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Rollup merge of rust-lang#64986 - skinny121:fn-ptr-const-generics, r=…
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…varkor

Function pointers as const generic arguments

Makes function pointers as const generic arguments usable.

Fixes rust-lang#62395

r? @varkor
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@Centril
Centril committed Oct 9, 2019
2 parents c1ef7d5 + 5986fe2 commit 6b1eab9
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Showing 16 changed files with 380 additions and 151 deletions.
8 changes: 8 additions & 0 deletions src/librustc/mir/interpret/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -470,6 +470,14 @@ impl<'tcx> AllocMap<'tcx> {
}
}

/// Panics if the `AllocId` does not refer to a function
pub fn unwrap_fn(&self, id: AllocId) -> Instance<'tcx> {
match self.get(id) {
Some(GlobalAlloc::Function(instance)) => instance,
_ => bug!("expected allocation ID {} to point to a function", id),
}
}

/// Freezes an `AllocId` created with `reserve` by pointing it at an `Allocation`. Trying to
/// call this function twice, even with the same `Allocation` will ICE the compiler.
pub fn set_alloc_id_memory(&mut self, id: AllocId, mem: &'tcx Allocation) {
Expand Down
217 changes: 106 additions & 111 deletions src/librustc/ty/print/pretty.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -863,125 +863,120 @@ pub trait PrettyPrinter<'tcx>:
}

let u8 = self.tcx().types.u8;
if let ty::FnDef(did, substs) = ct.ty.kind {
p!(print_value_path(did, substs));
return Ok(self);
}
if let ConstValue::Unevaluated(did, substs) = ct.val {
match self.tcx().def_kind(did) {
| Some(DefKind::Static)
| Some(DefKind::Const)
| Some(DefKind::AssocConst) => p!(print_value_path(did, substs)),
_ => if did.is_local() {
let span = self.tcx().def_span(did);
if let Ok(snip) = self.tcx().sess.source_map().span_to_snippet(span) {
p!(write("{}", snip))

match (ct.val, &ct.ty.kind) {
(_, ty::FnDef(did, substs)) => p!(print_value_path(*did, substs)),
(ConstValue::Unevaluated(did, substs), _) => {
match self.tcx().def_kind(did) {
| Some(DefKind::Static)
| Some(DefKind::Const)
| Some(DefKind::AssocConst) => p!(print_value_path(did, substs)),
_ => if did.is_local() {
let span = self.tcx().def_span(did);
if let Ok(snip) = self.tcx().sess.source_map().span_to_snippet(span) {
p!(write("{}", snip))
} else {
p!(write("_: "), print(ct.ty))
}
} else {
p!(write("_: "), print(ct.ty))
}
},
}
},
(ConstValue::Infer(..), _) => p!(write("_: "), print(ct.ty)),
(ConstValue::Param(ParamConst { name, .. }), _) => p!(write("{}", name)),
(ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Bool) =>
p!(write("{}", if data == 0 { "false" } else { "true" })),
(ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Float(ast::FloatTy::F32)) =>
p!(write("{}f32", Single::from_bits(data))),
(ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Float(ast::FloatTy::F64)) =>
p!(write("{}f64", Double::from_bits(data))),
(ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Uint(ui)) => {
let bit_size = Integer::from_attr(&self.tcx(), UnsignedInt(*ui)).size();
let max = truncate(u128::max_value(), bit_size);

if data == max {
p!(write("std::{}::MAX", ui))
} else {
p!(write("_: "), print(ct.ty))
},
}
return Ok(self);
}
if let ConstValue::Infer(..) = ct.val {
p!(write("_: "), print(ct.ty));
return Ok(self);
}
if let ConstValue::Param(ParamConst { name, .. }) = ct.val {
p!(write("{}", name));
return Ok(self);
}
if let ConstValue::Scalar(Scalar::Raw { data, .. }) = ct.val {
match ct.ty.kind {
ty::Bool => {
p!(write("{}", if data == 0 { "false" } else { "true" }));
return Ok(self);
},
ty::Float(ast::FloatTy::F32) => {
p!(write("{}f32", Single::from_bits(data)));
return Ok(self);
},
ty::Float(ast::FloatTy::F64) => {
p!(write("{}f64", Double::from_bits(data)));
return Ok(self);
},
ty::Uint(ui) => {
let bit_size = Integer::from_attr(&self.tcx(), UnsignedInt(ui)).size();
let max = truncate(u128::max_value(), bit_size);
p!(write("{}{}", data, ui))
};
},
(ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Int(i)) => {
let bit_size = Integer::from_attr(&self.tcx(), SignedInt(*i))
.size().bits() as u128;
let min = 1u128 << (bit_size - 1);
let max = min - 1;

let ty = self.tcx().lift(&ct.ty).unwrap();
let size = self.tcx().layout_of(ty::ParamEnv::empty().and(ty))
.unwrap()
.size;
match data {
d if d == min => p!(write("std::{}::MIN", i)),
d if d == max => p!(write("std::{}::MAX", i)),
_ => p!(write("{}{}", sign_extend(data, size) as i128, i))
}
},
(ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Char) =>
p!(write("{:?}", ::std::char::from_u32(data as u32).unwrap())),
(ConstValue::Scalar(Scalar::Ptr(ptr)), ty::FnPtr(_)) => {
let instance = {
let alloc_map = self.tcx().alloc_map.lock();
alloc_map.unwrap_fn(ptr.alloc_id)
};
p!(print_value_path(instance.def_id(), instance.substs));
},
_ => {
let printed = if let ty::Ref(_, ref_ty, _) = ct.ty.kind {
let byte_str = match (ct.val, &ref_ty.kind) {
(ConstValue::Scalar(Scalar::Ptr(ptr)), ty::Array(t, n)) if *t == u8 => {
let n = n.eval_usize(self.tcx(), ty::ParamEnv::empty());
Some(self.tcx()
.alloc_map.lock()
.unwrap_memory(ptr.alloc_id)
.get_bytes(&self.tcx(), ptr, Size::from_bytes(n)).unwrap())
},
(ConstValue::Slice { data, start, end }, ty::Slice(t)) if *t == u8 => {
// The `inspect` here is okay since we checked the bounds, and there are
// no relocations (we have an active slice reference here). We don't use
// this result to affect interpreter execution.
Some(data.inspect_with_undef_and_ptr_outside_interpreter(start..end))
},
_ => None,
};

if data == max {
p!(write("std::{}::MAX", ui))
if let Some(byte_str) = byte_str {
p!(write("b\""));
for &c in byte_str {
for e in std::ascii::escape_default(c) {
self.write_char(e as char)?;
}
}
p!(write("\""));
true
} else if let (ConstValue::Slice { data, start, end }, ty::Str) =
(ct.val, &ref_ty.kind)
{
// The `inspect` here is okay since we checked the bounds, and there are no
// relocations (we have an active `str` reference here). We don't use this
// result to affect interpreter execution.
let slice = data.inspect_with_undef_and_ptr_outside_interpreter(start..end);
let s = ::std::str::from_utf8(slice)
.expect("non utf8 str from miri");
p!(write("{:?}", s));
true
} else {
p!(write("{}{}", data, ui))
};
return Ok(self);
},
ty::Int(i) =>{
let bit_size = Integer::from_attr(&self.tcx(), SignedInt(i))
.size().bits() as u128;
let min = 1u128 << (bit_size - 1);
let max = min - 1;

let ty = self.tcx().lift(&ct.ty).unwrap();
let size = self.tcx().layout_of(ty::ParamEnv::empty().and(ty))
.unwrap()
.size;
match data {
d if d == min => p!(write("std::{}::MIN", i)),
d if d == max => p!(write("std::{}::MAX", i)),
_ => p!(write("{}{}", sign_extend(data, size) as i128, i))
}
return Ok(self);
},
ty::Char => {
p!(write("{:?}", ::std::char::from_u32(data as u32).unwrap()));
return Ok(self);
}
_ => {},
}
}
if let ty::Ref(_, ref_ty, _) = ct.ty.kind {
let byte_str = match (ct.val, &ref_ty.kind) {
(ConstValue::Scalar(Scalar::Ptr(ptr)), ty::Array(t, n)) if *t == u8 => {
let n = n.eval_usize(self.tcx(), ty::ParamEnv::empty());
Some(self.tcx()
.alloc_map.lock()
.unwrap_memory(ptr.alloc_id)
.get_bytes(&self.tcx(), ptr, Size::from_bytes(n)).unwrap())
},
(ConstValue::Slice { data, start, end }, ty::Slice(t)) if *t == u8 => {
// The `inspect` here is okay since we checked the bounds, and there are no
// relocations (we have an active slice reference here). We don't use this
// result to affect interpreter execution.
Some(data.inspect_with_undef_and_ptr_outside_interpreter(start..end))
},
(ConstValue::Slice { data, start, end }, ty::Str) => {
// The `inspect` here is okay since we checked the bounds, and there are no
// relocations (we have an active `str` reference here). We don't use this
// result to affect interpreter execution.
let slice = data.inspect_with_undef_and_ptr_outside_interpreter(start..end);
let s = ::std::str::from_utf8(slice)
.expect("non utf8 str from miri");
p!(write("{:?}", s));
return Ok(self);
},
_ => None,
};
if let Some(byte_str) = byte_str {
p!(write("b\""));
for &c in byte_str {
for e in std::ascii::escape_default(c) {
self.write_char(e as char)?;
false
}
} else {
false
};
if !printed {
// fallback
p!(write("{:?} : ", ct.val), print(ct.ty))
}
p!(write("\""));
return Ok(self);
}
}
p!(write("{:?} : ", ct.val), print(ct.ty));

};
Ok(self)
}
}
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58 changes: 30 additions & 28 deletions src/librustc/ty/relate.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ use crate::hir::def_id::DefId;
use crate::ty::subst::{GenericArg, GenericArgKind, SubstsRef};
use crate::ty::{self, Ty, TyCtxt, TypeFoldable};
use crate::ty::error::{ExpectedFound, TypeError};
use crate::mir::interpret::{ConstValue, get_slice_bytes, Scalar};
use crate::mir::interpret::{ConstValue, get_slice_bytes};
use std::rc::Rc;
use std::iter;
use rustc_target::spec::abi;
Expand Down Expand Up @@ -561,37 +561,39 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
// implement both `PartialEq` and `Eq`, corresponding to
// `structural_match` types.
// FIXME(const_generics): check for `structural_match` synthetic attribute.
match (eagerly_eval(a), eagerly_eval(b)) {
let new_const_val = match (eagerly_eval(a), eagerly_eval(b)) {
(ConstValue::Infer(_), _) | (_, ConstValue::Infer(_)) => {
// The caller should handle these cases!
bug!("var types encountered in super_relate_consts: {:?} {:?}", a, b)
}
(ConstValue::Param(a_p), ConstValue::Param(b_p)) if a_p.index == b_p.index => {
Ok(a)
return Ok(a);
}
(ConstValue::Placeholder(p1), ConstValue::Placeholder(p2)) if p1 == p2 => {
Ok(a)
return Ok(a);
}
(a_val @ ConstValue::Scalar(Scalar::Raw { .. }), b_val @ _)
if a.ty == b.ty && a_val == b_val =>
{
Ok(tcx.mk_const(ty::Const {
val: a_val,
ty: a.ty,
}))
(ConstValue::Scalar(a_val), ConstValue::Scalar(b_val)) if a.ty == b.ty => {
if a_val == b_val {
Ok(ConstValue::Scalar(a_val))
} else if let ty::FnPtr(_) = a.ty.kind {
let alloc_map = tcx.alloc_map.lock();
let a_instance = alloc_map.unwrap_fn(a_val.to_ptr().unwrap().alloc_id);
let b_instance = alloc_map.unwrap_fn(b_val.to_ptr().unwrap().alloc_id);
if a_instance == b_instance {
Ok(ConstValue::Scalar(a_val))
} else {
Err(TypeError::ConstMismatch(expected_found(relation, &a, &b)))
}
} else {
Err(TypeError::ConstMismatch(expected_found(relation, &a, &b)))
}
}

// FIXME(const_generics): we should either handle `Scalar::Ptr` or add a comment
// saying that we're not handling it intentionally.

(a_val @ ConstValue::Slice { .. }, b_val @ ConstValue::Slice { .. }) => {
let a_bytes = get_slice_bytes(&tcx, a_val);
let b_bytes = get_slice_bytes(&tcx, b_val);
if a_bytes == b_bytes {
Ok(tcx.mk_const(ty::Const {
val: a_val,
ty: a.ty,
}))
Ok(a_val)
} else {
Err(TypeError::ConstMismatch(expected_found(relation, &a, &b)))
}
Expand All @@ -602,16 +604,16 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
// FIXME(const_generics): this is wrong, as it is a projection
(ConstValue::Unevaluated(a_def_id, a_substs),
ConstValue::Unevaluated(b_def_id, b_substs)) if a_def_id == b_def_id => {
let substs =
relation.relate_with_variance(ty::Variance::Invariant, &a_substs, &b_substs)?;
Ok(tcx.mk_const(ty::Const {
val: ConstValue::Unevaluated(a_def_id, &substs),
ty: a.ty,
}))
}

_ => Err(TypeError::ConstMismatch(expected_found(relation, &a, &b))),
}
let substs =
relation.relate_with_variance(ty::Variance::Invariant, &a_substs, &b_substs)?;
Ok(ConstValue::Unevaluated(a_def_id, &substs))
}
_ => Err(TypeError::ConstMismatch(expected_found(relation, &a, &b))),
};
new_const_val.map(|val| tcx.mk_const(ty::Const {
val,
ty: a.ty,
}))
}

impl<'tcx> Relate<'tcx> for &'tcx ty::List<ty::ExistentialPredicate<'tcx>> {
Expand Down
17 changes: 9 additions & 8 deletions src/librustc_mir/monomorphize/collector.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1265,7 +1265,14 @@ fn collect_const<'tcx>(
) {
debug!("visiting const {:?}", constant);

match constant.val {
let param_env = ty::ParamEnv::reveal_all();
let substituted_constant = tcx.subst_and_normalize_erasing_regions(
param_substs,
param_env,
&constant,
);

match substituted_constant.val {
ConstValue::Scalar(Scalar::Ptr(ptr)) =>
collect_miri(tcx, ptr.alloc_id, output),
ConstValue::Slice { data: alloc, start: _, end: _ } |
Expand All @@ -1275,12 +1282,6 @@ fn collect_const<'tcx>(
}
}
ConstValue::Unevaluated(def_id, substs) => {
let param_env = ty::ParamEnv::reveal_all();
let substs = tcx.subst_and_normalize_erasing_regions(
param_substs,
param_env,
&substs,
);
let instance = ty::Instance::resolve(tcx,
param_env,
def_id,
Expand All @@ -1297,7 +1298,7 @@ fn collect_const<'tcx>(
tcx.def_span(def_id), "collection encountered polymorphic constant",
),
}
}
},
_ => {},
}
}
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