Files
carbon-lang/toolchain/check/handle_binding_pattern.cpp
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194 lines
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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "toolchain/check/context.h"
#include "toolchain/check/convert.h"
#include "toolchain/check/return.h"
namespace Carbon::Check {
auto HandleAnyBindingPattern(Context& context, Parse::NodeId node_id,
bool is_generic) -> bool {
auto [type_node, parsed_type_id] = context.node_stack().PopExprWithNodeId();
auto cast_type_id = ExprAsType(context, type_node, parsed_type_id);
// TODO: Handle `_` bindings.
// Every other kind of pattern binding has a name.
auto [name_node, name_id] = context.node_stack().PopNameWithNodeId();
// Create the appropriate kind of binding for this pattern.
auto make_bind_name = [&](SemIR::TypeId type_id,
SemIR::InstId value_id) -> SemIR::LocIdAndInst {
// TODO: Eventually the name will need to support associations with other
// scopes, but right now we don't support qualified names here.
auto bind_name_id = context.bind_names().Add(
{.name_id = name_id,
.enclosing_scope_id = context.scope_stack().PeekNameScopeId()});
if (is_generic) {
// TODO: Create a `BindTemplateName` instead inside a `template` pattern.
return {name_node,
SemIR::BindSymbolicName{type_id, bind_name_id, value_id}};
} else {
return {name_node, SemIR::BindName{type_id, bind_name_id, value_id}};
}
};
// A `self` binding can only appear in an implicit parameter list.
if (name_id == SemIR::NameId::SelfValue &&
!context.node_stack().PeekIs<Parse::NodeKind::ImplicitParamListStart>()) {
CARBON_DIAGNOSTIC(
SelfOutsideImplicitParamList, Error,
"`self` can only be declared in an implicit parameter list.");
context.emitter().Emit(node_id, SelfOutsideImplicitParamList);
}
// Allocate an instruction of the appropriate kind, linked to the name for
// error locations.
// TODO: The node stack is a fragile way of getting context information.
// Get this information from somewhere else.
switch (auto context_node_kind = context.node_stack().PeekNodeKind()) {
case Parse::NodeKind::ReturnedModifier:
case Parse::NodeKind::VariableIntroducer: {
if (is_generic) {
CARBON_DIAGNOSTIC(
CompileTimeBindingInVarDecl, Error,
"`var` declaration cannot declare a compile-time binding.");
context.emitter().Emit(type_node, CompileTimeBindingInVarDecl);
}
auto binding_id =
is_generic
? Parse::NodeId::Invalid
: context.parse_tree().As<Parse::BindingPatternId>(node_id);
// A `var` declaration at class scope introduces a field.
auto enclosing_class_decl = context.GetCurrentScopeAs<SemIR::ClassDecl>();
cast_type_id = context.AsCompleteType(cast_type_id, [&] {
CARBON_DIAGNOSTIC(IncompleteTypeInVarDecl, Error,
"{0} has incomplete type `{1}`.", llvm::StringLiteral,
SemIR::TypeId);
return context.emitter().Build(type_node, IncompleteTypeInVarDecl,
enclosing_class_decl
? llvm::StringLiteral("Field")
: llvm::StringLiteral("Variable"),
cast_type_id);
});
if (enclosing_class_decl) {
CARBON_CHECK(context_node_kind == Parse::NodeKind::VariableIntroducer)
<< "`returned var` at class scope";
auto& class_info =
context.classes().Get(enclosing_class_decl->class_id);
auto field_type_id = context.GetUnboundElementType(
class_info.self_type_id, cast_type_id);
auto field_id = context.AddInst(
{binding_id, SemIR::FieldDecl{
field_type_id, name_id,
SemIR::ElementIndex(context.args_type_info_stack()
.PeekCurrentBlockContents()
.size())}});
// Add a corresponding field to the object representation of the class.
context.args_type_info_stack().AddInstId(context.AddInstInNoBlock(
{binding_id, SemIR::StructTypeField{name_id, cast_type_id}}));
context.node_stack().Push(node_id, field_id);
break;
}
SemIR::InstId value_id = SemIR::InstId::Invalid;
if (context_node_kind == Parse::NodeKind::ReturnedModifier) {
// TODO: Should we check this for the `var` as a whole, rather than for
// the name binding?
value_id =
CheckReturnedVar(context, context.node_stack().PeekNodeId(),
name_node, name_id, type_node, cast_type_id);
} else {
value_id = context.AddInst(
{name_node, SemIR::VarStorage{cast_type_id, name_id}});
}
auto bind_id = context.AddInst(make_bind_name(cast_type_id, value_id));
context.node_stack().Push(node_id, bind_id);
if (context_node_kind == Parse::NodeKind::ReturnedModifier) {
RegisterReturnedVar(context, bind_id);
}
break;
}
case Parse::NodeKind::ImplicitParamListStart:
case Parse::NodeKind::TuplePatternStart: {
// Parameters can have incomplete types in a function declaration, but not
// in a function definition. We don't know which kind we have here.
// TODO: A tuple pattern can appear in other places than function
// parameters.
auto param_id =
context.AddInst({name_node, SemIR::Param{cast_type_id, name_id}});
auto bind_id = context.AddInst(make_bind_name(cast_type_id, param_id));
// TODO: Bindings should come into scope immediately in other contexts
// too.
context.AddNameToLookup(name_id, bind_id);
context.node_stack().Push(node_id, bind_id);
break;
}
case Parse::NodeKind::LetIntroducer:
cast_type_id = context.AsCompleteType(cast_type_id, [&] {
CARBON_DIAGNOSTIC(IncompleteTypeInLetDecl, Error,
"`let` binding has incomplete type `{0}`.",
SemIR::TypeId);
return context.emitter().Build(type_node, IncompleteTypeInLetDecl,
cast_type_id);
});
// Create the instruction, but don't add it to a block until after we've
// formed its initializer.
// TODO: For general pattern parsing, we'll need to create a block to hold
// the `let` pattern before we see the initializer.
context.node_stack().Push(
node_id, context.AddPlaceholderInstInNoBlock(
make_bind_name(cast_type_id, SemIR::InstId::Invalid)));
break;
default:
CARBON_FATAL() << "Found a pattern binding in unexpected context "
<< context_node_kind;
}
return true;
}
auto HandleBindingPattern(Context& context, Parse::BindingPatternId node_id)
-> bool {
return HandleAnyBindingPattern(context, node_id, /*is_generic=*/false);
}
auto HandleCompileTimeBindingPattern(Context& context,
Parse::CompileTimeBindingPatternId node_id)
-> bool {
return HandleAnyBindingPattern(context, node_id, /*is_generic=*/true);
}
auto HandleAddr(Context& context, Parse::AddrId node_id) -> bool {
auto self_param_id = context.node_stack().PopPattern();
if (auto self_param =
context.insts().TryGetAs<SemIR::AnyBindName>(self_param_id);
self_param &&
context.bind_names().Get(self_param->bind_name_id).name_id ==
SemIR::NameId::SelfValue) {
// TODO: The type of an `addr_pattern` should probably be the non-pointer
// type, because that's the type that the pattern matches.
context.AddInstAndPush(
{node_id, SemIR::AddrPattern{self_param->type_id, self_param_id}});
} else {
CARBON_DIAGNOSTIC(AddrOnNonSelfParam, Error,
"`addr` can only be applied to a `self` parameter.");
context.emitter().Emit(TokenOnly(node_id), AddrOnNonSelfParam);
context.node_stack().Push(node_id, self_param_id);
}
return true;
}
auto HandleTemplate(Context& context, Parse::TemplateId node_id) -> bool {
return context.TODO(node_id, "HandleTemplate");
}
} // namespace Carbon::Check