[Bug c++/54348] New: wrong error reported for type mismatch in conditional expression : "error: no match for ternary 'operator?:' in 'false ?"
jason.vas.dias at gmail dot com
gcc-bugzilla@gcc.gnu.org
Tue Aug 21 19:28:00 GMT 2012
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54348
Bug #: 54348
Summary: wrong error reported for type mismatch in conditional
expression : "error: no match for ternary 'operator?:'
in 'false ?"
Classification: Unclassified
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: c++
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: jason.vas.dias@gmail.com
Having made the simple mistake of returning an object of a different type
in the '? ( ... )' and ': ( ... )' clauses of a ternary expression ,
I'd expect and it would be helpful if g++ would emit the "C" error
"error: type mismatch in conditional expression" and not
"error: no match for ternary 'operator?:' in 'false ? ..."
This is extremely confusing, as it suggests that the ternary expression
somehow contains an unbalanced number of parentheses or something.
This code triggers the issue:
<code>
#include <string>
#include <list>
using namespace std;
void f()
{
struct strct { string name, items ;};
list <string> myItems;
string myName("");
string as ( ( (&(((strct*)0) -> items))
== (&(((strct*)0) -> name))
) ? myItems
: myName
)
;
}
</code>
Compilation with gcc-4.6.0 & gcc-4.6.3 returns this error:
$ g++ -c gxx_bug.cpp
gxx_bug.cpp: In function 'void f()':
gxx_bug.cpp:12:14: error: no match for ternary 'operator?:' in 'false ? myItems
: myName'
whereas changing 'list <string> myItems' to 'string myItems' allows compilation
to succeed.
Shouldn't g++ be complaining about initializing a string with a list<string>
rather than this cryptic "no match for ternary 'operator?:'" here ?
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