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Add const generics support for pattern types #123689

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merged 2 commits into from
Apr 10, 2024
Merged

Add const generics support for pattern types #123689

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a2bdb99
Add const generics failing test for pattern types
spastorino Apr 9, 2024
30c546a
Handle const generic pattern types
spastorino Feb 20, 2024
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18 changes: 18 additions & 0 deletions compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2223,6 +2223,24 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
Err(LitToConstError::TypeError) => todo!(),
}
}

hir::ExprKind::Path(hir::QPath::Resolved(
_,
&hir::Path {
res: Res::Def(DefKind::ConstParam, def_id), ..
},
)) => {
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@fmease fmease Apr 12, 2024 •
edited
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Note that we're missing a call to prohibit_generic_args here. Right now, we permit:

pattern_type!(u32 is START::<(), i32, 2>..=END::<_>)

where START and END are u32s like in the UI test.

While we could add this check, this just reinforces oli's point: #123689 (comment), Zulip discussion.

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Just noticed this while reviewing an unrelated PR.

let ty = tcx
.type_of(def_id)
.no_bound_vars()
.expect("const parameter types cannot be generic");
let item_def_id = tcx.parent(def_id);
let generics = tcx.generics_of(item_def_id);
let index = generics.param_def_id_to_index[&def_id];
let name = tcx.item_name(def_id);
ty::Const::new_param(tcx, ty::ParamConst::new(index, name), ty)
}

_ => {
let err = tcx
.dcx()
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8 changes: 6 additions & 2 deletions compiler/rustc_ty_utils/src/layout.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -133,10 +133,14 @@ fn layout_of_uncached<'tcx>(
ty::PatternKind::Range { start, end, include_end } => {
if let Abi::Scalar(scalar) | Abi::ScalarPair(scalar, _) = &mut layout.abi {
if let Some(start) = start {
scalar.valid_range_mut().start = start.eval_bits(tcx, param_env);
scalar.valid_range_mut().start = start
.try_eval_bits(tcx, param_env)
.ok_or_else(|| error(cx, LayoutError::Unknown(ty)))?;
}
if let Some(end) = end {
let mut end = end.eval_bits(tcx, param_env);
let mut end = end
.try_eval_bits(tcx, param_env)
.ok_or_else(|| error(cx, LayoutError::Unknown(ty)))?;
if !include_end {
end = end.wrapping_sub(1);
}
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13 changes: 13 additions & 0 deletions tests/ui/type/pattern_types/const_generics.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
//@ check-pass

#![feature(pattern_types)]
#![feature(core_pattern_types)]
#![feature(core_pattern_type)]

use std::pat::pattern_type;

trait Foo {}

impl<const START: u32, const END: u32> Foo for pattern_type!(u32 is START..=END) {}

fn main() {}
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