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Refactor ConvertGenericCallExpr #145

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bd0e046
Refactor ConvertGenericCallExpr
lucic71 May 23, 2026
2cae1e9
EmitArgBindings -> EmitHoistedArgs
lucic71 May 23, 2026
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203 changes: 117 additions & 86 deletions cpp2rust/converter/converter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1495,125 +1495,156 @@ void Converter::ConvertFunctionToFunctionPointer(
StrCat(std::format("Some({})", Mapper::MapFunctionName(fn_decl)));
}

void Converter::ConvertGenericCallExpr(clang::CallExpr *expr) {
clang::Expr *callee = expr->getCallee();
auto convert_param_ty = [&](clang::QualType param_type, clang::Expr *expr) {
if (param_type->isLValueReferenceType()) {
PushExprKind push(*this, ExprKind::AddrOf);
ConvertVarInit(param_type, expr);
} else {
ConvertVarInit(param_type, expr);
}
};
Converter::CallInfo Converter::CollectCallInfo(clang::CallExpr *expr) {
using Kind = CallArg::Kind;

unsigned arg_begin = 0; // skip count for operator()'s implicit object arg
CallInfo info{};
info.callee = expr->getCallee();
unsigned arg_begin = 0;
if (auto op_call = llvm::dyn_cast<clang::CXXOperatorCallExpr>(expr)) {
if (op_call->getOperator() == clang::OO_Call) {
callee = op_call->getArg(0);
info.callee = op_call->getArg(0);
arg_begin = 1;
}
}

PushParen outer(*this);
StrCat(keyword_unsafe_);
PushBrace unsafe_brace(*this);
const auto *function =
expr->getCalleeDecl() ? expr->getCalleeDecl()->getAsFunction() : nullptr;
const clang::FunctionProtoType *proto = nullptr;

if (!function) {
auto callee_ty = callee->getType().getDesugaredType(ctx_);
auto callee_ty = info.callee->getType().getDesugaredType(ctx_);
if (auto ptr_ty = callee_ty->getAs<clang::PointerType>()) {
proto = ptr_ty->getPointeeType()->getAs<clang::FunctionProtoType>();
}
}

assert((function || proto) &&
"Either function decl or function prototype should be known");

auto num_args = expr->getNumArgs() - arg_begin;
bool is_variadic =
function ? function->isVariadic() : (proto && proto->isVariadic());
unsigned num_named_params = function
? function->getNumParams()
: (proto ? proto->getNumParams() : num_args);

// Track which args are materialized temps bound to reference params
std::vector<std::string> temp_refs(num_args);
unsigned num_args = expr->getNumArgs() - arg_begin;
unsigned num_named_params =
function ? function->getNumParams() : proto->getNumParams();
info.is_variadic = function ? function->isVariadic() : proto->isVariadic();
info.is_fn_ptr_call = !function;

for (unsigned i = 0; i < num_named_params && i < num_args; ++i) {
auto *arg = expr->getArg(i + arg_begin);
std::string param_name = function
? function->getParamDecl(i)->getNameAsString()
: ("arg" + std::to_string(i));
clang::QualType param_type = function ? function->getParamDecl(i)->getType()
: proto->getParamType(i);

bool is_materialize_to_ref =
clang::isa<clang::MaterializeTemporaryExpr>(arg) &&
param_type->isLValueReferenceType();

if (is_materialize_to_ref) {
auto [binding, ref] =
MaterializeTemp(std::format("_{}", param_name), param_type, arg);
StrCat(binding);
temp_refs[i] = std::move(ref);
} else if (!clang::isa<clang::MaterializeTemporaryExpr>(arg)) {
StrCat("let", std::format("_{}: {}", param_name, ToString(param_type)),
"=");
convert_param_ty(param_type, arg);
StrCat(";");
CallArg ca{
.expr = arg,
.kind = Kind::Hoisted,
.param_name = function ? function->getParamDecl(i)->getNameAsString()
: ("arg" + std::to_string(i)),
.param_type = function ? function->getParamDecl(i)->getType()
: proto->getParamType(i),
.has_default = function && function->getParamDecl(i)->hasDefaultArg(),
};
bool is_materialize = clang::isa<clang::MaterializeTemporaryExpr>(arg);
if (is_materialize && ca.param_type->isLValueReferenceType()) {
ca.kind = Kind::Materialized;
} else if (is_materialize) {
ca.kind = Kind::Inline;
}
info.args.push_back(std::move(ca));
}

if (info.is_variadic) {
for (unsigned i = num_named_params; i < num_args; ++i) {
info.variadic_args.push_back(expr->getArg(i + arg_begin));
}
}

if (proto && !function) {
EmitFnPtrCall(callee);
return info;
}

void Converter::ConvertParamTy(clang::QualType param_type, clang::Expr *expr) {
if (param_type->isLValueReferenceType()) {
PushExprKind push(*this, ExprKind::AddrOf);
ConvertVarInit(param_type, expr);
} else {
PushExprKind push(*this, ExprKind::Callee);
Convert(callee);
ConvertVarInit(param_type, expr);
}
{
PushParen call_args(*this);
for (unsigned i = 0; i < num_named_params && i < num_args; ++i) {
auto *arg = expr->getArg(i + arg_begin);
std::string param_name =
function ? function->getParamDecl(i)->getNameAsString()
: ("arg" + std::to_string(i));
clang::QualType param_type = function
? function->getParamDecl(i)->getType()
: proto->getParamType(i);
bool is_parm_with_default_value =
function && function->getParamDecl(i)->hasDefaultArg();

if (is_parm_with_default_value) {
StrCat("Some(");
}
if (!temp_refs[i].empty()) {
StrCat(temp_refs[i]);
} else if (clang::isa<clang::MaterializeTemporaryExpr>(arg)) {
convert_param_ty(param_type, arg);
} else {
StrCat(std::format("_{}", param_name));
}
if (is_parm_with_default_value) {
StrCat(')');
}
StrCat(token::kComma);
}

void Converter::EmitHoistedArgs(CallInfo &info) {
using Kind = CallArg::Kind;
for (auto &ca : info.args) {
switch (ca.kind) {
case Kind::Hoisted:
StrCat("let",
std::format("_{}: {}", ca.param_name, ToString(ca.param_type)),
"=");
ConvertParamTy(ca.param_type, ca.expr);
StrCat(";");
break;
case Kind::Materialized: {
auto [binding, ref] = MaterializeTemp(std::format("_{}", ca.param_name),
ca.param_type, ca.expr);
StrCat(binding);
ca.ref_temp_name = std::move(ref);
break;
}
case Kind::Inline:
break;
}
}
}

void Converter::EmitArgList(const CallInfo &info) {
using Kind = CallArg::Kind;
PushParen call_args(*this);

// Variadic args: wrap in &[arg.into(), ...]
if (is_variadic) {
StrCat("& [");
for (unsigned i = num_named_params; i < num_args; ++i) {
auto *arg = expr->getArg(i + arg_begin);
ConvertVariadicArg(arg);
StrCat(".into()", token::kComma);
for (const auto &ca : info.args) {
if (ca.has_default) {
StrCat("Some");
}

{
PushParen push(*this, ca.has_default);
switch (ca.kind) {
case Kind::Hoisted:
StrCat(std::format("_{}", ca.param_name));
break;
case Kind::Materialized:
StrCat(ca.ref_temp_name);
break;
case Kind::Inline:
ConvertParamTy(ca.param_type, ca.expr);
break;
}
StrCat(']');
}

StrCat(token::kComma);
}

if (info.is_variadic) {
StrCat(token::kRef);
PushBracket push(*this);
for (auto *arg : info.variadic_args) {
ConvertVariadicArg(arg);
StrCat(".into()", token::kComma);
}
}
}

void Converter::EmitCall(CallInfo info) {
EmitHoistedArgs(info);

if (info.is_fn_ptr_call) {
EmitFnPtrCall(info.callee);
} else {
PushExprKind push(*this, ExprKind::Callee);
Convert(info.callee);
}

EmitArgList(info);
}

void Converter::ConvertGenericCallExpr(clang::CallExpr *expr) {
PushParen outer(*this);
StrCat(keyword_unsafe_);
PushBrace unsafe_brace(*this);
EmitCall(CollectCallInfo(expr));
}

std::optional<Converter::TempMaterializationCtx>
Converter::ConvertCallExpr(clang::CallExpr *expr) {
auto *callee = expr->getCallee();
Expand Down
33 changes: 33 additions & 0 deletions cpp2rust/converter/converter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -217,6 +217,39 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {

std::optional<TempMaterializationCtx> ConvertCallExpr(clang::CallExpr *expr);

struct CallArg {
enum class Kind {
Hoisted,
Inline,
Materialized,
};

clang::Expr *expr;
Kind kind;
std::string param_name;
clang::QualType param_type;
bool has_default;
std::string ref_temp_name;
};

struct CallInfo {
clang::Expr *callee;
bool is_variadic;
bool is_fn_ptr_call;
std::vector<CallArg> args;
std::vector<clang::Expr *> variadic_args;
};

CallInfo CollectCallInfo(clang::CallExpr *expr);

void ConvertParamTy(clang::QualType param_type, clang::Expr *expr);

void EmitHoistedArgs(CallInfo &info);

void EmitArgList(const CallInfo &info);

void EmitCall(CallInfo info);

void ConvertGenericCallExpr(clang::CallExpr *expr);

virtual void EmitFnPtrCall(clang::Expr *callee);
Expand Down
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