CVS head (gcc-3.4), problem with new parser?

[Andrew Pollard <andrewp at andypo dot net>]

Hi All,

 I've been trying out the new C++ parser on some of our source code
and it threw up a problem that I'm not sure is standard mandated or
not...

Should the following code compile?

a.cxx:
-------------------------
struct A {
       int a, b;
       A(int i, int j) : a(i), b(j) {}
       void foo() {};
};

int
main()
{
	int a = 2;
	A(a, a).foo();

	return (0);
}
--------------------------

% g++34 -v
Reading specs from /usr/local/gcc-3.4-20021231-i686-pc-linux-gnu/lib/gcc-lib/i686-pc-linux-gnu/3.4/specs
Configured with:
Thread model: posix
gcc version 3.4 20021230 (experimental)

% g++34 a.cxx
a.cxx: In function `int main()':
a.cxx:11: error: conflicting types for `A a'
a.cxx:10: error: previous declaration as `int a'
a.cxx:11: error: expected init-declarator
a.cxx:11: error: expected `,' or `;'

It appears to think that I want to declare a new variable 'a' with
type 'A', whereas I want to construct a temporary A(2,2) and invoke
foo() on it. [*]

Previous versions of g++ work (3.0-cvs, 3.2-cvs, 3.3-cvs) and so do
icc70 and VC++6.0

[ (*)

As an aside, I didn't realise until investigating this that things like

    int(a);

actually declare variables.... thus with the following struct

    struct A {
        int a;
        A(int _a = 0) : a(_a) {}
    };

Then

    A(a);

declares a variable called 'a' of type 'A' with value 0 (assuming that
there is no 'a' in scope)

    A(a);

causes a 'redefinition' or 'shadowing' error if there is an 'a' in scope, and

    A(1);

creates and destroys a temporary variable of type 'A' with value 1

which is all rather confusing... Is this what the standard indicates?

In the case that I provided, I think the parser is getting confused
since there are two arguments to A(a, a), so this can never be thought
of as declaring a new variable of type A, it must be a temporary, but
the parser isn't noticing this....

]

Comments?

Andrew.
--
 Andrew Pollard, Brooks-PRI Automation  | home: andrew@andypo.net
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