diff --git a/src/librustc_typeck/check/cast.rs b/src/librustc_typeck/check/cast.rs
index 7b35b46683099..d68c139894b92 100644
--- a/src/librustc_typeck/check/cast.rs
+++ b/src/librustc_typeck/check/cast.rs
@@ -83,28 +83,30 @@ enum PointerKind<'tcx> {
impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
/// Returns the kind of unsize information of t, or None
- /// if t is sized or it is unknown.
- fn pointer_kind(&self, t: Ty<'tcx>, span: Span) -> PointerKind<'tcx> {
+ /// if t is unknown.
+ fn pointer_kind(&self, t: Ty<'tcx>, span: Span) -> Option<PointerKind<'tcx>> {
if self.type_is_known_to_be_sized(t, span) {
- return PointerKind::Thin;
+ return Some(PointerKind::Thin);
}
match t.sty {
- ty::TySlice(_) | ty::TyStr => PointerKind::Length,
+ ty::TySlice(_) | ty::TyStr => Some(PointerKind::Length),
ty::TyDynamic(ref tty, ..) =>
- PointerKind::Vtable(tty.principal().map(|p| p.def_id())),
+ Some(PointerKind::Vtable(tty.principal().map(|p| p.def_id()))),
ty::TyAdt(def, substs) if def.is_struct() => {
// FIXME(arielb1): do some kind of normalization
match def.struct_variant().fields.last() {
- None => PointerKind::Thin,
+ None => Some(PointerKind::Thin),
Some(f) => self.pointer_kind(f.ty(self.tcx, substs), span),
}
}
// Pointers to foreign types are thin, despite being unsized
- ty::TyForeign(..) => PointerKind::Thin,
+ ty::TyForeign(..) => Some(PointerKind::Thin),
// We should really try to normalize here.
- ty::TyProjection(ref pi) => PointerKind::OfProjection(pi),
- ty::TyParam(ref p) => PointerKind::OfParam(p),
+ ty::TyProjection(ref pi) => Some(PointerKind::OfProjection(pi)),
+ ty::TyParam(ref p) => Some(PointerKind::OfParam(p)),
+ // Insufficient type information.
+ ty::TyInfer(_) => None,
_ => panic!(),
}
}
@@ -123,6 +125,8 @@ enum CastError {
NeedViaThinPtr,
NeedViaInt,
NonScalar,
+ UnknownExprPtrKind,
+ UnknownCastPtrKind,
}
fn make_invalid_casting_error<'a, 'gcx, 'tcx>(sess: &'a Session,
@@ -241,6 +245,25 @@ impl<'a, 'gcx, 'tcx> CastCheck<'tcx> {
self.expr_ty,
fcx.ty_to_string(self.cast_ty)).emit();
}
+ CastError::UnknownCastPtrKind |
+ CastError::UnknownExprPtrKind => {
+ let unknown_cast_to = match e {
+ CastError::UnknownCastPtrKind => true,
+ CastError::UnknownExprPtrKind => false,
+ _ => bug!(),
+ };
+ let mut err = struct_span_err!(fcx.tcx.sess, self.span, E0641,
+ "cannot cast {} a pointer of an unknown kind",
+ if unknown_cast_to { "to" } else { "from" });
+ err.note("The type information given here is insufficient to check whether \
+ the pointer cast is valid");
+ if unknown_cast_to {
+ err.span_suggestion_short(self.cast_span,
+ "consider giving more type information",
+ String::new());
+ }
+ err.emit();
+ }
}
}
@@ -457,14 +480,27 @@ impl<'a, 'gcx, 'tcx> CastCheck<'tcx> {
debug!("check_ptr_ptr_cast m_expr={:?} m_cast={:?}", m_expr, m_cast);
// ptr-ptr cast. vtables must match.
- // Cast to thin pointer is OK
+ let expr_kind = fcx.pointer_kind(m_expr.ty, self.span);
let cast_kind = fcx.pointer_kind(m_cast.ty, self.span);
+
+ let cast_kind = match cast_kind {
+ // We can't cast if target pointer kind is unknown
+ None => return Err(CastError::UnknownCastPtrKind),
+ Some(cast_kind) => cast_kind,
+ };
+
+ // Cast to thin pointer is OK
if cast_kind == PointerKind::Thin {
return Ok(CastKind::PtrPtrCast);
}
+ let expr_kind = match expr_kind {
+ // We can't cast to fat pointer if source pointer kind is unknown
+ None => return Err(CastError::UnknownExprPtrKind),
+ Some(expr_kind) => expr_kind,
+ };
+
// thin -> fat? report invalid cast (don't complain about vtable kinds)
- let expr_kind = fcx.pointer_kind(m_expr.ty, self.span);
if expr_kind == PointerKind::Thin {
return Err(CastError::SizedUnsizedCast);
}
@@ -483,10 +519,10 @@ impl<'a, 'gcx, 'tcx> CastCheck<'tcx> {
-> Result<CastKind, CastError> {
// fptr-ptr cast. must be to thin ptr
- if fcx.pointer_kind(m_cast.ty, self.span) == PointerKind::Thin {
- Ok(CastKind::FnPtrPtrCast)
- } else {
- Err(CastError::IllegalCast)
+ match fcx.pointer_kind(m_cast.ty, self.span) {
+ None => Err(CastError::UnknownCastPtrKind),
+ Some(PointerKind::Thin) => Ok(CastKind::FnPtrPtrCast),
+ _ => Err(CastError::IllegalCast),
}
}
@@ -496,10 +532,10 @@ impl<'a, 'gcx, 'tcx> CastCheck<'tcx> {
-> Result<CastKind, CastError> {
// ptr-addr cast. must be from thin ptr
- if fcx.pointer_kind(m_expr.ty, self.span) == PointerKind::Thin {
- Ok(CastKind::PtrAddrCast)
- } else {
- Err(CastError::NeedViaThinPtr)
+ match fcx.pointer_kind(m_expr.ty, self.span) {
+ None => Err(CastError::UnknownExprPtrKind),
+ Some(PointerKind::Thin) => Ok(CastKind::PtrAddrCast),
+ _ => Err(CastError::NeedViaThinPtr),
}
}
@@ -533,10 +569,10 @@ impl<'a, 'gcx, 'tcx> CastCheck<'tcx> {
m_cast: &'tcx ty::TypeAndMut<'tcx>)
-> Result<CastKind, CastError> {
// ptr-addr cast. pointer must be thin.
- if fcx.pointer_kind(m_cast.ty, self.span) == PointerKind::Thin {
- Ok(CastKind::AddrPtrCast)
- } else {
- Err(CastError::IllegalCast)
+ match fcx.pointer_kind(m_cast.ty, self.span) {
+ None => Err(CastError::UnknownCastPtrKind),
+ Some(PointerKind::Thin) => Ok(CastKind::AddrPtrCast),
+ _ => Err(CastError::IllegalCast),
}
}
diff --git a/src/librustc_typeck/diagnostics.rs b/src/librustc_typeck/diagnostics.rs
index 075367cbbb7cd..a23c7ded52636 100644
--- a/src/librustc_typeck/diagnostics.rs
+++ b/src/librustc_typeck/diagnostics.rs
@@ -4743,4 +4743,5 @@ register_diagnostics! {
E0627, // yield statement outside of generator literal
E0632, // cannot provide explicit type parameters when `impl Trait` is used in
// argument position.
+ E0641, // cannot cast to/from a pointer with an unknown kind
}
diff --git a/src/test/ui/issue-45730.rs b/src/test/ui/issue-45730.rs
new file mode 100644
index 0000000000000..f725d69ca65cd
--- /dev/null
+++ b/src/test/ui/issue-45730.rs
@@ -0,0 +1,19 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::fmt;
+fn main() {
+ let x: *const _ = 0 as _;
+
+ let x: *const _ = 0 as *const _;
+ let y: Option<*const fmt::Debug> = Some(x) as _;
+
+ let x = 0 as *const i32 as *const _ as *mut _;
+}
diff --git a/src/test/ui/issue-45730.stderr b/src/test/ui/issue-45730.stderr
new file mode 100644
index 0000000000000..c4f2e856b7b57
--- /dev/null
+++ b/src/test/ui/issue-45730.stderr
@@ -0,0 +1,32 @@
+error[E0641]: cannot cast to a pointer of an unknown kind
+ --> $DIR/issue-45730.rs:13:23
+ |
+13 | let x: *const _ = 0 as _;
+ | ^^^^^-
+ | |
+ | help: consider giving more type information
+ |
+ = note: The type information given here is insufficient to check whether the pointer cast is valid
+
+error[E0641]: cannot cast to a pointer of an unknown kind
+ --> $DIR/issue-45730.rs:15:23
+ |
+15 | let x: *const _ = 0 as *const _;
+ | ^^^^^--------
+ | |
+ | help: consider giving more type information
+ |
+ = note: The type information given here is insufficient to check whether the pointer cast is valid
+
+error[E0641]: cannot cast to a pointer of an unknown kind
+ --> $DIR/issue-45730.rs:18:13
+ |
+18 | let x = 0 as *const i32 as *const _ as *mut _;
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------
+ | |
+ | help: consider giving more type information
+ |
+ = note: The type information given here is insufficient to check whether the pointer cast is valid
+
+error: aborting due to 3 previous errors
+