(Re-submission of D39937 with fixed tests.)
Adjust wording for const-qualification mismatch to be a little more clear.
Also add another diagnostic for a ref qualifier mismatch, which previously produced a useless error (this error path is simply very old; see rL119336):
Before:
error: cannot initialize object parameter of type 'X0' with an expression of type 'X0'
After:
error: 'this' argument to member function 'rvalue' is an lvalue, but function has rvalue ref-qualifier
Reviewers: aaron.ballman
Reviewed By: aaron.ballman
Subscribers: lebedev.ri, cfe-commits
Differential Revision: https://reviews.llvm.org/D41646
llvm-svn: 321609
Summary:
Adjust wording for const-qualification mismatch to be a little more clear.
Also add another diagnostic for a ref qualifier mismatch, which previously produced a useless error (this error path is simply very old; see rL119336):
Before:
error: cannot initialize object parameter of type 'X0' with an expression of type 'X0'
After:
error: 'this' argument to member function 'rvalue' is an lvalue, but function has rvalue ref-qualifier
Reviewers: rsmith, aaron.ballman
Reviewed By: aaron.ballman
Subscribers: lebedev.ri, aaron.ballman, cfe-commits
Differential Revision: https://reviews.llvm.org/D39937
llvm-svn: 321592
In order to identify the copy deduction candidate, I considered two approaches:
- attempt to determine whether an implicit guide is a copy deduction candidate by checking certain properties of its subsituted parameter during overload-resolution.
- using one of the many bits (WillHaveBody) from FunctionDecl (that CXXDeductionGuideDecl inherits from) that are otherwise irrelevant for deduction guides
After some brittle gymnastics w the first strategy, I settled on the second, although to avoid confusion and to give that bit a better name, i turned it into a member of an anonymous union.
Given this identification 'bit', the tweak to overload resolution was a simple reordering of the deduction guide checks (in SemaOverload.cpp::isBetterOverloadCandidate), in-line with Jason Merrill's p0620r0 drafting which made it into the working paper. Concordant with that, I made sure the copy deduction candidate is always added.
References:
See https://bugs.llvm.org/show_bug.cgi?id=34970
See http://wg21.link/p0620r0
llvm-svn: 316292
such guides below explicit ones, and ensure that references to the class's
template parameters are not treated as forwarding references.
We make a few tweaks to the wording in the current standard:
1) The constructor parameter list is copied faithfully to the deduction guide,
without losing default arguments or a varargs ellipsis (which the standard
wording loses by omission).
2) If the class template declares no constructors, we add a T() -> T<...> guide
(which will only ever work if T has default arguments for all non-pack
template parameters).
3) If the class template declares nothing that looks like a copy or move
constructor, we add a T(T<...>) -> T<...> guide.
#2 and #3 follow from the "pretend we had a class type with these constructors"
philosophy for deduction guides.
llvm-svn: 295007
for converting an empty list to a scalar, be sure to initialize
the source and destination types so that comparison of conversion
sequences will work in case there are multiple viable candidates.
llvm-svn: 153993
explicit conversion functions to initialize the argument to a
copy/move constructor that itself is the subject of direct
initialization. Since we don't have that much context in overload
resolution, we end up threading more flags :(.
Fixes <rdar://problem/10903741> / PR10456.
llvm-svn: 151409
reference binding is for the implicit object parameter of a member
function with a ref-qualifier. My previous comment, that we didn't
need to track this explicitly, was wrong: we do in fact get
rvalue-references-prefer-rvalues overloading with ref-qualifiers.
llvm-svn: 124313
for reference binding (C++ [over.rank.ics]p3b1sb4), so that we prefer
the binding of an lvalue reference to a function lvalue over the
binding of an rvalue reference. This change resolves the ambiguity
with std::forward and lvalue references to function types in a way
that seems consistent with the original rvalue references proposal.
My proposed wording for this change is shown in
isBetterReferenceBindingKind(); we'll try to get this change adopted
in the C++0x working paper as well.
llvm-svn: 124236
(C++0x [over.ics.rank]p3) when one binding is an lvalue reference and
the other is an rvalue reference that binds to an rvalue. In
particular, we were using the predict "is an rvalue reference" rather
than "is an rvalue reference that binds to an rvalue", which was
incorrect in the one case where an rvalue reference can bind to an
lvalue: function references.
This particular issue cropped up with std::forward, where Clang was
picking an std::forward overload while forwarding an (lvalue)
reference to a function. However (and unfortunately!), the right
answer for this code is that the call to std::forward is
ambiguous. Clang now gets that right, but we need to revisit the
std::forward implementation in libc++.
llvm-svn: 124216
particular, we only add the implement object parameter type if only
one of the function templates is a non-static member function
template.
Moreover, since this DR differs from existing practice in C++98/03,
this commit implements the existing practice (which ignores the
first parameter of the function template that is not the non-static
member function template) in C++98/03 mode.
llvm-svn: 119145
from a conversion function template specialization to one of exact
match rank. We only know how to test this in C++0x with default
function template arguments, but it's also in the C++03 spec. Fixes
PR6285.
llvm-svn: 101089
- This is designed to make it obvious that %clang_cc1 is a "test variable"
which is substituted. It is '%clang_cc1' instead of '%clang -cc1' because it
can be useful to redefine what gets run as 'clang -cc1' (for example, to set
a default target).
llvm-svn: 91446
Jacob Bandes-Storch