafeFnPointer, ..) |
Rvalue::Cast(CastKind::ClosureFnPointer, ..) |
Rvalue::Cast(CastKind::ClosureFnPointer(_), ..) |
Rvalue::Cast(CastKind::Unsize, ..) |
Rvalue::Cast(CastKind::MutToConstPointer, ..) |
Rvalue::Discriminant(..) |
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_mir/transform/qualify_min_const_fn.rs
Expand Up @@ -156,7 +156,7 @@ fn check_rvalue(
check_operand(tcx, mir, operand, span)
}
Rvalue::Cast(CastKind::UnsafeFnPointer, _, _) |
Rvalue::Cast(CastKind::ClosureFnPointer, _, _) |
Rvalue::Cast(CastKind::ClosureFnPointer(_), _, _) |
Rvalue::Cast(CastKind::ReifyFnPointer, _, _) => Err((
span,
"function pointer casts are not allowed in const fn".into(),
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_passes/rvalue_promotion.rs
Expand Up @@ -586,7 +586,7 @@ fn check_adjustments<'a, 'tcx>(
Adjust::NeverToAny |
Adjust::ReifyFnPointer |
Adjust::UnsafeFnPointer |
Adjust::ClosureFnPointer |
Adjust::ClosureFnPointer(_) |
Adjust::MutToConstPointer |
Adjust::Borrow(_) |
Adjust::Unsize => {}
Expand Down
12 changes: 8 additions & 4 deletions src/librustc_typeck/check/coercion.rs
Expand Up @@ -225,7 +225,8 @@ impl<'f, 'gcx, 'tcx> Coerce<'f, 'gcx, 'tcx> {
}
ty::Closure(def_id_a, substs_a) => {
// Non-capturing closures are coercible to
// function pointers
// function pointers or unsafe function pointers.
// It cannot convert closures that require unsafe.
self.coerce_closure_to_fn(a, def_id_a, substs_a, b)
}
_ => {
Expand Down Expand Up @@ -714,16 +715,19 @@ impl<'f, 'gcx, 'tcx> Coerce<'f, 'gcx, 'tcx> {

let hir_id_a = self.tcx.hir().as_local_hir_id(def_id_a).unwrap();
match b.sty {
ty::FnPtr(_) if self.tcx.with_freevars(hir_id_a, |v| v.is_empty()) => {
ty::FnPtr(fn_ty) if self.tcx.with_freevars(hir_id_a, |v| v.is_empty()) => {
// We coerce the closure, which has fn type
// `extern "rust-call" fn((arg0,arg1,...)) -> _`
// to
// `fn(arg0,arg1,...) -> _`
// or
// `unsafe fn(arg0,arg1,...) -> _`
let sig = self.closure_sig(def_id_a, substs_a);
let pointer_ty = self.tcx.coerce_closure_fn_ty(sig);
let unsafety = fn_ty.unsafety();
let pointer_ty = self.tcx.coerce_closure_fn_ty(sig, unsafety);
debug!("coerce_closure_to_fn(a={:?}, b={:?}, pty={:?})",
a, b, pointer_ty);
self.unify_and(pointer_ty, b, simple(Adjust::ClosureFnPointer))
self.unify_and(pointer_ty, b, simple(Adjust::ClosureFnPointer(unsafety)))
}
_ => self.unify_and(a, b, identity),
}
Expand Down
@@ -0,0 +1,5 @@
fn main() {
let _: unsafe fn() = || { ::std::pin::Pin::new_unchecked(&0_u8); };
//~^ ERROR E0133
let _: unsafe fn() = || unsafe { ::std::pin::Pin::new_unchecked(&0_u8); }; // OK
}
7 changes: 7 additions & 0 deletions src/test/run-pass/typeck-closure-to-unsafe-fn-ptr.rs
@@ -0,0 +1,7 @@
unsafe fn call_unsafe(func: unsafe fn() -> ()) -> () {
func()
}

pub fn main() {
unsafe { call_unsafe(|| {}); }
}

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