This is related to bug #35167 in:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35167
The attached test case compiles if the preprocessor symbol MAKE_IT_WORK is
defined. Otherwise fails with:
main.cpp: In static member function 'static const X& A::getIt2() [with Q =
X]':
main.cpp:34: instantiated from here
main.cpp:28: error: 'static const X& A::getIt() [with Q = X]' cannot appear
in a constant-expression
This has hit us with 4.4.1 on sparc-sun-solaris2.10, and reproduced in 3.3.1 on
x86_64-linux-gnu.
The referred bug seems to imply that this behaviour is a non-bug, but then I
don't understand why the same explanation (based on the requirement of a
qualified-id for the address-of (&) operator) doesn't apply to the case in
which the class defining the scope (A in the test case when MAKE_IT_WORK is
defined), making it compile fine.
It seems to be a total inconsistency, unless the phrase "in the current
context" of Comment #2 refers specifically to "being compiling code".
In any case, about the referred paragraph in the other bug:
5.19/4
An address constant expression is a pointer to an lvalue designating
an object of static storage duration, a string literal (_lex.string_),
or a function. The pointer shall be created explicitly, using the
unary & operator, or implicitly using a non-type template parameter of
pointer type, or using an expression of array (_conv.array_) or
function (_conv.func_) type.
Creating the pointer implicitly from a function type doesn't explicitly (no pun
intended) require that creation to use an expression with the unary & operator.
I mean, if the function type named by a unqualified-id has no ambiguity (as
it's the case, since the unqualified-id has been declared at the current
template class and not hidden at the current function scope), I don't see the
point in forcing usage of the class qualifier, moreover if the case works ok
for a non-template class.
The thing is this will force us to update some macros to take also the name of
the enclosing class to generate a qualified static member function identifier,
while it's not needed for the other compilers we use.
So, I would request the compiler to be fixed to treat both cases (A being a
template class or not) equally, seeming the most sensible option not requiring
a explicit A::getIt() in the IndirectCaller template parameter for the code to
compile.
--
Summary: unqualified member function reference is or not valid in
constant expression depending on class being a template
or not
Product: gcc
Version: 4.4.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: skandalfo at gmail dot com
GCC build triplet: sparc-sun-solaris2.10
GCC host triplet: sparc-sun-solaris2.10
GCC target triplet: sparc-sun-solaris2.10
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41544
