Same functions with different return types in C++

Question

Normally the following two functions would be considered the same:
int getdata ( char *s, int i )
long getdata ( char *s, int i )
Every other compiler we use would resolve both of these to the same function. In fact, it is not valid C++ code otherwise.
We include some 3rd party source in our build which sometimes messes with our typedefs causing this to happen. We have accounted for all of the function input types but never had a problem with the return types. I just installed Sun ONE Studio 8, Compiler Collection and it is generating two symbols in our libraries every time this occurs.
Is there a compiler flag I can use to stop it from doing this? I've got over 100 unresolved symbols and I'd rather not go and fix all of them if there is an easier way.

Answer 1

Normally the following two functions would be
considered the same:
int getdata ( char *s, int i )
long getdata ( char *s, int i )Not at all. Types int and long are different types, even if they are implemented the same way.
Reference: C++ Standard, section 3.9.1 paragraph 10.
For example, you can define two functions
void foo(int);
void foo(long);
and they are distinct functions. The function that gets called depends on function overload resolution at the point of the call.
Overloaded functions must differ in the number or the type of at least one parameter. They cannot differ only in the return type. A program that declares or defines two functions that differ only in their return types is invalid and has undefined behavior. Reference: C++ Standard section 13.1, paragraph 2.
The usual way to implement overloaded functions is to encode the scope and the parameter types, and maybe the return type, and attach the encoding to the function name. This technique is known as "name mangling". The compiler generates the same mangled name for the declaration and definition of a given function, and different mangled names for different functions. The linker matches up the mangled names, and can tell you when no definition matches a reference.
Some compilers choose not to include the return type in the mangled name of a function. In that case, the declaration
int foo(char*);
will match the definition
long foo(char*) { ... }
But it will also match the definitions
myClass foo(char*) { ... }
double foo(char*) { ... }
You are unlikely to get good results from such a mismatch. For that reason, and because a pointer-to-function must encode the function return type, Sun C++ always encodes the function return type in the mangled name. (That is, we simplify things by not using different encodings for the same function type.)
If you built your code for a 64-bit platform, it would presumably link using your other compilers, but would fail in mysterious ways at run time. With the Sun compiler, you can't get into that mess.
To make your program valid, you will have to ensure your function declarations match their definitions.