Map default initializer of translated type

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -3003,6 +3003,11 @@ std::string Converter::GetDefaultAsString(clang::QualType qual_type) {
     return "VaList::default()";
   }
 
+  if (auto init = Mapper::MapInitializer(qual_type); !init.empty()) {
+    computed_expr_type_ = ComputedExprType::FreshValue;
+    return init;
+  }
+
   if (qual_type->isPointerType()) {
     auto pointee = qual_type->getPointeeType();
     if (pointee->isFunctionType()) {
@@ -3026,13 +3031,7 @@ std::string Converter::GetDefaultAsString(clang::QualType qual_type) {
     return GetDefaultAsString(array_type->getElementType());
   } else {
     auto qual_type_str = Mapper::ToString(qual_type);
-    if (qual_type_str == "struct std::pair") {
-      auto template_args = *GetTemplateArgs(qual_type);
-      auto first_type = template_args[0].getAsType();
-      auto second_type = template_args[1].getAsType();
-      return std::format("({}, {})", GetDefaultAsString(first_type),
-                         GetDefaultAsString(second_type));
-    } else if (qual_type_str.contains("std::array")) {
+    if (qual_type_str.contains("std::array")) {
       assert(GetTemplateArgs(qual_type).has_value());
       auto template_args = *GetTemplateArgs(qual_type);
       assert(template_args.size() == 2);

cpp2rust/converter/mapper.cpp

@@ -625,6 +625,18 @@ std::string Map(clang::QualType qual_type) {
   return {};
 }
 
+std::string MapInitializer(clang::QualType qual_type) {
+  auto type_str = ToString(qual_type);
+  auto [rule, subs] = search(types_, type_str, GetTypeMapKey(type_str));
+  if (rule && !rule->initializer.empty()) {
+    for (auto &ty : subs) {
+      ty = mapTypeStringRecursive(ty);
+    }
+    return instantiateTgt(subs, rule->initializer);
+  }
+  return {};
+}
+
 bool MapsToPointer(clang::QualType qual_type) {
   auto rule = search(qual_type);
   return rule && rule->type_info.is_pointer();

cpp2rust/converter/mapper.h

@@ -28,6 +28,7 @@ bool Contains(clang::QualType qual_type);
 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);
 std::string MapFunctionName(const clang::FunctionDecl *decl);
 std::string InstantiateTemplate(const clang::Expr *expr, unsigned n);

rules/pair/ir_unsafe.json

@@ -459,7 +459,7 @@
     }
   },
   "t1": {
-    "init": "(T1::default(), T2::default())",
+    "init": "<(T1, T2)>::default()",
     "type": "(T1, T2)"
   }
 }

rules/pair/tgt_unsafe.rs

@@ -8,7 +8,7 @@ struct T1;
 struct T2;
 
 fn types() {
-    let t1: (T1, T2) = (T1::default(), T2::default());
+    let t1: (T1, T2) = <(T1, T2)>::default();
 }
 
 unsafe fn f1<T1, T2>(a0: (T1, T2)) -> T2 {

rules/stdio/ir_unsafe.json

@@ -756,7 +756,7 @@
     }
   },
   "t1": {
-    "init": "Default::default()",
+    "init": "std::ptr::null_mut()",
     "type": "*mut ::std::fs::File",
     "is_unsafe_pointer": true
   }

rules/stdio/tgt_unsafe.rs

@@ -5,7 +5,7 @@ use libcc2rs::*;
 use std::io::prelude::*;
 
 fn types() -> Result<(), Box<dyn std::error::Error>> {
-    let t1: *mut ::std::fs::File = Default::default();
+    let t1: *mut ::std::fs::File = std::ptr::null_mut();
     Ok(())
 }