An unpleasant surprise while migrating unique_ptrs (see changes in
lib/Object): ErrorOr<int*> was implicitly convertible to
ErrorOr<std::unique_ptr<int>>.
Keep the explicit conversions otherwise it's a pain to convert
ErrorOr<int*> to ErrorOr<std::unique_ptr<int>>.
I'm not sure if there should be more SFINAE on those explicit ctors (I
could check if !is_convertible && is_constructible, but since the ctor
has to be called explicitly I don't think there's any need to disable
them when !is_constructible - they'll just fail anyway. It's the
converting ctors that can create interesting ambiguities without proper
SFINAE). I had to SFINAE the explicit ones because otherwise they'd be
ambiguous with the implicit ones in an explicit context, so far as I
could tell.
The converting assignment operators seemed unnecessary (and similarly
buggy/dangerous) - just rely on the converting ctors to convert to the
right type for assignment instead.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217048
91177308-0d34-0410-b5e6-
96231b3b80d8
}
template <class OtherT>
- ErrorOr(const ErrorOr<OtherT> &Other) {
+ ErrorOr(
+ const ErrorOr<OtherT> &Other,
+ typename std::enable_if<std::is_convertible<OtherT, T>::value>::type * =
+ nullptr) {
copyConstruct(Other);
}
- ErrorOr &operator =(const ErrorOr &Other) {
- copyAssign(Other);
- return *this;
- }
-
template <class OtherT>
- ErrorOr &operator =(const ErrorOr<OtherT> &Other) {
- copyAssign(Other);
- return *this;
+ explicit ErrorOr(
+ const ErrorOr<OtherT> &Other,
+ typename std::enable_if<
+ !std::is_convertible<OtherT, const T &>::value>::type * = nullptr) {
+ copyConstruct(Other);
}
ErrorOr(ErrorOr &&Other) {
}
template <class OtherT>
- ErrorOr(ErrorOr<OtherT> &&Other) {
+ ErrorOr(
+ ErrorOr<OtherT> &&Other,
+ typename std::enable_if<std::is_convertible<OtherT, T>::value>::type * =
+ nullptr) {
moveConstruct(std::move(Other));
}
- ErrorOr &operator =(ErrorOr &&Other) {
- moveAssign(std::move(Other));
+ // This might eventually need SFINAE but it's more complex than is_convertible
+ // & I'm too lazy to write it right now.
+ template <class OtherT>
+ explicit ErrorOr(
+ ErrorOr<OtherT> &&Other,
+ typename std::enable_if<!std::is_convertible<OtherT, T>::value>::type * =
+ nullptr) {
+ moveConstruct(std::move(Other));
+ }
+
+ ErrorOr &operator=(const ErrorOr &Other) {
+ copyAssign(Other);
return *this;
}
- template <class OtherT>
- ErrorOr &operator =(ErrorOr<OtherT> &&Other) {
+ ErrorOr &operator=(ErrorOr &&Other) {
moveAssign(std::move(Other));
return *this;
}
case sys::fs::file_magic::bitcode:
return ObjectFile::createSymbolicFile(Buffer, Type, Context);
case sys::fs::file_magic::macho_universal_binary:
- return MachOUniversalBinary::create(Buffer);
+ return ErrorOr<std::unique_ptr<Binary>>(
+ MachOUniversalBinary::create(Buffer));
case sys::fs::file_magic::unknown:
case sys::fs::file_magic::windows_resource:
// Unrecognized object file format.
switch (Type) {
case sys::fs::file_magic::bitcode:
if (Context)
- return IRObjectFile::createIRObjectFile(Object, *Context);
+ return ErrorOr<std::unique_ptr<SymbolicFile>>(
+ IRObjectFile::createIRObjectFile(Object, *Context));
// Fallthrough
case sys::fs::file_magic::unknown:
case sys::fs::file_magic::archive:
ErrorOr<std::unique_ptr<B> > b1(ErrorOr<std::unique_ptr<D> >(nullptr));
b1 = ErrorOr<std::unique_ptr<D> >(nullptr);
+
+ ErrorOr<std::unique_ptr<int>> b2(ErrorOr<int *>(nullptr));
+ ErrorOr<int *> b3(nullptr);
+ ErrorOr<std::unique_ptr<int>> b4(b3);
}
+
+// ErrorOr<int*> x(nullptr);
+// ErrorOr<std::unique_ptr<int>> y = x; // invalid conversion
+static_assert(
+ !std::is_convertible<const ErrorOr<int *> &,
+ ErrorOr<std::unique_ptr<int>>>::value,
+ "do not invoke explicit ctors in implicit conversion from lvalue");
+
+// ErrorOr<std::unique_ptr<int>> y = ErrorOr<int*>(nullptr); // invalid
+// // conversion
+static_assert(
+ !std::is_convertible<ErrorOr<int *> &&,
+ ErrorOr<std::unique_ptr<int>>>::value,
+ "do not invoke explicit ctors in implicit conversion from rvalue");
+
+// ErrorOr<int*> x(nullptr);
+// ErrorOr<std::unique_ptr<int>> y;
+// y = x; // invalid conversion
+static_assert(!std::is_assignable<ErrorOr<std::unique_ptr<int>>,
+ const ErrorOr<int *> &>::value,
+ "do not invoke explicit ctors in assignment");
+
+// ErrorOr<std::unique_ptr<int>> x;
+// x = ErrorOr<int*>(nullptr); // invalid conversion
+static_assert(!std::is_assignable<ErrorOr<std::unique_ptr<int>>,
+ ErrorOr<int *> &&>::value,
+ "do not invoke explicit ctors in assignment");
} // end anon namespace