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Consistently use a Witness rather than an expression to represent a possibly-symbolic witness. (#2245)

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Previously we used an expression in some places and a `Witness` values in others. The eventual goal is to make `Witness` values behave like other symbolic values such as `NominalClassType`, but the first step is to consistently treat them like values rather than expressions.

No functionality change intended.
This commit is contained in:
Richard Smith
2022-10-03 14:00:41 -07:00
committed by GitHub
parent c198dafbe8
commit 04d49cebd8
11 changed files with 222 additions and 152 deletions
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explorer/interpreter/impl_scope.cpp
+19 -18
View File
@@ -15,16 +15,16 @@ using llvm::dyn_cast;
namespace Carbon {
void ImplScope::Add(Nonnull<const Value*> iface, Nonnull<const Value*> type,
Nonnull<Expression*> impl,
Nonnull<const Witness*> witness,
const TypeChecker& type_checker) {
Add(iface, {}, type, {}, impl, type_checker);
Add(iface, {}, type, {}, witness, type_checker);
}
void ImplScope::Add(Nonnull<const Value*> iface,
llvm::ArrayRef<Nonnull<const GenericBinding*>> deduced,
Nonnull<const Value*> type,
llvm::ArrayRef<Nonnull<const ImplBinding*>> impl_bindings,
Nonnull<Expression*> impl_expr,
Nonnull<const Witness*> witness,
const TypeChecker& type_checker) {
if (auto* orig_constraint = dyn_cast<ConstraintType>(iface)) {
BindingMap map;
@@ -34,7 +34,7 @@ void ImplScope::Add(Nonnull<const Value*> iface,
for (size_t i = 0; i != constraint->impl_constraints().size(); ++i) {
ConstraintType::ImplConstraint impl = constraint->impl_constraints()[i];
Add(impl.interface, deduced, impl.type, impl_bindings,
type_checker.MakeConstraintWitnessAccess(impl_expr, i), type_checker);
type_checker.MakeConstraintWitnessAccess(witness, i), type_checker);
}
// A parameterized impl declaration doesn't contribute any equality
// constraints to the scope. Instead, we'll resolve the equality
@@ -51,7 +51,7 @@ void ImplScope::Add(Nonnull<const Value*> iface,
.deduced = deduced,
.type = type,
.impl_bindings = impl_bindings,
.impl = impl_expr});
.witness = witness});
}
void ImplScope::AddParent(Nonnull<const ImplScope*> parent) {
@@ -62,17 +62,17 @@ auto ImplScope::Resolve(Nonnull<const Value*> constraint_type,
Nonnull<const Value*> impl_type,
SourceLocation source_loc,
const TypeChecker& type_checker) const
-> ErrorOr<Nonnull<Expression*>> {
-> ErrorOr<Nonnull<const Witness*>> {
if (const auto* iface_type = dyn_cast<InterfaceType>(constraint_type)) {
return ResolveInterface(iface_type, impl_type, source_loc, type_checker);
}
if (const auto* constraint = dyn_cast<ConstraintType>(constraint_type)) {
std::vector<Nonnull<Expression*>> witnesses;
std::vector<Nonnull<const Witness*>> witnesses;
BindingMap map;
map[constraint->self_binding()] = impl_type;
for (auto impl : constraint->impl_constraints()) {
CARBON_ASSIGN_OR_RETURN(
Nonnull<Expression*> result,
Nonnull<const Witness*> result,
ResolveInterface(
cast<InterfaceType>(type_checker.Substitute(map, impl.interface)),
type_checker.Substitute(map, impl.type), source_loc,
@@ -106,9 +106,9 @@ auto ImplScope::ResolveInterface(Nonnull<const InterfaceType*> iface_type,
Nonnull<const Value*> type,
SourceLocation source_loc,
const TypeChecker& type_checker) const
-> ErrorOr<Nonnull<Expression*>> {
-> ErrorOr<Nonnull<const Witness*>> {
CARBON_ASSIGN_OR_RETURN(
std::optional<Nonnull<Expression*>> result,
std::optional<Nonnull<const Witness*>> result,
TryResolve(iface_type, type, source_loc, *this, type_checker));
if (!result.has_value()) {
return CompilationError(source_loc) << "could not find implementation of "
@@ -122,14 +122,15 @@ auto ImplScope::TryResolve(Nonnull<const InterfaceType*> iface_type,
SourceLocation source_loc,
const ImplScope& original_scope,
const TypeChecker& type_checker) const
-> ErrorOr<std::optional<Nonnull<Expression*>>> {
-> ErrorOr<std::optional<Nonnull<const Witness*>>> {
CARBON_ASSIGN_OR_RETURN(
std::optional<Nonnull<Expression*>> result,
std::optional<Nonnull<const Witness*>> result,
ResolveHere(iface_type, type, source_loc, original_scope, type_checker));
for (Nonnull<const ImplScope*> parent : parent_scopes_) {
CARBON_ASSIGN_OR_RETURN(std::optional<Nonnull<Expression*>> parent_result,
parent->TryResolve(iface_type, type, source_loc,
original_scope, type_checker));
CARBON_ASSIGN_OR_RETURN(
std::optional<Nonnull<const Witness*>> parent_result,
parent->TryResolve(iface_type, type, source_loc, original_scope,
type_checker));
if (parent_result.has_value()) {
if (result.has_value()) {
return CompilationError(source_loc) << "ambiguous implementations of "
@@ -147,10 +148,10 @@ auto ImplScope::ResolveHere(Nonnull<const InterfaceType*> iface_type,
SourceLocation source_loc,
const ImplScope& original_scope,
const TypeChecker& type_checker) const
-> ErrorOr<std::optional<Nonnull<Expression*>>> {
std::optional<Nonnull<Expression*>> result = std::nullopt;
-> ErrorOr<std::optional<Nonnull<const Witness*>>> {
std::optional<Nonnull<const Witness*>> result = std::nullopt;
for (const Impl& impl : impls_) {
std::optional<Nonnull<Expression*>> m = type_checker.MatchImpl(
std::optional<Nonnull<const Witness*>> m = type_checker.MatchImpl(
*iface_type, impl_type, impl, original_scope, source_loc);
if (m.has_value()) {
if (result.has_value()) {