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Remove VariantMatch; use CARBON_KIND_SWITCH for std::variants (#5437)

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Teach CARBON_KIND_SWITCH to handle mutable lvalues and rvalues, and
CARBON_KIND to forward along rvalues so that it's possible to write
`case CARBON_KIND(const T& t)`, `case CARBON_KIND(T& t)`, and `case
CARBON_KIND(T&& t)`, depending on the type that was passed to
CARBON_KIND_SWITCH.

Replace all uses of VariantMatch with their equivalent of a switch using
CARBON_KIND_SWITCH, and remove the VariantMatch helper from the
codebase.
This commit is contained in:
Dana Jansens
2025-05-12 18:56:52 +00:00
committed by GitHub
parent 010efd2e40
commit 517c4d3c20
9 changed files with 107 additions and 141 deletions
Download Patch File Download Diff File Expand all files Collapse all files
common/BUILD
-9
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@@ -553,15 +553,6 @@ cc_test(
],
)
cc_library(
name = "variant_helpers",
hdrs = ["variant_helpers.h"],
deps = [
":error",
"@llvm-project//llvm:Support",
],
)
# The base version source file only uses non-stamped parts of the version
# information so we expand it once here without any stamping.
expand_version_build_info(
common/variant_helpers.h
-42
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@@ -1,42 +0,0 @@
// 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
#ifndef CARBON_COMMON_VARIANT_HELPERS_H_
#define CARBON_COMMON_VARIANT_HELPERS_H_
#include <variant>
#include "common/error.h"
#include "llvm/ADT/StringRef.h"
namespace Carbon {
namespace Internal {
// Form an overload set from a list of functions. For example:
//
// ```
// auto overloaded = Overload{[] (int) {}, [] (float) {}};
// ```
template <typename... Fs>
struct Overload : Fs... {
using Fs::operator()...;
};
template <typename... Fs>
Overload(Fs...) -> Overload<Fs...>;
} // namespace Internal
// Pattern-match against the type of the value stored in the variant `V`. Each
// element of `fs` should be a function that takes one or more of the variant
// values in `V`.
template <typename V, typename... Fs>
auto VariantMatch(V&& v, Fs&&... fs) -> decltype(auto) {
return std::visit(Internal::Overload{std::forward<Fs&&>(fs)...},
std::forward<V&&>(v));
}
} // namespace Carbon
#endif // CARBON_COMMON_VARIANT_HELPERS_H_
toolchain/base/kind_switch.h
+16 -13
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@@ -190,7 +190,8 @@ template <typename SwitchT, typename CaseFnT>
consteval auto ForCase() -> auto {
using CaseT = llvm::function_traits<CaseFnT>::template arg_t<0>;
if constexpr (IsStdVariant<SwitchT>) {
return CaseValueOfTypeInStdVariant<CaseT, SwitchT>;
using NoRefCaseT = std::remove_cvref_t<CaseT>;
return CaseValueOfTypeInStdVariant<NoRefCaseT, SwitchT>;
} else {
using KindT = llvm::function_traits<
decltype(&std::remove_cvref_t<SwitchT>::kind)>::result_t;
@@ -204,7 +205,8 @@ template <typename CaseFnT, typename SwitchT>
auto Cast(SwitchT&& kind_switch_value) -> decltype(auto) {
using CaseT = llvm::function_traits<CaseFnT>::template arg_t<0>;
if constexpr (IsStdVariant<SwitchT>) {
return std::get<CaseT>(kind_switch_value);
using NoRefCaseT = std::remove_cvref_t<CaseT>;
return std::get<NoRefCaseT>(std::forward<SwitchT>(kind_switch_value));
} else {
return kind_switch_value.template As<CaseT>();
}
@@ -217,9 +219,9 @@ auto Cast(SwitchT&& kind_switch_value) -> decltype(auto) {
} // namespace Carbon::Internal::Kind
// Produces a switch statement on value.kind().
#define CARBON_KIND_SWITCH(value) \
switch ( \
const auto& carbon_internal_kind_switch_value = value; \
#define CARBON_KIND_SWITCH(value) \
switch ( \
auto&& carbon_internal_kind_switch_value = value; \
::Carbon::Internal::Kind::SwitchOn(carbon_internal_kind_switch_value))
// Produces a case-compatible block of code that also instantiates a local typed
@@ -228,14 +230,15 @@ auto Cast(SwitchT&& kind_switch_value) -> decltype(auto) {
// This uses `if` to scope the variable, and provides a dangling `else` in order
// to prevent accidental `else` use. The label allows `:` to follow the macro
// name, making it look more like a typical `case`.
#define CARBON_KIND(typed_variable_decl) \
::Carbon::Internal::Kind::ForCase< \
decltype(carbon_internal_kind_switch_value), \
decltype([]([[maybe_unused]] typed_variable_decl) {})>() \
: if (typed_variable_decl = ::Carbon::Internal::Kind::Cast< \
decltype([]([[maybe_unused]] typed_variable_decl) {})>( \
carbon_internal_kind_switch_value); \
false) {} \
#define CARBON_KIND(typed_variable_decl) \
::Carbon::Internal::Kind::ForCase< \
decltype(carbon_internal_kind_switch_value), \
decltype([]([[maybe_unused]] typed_variable_decl) {})>() \
: if (typed_variable_decl = ::Carbon::Internal::Kind::Cast< \
decltype([]([[maybe_unused]] typed_variable_decl) {})>( \
std::forward<decltype(carbon_internal_kind_switch_value)>( \
carbon_internal_kind_switch_value)); \
false) {} \
else [[maybe_unused]] CARBON_INTERNAL_KIND_LABEL(__LINE__)
#endif // CARBON_TOOLCHAIN_BASE_KIND_SWITCH_H_
toolchain/check/BUILD
-1
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@@ -178,7 +178,6 @@ cc_library(
"//common:find",
"//common:map",
"//common:ostream",
"//common:variant_helpers",
"//common:vlog",
"//toolchain/base:kind_switch",
"//toolchain/base:pretty_stack_trace_function",
toolchain/check/deferred_definition_worklist.cpp
+18 -17
View File
@@ -7,8 +7,8 @@
#include <algorithm>
#include <optional>
#include "common/variant_helpers.h"
#include "common/vlog.h"
#include "toolchain/base/kind_switch.h"
#include "toolchain/check/handle.h"
namespace Carbon::Check {
@@ -106,22 +106,23 @@ auto DeferredDefinitionWorklist::SuspendFinishedScopeAndPush(Context& context)
auto DeferredDefinitionWorklist::Pop(
llvm::function_ref<auto(Task&&)->void> handle_fn) -> void {
if (vlog_stream_) {
VariantMatch(
worklist_.back(),
[&](CheckSkippedDefinition& definition) {
CARBON_VLOG("{0}Handle CheckSkippedDefinition {1}\n", VlogPrefix,
definition.definition_index.index);
},
[&](EnterDeferredDefinitionScope& enter) {
CARBON_CHECK(enter.in_deferred_definition_scope);
CARBON_VLOG("{0}Handle EnterDeferredDefinitionScope (nested)\n",
VlogPrefix);
},
[&](LeaveDeferredDefinitionScope& leave) {
bool nested = leave.in_deferred_definition_scope;
CARBON_VLOG("{0}Handle LeaveDeferredDefinitionScope {1}\n",
VlogPrefix, nested ? "(nested)" : "(non-nested)");
});
CARBON_KIND_SWITCH(worklist_.back()) {
case CARBON_KIND(const CheckSkippedDefinition& definition):
CARBON_VLOG("{0}Handle CheckSkippedDefinition {1}\n", VlogPrefix,
definition.definition_index.index);
break;
case CARBON_KIND(const EnterDeferredDefinitionScope& enter):
CARBON_CHECK(enter.in_deferred_definition_scope);
CARBON_VLOG("{0}Handle EnterDeferredDefinitionScope (nested)\n",
VlogPrefix);
break;
case CARBON_KIND(const LeaveDeferredDefinitionScope& leave): {
bool nested = leave.in_deferred_definition_scope;
CARBON_VLOG("{0}Handle LeaveDeferredDefinitionScope {1}\n", VlogPrefix,
nested ? "(nested)" : "(non-nested)");
break;
}
}
}
handle_fn(std::move(worklist_.back()));
toolchain/lex/BUILD
+1 -1
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@@ -192,7 +192,7 @@ cc_library(
":token_kind",
":tokenized_buffer",
"//common:check",
"//common:variant_helpers",
"//toolchain/base:kind_switch",
"//toolchain/base:shared_value_stores",
"//toolchain/diagnostics:diagnostic_emitter",
"//toolchain/source:source_buffer",
toolchain/lex/lex.cpp
+19 -21
View File
@@ -10,10 +10,10 @@
#include <utility>
#include "common/check.h"
#include "common/variant_helpers.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Support/Compiler.h"
#include "toolchain/base/kind_switch.h"
#include "toolchain/base/shared_value_stores.h"
#include "toolchain/lex/character_set.h"
#include "toolchain/lex/helpers.h"
@@ -1112,26 +1112,24 @@ auto Lexer::LexNumericLiteral(llvm::StringRef source_text, ssize_t& position)
int token_size = literal->text().size();
position += token_size;
return VariantMatch(
literal->ComputeValue(emitter_),
[&](NumericLiteral::IntValue&& value) {
return LexTokenWithPayload(TokenKind::IntLiteral,
buffer_.value_stores_->ints()
.AddUnsigned(std::move(value.value))
.AsTokenPayload(),
byte_offset);
},
[&](NumericLiteral::RealValue&& value) {
auto real_id = buffer_.value_stores_->reals().Add(Real{
.mantissa = value.mantissa,
.exponent = value.exponent,
.is_decimal = (value.radix == NumericLiteral::Radix::Decimal)});
return LexTokenWithPayload(TokenKind::RealLiteral, real_id.index,
byte_offset);
},
[&](NumericLiteral::UnrecoverableError) {
return LexTokenWithPayload(TokenKind::Error, token_size, byte_offset);
});
CARBON_KIND_SWITCH(literal->ComputeValue(emitter_)) {
case CARBON_KIND(NumericLiteral::IntValue && value):
return LexTokenWithPayload(TokenKind::IntLiteral,
buffer_.value_stores_->ints()
.AddUnsigned(std::move(value.value))
.AsTokenPayload(),
byte_offset);
case CARBON_KIND(NumericLiteral::RealValue && value): {
auto real_id = buffer_.value_stores_->reals().Add(
Real{.mantissa = value.mantissa,
.exponent = value.exponent,
.is_decimal = (value.radix == NumericLiteral::Radix::Decimal)});
return LexTokenWithPayload(TokenKind::RealLiteral, real_id.index,
byte_offset);
}
case CARBON_KIND(NumericLiteral::UnrecoverableError _):
return LexTokenWithPayload(TokenKind::Error, token_size, byte_offset);
}
}
auto Lexer::LexStringLiteral(llvm::StringRef source_text, ssize_t& position)
toolchain/sem_ir/BUILD
-1
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@@ -140,7 +140,6 @@ cc_library(
":typed_insts",
"//common:check",
"//common:raw_string_ostream",
"//common:variant_helpers",
"//toolchain/base:kind_switch",
"@llvm-project//llvm:Support",
],
toolchain/sem_ir/stringify.cpp
+53 -36
View File
@@ -10,7 +10,6 @@
#include <variant>
#include "common/raw_string_ostream.h"
#include "common/variant_helpers.h"
#include "toolchain/base/kind_switch.h"
#include "toolchain/sem_ir/entity_with_params_base.h"
#include "toolchain/sem_ir/ids.h"
@@ -122,25 +121,38 @@ class StepStack {
// safe.
auto PushArray(llvm::ArrayRef<PushItem> items) -> void {
for (auto item : llvm::reverse(items)) {
VariantMatch(
item, [&](InstId inst_id) { PushInstId(inst_id); },
[&](llvm::StringRef string) { PushString(string); },
[&](NameId name_id) { PushNameId(name_id); },
[&](ElementIndex element_index) { PushElementIndex(element_index); },
[&](QualifiedNameItem qualified_name) {
PushQualifiedName(qualified_name.first, qualified_name.second);
},
[&](EntityNameItem entity_name) {
PushEntityName(entity_name.first, entity_name.second);
},
[&](EntityNameId entity_name_id) {
PushEntityNameId(entity_name_id);
},
[&](TypeId type_id) { PushTypeId(type_id); },
[&](SpecificInterface specific_interface) {
PushSpecificInterface(specific_interface);
},
[&](llvm::ListSeparator* sep) { PushString(*sep); });
CARBON_KIND_SWITCH(item) {
case CARBON_KIND(InstId inst_id):
PushInstId(inst_id);
break;
case CARBON_KIND(llvm::StringRef string):
PushString(string);
break;
case CARBON_KIND(NameId name_id):
PushNameId(name_id);
break;
case CARBON_KIND(ElementIndex element_index):
PushElementIndex(element_index);
break;
case CARBON_KIND(QualifiedNameItem qualified_name):
PushQualifiedName(qualified_name.first, qualified_name.second);
break;
case CARBON_KIND(EntityNameItem entity_name):
PushEntityName(entity_name.first, entity_name.second);
break;
case CARBON_KIND(EntityNameId entity_name_id):
PushEntityNameId(entity_name_id);
break;
case CARBON_KIND(TypeId type_id):
PushTypeId(type_id);
break;
case CARBON_KIND(SpecificInterface specific_interface):
PushSpecificInterface(specific_interface);
break;
case CARBON_KIND(llvm::ListSeparator * sep):
PushString(*sep);
break;
}
}
}
@@ -641,28 +653,33 @@ static auto Stringify(const File& sem_ir, StepStack& step_stack)
Stringifier stringifier(&sem_ir, &step_stack, &out);
while (!step_stack.empty()) {
auto step = step_stack.Pop();
VariantMatch(
step,
[&](InstId inst_id) {
if (!inst_id.has_value()) {
out << "<invalid>";
return;
}
auto untyped_inst = sem_ir.insts().Get(inst_id);
CARBON_KIND_SWITCH(untyped_inst) {
CARBON_KIND_SWITCH(step_stack.Pop()) {
case CARBON_KIND(InstId inst_id): {
if (!inst_id.has_value()) {
out << "<invalid>";
break;
}
auto untyped_inst = sem_ir.insts().Get(inst_id);
CARBON_KIND_SWITCH(untyped_inst) {
#define CARBON_SEM_IR_INST_KIND(InstT) \
case CARBON_KIND(InstT typed_inst): { \
stringifier.StringifyInst(inst_id, typed_inst); \
break; \
}
#include "toolchain/sem_ir/inst_kind.def"
}
},
[&](llvm::StringRef string) { out << string; },
[&](NameId name_id) { out << sem_ir.names().GetFormatted(name_id); },
[&](ElementIndex element_index) { out << element_index.index; });
}
break;
}
case CARBON_KIND(llvm::StringRef string):
out << string;
break;
case CARBON_KIND(NameId name_id):
out << sem_ir.names().GetFormatted(name_id);
break;
case CARBON_KIND(ElementIndex element_index):
out << element_index.index;
break;
}
}
return out.TakeStr();