Add Mapper::IsLibcPassthrough

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -1524,11 +1524,9 @@ bool Converter::VisitCallExpr(clang::CallExpr *expr) {
   }
 
   if (Mapper::Contains(expr->getCallee())) {
-    if (auto tgt_ir = Mapper::GetExprRule(GetCalleeOrExpr(expr))) {
-      if (tgt_ir->body.empty() && tgt_ir->is_variadic) {
-        ConvertGenericCallExpr(expr);
-        return false;
-      }
+    if (Mapper::IsLibcPassthrough(GetCalleeOrExpr(expr))) {
+      ConvertGenericCallExpr(expr);
+      return false;
     }
 
     auto **args = expr->getArgs();
@@ -1631,12 +1629,7 @@ 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 = false;
-  if (auto tgt_ir = Mapper::GetExprRule(GetCalleeOrExpr(expr))) {
-    if (tgt_ir->body.empty() && tgt_ir->is_variadic) {
-      info.is_libc_passthrough = true;
-    }
-  }
+  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);

cpp2rust/converter/mapper.cpp

@@ -588,6 +588,19 @@ 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) &&

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);