Question

Starting to use the googletest ASSERT_THROW clause, it seems that ‘sometimes’ the base type of the thrown exception is handled. I reduced the relevant code section to this:

// myexception.h
struct myexception : public std::logic_error {
   myexception(const char* what):std::logic_error(what){}
};
void throwMy();

// myexception.cpp
void throwMy(){ throw myexception(NULL); }

This is my test code:

//
void localThrowMy(){ throw myexception(""); }

// test code, based upon the ASSERT_THROW macro
try {
  throwMy();        // outputs "logic_error"
  //localThrowMy(); // would output "what I expected"
}
catch( myexception & ) { cout << "what I expected"; }
catch( std::logic_error & ) { cout << "logic_error"; } // my addition
catch(...) { cout << "mmmh."; }

The strange thing is: if I declare the throwMy function in the same compilation unit as the test code, “what I expected” is output. If it’s in another unit, the test outputs “logic_error.”.

• g++ –version: (Debian 4.4.5-8) 4.4.5
• ld –version: (GNU Binutils for Debian) 2.20.1-system.20100303

Is this code correct? Could the linker be in error here?

Answer 1

Mea Culpa.

Once again, select wasn’t broken.

The logic_error was thrown within the std::string constructor: “basic_string::_S_construct NULL not valid”. I falsely deduced that there was a problem with the inheritance; it was a plain case of pebkac.

Actually, I didn’t know. But you can’t pass a null pointer into the std::string constructor.