Improve our handling of user-defined conversions as part of overload
resolution. There are two sources of problems involving user-defined
conversions that this change eliminates, along with providing simpler
interfaces for checking implicit conversions:
- It eliminates a case of infinite recursion found in Boost.
- It eliminates the search for the constructor needed to copy a temporary
generated by an implicit conversion from overload
resolution. Overload resolution assumes that, if it gets a value
of the parameter's class type (or a derived class thereof), there
is a way to copy if... even if there isn't. We now model this
properly.
llvm-svn: 101680
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 76de072..4986fcb 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -2531,8 +2531,7 @@
ImplicitConversionSequence ICS
= S.TryImplicitConversion(Initializer, cv1T1,
/*SuppressUserConversions=*/false, AllowExplicit,
- /*FIXME:InOverloadResolution=*/false,
- /*UserCast=*/Kind.isExplicitCast());
+ /*FIXME:InOverloadResolution=*/false);
if (ICS.isBad()) {
// FIXME: Use the conversion function set stored in ICS to turn
@@ -2867,10 +2866,21 @@
// Add the user-defined conversion step that calls the conversion function.
QualType ConvType = Function->getResultType().getNonReferenceType();
- Sequence.AddUserConversionStep(Function, Best->FoundDecl, ConvType);
+ if (ConvType->getAs<RecordType>()) {
+ // If we're converting to a class type, there may be an copy if
+ // the resulting temporary object (possible to create an object of
+ // a base class type). That copy is not a separate conversion, so
+ // we just make a note of the actual destination type (possibly a
+ // base class of the type returned by the conversion function) and
+ // let the user-defined conversion step handle the conversion.
+ Sequence.AddUserConversionStep(Function, Best->FoundDecl, DestType);
+ return;
+ }
- // If the conversion following the call to the conversion function is
- // interesting, add it as a separate step.
+ Sequence.AddUserConversionStep(Function, Best->FoundDecl, ConvType);
+
+ // If the conversion following the call to the conversion function
+ // is interesting, add it as a separate step.
if (Best->FinalConversion.First || Best->FinalConversion.Second ||
Best->FinalConversion.Third) {
ImplicitConversionSequence ICS;
@@ -2891,8 +2901,7 @@
= S.TryImplicitConversion(Initializer, Entity.getType(),
/*SuppressUserConversions=*/true,
/*AllowExplicit=*/false,
- /*FIXME:InOverloadResolution=*/false,
- /*UserCast=*/Kind.isExplicitCast());
+ /*InOverloadResolution=*/false);
if (ICS.isBad()) {
Sequence.SetFailed(InitializationSequence::FK_ConversionFailed);
@@ -3103,10 +3112,11 @@
const InitializedEntity &Entity,
const InitializationKind &Kind,
Sema::OwningExprResult CurInit) {
- // Determine which class type we're copying.
+ // Determine which class type we're copying to.
Expr *CurInitExpr = (Expr *)CurInit.get();
CXXRecordDecl *Class = 0;
- if (const RecordType *Record = CurInitExpr->getType()->getAs<RecordType>())
+ if (const RecordType *Record
+ = Entity.getType().getNonReferenceType()->getAs<RecordType>())
Class = cast<CXXRecordDecl>(Record->getDecl());
if (!Class)
return move(CurInit);
@@ -3203,16 +3213,26 @@
return S.ExprError();
}
- S.CheckConstructorAccess(Loc,
- cast<CXXConstructorDecl>(Best->Function),
+ CXXConstructorDecl *Constructor = cast<CXXConstructorDecl>(Best->Function);
+ ASTOwningVector<&ActionBase::DeleteExpr> ConstructorArgs(S);
+ CurInit.release(); // Ownership transferred into MultiExprArg, below.
+
+ // Determine the arguments required to actually perform the
+ // constructor call (we might have derived-to-base conversions).
+ if (S.CompleteConstructorCall(Constructor,
+ Sema::MultiExprArg(S,
+ (void **)&CurInitExpr,
+ 1),
+ Loc, ConstructorArgs))
+ return S.ExprError();
+
+ S.CheckConstructorAccess(Loc, Constructor,
Best->FoundDecl.getAccess());
- CurInit.release();
return S.BuildCXXConstructExpr(Loc, Entity.getType().getNonReferenceType(),
- cast<CXXConstructorDecl>(Best->Function),
+ Constructor,
Elidable,
- Sema::MultiExprArg(S,
- (void**)&CurInitExpr, 1));
+ move_arg(ConstructorArgs));
}
Action::OwningExprResult