https://bugs.llvm.org/show_bug.cgi?id=41705
Bug ID: 41705
Summary: exception specification does not match error for extra
parentheses (Derived from libstdc++ trunk)
Product: clang
Version: unspecified
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: C++11
Assignee: unassignedclangb...@nondot.org
Reporter: peter.sm...@linaro.org
CC: blitzrak...@gmail.com, dgre...@apple.com,
erik.pilking...@gmail.com, llvm-bugs@lists.llvm.org,
richard-l...@metafoo.co.uk
I've derived this from trunk libstdc++ which as of r270650 with commit Use
_GLIBCXX_NOEXCEPT_IF for std::swap is now failing to compile with clang due to
a
error: exception specification in declaration does not match previous
declaration
clash with type_traits.
It looks like the error is caused by an extra set of parentheses introduced by
the _GLIBCXX_NOEXCEPT_IF macro. I can reproduce with the stripped down example:
cat t.cpp
template <class T> struct Foo {
enum { value = 0 };
};
template <> struct Foo<bool> {
enum { value = 1 };
};
template <class T>
void f1(T a) noexcept(Foo<T>::value);
template <class T>
void f1(T a) noexcept((Foo<T>::value)) {}
clang -c t.cpp
t.cpp:14:6: error: exception specification in declaration does not match
previous declaration
void f1(T a) noexcept((Foo<T>::value)) {}
^
t.cpp:11:6: note: previous declaration is here
void f1(T a) noexcept(Foo<T>::value);
^
The error doesn't seem to be provoked if I just use noexcept(true) and
noexcept((true)).
My knowledge of the C++ standard isn't good enough to know whether the extra
parentheses allow the compiler to error in this case as the expressions aren't
identical?
I'm intending to raise a PR on libstdc++ to see if I can get the type_traits to
precisely match move.h.
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