Re: Debugging a template. I'm stuck!
On Sun, 25 Jan 2015 14:28:05 -0500, DSF <notavalid@address.here>
wrote:
Hello, group!
I have a template class that requires "==" to be overloaded in any
class that uses it. If the class doesn't overload "==", I get the
compile time message "Illegal structure operation" on the "=="
comparison line. This is the error I am receiving. I have gone
through the entire project and every class is never used with the
template class or has "==" overloaded.
If it were a runtime error, I could track down the class involved.
But as it stands, I'm stuck! Any ideas on how to track down this
error?
Problem found and solved! In retrospect, there was an "if it was a
snake, it would've bitten you" clue in my post "Linker errors
involving template". It only became obvious since I found this error.
How did I find it? Through many sleepless nights and blurry-eyed
days. :o)
Until I got the idea about 45 minutes ago to use the command line
version of the compiler and see if it gave a more detailed answer. It
did:
Error e:\library\include\CPP/FAList.h 530: Illegal structure operation
in function FAList<HashIndex>::Find(const HashIndex &) const
Finally! A class to go with FAList! (The same class referred to in
"Linker errors involving template".)
The problem? Almost too embarrassing to relate...almost.
HashIndex has six members:
bool firsthash;
int64 hash;
FString firstname;
FString originalname;
FAList<AlternateNames> altnames;
uint duplicates;
It overloads all of the comparison operators through friends. The
comparisons are all based on the member "hash". For some now unknown
reason, that was what I concentrated on. So I had the following code:
(Only one comparison operator shown for brevity, but they were all
this way...Sigh!)
HashIndex
{
public:
....
friend bool operator == (int64 h1, int64 h2);
};
inline bool operator==(int64 h1, int64 h2)
{return Cmp64To64(h1, h2) == 0);}
It finally occurred to me half an hour ago that you're supposed to
pass const references of the class to operator ==, not the member you
want to test! D'Oh!
So it became:
HashIndex
{
public:
....
friend bool operator==(const HashIndex& h1, const HashIndex& h2);
};
inline bool operator==(const HashIndex& h1, const HashIndex& h2)
{return Cmp64To64(h1.hash, h2.hash) == 0;}
And all is peaceful again in Whoville!
DSF
"'Later' is the beginning of what's not to be."
D.S. Fiscus