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Add support for var patterns #5069

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Add support for var patterns #5069

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286bcef
Add support for `var` patterns
geoffromer Mar 4, 2025
d254f16
Remove unused #include
geoffromer Mar 4, 2025
281db83
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geoffromer Mar 5, 2025
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geoffromer Mar 6, 2025
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10 changes: 6 additions & 4 deletions toolchain/check/handle_binding_pattern.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
#include "toolchain/diagnostics/format_providers.h"
#include "toolchain/sem_ir/ids.h"
#include "toolchain/sem_ir/inst.h"
#include "toolchain/sem_ir/pattern.h"

namespace Carbon::Check {

Expand Down Expand Up @@ -193,8 +194,6 @@ static auto HandleAnyBindingPattern(Context& context, Parse::NodeId node_id,
case FullPatternStack::Kind::ExplicitParamList: {
// 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.
bool had_error = false;
switch (introducer.kind) {
case Lex::TokenKind::Fn: {
Expand Down Expand Up @@ -250,6 +249,10 @@ static auto HandleAnyBindingPattern(Context& context, Parse::NodeId node_id,
} else {
result_inst_id = make_binding_pattern();
if (node_kind == Parse::NodeKind::LetBindingPattern) {
// A value binding pattern in a function signature is a `Call`
// parameter, but a variable binding pattern is not (instead the
// enclosing `var` pattern is), and a symbolic binding pattern is not
// (because it's not passed to the `Call` inst).
result_inst_id = AddPatternInst<SemIR::ValueParamPattern>(
context, node_id,
{.type_id = context.insts().Get(result_inst_id).type_id(),
Expand Down Expand Up @@ -347,8 +350,7 @@ auto HandleParseNode(Context& context,

auto HandleParseNode(Context& context, Parse::AddrId node_id) -> bool {
auto param_pattern_id = context.node_stack().PopPattern();
if (SemIR::Function::GetNameFromPatternId(
context.sem_ir(), param_pattern_id) == SemIR::NameId::SelfValue) {
if (SemIR::IsSelfPattern(context.sem_ir(), param_pattern_id)) {
auto pointer_type = context.types().TryGetAs<SemIR::PointerType>(
context.insts().Get(param_pattern_id).type_id());
if (pointer_type) {
Expand Down
13 changes: 6 additions & 7 deletions toolchain/check/handle_function.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
#include "toolchain/sem_ir/entry_point.h"
#include "toolchain/sem_ir/function.h"
#include "toolchain/sem_ir/ids.h"
#include "toolchain/sem_ir/pattern.h"
#include "toolchain/sem_ir/typed_insts.h"

namespace Carbon::Check {
Expand Down Expand Up @@ -267,13 +268,11 @@ static auto BuildFunctionDecl(Context& context,
auto self_param_id = SemIR::InstId::None;
auto implicit_param_patterns =
context.inst_blocks().GetOrEmpty(name.implicit_param_patterns_id);
if (const auto* i =
llvm::find_if(implicit_param_patterns,
[&](auto implicit_param_id) {
return SemIR::Function::GetNameFromPatternId(
context.sem_ir(), implicit_param_id) ==
SemIR::NameId::SelfValue;
});
if (const auto* i = llvm::find_if(implicit_param_patterns,
[&](auto implicit_param_id) {
return SemIR::IsSelfPattern(
context.sem_ir(), implicit_param_id);
});
i != implicit_param_patterns.end()) {
self_param_id = *i;
}
Expand Down
43 changes: 27 additions & 16 deletions toolchain/check/handle_let_and_var.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
#include "toolchain/sem_ir/ids.h"
#include "toolchain/sem_ir/inst.h"
#include "toolchain/sem_ir/name_scope.h"
#include "toolchain/sem_ir/pattern.h"
#include "toolchain/sem_ir/typed_insts.h"

namespace Carbon::Check {
Expand Down Expand Up @@ -102,10 +103,10 @@ auto HandleParseNode(Context& context, Parse::VariableIntroducerId node_id)
return HandleIntroducer<Lex::TokenKind::Var>(context, node_id);
}

// Returns a VarStorage inst for the given pattern. If the pattern
// Returns a VarStorage inst for the given `var` pattern. If the pattern
// is the body of a returned var, this reuses the return slot, and otherwise it
// adds a new inst.
static auto GetOrAddStorage(Context& context, SemIR::InstId pattern_id)
static auto GetOrAddStorage(Context& context, SemIR::InstId var_pattern_id)
-> SemIR::InstId {
if (context.decl_introducer_state_stack().innermost().modifier_set.HasAnyOf(
KeywordModifierSet::Returned)) {
Expand All @@ -116,29 +117,39 @@ static auto GetOrAddStorage(Context& context, SemIR::InstId pattern_id)
return GetCurrentReturnSlot(context);
}
}
auto pattern = context.insts().GetWithLocId(pattern_id);
auto subpattern =
context.insts().Get(pattern.inst.As<SemIR::VarPattern>().subpattern_id);

// Try to populate name_id on a best-effort basis.
auto name_id = SemIR::NameId::None;
if (auto binding_pattern = subpattern.TryAs<SemIR::BindingPattern>()) {
name_id =
context.entity_names().Get(binding_pattern->entity_name_id).name_id;
}
auto pattern = context.insts().GetWithLocId(var_pattern_id);

return AddInst(
context,
SemIR::LocIdAndInst::UncheckedLoc(
pattern.loc_id, SemIR::VarStorage{.type_id = pattern.inst.type_id(),
.pretty_name_id = name_id}));
pattern.loc_id,
SemIR::VarStorage{
.type_id = pattern.inst.type_id(),
.pretty_name_id = SemIR::GetPrettyNameFromPatternId(
context.sem_ir(),
pattern.inst.As<SemIR::VarPattern>().subpattern_id)}));
}

auto HandleParseNode(Context& context, Parse::VariablePatternId node_id)
-> bool {
auto subpattern_id = SemIR::InstId::None;
subpattern_id = context.node_stack().PopPattern();
auto subpattern_id = context.node_stack().PopPattern();
auto type_id = context.insts().Get(subpattern_id).type_id();

// In a parameter list, a `var` pattern is always a single `Call` parameter,
// even if it contains multiple binding patterns.
switch (context.full_pattern_stack().CurrentKind()) {
case FullPatternStack::Kind::ExplicitParamList:
case FullPatternStack::Kind::ImplicitParamList:
subpattern_id = AddPatternInst<SemIR::RefParamPattern>(
context, node_id,
{.type_id = type_id,
.subpattern_id = subpattern_id,
.index = SemIR::CallParamIndex::None});
break;
case FullPatternStack::Kind::NameBindingDecl:
break;
}

auto pattern_id = AddPatternInst<SemIR::VarPattern>(
context, node_id, {.type_id = type_id, .subpattern_id = subpattern_id});
context.node_stack().Push(node_id, pattern_id);
Expand Down
133 changes: 97 additions & 36 deletions toolchain/check/pattern_match.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -15,25 +15,10 @@
#include "toolchain/check/subpattern.h"
#include "toolchain/check/type.h"
#include "toolchain/diagnostics/format_providers.h"
#include "toolchain/sem_ir/pattern.h"

namespace Carbon::Check {

// Returns a best-effort name for the given ParamPattern, suitable for use in
// IR pretty-printing.
template <typename ParamPattern>
static auto GetPrettyName(Context& context, ParamPattern param_pattern)
-> SemIR::NameId {
if (context.insts().Is<SemIR::ReturnSlotPattern>(
param_pattern.subpattern_id)) {
return SemIR::NameId::ReturnSlot;
}
if (auto binding_pattern = context.insts().TryGetAs<SemIR::AnyBindingPattern>(
param_pattern.subpattern_id)) {
return context.entity_names().Get(binding_pattern->entity_name_id).name_id;
}
return SemIR::NameId::None;
}

namespace {

// Selects between the different kinds of pattern matching.
Expand Down Expand Up @@ -110,6 +95,9 @@ class MatchContext {
auto DoEmitPatternMatch(Context& context,
SemIR::ValueParamPattern param_pattern,
SemIR::LocId pattern_loc_id, WorkItem entry) -> void;
auto DoEmitPatternMatch(Context& context,
SemIR::RefParamPattern param_pattern,
SemIR::LocId pattern_loc_id, WorkItem entry) -> void;
auto DoEmitPatternMatch(Context& context,
SemIR::OutParamPattern param_pattern,
SemIR::LocId pattern_loc_id, WorkItem entry) -> void;
Expand Down Expand Up @@ -274,13 +262,12 @@ auto MatchContext::DoEmitPatternMatch(Context& context,
SemIR::ValueParamPattern param_pattern,
SemIR::LocId pattern_loc_id,
WorkItem entry) -> void {
CARBON_CHECK(
param_pattern.index.index < 0 ||
static_cast<size_t>(param_pattern.index.index) == results_.size(),
"Parameters out of order; expecting {0} but got {1}", results_.size(),
param_pattern.index.index);
switch (kind_) {
case MatchKind::Caller: {
CARBON_CHECK(
static_cast<size_t>(param_pattern.index.index) == results_.size(),
"Parameters out of order; expecting {0} but got {1}", results_.size(),
param_pattern.index.index);
CARBON_CHECK(entry.scrutinee_id.has_value());
if (entry.scrutinee_id == SemIR::ErrorInst::SingletonInstId) {
results_.push_back(SemIR::ErrorInst::SingletonInstId);
Expand All @@ -296,15 +283,15 @@ auto MatchContext::DoEmitPatternMatch(Context& context,
break;
}
case MatchKind::Callee: {
if (!param_pattern.index.has_value()) {
param_pattern.index = NextRuntimeIndex();
ReplaceInstBeforeConstantUse(context, entry.pattern_id, param_pattern);
}
CARBON_CHECK(!param_pattern.index.has_value());
param_pattern.index = NextRuntimeIndex();
ReplaceInstBeforeConstantUse(context, entry.pattern_id, param_pattern);
auto param_id = AddInst<SemIR::ValueParam>(
context, pattern_loc_id,
{.type_id = param_pattern.type_id,
.index = param_pattern.index,
.pretty_name_id = GetPrettyName(context, param_pattern)});
.pretty_name_id = SemIR::GetPrettyNameFromPatternId(
context.sem_ir(), entry.pattern_id)});
AddWork({.pattern_id = param_pattern.subpattern_id,
.scrutinee_id = param_id});
results_.push_back(param_id);
Expand All @@ -316,12 +303,57 @@ auto MatchContext::DoEmitPatternMatch(Context& context,
}
}

auto MatchContext::DoEmitPatternMatch(Context& context,
SemIR::RefParamPattern param_pattern,
SemIR::LocId pattern_loc_id,
WorkItem entry) -> void {
switch (kind_) {
case MatchKind::Caller: {
CARBON_CHECK(
static_cast<size_t>(param_pattern.index.index) == results_.size(),
"Parameters out of order; expecting {0} but got {1}", results_.size(),
param_pattern.index.index);
CARBON_CHECK(entry.scrutinee_id.has_value());
auto expr_category =
SemIR::GetExprCategory(context.sem_ir(), entry.scrutinee_id);
CARBON_CHECK(expr_category == SemIR::ExprCategory::EphemeralRef ||
expr_category == SemIR::ExprCategory::DurableRef);
results_.push_back(entry.scrutinee_id);
// Do not traverse farther, because the caller side of the pattern
// ends here.
break;
}
case MatchKind::Callee: {
CARBON_CHECK(!param_pattern.index.has_value());
param_pattern.index = NextRuntimeIndex();
ReplaceInstBeforeConstantUse(context, entry.pattern_id, param_pattern);
auto param_id = AddInst<SemIR::RefParam>(
context, pattern_loc_id,
{.type_id = param_pattern.type_id,
.index = param_pattern.index,
.pretty_name_id = SemIR::GetPrettyNameFromPatternId(
context.sem_ir(), entry.pattern_id)});
AddWork({.pattern_id = param_pattern.subpattern_id,
.scrutinee_id = param_id});
results_.push_back(param_id);
break;
}
case MatchKind::Local: {
CARBON_FATAL("Found RefParamPattern during local pattern match");
}
}
}

auto MatchContext::DoEmitPatternMatch(Context& context,
SemIR::OutParamPattern param_pattern,
SemIR::LocId pattern_loc_id,
WorkItem entry) -> void {
switch (kind_) {
case MatchKind::Caller: {
CARBON_CHECK(
static_cast<size_t>(param_pattern.index.index) == results_.size(),
"Parameters out of order; expecting {0} but got {1}", results_.size(),
param_pattern.index.index);
CARBON_CHECK(entry.scrutinee_id.has_value());
CARBON_CHECK(context.insts().Get(entry.scrutinee_id).type_id() ==
SemIR::GetTypeInSpecific(context.sem_ir(),
Expand All @@ -334,16 +366,16 @@ auto MatchContext::DoEmitPatternMatch(Context& context,
}
case MatchKind::Callee: {
// TODO: Consider ways to address near-duplication with the
// ValueParamPattern case.
if (!param_pattern.index.has_value()) {
param_pattern.index = NextRuntimeIndex();
ReplaceInstBeforeConstantUse(context, entry.pattern_id, param_pattern);
}
// other ParamPattern cases.
CARBON_CHECK(!param_pattern.index.has_value());
param_pattern.index = NextRuntimeIndex();
ReplaceInstBeforeConstantUse(context, entry.pattern_id, param_pattern);
auto param_id = AddInst<SemIR::OutParam>(
context, pattern_loc_id,
{.type_id = param_pattern.type_id,
.index = param_pattern.index,
.pretty_name_id = GetPrettyName(context, param_pattern)});
.pretty_name_id = SemIR::GetPrettyNameFromPatternId(
context.sem_ir(), entry.pattern_id)});
AddWork({.pattern_id = param_pattern.subpattern_id,
.scrutinee_id = param_id});
results_.push_back(param_id);
Expand Down Expand Up @@ -375,7 +407,31 @@ auto MatchContext::DoEmitPatternMatch(Context& context,
SemIR::VarPattern var_pattern,
SemIR::LocId pattern_loc_id,
WorkItem entry) -> void {
auto var_id = context.var_storage_map().Lookup(entry.pattern_id).value();
auto storage_id = SemIR::InstId::None;
switch (kind_) {
case MatchKind::Callee: {
// We're emitting pattern-match IR for the callee, but we're still on
// the caller side of the pattern, so we traverse without emitting any
// insts.
AddWork({.pattern_id = var_pattern.subpattern_id,
.scrutinee_id = SemIR::InstId::None});
return;
}
case MatchKind::Local: {
// In a `var`/`let` declaration, the `VarStorage` inst is created before
// we start pattern matching.
auto lookup_result = context.var_storage_map().Lookup(entry.pattern_id);
CARBON_CHECK(lookup_result);
storage_id = lookup_result.value();
break;
}
case MatchKind::Caller: {
storage_id = AddInst<SemIR::TemporaryStorage>(
context, pattern_loc_id, {.type_id = var_pattern.type_id});
CARBON_CHECK(entry.scrutinee_id.has_value());
break;
}
}
// TODO: Find a more efficient way to put these insts in the global_init
// block (or drop the distinction between the global_init block and the
// file scope?)
Expand All @@ -384,13 +440,14 @@ auto MatchContext::DoEmitPatternMatch(Context& context,
}
if (entry.scrutinee_id.has_value()) {
auto init_id =
Initialize(context, pattern_loc_id, var_id, entry.scrutinee_id);
Initialize(context, pattern_loc_id, storage_id, entry.scrutinee_id);
// TODO: Consider using different instruction kinds for assignment
// versus initialization.
AddInst<SemIR::Assign>(context, pattern_loc_id,
{.lhs_id = var_id, .rhs_id = init_id});
{.lhs_id = storage_id, .rhs_id = init_id});
}
AddWork({.pattern_id = var_pattern.subpattern_id, .scrutinee_id = var_id});
AddWork(
{.pattern_id = var_pattern.subpattern_id, .scrutinee_id = storage_id});
if (context.scope_stack().PeekIndex() == ScopeIndex::Package) {
context.global_init().Suspend();
}
Expand Down Expand Up @@ -488,6 +545,10 @@ auto MatchContext::EmitPatternMatch(Context& context,
DoEmitPatternMatch(context, param_pattern, pattern.loc_id, entry);
break;
}
case CARBON_KIND(SemIR::RefParamPattern param_pattern): {
DoEmitPatternMatch(context, param_pattern, pattern.loc_id, entry);
break;
}
case CARBON_KIND(SemIR::OutParamPattern param_pattern): {
DoEmitPatternMatch(context, param_pattern, pattern.loc_id, entry);
break;
Expand Down
4 changes: 2 additions & 2 deletions toolchain/check/testdata/class/no_prelude/comp_time_field.carbon
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Expand Up @@ -35,13 +35,13 @@ class Class {
// CHECK:STDERR: var C:! type = Class;
// CHECK:STDERR: ^~~~~~~~
// CHECK:STDERR:
// CHECK:STDERR: fail_var.carbon:[[@LINE+4]]:16: error: `var` declaration cannot declare a compile-time binding [CompileTimeBindingInVarDecl]
// CHECK:STDERR: fail_var.carbon:[[@LINE+4]]:16: error: `var` pattern cannot declare a compile-time binding [CompileTimeBindingInVarDecl]
// CHECK:STDERR: var C:! type = Class;
// CHECK:STDERR: ^
// CHECK:STDERR:
var C:! type = Class;

// CHECK:STDERR: fail_var.carbon:[[@LINE+4]]:25: error: `var` declaration cannot declare a compile-time binding [CompileTimeBindingInVarDecl]
// CHECK:STDERR: fail_var.carbon:[[@LINE+4]]:25: error: `var` pattern cannot declare a compile-time binding [CompileTimeBindingInVarDecl]
// CHECK:STDERR: var template D:! type = Class;
// CHECK:STDERR: ^
// CHECK:STDERR:
Expand Down
2 changes: 1 addition & 1 deletion toolchain/check/testdata/function/declaration/no_prelude/fail_todo_no_params.carbon
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Expand Up @@ -58,7 +58,7 @@ library "[[@TEST_NAME]]";
// CHECK:STDERR: var x:! () = ();
// CHECK:STDERR: ^~~~~~
// CHECK:STDERR:
// CHECK:STDERR: fail_invalid_file_generic_regression_test.carbon:[[@LINE+4]]:12: error: `var` declaration cannot declare a compile-time binding [CompileTimeBindingInVarDecl]
// CHECK:STDERR: fail_invalid_file_generic_regression_test.carbon:[[@LINE+4]]:12: error: `var` pattern cannot declare a compile-time binding [CompileTimeBindingInVarDecl]
// CHECK:STDERR: var x:! () = ();
// CHECK:STDERR: ^
// CHECK:STDERR:
Expand Down
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