Add translation rules for variadic libc calls

cpp2rust/converter/converter.cpp

@@ -1553,6 +1553,11 @@ bool Converter::VisitCallExpr(clang::CallExpr *expr) {
   }
 
   if (Mapper::Contains(expr->getCallee())) {
+    if (Mapper::IsLibcPassthrough(GetCalleeOrExpr(expr))) {
+      ConvertGenericCallExpr(expr);
+      return false;
+    }
+
     auto **args = expr->getArgs();
     auto num_args = expr->getNumArgs();
     auto ctx = CollectRefBindingTempArgs(expr);
@@ -1627,20 +1632,20 @@ Converter::CallInfo Converter::CollectCallInfo(clang::CallExpr *expr) {
   using Kind = CallArg::Kind;
 
   CallInfo info;
-  info.callee = expr->getCallee();
+  info.expr = expr;
+  auto callee = GetCallee(expr);
   unsigned arg_begin = 0;
   if (auto op_call = llvm::dyn_cast<clang::CXXOperatorCallExpr>(expr)) {
     if (op_call->getOperator() == clang::OO_Call) {
-      info.callee = op_call->getArg(0);
       arg_begin = 1;
     }
   }
 
-  const auto *function =
-      expr->getCalleeDecl() ? expr->getCalleeDecl()->getAsFunction() : nullptr;
+  auto decl = expr->getCalleeDecl();
+  const auto *function = decl ? decl->getAsFunction() : nullptr;
   const clang::FunctionProtoType *proto = nullptr;
   if (!function) {
-    auto callee_ty = info.callee->getType().getDesugaredType(ctx_);
+    auto callee_ty = callee->getType().getDesugaredType(ctx_);
     if (auto ptr_ty = callee_ty->getAs<clang::PointerType>()) {
       proto = ptr_ty->getPointeeType()->getAs<clang::FunctionProtoType>();
     }
@@ -1653,6 +1658,7 @@ Converter::CallInfo Converter::CollectCallInfo(clang::CallExpr *expr) {
       function ? function->getNumParams() : proto->getNumParams();
   info.is_variadic = function ? function->isVariadic() : proto->isVariadic();
   info.is_fn_ptr_call = !function;
+  info.is_libc_passthrough = Mapper::IsLibcPassthrough(GetCalleeOrExpr(expr));
 
   for (unsigned i = 0; i < num_named_params && i < num_args; ++i) {
     auto *arg = expr->getArg(i + arg_begin);
@@ -1664,7 +1670,8 @@ Converter::CallInfo Converter::CollectCallInfo(clang::CallExpr *expr) {
                                : proto->getParamType(i),
         .expr = arg,
         .has_default = function && function->getParamDecl(i)->hasDefaultArg(),
-        .kind = IsLiteral(arg) ? Kind::Inline : Kind::Hoisted,
+        .kind = (IsLiteral(arg) || info.is_libc_passthrough) ? Kind::Inline
+                                                             : Kind::Hoisted,
     };
     bool is_materialize = clang::isa<clang::MaterializeTemporaryExpr>(arg);
     if (is_materialize && ca.param_type->isLValueReferenceType()) {
@@ -1720,7 +1727,9 @@ void Converter::EmitArgList(const CallInfo &info) {
   using Kind = CallArg::Kind;
   PushParen call_args(*this);
 
-  for (const auto &ca : info.args) {
+  for (unsigned i = 0; i < info.args.size(); i++) {
+    const auto &ca = info.args[i];
+
     if (ca.has_default) {
       StrCat("Some");
     }
@@ -1736,6 +1745,10 @@ void Converter::EmitArgList(const CallInfo &info) {
         break;
       case Kind::Inline:
         ConvertParamTy(ca.param_type, ca.expr);
+        if (info.is_libc_passthrough) {
+          StrCat(std::format(
+              "as {}", Mapper::GetParamType(GetCalleeOrExpr(info.expr), i)));
+        }
         break;
       }
     }
@@ -1744,14 +1757,19 @@ void Converter::EmitArgList(const CallInfo &info) {
   }
 
   if (info.is_variadic) {
-    StrCat(token::kRef);
-    PushBracket push(*this);
+    if (!info.is_libc_passthrough) {
+      StrCat(token::kRef);
+    }
+    PushBracket push(*this, !info.is_libc_passthrough);
     for (auto *arg : info.variadic_args) {
       {
         PushParen p(*this);
         ConvertVariadicArg(arg);
       }
-      StrCat(".into()", token::kComma);
+      if (!info.is_libc_passthrough) {
+        StrCat(".into()");
+      }
+      StrCat(token::kComma);
     }
   }
 }
@@ -1760,10 +1778,14 @@ void Converter::EmitCall(CallInfo &&info) {
   EmitHoistedArgs(info);
 
   if (info.is_fn_ptr_call) {
-    EmitFnPtrCall(info.callee);
+    EmitFnPtrCall(GetCallee(info.expr));
+  } else if (info.is_libc_passthrough) {
+    auto *direct_callee = info.expr->getDirectCallee();
+    assert(direct_callee);
+    StrCat("libc::", direct_callee->getName());
   } else {
     PushExprKind push(*this, ExprKind::Callee);
-    Convert(info.callee);
+    Convert(GetCallee(info.expr));
   }
 
   EmitArgList(info);
@@ -4193,6 +4215,8 @@ std::string Converter::ConvertIRFragment(
           .is_index_base = ph->is_index_base,
       };
       result += ConvertPlaceholder(expr, arg, ph_ctx);
+    } else if (std::get_if<TranslationRule::VaArgsFragment>(&frag)) {
+      result += ConvertVariadicTail(expr, all_args);
     } else if (auto *mc =
                    std::get_if<std::unique_ptr<MethodCallFragment>>(&frag)) {
       result += ConvertMappedMethodCall(expr, **mc, args, num_args, ctx);
@@ -4202,6 +4226,25 @@ std::string Converter::ConvertIRFragment(
   return result;
 }
 
+std::string
+Converter::ConvertVariadicTail(clang::Expr *expr,
+                               const std::vector<clang::Expr *> &all_args) {
+  const auto *tgt_ir = Mapper::GetExprRule(GetCalleeOrExpr(expr));
+  unsigned fixed = tgt_ir ? tgt_ir->params.size() : 0;
+
+  Buffer buf(*this);
+  StrCat("&[");
+  for (unsigned i = fixed; i < all_args.size(); ++i) {
+    {
+      PushParen p(*this);
+      ConvertVariadicArg(all_args[i]);
+    }
+    StrCat(".into()", token::kComma);
+  }
+  StrCat("]");
+  return std::move(buf).str();
+}
+
 std::string Converter::AccessLValueObject(clang::MemberExpr *member) {
   auto *object = member->getBase();
   auto type = object->getType();

cpp2rust/converter/converter.h

@@ -245,9 +245,10 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
   struct CallInfo {
     std::vector<CallArg> args;
     std::vector<clang::Expr *> variadic_args;
-    clang::Expr *callee;
+    clang::CallExpr *expr;
     bool is_variadic;
     bool is_fn_ptr_call;
+    bool is_libc_passthrough;
   };
 
   CallInfo CollectCallInfo(clang::CallExpr *expr);
@@ -573,6 +574,9 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
   std::string ConvertPlaceholder(clang::Expr *expr, clang::Expr *arg,
                                  const PlaceholderCtx &ph_ctx);
 
+  std::string ConvertVariadicTail(clang::Expr *expr,
+                                  const std::vector<clang::Expr *> &all_args);
+
   virtual std::string ConvertMappedMethodCall(
       clang::Expr *expr, const TranslationRule::MethodCallFragment &mc,
       clang::Expr **args, unsigned num_args, TempMaterializationCtx *ctx);

cpp2rust/converter/converter_lib.cpp

@@ -657,6 +657,15 @@ BuildUnifiedArgs(clang::Expr *expr, clang::Expr **args, unsigned num_args) {
   return all_args;
 }
 
+clang::Expr *GetCallee(clang::CallExpr *expr) {
+  if (auto op_call = clang::dyn_cast<clang::CXXOperatorCallExpr>(expr)) {
+    if (op_call->getOperator() == clang::OO_Call) {
+      return op_call->getArg(0);
+    }
+  }
+  return expr->getCallee();
+}
+
 clang::Expr *GetCalleeOrExpr(clang::Expr *expr) {
   if (auto *call = clang::dyn_cast<clang::CallExpr>(expr)) {
     return call->getCallee();

cpp2rust/converter/converter_lib.h

@@ -139,6 +139,8 @@ void ForEachTemplateArgument(
 
 clang::Expr *GetCallObject(clang::CallExpr *expr);
 
+clang::Expr *GetCallee(clang::CallExpr *expr);
+
 clang::Expr *GetCalleeOrExpr(clang::Expr *expr);
 
 bool HasReceiver(clang::Expr *expr);

cpp2rust/converter/mapper.cpp

@@ -641,6 +641,19 @@ const TranslationRule::ExprRule *GetExprRule(const clang::Expr *expr) {
   return search(expr);
 }
 
+bool IsLibcPassthrough(const clang::Expr *expr) {
+  const auto *tgt_ir = GetExprRule(expr);
+  if (tgt_ir == nullptr || !tgt_ir->body.empty() || !tgt_ir->is_extern) {
+    return false;
+  }
+  const auto *ref =
+      clang::dyn_cast<clang::DeclRefExpr>(expr->IgnoreParenImpCasts());
+  const auto *decl = ref != nullptr ? ref->getDecl() : nullptr;
+  return decl != nullptr &&
+         decl->getASTContext().getSourceManager().isInSystemHeader(
+             decl->getLocation());
+}
+
 std::string MapFunctionName(const clang::FunctionDecl *decl) {
   assert(decl);
   if (!IsUserDefinedDecl(decl) &&
@@ -920,6 +933,12 @@ std::string ToString(const clang::NamedDecl *decl) {
     }
     os << ToString(func_decl->getParamDecl(i)->getType());
   }
+  if (func_decl->isVariadic()) {
+    if (func_decl->getNumParams()) {
+      os << ", ";
+    }
+    os << "...";
+  }
   os << ')';
 
   if (const auto *method_decl =

cpp2rust/converter/mapper.h

@@ -30,6 +30,7 @@ bool Contains(const clang::Expr *expr);
 std::string Map(clang::QualType qual_type);
 std::string MapInitializer(clang::QualType qual_type);
 const TranslationRule::ExprRule *GetExprRule(const clang::Expr *expr);
+bool IsLibcPassthrough(const clang::Expr *expr);
 std::string MapFunctionName(const clang::FunctionDecl *decl);
 std::string InstantiateTemplate(const clang::Expr *expr, unsigned n);
 bool ReturnsPointer(const clang::Expr *expr);

cpp2rust/converter/translation_rule.cpp

@@ -86,6 +86,8 @@ std::vector<BodyFragment> ParseBodyFragmentsJSON(const llvm::json::Array &arr) {
     } else if (auto *mc = frag_obj->getObject("method_call")) {
       result.push_back(std::make_unique<MethodCallFragment>(
           ParseMethodCallFragmentJSON(*mc)));
+    } else if (frag_obj->get("va_args")) {
+      result.push_back(VaArgsFragment{});
     }
   }
   return result;
@@ -104,11 +106,17 @@ ExprRule ParseExprRuleJSON(const llvm::json::Object &obj) {
     }
   }
 
-  if (auto *rt = obj.getObject("return_type"))
+  if (auto *rt = obj.getObject("return_type")) {
     ir.return_type = ParseTypeInfoJSON(*rt);
+  }
 
-  if (auto ms = obj.getBoolean("multi_statement"))
+  if (auto ms = obj.getBoolean("multi_statement")) {
     ir.multi_statement = *ms;
+  }
+
+  if (auto v = obj.getBoolean("is_extern")) {
+    ir.is_extern = *v;
+  }
 
   if (auto *generics = obj.getObject("generics")) {
     for (auto &[key, val] : *generics) {
@@ -222,6 +230,8 @@ void BodyFragmentDump(const BodyFragment &frag) {
     p->dump();
   } else if (auto *g = std::get_if<GenericFragment>(&frag)) {
     g->dump();
+  } else if (auto *v = std::get_if<VaArgsFragment>(&frag)) {
+    v->dump();
   } else if (auto *mc =
                  std::get_if<std::unique_ptr<MethodCallFragment>>(&frag)) {
     (*mc)->dump();
@@ -232,6 +242,8 @@ void BodyFragmentDump(const BodyFragment &frag) {
 
 void TextFragment::dump() const { log() << "  text: \"" << text << "\"\n"; }
 
+void VaArgsFragment::dump() const { log() << "  va_args\n"; }
+
 void PlaceholderFragment::dump() const {
   log() << "  placeholder: " << n;
   switch (access) {

cpp2rust/converter/translation_rule.h

@@ -39,11 +39,15 @@ struct GenericFragment {
   void dump() const;
 };
 
+struct VaArgsFragment {
+  void dump() const;
+};
+
 struct MethodCallFragment; // forward declaration
 
 using BodyFragment =
     std::variant<TextFragment, PlaceholderFragment, GenericFragment,
-                 std::unique_ptr<MethodCallFragment>>;
+                 VaArgsFragment, std::unique_ptr<MethodCallFragment>>;
 
 struct MethodCallFragment {
   std::vector<BodyFragment> receiver;
@@ -71,6 +75,7 @@ struct ExprRule {
   std::vector<std::vector<std::string>> generics; // "T1" -> ["Ord", "Clone"]
   std::vector<BodyFragment> body;
   bool multi_statement = false;
+  bool is_extern = false;
 
   void dump() const;
   void validate(const std::string &name) const;

cpp2rust/cpp_rule_preprocessor.cpp

@@ -354,7 +354,9 @@ class Callback : public clang::ast_matchers::MatchFinder::MatchCallback {
   createTemplateArguments(clang::TemplateDecl *decl,
                           llvm::SmallVectorImpl<clang::TemplateArgument> &out) {
     for (clang::NamedDecl *param : *decl->getTemplateParameters()) {
-      if (llvm::isa<clang::TemplateTypeParmDecl>(param)) {
+      if (param->isTemplateParameterPack()) {
+        out.emplace_back(clang::TemplateArgument::getEmptyPack());
+      } else if (llvm::isa<clang::TemplateTypeParmDecl>(param)) {
         clang::RecordDecl *rdecl = createRecordDecl(param->getName());
         clang::QualType type =
             sema_->Context.getTagType(clang::ElaboratedTypeKeyword::None,
@@ -414,7 +416,14 @@ class Callback : public clang::ast_matchers::MatchFinder::MatchCallback {
                          clang::OverloadCandidateSet &candidates) {
     clang::LookupResult decls(*sema_, name, loc_,
                               clang::Sema::LookupOrdinaryName);
-    sema_->LookupQualifiedName(decls, sema_->getStdNamespace());
+    if (clang::NamespaceDecl *std_ns = sema_->getStdNamespace()) {
+      sema_->LookupQualifiedName(decls, std_ns);
+    }
+    if (decls.empty()) {
+      decls.clear();
+      sema_->LookupQualifiedName(decls,
+                                 sema_->Context.getTranslationUnitDecl());
+    }
     for (auto *ndecl : decls) {
       if (auto *candidate = createCandidate(ndecl, callArgs, explicitTArgs)) {
         sema_->AddOverloadCandidate(
@@ -578,6 +587,7 @@ class Callback : public clang::ast_matchers::MatchFinder::MatchCallback {
       cxxConstructorNameLookup(rule->getReturnType(), callArgs, candidates);
       break;
     case LookupKind::ADL:
+      regularNameLookup(callArgs, &explicitTArgs, name, candidates);
       adlLookup(callArgs, name, candidates);
       break;
     }

rule-preprocessor/src/ir.rs

@@ -59,6 +59,8 @@ pub struct FnIr {
     pub params: Option<BTreeMap<String, TypeInfo>>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub return_type: Option<TypeInfo>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub is_extern: Option<bool>,
 }
 
 impl FnIr {
@@ -106,7 +108,10 @@ impl FnIr {
             1,
             &format!("Rule {name} generics"),
         );
-        assert!(!self.body.is_empty(), "Rule {name}: body must not be empty");
+        assert!(
+            self.is_extern == Some(true) || !self.body.is_empty(),
+            "Rule {name}: body must not be empty"
+        );
     }
 }
 
@@ -120,10 +125,21 @@ pub struct TypeIr {
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(untagged)]
 pub enum BodyFragment {
-    Text { text: String },
-    Placeholder { placeholder: PlaceholderInner },
-    Generic { generic: i32 },
-    MethodCall { method_call: MethodCallInner },
+    Text {
+        text: String,
+    },
+    Placeholder {
+        placeholder: PlaceholderInner,
+    },
+    Generic {
+        generic: i32,
+    },
+    MethodCall {
+        method_call: MethodCallInner,
+    },
+    VaArgs {
+        va_args: std::marker::PhantomData<()>,
+    },
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]