bjoernager/rust
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don't supply generics to AnonConsts in param lists

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This commit is contained in:
Bastian Kauschke 2020-07-09 22:26:49 +02:00
parent 3f55840243
commit 6f5d8bf5c8
4 changed files with 68 additions and 37 deletions
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61
src/librustc_typeck/collect.rs
View file

@ -29,7 +29,7 @@ use rustc_hir::def::{CtorKind, DefKind, Res};
use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc_hir::weak_lang_items;
use rustc_hir::{GenericParamKind, Node};
use rustc_hir::{GenericParamKind, HirId, Node};
use rustc_middle::hir::map::blocks::FnLikeNode;
use rustc_middle::hir::map::Map;
use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
@ -1155,6 +1155,35 @@ fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<S
}
}
struct AnonConstInParamListDetector {
in_param_list: bool,
found_anon_const_in_list: bool,
ct: HirId,
}
impl<'v> Visitor<'v> for AnonConstInParamListDetector {
type Map = intravisit::ErasedMap<'v>;
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
NestedVisitorMap::None
}
fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
let prev = self.in_param_list;
self.in_param_list = true;
intravisit::walk_generic_param(self, p);
self.in_param_list = prev;
}
fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
if self.in_param_list && self.ct == c.hir_id {
self.found_anon_const_in_list = true;
} else {
intravisit::walk_anon_const(self, c)
}
}
}
fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
use rustc_hir::*;
@ -1176,10 +1205,32 @@ fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
let parent_id = tcx.hir().get_parent_item(hir_id);
let parent_def_id = tcx.hir().local_def_id(parent_id);
// HACK(eddyb) this provides the correct generics when
// `feature(const_generics)` is enabled, so that const expressions
// used with const generics, e.g. `Foo<{N+1}>`, can work at all.
if tcx.lazy_normalization() {
let mut in_param_list = false;
for (_parent, node) in tcx.hir().parent_iter(hir_id) {
if let Some(generics) = node.generics() {
let mut visitor = AnonConstInParamListDetector {
in_param_list: false,
found_anon_const_in_list: false,
ct: hir_id,
};
visitor.visit_generics(generics);
in_param_list = visitor.found_anon_const_in_list;
break;
}
}
if in_param_list {
// We do not allow generic parameters in anon consts if we are inside
// of a param list.
//
// This affects both default type bindings, e.g. `struct<T, U = [u8; std::mem::size_of::<T>()]>(T, U)`,
// and the types of const parameters, e.g. `struct V<const N: usize, const M: [u8; N]>();`.
None
} else if tcx.lazy_normalization() {
// HACK(eddyb) this provides the correct generics when
// `feature(const_generics)` is enabled, so that const expressions
// used with const generics, e.g. `Foo<{N+1}>`, can work at all.
Some(parent_def_id.to_def_id())
} else {
let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));

2
src/test/ui/const-generics/const-param-type-depends-on-const-param.rs
View file

@ -8,10 +8,8 @@
pub struct Dependent<const N: usize, const X: [u8; N]>([(); N]);
//~^ ERROR: the type of const parameters must not depend on other generic parameters
//~| ERROR: cycle detected when computing type of `Dependent::X`
pub struct SelfDependent<const N: [u8; N]>;
//~^ ERROR: the type of const parameters must not depend on other generic parameters
//~| ERROR: cycle detected when computing type of `SelfDependent::N`
fn main() {}

33
src/test/ui/const-generics/const-param-type-depends-on-const-param.stderr
View file

@ -4,8 +4,8 @@ error[E0770]: the type of const parameters must not depend on other generic para
LL | pub struct Dependent<const N: usize, const X: [u8; N]>([(); N]);
| ^ const parameters must have a concrete type
error[E0769]: the type of const parameters must not depend on other generic parameters
--> $DIR/const-param-type-depends-on-const-param.rs:13:40
error[E0770]: the type of const parameters must not depend on other generic parameters
--> $DIR/const-param-type-depends-on-const-param.rs:12:40
|
LL | pub struct SelfDependent<const N: [u8; N]>;
| ^ const parameters must have a concrete type
@ -19,32 +19,5 @@ LL | #![feature(const_generics)]
= note: `#[warn(incomplete_features)]` on by default
= note: see issue #44580 <https://github.com/rust-lang/rust/issues/44580> for more information
error[E0391]: cycle detected when computing type of `Dependent::X`
--> $DIR/const-param-type-depends-on-const-param.rs:9:44
|
LL | pub struct Dependent<const N: usize, const X: [u8; N]>([(); N]);
| ^
|
= note: ...which again requires computing type of `Dependent::X`, completing the cycle
note: cycle used when computing type of `Dependent`
--> $DIR/const-param-type-depends-on-const-param.rs:9:1
|
LL | pub struct Dependent<const N: usize, const X: [u8; N]>([(); N]);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 2 previous errors; 1 warning emitted
error[E0391]: cycle detected when computing type of `SelfDependent::N`
--> $DIR/const-param-type-depends-on-const-param.rs:13:32
|
LL | pub struct SelfDependent<const N: [u8; N]>;
| ^
|
= note: ...which again requires computing type of `SelfDependent::N`, completing the cycle
note: cycle used when computing type of `SelfDependent`
--> $DIR/const-param-type-depends-on-const-param.rs:13:1
|
LL | pub struct SelfDependent<const N: [u8; N]>;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 4 previous errors; 1 warning emitted
For more information about this error, try `rustc --explain E0391`.

9
src/test/ui/const-generics/issues/issue-74101.rs Normal file
View file

@ -0,0 +1,9 @@
// check-pass
#![feature(const_generics)]
#![allow(incomplete_features)]
fn test<const N: [u8; 1 + 2]>() {}
struct Foo<const N: [u8; 1 + 2]>;
fn main() {}