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Add support for _ binding patterns (#5097)

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Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
This commit is contained in:
Geoff Romer
2025-03-17 22:29:56 +00:00
committed by GitHub
co-authored by Jon Ross-Perkins
parent d8d2da4ea0
commit a584ee120e
15 changed files with 423 additions and 45 deletions
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toolchain/check/handle_binding_pattern.cpp
+55 -29
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@@ -19,6 +19,13 @@
namespace Carbon::Check {
auto HandleParseNode(Context& context, Parse::UnderscoreNameId node_id)
-> bool {
context.node_stack().Push(node_id, SemIR::NameId::Underscore);
return true;
}
// TODO: make this function shorter by factoring pieces out.
static auto HandleAnyBindingPattern(Context& context, Parse::NodeId node_id,
Parse::NodeKind node_kind) -> bool {
// TODO: split this into smaller, more focused functions.
@@ -26,8 +33,6 @@ static auto HandleAnyBindingPattern(Context& context, Parse::NodeId node_id,
auto [cast_type_inst_id, cast_type_id] =
ExprAsType(context, type_node, parsed_type_id);
// TODO: Handle `_` bindings.
SemIR::ExprRegionId type_expr_region_id =
EndSubpatternAsExpr(context, cast_type_inst_id);
@@ -39,54 +44,63 @@ static auto HandleAnyBindingPattern(Context& context, Parse::NodeId node_id,
// A non-generic template binding is diagnosed by the parser.
is_template &= is_generic;
// Every other kind of pattern binding has a name.
auto [name_node, name_id] = context.node_stack().PopNameWithNodeId();
const DeclIntroducerState& introducer =
context.decl_introducer_state_stack().innermost();
auto make_binding_pattern = [&]() -> SemIR::InstId {
// bind_id and entity_name_id are not populated if name_id is Underscore.
auto bind_id = SemIR::InstId::None;
auto binding_pattern_id = SemIR::InstId::None;
// TODO: Eventually the name will need to support associations with other
// scopes, but right now we don't support qualified names here.
auto entity_name_id = context.entity_names().AddSymbolicBindingName(
name_id, context.scope_stack().PeekNameScopeId(),
is_generic ? context.scope_stack().AddCompileTimeBinding()
: SemIR::CompileTimeBindIndex::None,
is_template);
if (is_generic) {
bind_id = AddInstInNoBlock(
context,
SemIR::LocIdAndInst(name_node, SemIR::BindSymbolicName{
auto entity_name_id = SemIR::EntityNameId::None;
if (name_id != SemIR::NameId::Underscore) {
entity_name_id = context.entity_names().AddSymbolicBindingName(
name_id, context.scope_stack().PeekNameScopeId(),
is_generic ? context.scope_stack().AddCompileTimeBinding()
: SemIR::CompileTimeBindIndex::None,
is_template);
if (is_generic) {
bind_id = AddInstInNoBlock(
context, SemIR::LocIdAndInst(name_node,
SemIR::BindSymbolicName{
.type_id = cast_type_id,
.entity_name_id = entity_name_id,
.value_id = SemIR::InstId::None}));
} else {
bind_id = AddInstInNoBlock(
context,
SemIR::LocIdAndInst(
name_node, SemIR::BindName{.type_id = cast_type_id,
.entity_name_id = entity_name_id,
.value_id = SemIR::InstId::None}));
}
}
auto binding_pattern_id = SemIR::InstId::None;
if (is_generic) {
binding_pattern_id = AddPatternInst<SemIR::SymbolicBindingPattern>(
context, name_node,
{.type_id = cast_type_id, .entity_name_id = entity_name_id});
} else {
bind_id = AddInstInNoBlock(
context,
SemIR::LocIdAndInst(
name_node, SemIR::BindName{.type_id = cast_type_id,
.entity_name_id = entity_name_id,
.value_id = SemIR::InstId::None}));
binding_pattern_id = AddPatternInst<SemIR::BindingPattern>(
context, name_node,
{.type_id = cast_type_id, .entity_name_id = entity_name_id});
}
// Add name to lookup immediately, so it can be used in the rest of the
// enclosing pattern.
if (is_generic) {
context.scope_stack().PushCompileTimeBinding(bind_id);
if (name_id != SemIR::NameId::Underscore) {
// Add name to lookup immediately, so it can be used in the rest of the
// enclosing pattern.
if (is_generic) {
context.scope_stack().PushCompileTimeBinding(bind_id);
}
auto name_context =
context.decl_name_stack().MakeUnqualifiedName(name_node, name_id);
context.decl_name_stack().AddNameOrDiagnose(
name_context, bind_id, introducer.modifier_set.GetAccessKind());
context.full_pattern_stack().AddBindName(name_id);
}
auto name_context =
context.decl_name_stack().MakeUnqualifiedName(name_node, name_id);
context.decl_name_stack().AddNameOrDiagnose(
name_context, bind_id, introducer.modifier_set.GetAccessKind());
context.full_pattern_stack().AddBindName(name_id);
bool inserted = context.bind_name_map()
.Insert(binding_pattern_id,
@@ -112,6 +126,11 @@ static auto HandleAnyBindingPattern(Context& context, Parse::NodeId node_id,
context.scope_stack().GetCurrentScopeAs<SemIR::ClassDecl>();
parent_class_decl.has_value() && !is_generic &&
node_kind == Parse::NodeKind::VarBindingPattern) {
if (name_id == SemIR::NameId::Underscore) {
// The action item here may be to document this as not allowed, and
// add a proper diagnostic.
context.TODO(node_id, "_ used as field name");
}
cast_type_id = AsConcreteType(
context, cast_type_id, type_node,
[&] {
@@ -151,6 +170,11 @@ static auto HandleAnyBindingPattern(Context& context, Parse::NodeId node_id,
if (auto parent_interface_decl =
context.scope_stack().GetCurrentScopeAs<SemIR::InterfaceDecl>();
parent_interface_decl.has_value() && is_generic) {
if (name_id == SemIR::NameId::Underscore) {
// The action item here may be to document this as not allowed, and
// add a proper diagnostic.
context.TODO(node_id, "_ used as associated constant name");
}
cast_type_id = AsCompleteType(context, cast_type_id, type_node, [&] {
CARBON_DIAGNOSTIC(IncompleteTypeInAssociatedConstantDecl, Error,
"associated constant has incomplete type {0}",
@@ -242,7 +266,9 @@ static auto HandleAnyBindingPattern(Context& context, Parse::NodeId node_id,
}
auto result_inst_id = SemIR::InstId::None;
if (had_error) {
AddNameToLookup(context, name_id, SemIR::ErrorInst::SingletonInstId);
if (name_id != SemIR::NameId::Underscore) {
AddNameToLookup(context, name_id, SemIR::ErrorInst::SingletonInstId);
}
// Replace the parameter with `ErrorInst` so that we don't try
// constructing a generic based on it.
result_inst_id = SemIR::ErrorInst::SingletonInstId;