Navigation Menu

Skip to content

Commit

Permalink
Move all intrinsic whitelists into the constness check file
Browse files Browse the repository at this point in the history
  • Loading branch information
@oli-obk
oli-obk committed Dec 3, 2019
1 parent 52be0b0 commit 46c00a2
Show file tree
Hide file tree
Showing 4 changed files with 42 additions and 56 deletions.
35 changes: 35 additions & 0 deletions src/librustc/ty/constness.rs
View file
Expand Up @@ -36,12 +36,47 @@ impl<'tcx> TyCtxt<'tcx> {
}
}

/// Returns `true` if the `def_id` refers to an intrisic which we've whitelisted
/// for being called from stable `const fn`s (`min_const_fn`).
///
/// Adding more intrinsics requires sign-off from @rust-lang/lang.
fn is_intrinsic_min_const_fn(self, def_id: DefId) -> bool {
match self.item_name(def_id) {
| sym::size_of
| sym::min_align_of
| sym::needs_drop
// Arithmetic:
| sym::add_with_overflow // ~> .overflowing_add
| sym::sub_with_overflow // ~> .overflowing_sub
| sym::mul_with_overflow // ~> .overflowing_mul
| sym::wrapping_add // ~> .wrapping_add
| sym::wrapping_sub // ~> .wrapping_sub
| sym::wrapping_mul // ~> .wrapping_mul
| sym::saturating_add // ~> .saturating_add
| sym::saturating_sub // ~> .saturating_sub
| sym::unchecked_shl // ~> .wrapping_shl
| sym::unchecked_shr // ~> .wrapping_shr
| sym::rotate_left // ~> .rotate_left
| sym::rotate_right // ~> .rotate_right
| sym::ctpop // ~> .count_ones
| sym::ctlz // ~> .leading_zeros
| sym::cttz // ~> .trailing_zeros
| sym::bswap // ~> .swap_bytes
| sym::bitreverse // ~> .reverse_bits
=> true,
_ => false,
}
}

/// Returns `true` if this function must conform to `min_const_fn`
pub fn is_min_const_fn(self, def_id: DefId) -> bool {
// Bail out if the signature doesn't contain `const`
if !self.is_const_fn_raw(def_id) {
return false;
}
if let Abi::RustIntrinsic = self.fn_sig(def_id).abi() {
return self.is_intrinsic_min_const_fn(def_id);
}

if self.features().staged_api {
// in order for a libstd function to be considered min_const_fn
Expand Down
55 changes: 3 additions & 52 deletions src/librustc_mir/transform/qualify_min_const_fn.rs
View file
Expand Up @@ -2,7 +2,6 @@ use rustc::hir::def_id::DefId;
use rustc::hir;
use rustc::mir::*;
use rustc::ty::{self, Predicate, Ty, TyCtxt, adjustment::{PointerCast}};
use rustc_target::spec::abi;
use std::borrow::Cow;
use syntax_pos::Span;
use syntax::symbol::{sym, Symbol};
Expand Down Expand Up @@ -356,33 +355,16 @@ fn check_terminator(
} => {
let fn_ty = func.ty(body, tcx);
if let ty::FnDef(def_id, _) = fn_ty.kind {

// some intrinsics are waved through if called inside the
// standard library. Users never need to call them directly
match tcx.fn_sig(def_id).abi() {
abi::Abi::RustIntrinsic => if !is_intrinsic_whitelisted(tcx, def_id) {
return Err((
span,
"can only call a curated list of intrinsics in `min_const_fn`".into(),
))
},
abi::Abi::Rust if tcx.is_min_const_fn(def_id) => {},
abi::Abi::Rust => return Err((
if !tcx.is_min_const_fn(def_id) {
return Err((
span,
format!(
"can only call other `const fn` within a `const fn`, \
but `{:?}` is not stable as `const fn`",
func,
)
.into(),
)),
abi => return Err((
span,
format!(
"cannot call functions with `{}` abi in `min_const_fn`",
abi,
).into(),
)),
));
}

check_operand(tcx, func, span, def_id, body)?;
Expand Down Expand Up @@ -410,34 +392,3 @@ fn check_terminator(
}
}

/// Returns `true` if the `def_id` refers to an intrisic which we've whitelisted
/// for being called from stable `const fn`s (`min_const_fn`).
///
/// Adding more intrinsics requires sign-off from @rust-lang/lang.
fn is_intrinsic_whitelisted(tcx: TyCtxt<'tcx>, def_id: DefId) -> bool {
match tcx.item_name(def_id) {
| sym::size_of
| sym::min_align_of
| sym::needs_drop
// Arithmetic:
| sym::add_with_overflow // ~> .overflowing_add
| sym::sub_with_overflow // ~> .overflowing_sub
| sym::mul_with_overflow // ~> .overflowing_mul
| sym::wrapping_add // ~> .wrapping_add
| sym::wrapping_sub // ~> .wrapping_sub
| sym::wrapping_mul // ~> .wrapping_mul
| sym::saturating_add // ~> .saturating_add
| sym::saturating_sub // ~> .saturating_sub
| sym::unchecked_shl // ~> .wrapping_shl
| sym::unchecked_shr // ~> .wrapping_shr
| sym::rotate_left // ~> .rotate_left
| sym::rotate_right // ~> .rotate_right
| sym::ctpop // ~> .count_ones
| sym::ctlz // ~> .leading_zeros
| sym::cttz // ~> .trailing_zeros
| sym::bswap // ~> .swap_bytes
| sym::bitreverse // ~> .reverse_bits
=> true,
_ => false,
}
}
4 changes: 2 additions & 2 deletions src/test/ui/consts/const-extern-fn/const-extern-fn-call-extern-fn.rs
View file
Expand Up @@ -7,7 +7,7 @@ extern "C" {
const extern fn bar() {
unsafe {
regular_in_block();
//~^ ERROR: cannot call functions with `"C"` abi in `min_const_fn`
//~^ ERROR: can only call other `const fn` within a `const fn`
}
}

Expand All @@ -16,7 +16,7 @@ extern fn regular() {}
const extern fn foo() {
unsafe {
regular();
//~^ ERROR: cannot call functions with `"C"` abi in `min_const_fn`
//~^ ERROR: can only call other `const fn` within a `const fn`
}
}

Expand Down
4 changes: 2 additions & 2 deletions src/test/ui/consts/const-extern-fn/const-extern-fn-call-extern-fn.stderr
View file
@@ -1,4 +1,4 @@
error[E0723]: cannot call functions with `"C"` abi in `min_const_fn`
error[E0723]: can only call other `const fn` within a `const fn`, but `const regular_in_block` is not stable as `const fn`
--> $DIR/const-extern-fn-call-extern-fn.rs:9:9
|
LL | regular_in_block();
Expand All @@ -7,7 +7,7 @@ LL | regular_in_block();
= note: for more information, see issue https://github.com/rust-lang/rust/issues/57563
= help: add `#![feature(const_fn)]` to the crate attributes to enable

error[E0723]: cannot call functions with `"C"` abi in `min_const_fn`
error[E0723]: can only call other `const fn` within a `const fn`, but `const regular` is not stable as `const fn`
--> $DIR/const-extern-fn-call-extern-fn.rs:18:9
|
LL | regular();
Expand Down

0 comments on commit 46c00a2

Please sign in to comment.