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fix name resolution for param defaults

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This commit is contained in:
lcnr 2021-04-18 13:57:22 +02:00
parent d7c3386414
commit 259a368e9e
15 changed files with 141 additions and 104 deletions
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11
compiler/rustc_resolve/src/diagnostics.rs
View file

@ -472,17 +472,6 @@ impl<'a> Resolver<'a> {
);
err
}
ResolutionError::ParamInAnonConstInTyDefault(name) => {
let mut err = self.session.struct_span_err(
span,
"constant values inside of type parameter defaults must not depend on generic parameters",
);
err.span_label(
span,
format!("the anonymous constant must not depend on the parameter `{}`", name),
);
err
}
ResolutionError::ParamInNonTrivialAnonConst { name, is_type } => {
let mut err = self.session.struct_span_err(
span,

69
compiler/rustc_resolve/src/late.rs
View file

@ -555,18 +555,23 @@ impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
// provide previous type parameters as they're built. We
// put all the parameters on the ban list and then remove
// them one by one as they are processed and become available.
let mut default_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
let mut found_default = false;
default_ban_rib.bindings.extend(generics.params.iter().filter_map(
|param| match param.kind {
GenericParamKind::Type { default: Some(_), .. }
| GenericParamKind::Const { default: Some(_), .. } => {
found_default = true;
Some((Ident::with_dummy_span(param.ident.name), Res::Err))
let mut forward_ty_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
let mut forward_const_ban_rib = Rib::new(ForwardGenericParamBanRibKind);
for param in generics.params.iter() {
match param.kind {
GenericParamKind::Type { .. } => {
forward_ty_ban_rib
.bindings
.insert(Ident::with_dummy_span(param.ident.name), Res::Err);
}
_ => None,
},
));
GenericParamKind::Const { .. } => {
forward_const_ban_rib
.bindings
.insert(Ident::with_dummy_span(param.ident.name), Res::Err);
}
GenericParamKind::Lifetime => {}
}
}
// rust-lang/rust#61631: The type `Self` is essentially
// another type parameter. For ADTs, we consider it
@ -579,7 +584,7 @@ impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
// such as in the case of `trait Add<Rhs = Self>`.)
if self.diagnostic_metadata.current_self_item.is_some() {
// (`Some` if + only if we are in ADT's generics.)
default_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
forward_ty_ban_rib.bindings.insert(Ident::with_dummy_span(kw::SelfUpper), Res::Err);
}
for param in &generics.params {
@ -591,32 +596,38 @@ impl<'a: 'ast, 'ast> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast> {
}
if let Some(ref ty) = default {
self.ribs[TypeNS].push(default_ban_rib);
self.with_rib(ValueNS, ForwardGenericParamBanRibKind, |this| {
// HACK: We use an empty `ForwardGenericParamBanRibKind` here which
// is only used to forbid the use of const parameters inside of
// type defaults.
//
// While the rib name doesn't really fit here, it does allow us to use the same
// code for both const and type parameters.
this.visit_ty(ty);
});
default_ban_rib = self.ribs[TypeNS].pop().unwrap();
self.ribs[TypeNS].push(forward_ty_ban_rib);
self.ribs[ValueNS].push(forward_const_ban_rib);
self.visit_ty(ty);
forward_const_ban_rib = self.ribs[ValueNS].pop().unwrap();
forward_ty_ban_rib = self.ribs[TypeNS].pop().unwrap();
}
// Allow all following defaults to refer to this type parameter.
default_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
forward_ty_ban_rib.bindings.remove(&Ident::with_dummy_span(param.ident.name));
}
GenericParamKind::Const { ref ty, kw_span: _, default: _ } => {
// FIXME(const_generics_defaults): handle `default` value here
for bound in &param.bounds {
self.visit_param_bound(bound);
}
GenericParamKind::Const { ref ty, kw_span: _, ref default } => {
// Const parameters can't have param bounds.
assert!(param.bounds.is_empty());
self.ribs[TypeNS].push(Rib::new(ConstParamTyRibKind));
self.ribs[ValueNS].push(Rib::new(ConstParamTyRibKind));
self.visit_ty(ty);
self.ribs[TypeNS].pop().unwrap();
self.ribs[ValueNS].pop().unwrap();
if let Some(ref expr) = default {
self.ribs[TypeNS].push(forward_ty_ban_rib);
self.ribs[ValueNS].push(forward_const_ban_rib);
self.visit_anon_const(expr);
forward_const_ban_rib = self.ribs[ValueNS].pop().unwrap();
forward_ty_ban_rib = self.ribs[TypeNS].pop().unwrap();
}
// Allow all following defaults to refer to this const parameter.
forward_const_ban_rib
.bindings
.remove(&Ident::with_dummy_span(param.ident.name));
}
}
}

56
compiler/rustc_resolve/src/lib.rs
View file

@ -239,8 +239,6 @@ enum ResolutionError<'a> {
ForwardDeclaredTyParam, // FIXME(const_generics_defaults)
/// ERROR E0770: the type of const parameters must not depend on other generic parameters.
ParamInTyOfConstParam(Symbol),
/// constant values inside of type parameter defaults must not depend on generic parameters.
ParamInAnonConstInTyDefault(Symbol),
/// generic parameters must not be used inside const evaluations.
///
/// This error is only emitted when using `min_const_generics`.
@ -2672,26 +2670,18 @@ impl<'a> Resolver<'a> {
}
}
Res::Def(DefKind::TyParam, _) | Res::SelfTy(..) => {
let mut in_ty_param_default = false;
for rib in ribs {
let has_generic_params = match rib.kind {
let has_generic_params: HasGenericParams = match rib.kind {
NormalRibKind
| ClosureOrAsyncRibKind
| AssocItemRibKind
| ModuleRibKind(..)
| MacroDefinition(..) => {
| MacroDefinition(..)
| ForwardGenericParamBanRibKind => {
// Nothing to do. Continue.
continue;
}
// We only forbid constant items if we are inside of type defaults,
// for example `struct Foo<T, U = [u8; std::mem::size_of::<T>()]>`
ForwardGenericParamBanRibKind => {
// FIXME(const_generic_defaults): we may need to distinguish between
// being in type parameter defaults and const parameter defaults
in_ty_param_default = true;
continue;
}
ConstantItemRibKind(trivial, _) => {
let features = self.session.features_untracked();
// HACK(min_const_generics): We currently only allow `N` or `{ N }`.
@ -2720,19 +2710,7 @@ impl<'a> Resolver<'a> {
}
}
if in_ty_param_default {
if record_used {
self.report_error(
span,
ResolutionError::ParamInAnonConstInTyDefault(
rib_ident.name,
),
);
}
return Res::Err;
} else {
continue;
}
continue;
}
// This was an attempt to use a type parameter outside its scope.
@ -2770,23 +2748,15 @@ impl<'a> Resolver<'a> {
ribs.next();
}
let mut in_ty_param_default = false;
for rib in ribs {
let has_generic_params = match rib.kind {
NormalRibKind
| ClosureOrAsyncRibKind
| AssocItemRibKind
| ModuleRibKind(..)
| MacroDefinition(..) => continue,
| MacroDefinition(..)
| ForwardGenericParamBanRibKind => continue,
// We only forbid constant items if we are inside of type defaults,
// for example `struct Foo<T, U = [u8; std::mem::size_of::<T>()]>`
ForwardGenericParamBanRibKind => {
// FIXME(const_generic_defaults): we may need to distinguish between
// being in type parameter defaults and const parameter defaults
in_ty_param_default = true;
continue;
}
ConstantItemRibKind(trivial, _) => {
let features = self.session.features_untracked();
// HACK(min_const_generics): We currently only allow `N` or `{ N }`.
@ -2808,19 +2778,7 @@ impl<'a> Resolver<'a> {
return Res::Err;
}
if in_ty_param_default {
if record_used {
self.report_error(
span,
ResolutionError::ParamInAnonConstInTyDefault(
rib_ident.name,
),
);
}
return Res::Err;
} else {
continue;
}
continue;
}
ItemRibKind(has_generic_params) => has_generic_params,

9
src/test/ui/const-generics/defaults/complex-generic-default-expr.rs Normal file
View file

@ -0,0 +1,9 @@
#![feature(const_generics, const_generics_defaults)]
#![allow(incomplete_features)]
struct Foo<const N: usize, const M: usize = { N + 1 }>;
struct Bar<T, const TYPE_SIZE: usize = { std::mem::size_of::<T>() }>(T);
//~^ ERROR the size for values of type `T` cannot be known at compilation time
fn main() {}

16
src/test/ui/const-generics/defaults/complex-generic-default-expr.stderr Normal file
View file

@ -0,0 +1,16 @@
error[E0277]: the size for values of type `T` cannot be known at compilation time
--> $DIR/complex-generic-default-expr.rs:6:62
|
LL | struct Bar<T, const TYPE_SIZE: usize = { std::mem::size_of::<T>() }>(T);
| - ^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
|
::: $SRC_DIR/core/src/mem/mod.rs:LL:COL
|
LL | pub const fn size_of<T>() -> usize {
| - required by this bound in `std::mem::size_of`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0277`.

9
src/test/ui/const-generics/defaults/default-on-impl.rs Normal file
View file

@ -0,0 +1,9 @@
#![feature(const_generics, const_generics_defaults)]
#![allow(incomplete_features)]
struct Foo<const N: usize>;
impl<const N: usize = 1> Foo<N> {}
//~^ ERROR defaults for const parameters are only allowed
fn main() {}

8
src/test/ui/const-generics/defaults/default-on-impl.stderr Normal file
View file

@ -0,0 +1,8 @@
error: defaults for const parameters are only allowed in `struct`, `enum`, `type`, or `trait` definitions
--> $DIR/default-on-impl.rs:6:12
|
LL | impl<const N: usize = 1> Foo<N> {}
| ^
error: aborting due to previous error

3
src/test/ui/const-generics/defaults/pretty-printing-ast.rs
View file

@ -10,4 +10,5 @@ trait Foo<const KIND: bool = true> {}
fn foo<const SIZE: usize = 5>() {}
struct Range<const FROM: usize = 0, const LEN: usize = 0, const TO: usize = {FROM + LEN}>;
struct Range<const FROM: usize = 0, const LEN: usize = 0, const TO: usize = FROM>;

3
src/test/ui/const-generics/defaults/pretty-printing-ast.stdout
View file

@ -17,4 +17,5 @@ trait Foo<const KIND : bool = true> { }
fn foo<const SIZE : usize = 5>() { }
struct Range<const FROM : usize = 0, const LEN : usize = 0, const TO : usize =
{ FROM + LEN }>;
FROM>;

17
src/test/ui/const-generics/defaults/type-default-const-param-name.rs Normal file
View file

@ -0,0 +1,17 @@
// check-pass
#![feature(const_generics, const_generics_defaults)]
#![allow(incomplete_features)]
struct N;
struct Foo<const N: usize = 1, T = N>(T);
impl Foo {
fn new() -> Self {
Foo(N)
}
}
fn main() {
let Foo::<1, N>(N) = Foo::new();
}

25
src/test/ui/const-generics/params-in-ct-in-ty-param-lazy-norm.full.stderr
View file

@ -6,17 +6,26 @@ LL | struct Bar<T = [u8; N], const N: usize>(T);
|
= note: using type defaults and const parameters in the same parameter list is currently not permitted
error: constant values inside of type parameter defaults must not depend on generic parameters
--> $DIR/params-in-ct-in-ty-param-lazy-norm.rs:6:44
|
LL | struct Foo<T, U = [u8; std::mem::size_of::<T>()]>(T, U);
| ^ the anonymous constant must not depend on the parameter `T`
error: constant values inside of type parameter defaults must not depend on generic parameters
error[E0128]: generic parameters with a default cannot use forward declared identifiers
--> $DIR/params-in-ct-in-ty-param-lazy-norm.rs:11:21
|
LL | struct Bar<T = [u8; N], const N: usize>(T);
| ^ the anonymous constant must not depend on the parameter `N`
| ^ defaulted generic parameters cannot be forward declared
error[E0277]: the size for values of type `T` cannot be known at compilation time
--> $DIR/params-in-ct-in-ty-param-lazy-norm.rs:6:44
|
LL | struct Foo<T, U = [u8; std::mem::size_of::<T>()]>(T, U);
| - ^ doesn't have a size known at compile-time
| |
| this type parameter needs to be `std::marker::Sized`
|
::: $SRC_DIR/core/src/mem/mod.rs:LL:COL
|
LL | pub const fn size_of<T>() -> usize {
| - required by this bound in `std::mem::size_of`
error: aborting due to 3 previous errors
Some errors have detailed explanations: E0128, E0277.
For more information about an error, try `rustc --explain E0128`.

5
src/test/ui/const-generics/params-in-ct-in-ty-param-lazy-norm.min.stderr
View file

@ -15,11 +15,12 @@ LL | struct Foo<T, U = [u8; std::mem::size_of::<T>()]>(T, U);
= note: type parameters may not be used in const expressions
= help: use `#![feature(const_generics)]` and `#![feature(const_evaluatable_checked)]` to allow generic const expressions
error: constant values inside of type parameter defaults must not depend on generic parameters
error[E0128]: generic parameters with a default cannot use forward declared identifiers
--> $DIR/params-in-ct-in-ty-param-lazy-norm.rs:11:21
|
LL | struct Bar<T = [u8; N], const N: usize>(T);
| ^ the anonymous constant must not depend on the parameter `N`
| ^ defaulted generic parameters cannot be forward declared
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0128`.

4
src/test/ui/const-generics/params-in-ct-in-ty-param-lazy-norm.rs
View file

@ -4,12 +4,12 @@
#![cfg_attr(full, allow(incomplete_features))]
struct Foo<T, U = [u8; std::mem::size_of::<T>()]>(T, U);
//[full]~^ ERROR constant values inside of type parameter defaults
//[full]~^ ERROR the size for values of type `T` cannot be known at compilation time
//[min]~^^ ERROR generic parameters may not be used in const operations
// FIXME(const_generics_defaults): We still don't know how to deal with type defaults.
struct Bar<T = [u8; N], const N: usize>(T);
//~^ ERROR constant values inside of type parameter defaults
//~^ ERROR generic parameters with a default cannot use forward declared identifiers
//~| ERROR generic parameters with a default
fn main() {}

1
src/test/ui/generics/generic-non-trailing-defaults.rs
View file

@ -5,5 +5,6 @@ struct Vec<A = Heap, T>(A, T);
struct Foo<A, B = Vec<C>, C>(A, B, C);
//~^ ERROR generic parameters with a default must be trailing
//~| ERROR generic parameters with a default cannot use
fn main() {}

9
src/test/ui/generics/generic-non-trailing-defaults.stderr
View file

@ -10,5 +10,12 @@ error: generic parameters with a default must be trailing
LL | struct Foo<A, B = Vec<C>, C>(A, B, C);
| ^
error: aborting due to 2 previous errors
error[E0128]: generic parameters with a default cannot use forward declared identifiers
--> $DIR/generic-non-trailing-defaults.rs:6:23
|
LL | struct Foo<A, B = Vec<C>, C>(A, B, C);
| ^ defaulted generic parameters cannot be forward declared
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0128`.