When enable_if disables a particular overload resolution candidate,
rummage through the enable_if condition to find the specific condition
that caused the failure. For example, if we have something like:
template<
typename Iter,
typename = std::enable_if_t<Random_access_iterator<Iter> &&
Comparable<Iterator_value_type<Iter>>>>
void mysort(Iter first, Iter last) {}
and we call "mysort" with "std::list<int>" iterators, we'll get a
diagnostic saying that the "Random_access_iterator<Iter>" requirement
failed. If we call "mysort" with
"std::vector<something_not_comparable>", we'll get a diagnostic saying
that the "Comparable<...>" requirement failed.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@307196 91177308-0d34-0410-b5e6-96231b3b80d8
This is the 5th Lit test patch.
Expanded expected diagnostics to vary by C++ dialect.
Expanded RUN line to: default, C++98/03 and C++11.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@255196 91177308-0d34-0410-b5e6-96231b3b80d8
substitution failed, report that as a substitution failure rather than
pretending that there was no default argument.
The test cases in PR15673 have exposed some pre-existing poor diagnostics here.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@185604 91177308-0d34-0410-b5e6-96231b3b80d8
When two template decls with the same name are used in this diagnostic,
force them to print their qualified names. This changes the bad message of:
candidate template ignored: could not match 'array' against 'array'
to the better message of:
candidate template ignored: could not match 'NS2::array' against 'NS1::array'
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179056 91177308-0d34-0410-b5e6-96231b3b80d8
candidate template ignored: substitution failed [with T = int]: no type named 'type' in 'std::enable_if<false, void>'
Instead, just say:
candidate template ignored: disabled by 'enable_if' [with T = int]
... and point at the enable_if condition which (we assume) failed.
This is applied to all cases where the user writes 'typename enable_if<...>::type' (optionally prefixed with a nested name specifier), and 'enable_if<...>' names a complete class type which does not have a member named 'type', and this results in a candidate function being ignored in a SFINAE context. Thus it catches 'std::enable_if', 'std::__1::enable_if', 'boost::enable_if' and 'llvm::enable_if'.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156463 91177308-0d34-0410-b5e6-96231b3b80d8
overload candidate, and include its message in any subsequent 'candidate not
viable due to substitution failure' note we may produce.
To keep the note small (since the 'overload resolution failed' diagnostics are
often already very verbose), the text of the SFINAE diagnostic is included as
part of the text of the note, and any notes which were attached to it are
discarded.
There happened to be spare space in OverloadCandidate into which a
PartialDiagnosticAt could be squeezed, and this patch goes to lengths to avoid
unnecessary PartialDiagnostic copies, resulting in no slowdown that I could
measure. (Removal in passing of some PartialDiagnostic copies has resulted in a
slightly smaller clang binary overall.) Even on a torture test, I was unable to
measure a memory increase of above 0.2%.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156297 91177308-0d34-0410-b5e6-96231b3b80d8
conflicting deduced template argument values, give a more specific
reason along with those values, e.g.,
test/SemaTemplate/overload-candidates.cpp:4:10: note: candidate template
ignored: deduced conflicting types for parameter 'T' ('int' vs. 'long')
const T& min(const T&, const T&);
^
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@103339 91177308-0d34-0410-b5e6-96231b3b80d8
Douglas Gregor