problem in compiling Bench++ analysis program

problem in compiling Bench++ analysis program

[Brad Lucier]

When compiling the program a000096.cpp with the 19981019 snapshot
of egcs, I get the following errors:

peano-53% make a000096
/opt/egcs-19981019/bin/g++ -o a000096 a000096.cpp  ;	\
E=$?; if [ $E -ne 0 ]; then echo a000096: error >>bench++.err; fi;	exit $E
a000096.cpp: In method `char * test_keeper::host()':
a000096.cpp:88: return to `char *' from `const char *' discards const
a000096.cpp: In method `char * test_keeper::compiler()':
a000096.cpp:91: return to `char *' from `const char *' discards const
a000096.cpp: In method `char * test_keeper::options()':
a000096.cpp:94: return to `char *' from `const char *' discards const
make: *** [a000096] Error 1

The offending code is

class test_keeper {
public:
	friend class test_keeper_iterator;
	test_keeper() {			// constructor
		head = tail = (test_keeper_impl *)0;
		h = (char *)0;
	}
	void insert_host(char *host) {
		h = new char[strlen(host)+1];
		strcpy(h, host);
	}
	void insert_compiler(char *compiler) {
		c = new char[strlen(compiler)+1];
		strcpy(c, compiler);
	}
	void insert_options(char *options) {
		o = new char[strlen(options)+1];
		strcpy(o, options);
	}
	void insert(test_description d) {
		test_keeper_impl *i = new test_keeper_impl;
		i->next = (test_keeper_impl *) 0;
		i->desc.test_name = new char[strlen(d.test_name)+1];
		strcpy(i->desc.test_name, d.test_name);
		i->desc.seconds = d.seconds;
		if(tail) {
			tail->next = i;
			tail = i;
		} else {
			head = tail = i;
		}
	}

	char *host(void) {
		return h ? h : "";  // problem here
	}
	char *compiler(void) {
		return c ? c : "";  // here
	}
	char *options(void) {
		return o ? o : "";  // and here
	}
	double lookup(char *test_name) {
		for(test_keeper_impl *i = head; i; i = i->next) {
			if(strcasecmp(test_name, i->desc.test_name) == 0) {
				return i->desc.seconds;
			}
		}
		return -1.0;
	}
private:
	class test_keeper_impl {
	public:
		test_keeper_impl *next;
		test_description desc;
	} *head, *tail;
	char *h, *c, *o;
};

This compiled fine with egcs-1.0.3a.

I don't know whether the code is right or whether the compiler is right,
I'm just passing this on to you.

Brad Lucier    lucier@math.purdue.edu

Re: problem in compiling Bench++ analysis program

[Joe Buck]

> When compiling the program a000096.cpp with the 19981019 snapshot
> of egcs, I get the following errors:

That's because Bench++ has invalid C++ code (invalid thanks to recent
changes).  Literal strings are now of type const char*.  This is also
likely to break many Tcl programs, thanks to Tcl's annoying lack of
const correctness.

> 	char *host(void) {
> 		return h ? h : "";  // problem here
> 	}
> 	char *compiler(void) {
> 		return c ? c : "";  // here
> 	}
> 	char *options(void) {
> 		return o ? o : "";  // and here
> 	}

You could write

	return o ? o : (char*)"";

to fix the problem.  It appears that the author of Bench++ was using it
mainly to compare Sun C++ with g++ 2.7.2.x and never tested it with a 
more rigorous compiler.