use std::sync::Arc;
use base_db::CrateId;
use chalk_ir::cast::Cast;
use chalk_solve::{logging_db::LoggingRustIrDatabase, Solver};
use hir_def::{lang_item::LangItemTarget, TraitId};
use crate::{db::HirDatabase, DebruijnIndex, Substs};
use super::{Canonical, GenericPredicate, HirDisplay, ProjectionTy, TraitRef, Ty, TypeWalk};
use self::chalk::{from_chalk, Interner, ToChalk};
pub(crate) mod chalk;
const CHALK_SOLVER_FUEL: i32 = 100;
#[derive(Debug, Copy, Clone)]
struct ChalkContext<'a> {
db: &'a dyn HirDatabase,
krate: CrateId,
}
fn create_chalk_solver() -> chalk_recursive::RecursiveSolver<Interner> {
let overflow_depth = 100;
let caching_enabled = true;
chalk_recursive::RecursiveSolver::new(overflow_depth, caching_enabled)
}
#[derive(Clone, Debug, PartialEq, Eq, Hash)]
pub struct TraitEnvironment {
pub predicates: Vec<GenericPredicate>,
}
impl TraitEnvironment {
pub(crate) fn trait_predicates_for_self_ty<'a>(
&'a self,
ty: &'a Ty,
) -> impl Iterator<Item = &'a TraitRef> + 'a {
self.predicates.iter().filter_map(move |pred| match pred {
GenericPredicate::Implemented(tr) if tr.self_ty() == ty => Some(tr),
_ => None,
})
}
}
#[derive(Clone, Debug, PartialEq, Eq, Hash)]
pub struct InEnvironment<T> {
pub environment: Arc<TraitEnvironment>,
pub value: T,
}
impl<T> InEnvironment<T> {
pub fn new(environment: Arc<TraitEnvironment>, value: T) -> InEnvironment<T> {
InEnvironment { environment, value }
}
}
#[derive(Clone, Debug, PartialEq, Eq, Hash)]
pub enum Obligation {
Trait(TraitRef),
Projection(ProjectionPredicate),
}
impl Obligation {
pub fn from_predicate(predicate: GenericPredicate) -> Option<Obligation> {
match predicate {
GenericPredicate::Implemented(trait_ref) => Some(Obligation::Trait(trait_ref)),
GenericPredicate::Projection(projection_pred) => {
Some(Obligation::Projection(projection_pred))
}
GenericPredicate::Error => None,
}
}
}
#[derive(Clone, Debug, PartialEq, Eq, Hash)]
pub struct ProjectionPredicate {
pub projection_ty: ProjectionTy,
pub ty: Ty,
}
impl TypeWalk for ProjectionPredicate {
fn walk(&self, f: &mut impl FnMut(&Ty)) {
self.projection_ty.walk(f);
self.ty.walk(f);
}
fn walk_mut_binders(
&mut self,
f: &mut impl FnMut(&mut Ty, DebruijnIndex),
binders: DebruijnIndex,
) {
self.projection_ty.walk_mut_binders(f, binders);
self.ty.walk_mut_binders(f, binders);
}
}
pub(crate) fn trait_solve_query(
db: &dyn HirDatabase,
krate: CrateId,
goal: Canonical<InEnvironment<Obligation>>,
) -> Option<Solution> {
let _p = profile::span("trait_solve_query").detail(|| match &goal.value.value {
Obligation::Trait(it) => db.trait_data(it.trait_).name.to_string(),
Obligation::Projection(_) => "projection".to_string(),
});
log::info!("trait_solve_query({})", goal.value.value.display(db));
if let Obligation::Projection(pred) = &goal.value.value {
if let Ty::Bound(_) = &pred.projection_ty.parameters[0] {
return Some(Solution::Ambig(Guidance::Unknown));
}
}
let canonical = goal.to_chalk(db).cast(&Interner);
let u_canonical = chalk_ir::UCanonical { canonical, universes: 1 };
let solution = solve(db, krate, &u_canonical);
solution.map(|solution| solution_from_chalk(db, solution))
}
fn solve(
db: &dyn HirDatabase,
krate: CrateId,
goal: &chalk_ir::UCanonical<chalk_ir::InEnvironment<chalk_ir::Goal<Interner>>>,
) -> Option<chalk_solve::Solution<Interner>> {
let context = ChalkContext { db, krate };
log::debug!("solve goal: {:?}", goal);
let mut solver = create_chalk_solver();
let fuel = std::cell::Cell::new(CHALK_SOLVER_FUEL);
let should_continue = || {
context.db.check_canceled();
let remaining = fuel.get();
fuel.set(remaining - 1);
if remaining == 0 {
log::debug!("fuel exhausted");
}
remaining > 0
};
let mut solve = || {
if is_chalk_print() {
let logging_db = LoggingRustIrDatabase::new(context);
let solution = solver.solve_limited(&logging_db, goal, &should_continue);
log::debug!("chalk program:\n{}", logging_db);
solution
} else {
solver.solve_limited(&context, goal, &should_continue)
}
};
let solution =
if is_chalk_debug() { chalk::tls::set_current_program(db, solve) } else { solve() };
log::debug!("solve({:?}) => {:?}", goal, solution);
solution
}
fn is_chalk_debug() -> bool {
std::env::var("CHALK_DEBUG").is_ok()
}
fn is_chalk_print() -> bool {
std::env::var("CHALK_PRINT").is_ok()
}
fn solution_from_chalk(
db: &dyn HirDatabase,
solution: chalk_solve::Solution<Interner>,
) -> Solution {
let convert_subst = |subst: chalk_ir::Canonical<chalk_ir::Substitution<Interner>>| {
let result = from_chalk(db, subst);
SolutionVariables(result)
};
match solution {
chalk_solve::Solution::Unique(constr_subst) => {
let subst = chalk_ir::Canonical {
value: constr_subst.value.subst,
binders: constr_subst.binders,
};
Solution::Unique(convert_subst(subst))
}
chalk_solve::Solution::Ambig(chalk_solve::Guidance::Definite(subst)) => {
Solution::Ambig(Guidance::Definite(convert_subst(subst)))
}
chalk_solve::Solution::Ambig(chalk_solve::Guidance::Suggested(subst)) => {
Solution::Ambig(Guidance::Suggested(convert_subst(subst)))
}
chalk_solve::Solution::Ambig(chalk_solve::Guidance::Unknown) => {
Solution::Ambig(Guidance::Unknown)
}
}
}
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct SolutionVariables(pub Canonical<Substs>);
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum Solution {
Unique(SolutionVariables),
Ambig(Guidance),
}
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum Guidance {
Definite(SolutionVariables),
Suggested(SolutionVariables),
Unknown,
}
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub enum FnTrait {
FnOnce,
FnMut,
Fn,
}
impl FnTrait {
fn lang_item_name(self) -> &'static str {
match self {
FnTrait::FnOnce => "fn_once",
FnTrait::FnMut => "fn_mut",
FnTrait::Fn => "fn",
}
}
pub fn get_id(&self, db: &dyn HirDatabase, krate: CrateId) -> Option<TraitId> {
let target = db.lang_item(krate, self.lang_item_name().into())?;
match target {
LangItemTarget::TraitId(t) => Some(t),
_ => None,
}
}
}