Unverified Commit 273ceb13 authored by cor3ntin's avatar cor3ntin Committed by GitHub
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[Clang] Diagnose defaulted assignment operator with incompatible object parameter (#70176) 

Per https://eel.is/c++draft/dcl.fct.def.default#2.2, the explicit object
parameter of a defaulted special member function must be of the same
type as the one of an equivalent implicitly defaulted function, ignoring
references.

Fixes #69233
parent 6a62707c

clang/include/clang/Basic/DiagnosticSemaKinds.td

+3 −0
Original line number Diff line number Diff line
@@ -9483,6 +9483,9 @@ def err_defaulted_special_member_return_type : Error< 
def err_defaulted_special_member_quals : Error<

  "an explicitly-defaulted %select{copy|move}0 assignment operator may not "

  "have 'const'%select{, 'constexpr'|}1 or 'volatile' qualifiers">;

def err_defaulted_special_member_explicit_object_mismatch : Error<

  "the type of the explicit object parameter of an explicitly-defaulted "

  "%select{copy|move}0 assignment operator should match the type of the class %1">;

def err_defaulted_special_member_volatile_param : Error<

  "the parameter for an explicitly-defaulted %sub{select_special_member_kind}0 "

  "may not be volatile">;

clang/lib/Sema/SemaDeclCXX.cpp

+18 −0
Original line number Diff line number Diff line
@@ -7748,6 +7748,24 @@ bool Sema::CheckExplicitlyDefaultedSpecialMember(CXXMethodDecl *MD, 
        HadError = true;

      }

    }

    // [C++23][dcl.fct.def.default]/p2.2

    // if F2 has an implicit object parameter of type “reference to C”,

    // F1 may be an explicit object member function whose explicit object

    // parameter is of (possibly different) type “reference to C”,

    // in which case the type of F1 would differ from the type of F2

    // in that the type of F1 has an additional parameter;

    if (!Context.hasSameType(

            ThisType.getNonReferenceType().getUnqualifiedType(),

            Context.getRecordType(RD))) {

      if (DeleteOnTypeMismatch)

        ShouldDeleteForTypeMismatch = true;

      else {

        Diag(MD->getLocation(),

             diag::err_defaulted_special_member_explicit_object_mismatch)

            << (CSM == CXXMoveAssignment) << RD << MD->getSourceRange();

        HadError = true;

      }

    }

  }















  // Check for parameter type matching.

































clang/test/SemaCXX/cxx2b-deducing-this.cpp



+41
−0






























Original line number
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@@ -585,3 +585,44 @@ class Server : public Thing {













    S name_;















};















}



























namespace GH69233 {













struct Base {};













struct S : Base {













    int j;













    S& operator=(this Base& self, const S&) = default;













    // expected-warning@-1 {{explicitly defaulted copy assignment operator is implicitly deleted}}













    // expected-note@-2 {{function is implicitly deleted because its declared type does not match the type of an implicit copy assignment operator}}













    // expected-note@-3 {{explicitly defaulted function was implicitly deleted here}}













};



























struct S2 {













    S2& operator=(this int&& self, const S2&);













    S2& operator=(this int&& self, S2&&);













    operator int();













};



























S2& S2::operator=(this int&& self, const S2&) = default;













// expected-error@-1 {{the type of the explicit object parameter of an explicitly-defaulted copy assignment operator should match the type of the class 'S2'}}



























S2& S2::operator=(this int&& self, S2&&) = default;













// expected-error@-1 {{the type of the explicit object parameter of an explicitly-defaulted move assignment operator should match the type of the class 'S2'}}



























struct Move {













    Move& operator=(this int&, Move&&) = default;













    // expected-warning@-1 {{explicitly defaulted move assignment operator is implicitly deleted}}













    // expected-note@-2 {{function is implicitly deleted because its declared type does not match the type of an implicit move assignment operator}}













    // expected-note@-3 {{copy assignment operator is implicitly deleted because 'Move' has a user-declared move assignment operator}}













};



























void test() {













    S s;













    s = s; // expected-error {{object of type 'S' cannot be assigned because its copy assignment operator is implicitly deleted}}













    S2 s2;













    s2 = s2;



























    Move m;













    m = Move{}; // expected-error {{object of type 'Move' cannot be assigned because its copy assignment operator is implicitly deleted}}













}



























}