In unsafe, const variables that need destruction need to be mut

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -480,7 +480,7 @@ bool Converter::NeedsMut(const clang::VarDecl *decl, clang::QualType type,
   auto *method_or_null =
       curr_function_ ? clang::dyn_cast<clang::CXXMethodDecl>(curr_function_)
                      : nullptr;
-  return ((hoisted_decls_.contains(decl) ||
+  return ((hoisted_decls_.contains(decl) || NeedsScopedDestructor(decl) ||
            (!type.isConstQualified() && !type->isReferenceType())) &&
           ((method_or_null == nullptr) || !method_or_null->isVirtual()) &&
           !IsGlobalVar(decl) && name != "_");
@@ -627,8 +627,21 @@ bool Converter::VisitVarDecl(clang::VarDecl *decl) {
   return false;
 }
 
-void Converter::EmitScopedDestructor(const clang::VarDecl *decl) {
+bool Converter::NeedsScopedDestructor(const clang::VarDecl *decl) const {
   if (in_function_formals_ || !decl->isLocalVarDecl() || IsGlobalVar(decl)) {
+    return false;
+  }
+  auto type = decl->getType();
+  if (auto lambda = AsLambdaClass(type);
+      lambda && LambdaNeedsDestruction(lambda)) {
+    return true;
+  }
+  return !type->isReferenceType() && !type->isArrayType() &&
+         TypeNeedsDestruction(type);
+}
+
+void Converter::EmitScopedDestructor(const clang::VarDecl *decl) {
+  if (!NeedsScopedDestructor(decl)) {
     return;
   }
   auto type = decl->getType();
@@ -640,10 +653,6 @@ void Converter::EmitScopedDestructor(const clang::VarDecl *decl) {
                        GetNamedDeclAsString(decl)));
     return;
   }
-  if (type->isReferenceType() || type->isArrayType() ||
-      !TypeNeedsDestruction(type)) {
-    return;
-  }
   auto name = GetNamedDeclAsString(decl);
   StrCat(token::kSemiColon,
          std::format("let _dtor_{0} = ScopedDestructorUnsafe::new(&raw mut "

cpp2rust/converter/converter.h

@@ -150,6 +150,8 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
 
   virtual std::string DestroyMembers(const clang::CXXRecordDecl *decl);
 
+  bool NeedsScopedDestructor(const clang::VarDecl *decl) const;
+
   virtual void EmitScopedDestructor(const clang::VarDecl *decl);
 
   void EmitDeallocation(clang::CXXDeleteExpr *expr,

tests/unit/destructor.cpp

@@ -106,5 +106,12 @@ int main() {
   assert(order[1] == 2);
   assert(order[2] == 1);
 
+  int before = global;
+  {
+    const S cs;
+    (void)cs;
+  }
+  assert(global == before + 1);
+
   return 0;
 }