bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir-ty/src/lib.rs')
-rw-r--r--crates/hir-ty/src/lib.rs69
1 files changed, 68 insertions, 1 deletions
diff --git a/crates/hir-ty/src/lib.rs b/crates/hir-ty/src/lib.rs
index 42c3b58d5a..2b5989c6c6 100644
--- a/crates/hir-ty/src/lib.rs
+++ b/crates/hir-ty/src/lib.rs
@@ -38,10 +38,12 @@ use std::sync::Arc;
use chalk_ir::{
fold::{Shift, TypeFoldable},
interner::HasInterner,
- NoSolution,
+ NoSolution, UniverseIndex,
};
use hir_def::{expr::ExprId, type_ref::Rawness, TypeOrConstParamId};
+use hir_expand::name;
use itertools::Either;
+use traits::FnTrait;
use utils::Generics;
use crate::{consteval::unknown_const, db::HirDatabase, utils::generics};
@@ -508,3 +510,68 @@ where
});
Canonical { value, binders: chalk_ir::CanonicalVarKinds::from_iter(Interner, kinds) }
}
+
+pub fn callable_sig_from_fnonce(
+ self_ty: &Canonical<Ty>,
+ env: Arc<TraitEnvironment>,
+ db: &dyn HirDatabase,
+) -> Option<CallableSig> {
+ let krate = env.krate;
+ let fn_once_trait = FnTrait::FnOnce.get_id(db, krate)?;
+ let output_assoc_type = db.trait_data(fn_once_trait).associated_type_by_name(&name![Output])?;
+
+ let mut kinds = self_ty.binders.interned().to_vec();
+ let b = TyBuilder::trait_ref(db, fn_once_trait);
+ if b.remaining() != 2 {
+ return None;
+ }
+ let fn_once = b
+ .push(self_ty.value.clone())
+ .fill_with_bound_vars(DebruijnIndex::INNERMOST, kinds.len())
+ .build();
+ kinds.extend(fn_once.substitution.iter(Interner).skip(1).map(|x| {
+ let vk = match x.data(Interner) {
+ chalk_ir::GenericArgData::Ty(_) => {
+ chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General)
+ }
+ chalk_ir::GenericArgData::Lifetime(_) => chalk_ir::VariableKind::Lifetime,
+ chalk_ir::GenericArgData::Const(c) => {
+ chalk_ir::VariableKind::Const(c.data(Interner).ty.clone())
+ }
+ };
+ chalk_ir::WithKind::new(vk, UniverseIndex::ROOT)
+ }));
+
+ // FIXME: chalk refuses to solve `<Self as FnOnce<^0.0>>::Output == ^0.1`, so we first solve
+ // `<Self as FnOnce<^0.0>>` and then replace `^0.0` with the concrete argument tuple.
+ let trait_env = env.env.clone();
+ let obligation = InEnvironment { goal: fn_once.cast(Interner), environment: trait_env };
+ let canonical =
+ Canonical { binders: CanonicalVarKinds::from_iter(Interner, kinds), value: obligation };
+ let subst = match db.trait_solve(krate, canonical) {
+ Some(Solution::Unique(vars)) => vars.value.subst,
+ _ => return None,
+ };
+ let args = subst.at(Interner, self_ty.binders.interned().len()).ty(Interner)?;
+ let params = match args.kind(Interner) {
+ chalk_ir::TyKind::Tuple(_, subst) => {
+ subst.iter(Interner).filter_map(|arg| arg.ty(Interner).cloned()).collect::<Vec<_>>()
+ }
+ _ => return None,
+ };
+ if params.iter().any(|ty| ty.is_unknown()) {
+ return None;
+ }
+
+ let fn_once = TyBuilder::trait_ref(db, fn_once_trait)
+ .push(self_ty.value.clone())
+ .push(args.clone())
+ .build();
+ let projection =
+ TyBuilder::assoc_type_projection(db, output_assoc_type, Some(fn_once.substitution.clone()))
+ .build();
+
+ let ret_ty = db.normalize_projection(projection, env);
+
+ Some(CallableSig::from_params_and_return(params, ret_ty.clone(), false))
+}