Write the shortest program that generates the most compiler warnings and errors

Question

The challenge:

Write a very short program that, when compiled, creates the most amount of compiler warnings and errors. It can be written in any programming language.

Scoring:

The score is determined by this equation: errors_and_warnings_length/code_length. Highest score wins.

Example:

The C# program class is 5 chars long and generates 3 warnings, which is a score of (1/5)*3 = 0.6.

EDIT:

Because of some confusion, programs have to be at least 1 char long. Otherwise it would get a score of infinity.

Answer 1

GCC, score 2²⁰⁰ / 36 ≈ 4.5 × 10⁵⁸

#include __FILE__
#include __FILE__

I have not actually finished compiling this code, but based on testing and simple mathematics, it should produce a total of 2²⁰⁰ #include nested too deeply errors.

Of course, the program is trivially extensible. Adding a third line brings the score up to 3²⁰⁰ / 54 ≈ 4.9 × 10⁹³. Four lines give 4²⁰⁰ / 72 ≈ 3.6 × 10¹¹⁸, and so on.

Answer 2

C, 0 characters - Score=(1/0)*1=Infinity

generates 1 error:

/usr/lib/gcc/i686-pc-linux-gnu/4.7.0/../../../crt1.o: In function `_start':
(.text+0x18): undefined reference to `main'
collect2: error: ld returned 1 exit status

Note: http://ideone.com/xdoJyA

Answer 3

GCC, score 5586.6 (and more if needed)

179 chars, 1000003 warnings/errors (using -Wall)

#define E a,a,a,a,a,a,a,a,a,a
#define D E,E,E,E,E,E,E,E,E,E
#define C D,D,D,D,D,D,D,D,D,D
#define B C,C,C,C,C,C,C,C,C,C
#define A B,B,B,B,B,B,B,B,B,B
_(){A,A,A,A,A,A,A,A,A,A}

This can be extended arbitrarily, of course. For example, using 10 #defines instead of 5 and a length of 20 "calls" instead of 10 would lead to a score of about (20**10)/(179*4) = 14301675977.65 (and would take quite some time to run ;)

Answer 4

GCC twice, 86

22 chars, 1898 errors+warnings on my system.
I'm sure this approach can be much improved, by choosing longer files with shorter names.

#include</usr/bin/gcc>

Answer 5

HQ9++, 1 (limit of (n+29)/n)

The following emits the warning Warning: this is not a quine for each Q in the code.

QQQQQ...Q
Warning: this is not a quine

Small is good, right? Hmm...

Answer 6

C, .727

11 chars, 5 errors, 3 warnings, (1/11)*8 = .727273

m(;){@,x}2

cc -g -Wall    er.c   -o er
er.c:1: error: expected declaration specifiers or '...' before ';' token
er.c:1: warning: return type defaults to 'int'
er.c: In function 'm':
er.c:1: error: stray '@' in program
er.c:1: error: expected expression before ',' token
er.c:1: error: 'x' undeclared (first use in this function)
er.c:1: error: (Each undeclared identifier is reported only once
er.c:1: error: for each function it appears in.)
er.c:1: warning: left-hand operand of comma expression has no effect
er.c:1: warning: control reaches end of non-void function
er.c: At top level:
er.c:1: error: expected identifier or '(' before numeric constant

Answer 7

NASM, score 63/40 * 2^32 ≈ 2.905 * 10^19

%rep 1<<32
%rep 1<<32
!
%endrep
%endrep

Will output c.asm:3: error: label or instruction expected at start of line 2^64 times. Again this is easily extensible to much bigger outputs.

Answer 8

C++98 (211 bytes) g++-5 (Ubuntu 5.2.1-23ubuntu1~12.04) 5.2.1 0151031

I wanted to see how well I could do in C++ without using the preprocessor at all. This program produces 2,139,390,572 bytes of output, most of which is a single error message.

template<int i,class S,class T>struct R{typedef R<i,typename R<i-1,S,S>::D,typename R<i-1,S,S>::D>D;};template<class S,class T>struct R<0,S,T>{typedef S D;};void f(){R<27,float,R<24,int*const*,int>::D>::D&E=4;}

me@Basement:~/src/junk$ ls -l a.C
-rw-rw-r-- 1 me me 211 Apr 27 21:44 a.C
me@Basement:~/src/junk$ g++-5 a.C -fmax-errors=1 2>a.C.errors.txt
me@Basement:~/src/junk$ ls -l a.C.errors.txt 
-rw-rw-r-- 1 me me 2139390572 Apr 27 22:01 a.C.errors.txt

Ungolfed:

template <int i, class S, class T>
struct R {
    typedef R<i, typename R<i-1,S,S>::D, typename R<i-1,S,S>::D> D;
};
template <class S, class T>
struct R<0, S, T> {
    typedef S D;
};
void f() {
    R<27, float, R<24, int*const*, int>::D>::D &E = 4;
}

This program works by defining a recursive struct template R which holds a typedef D containing two copies of R. This results in an type name which grows exponentially, which is printed out in full in the error message. Unfortunately, g++ seems to choke while attempting to print an error message longer than (1<<31) bytes. 2,139,390,572 bytes was the closest I could get to the limit without going over. I'm curious if anyone can adjust the recursion limits and parameter types 27, float, 24, int*const* to get closer to the limit (or find a compiler which can print an even longer error message).

Excerpts from the error message:

a.C: In function ‘void f()’:
a.C:1:208:  error:  invalid  initialization  of non-const reference of type
‘R<27, float, R<24, R<23, R<22, R<21, R<20, R<19, R<18, R<17, R<16, R<15,
R<14,  R<13, R<12, R<11, R<10, R<9, R<8, R<7, R<6, R<5, R<4, R<3, R<2, R<1,
int* const*, int* const*>, R<1, int* const*, int* const*> >, R<2, R<1, int*
const*,  int*  const*>,  R<1, int* const*, int* const*> > >, R<3, R<2, R<1,
int* const*, int* const*>, R<1, int* const*, int* const*> >, R<2, R<1, int*
const*,  int* const*>, R<1, int* const*, int* const*> > > >, R<4, R<3, R<2,
R<1, int* const*, int* const*>, R<1,
...
int*  const*,  int*  const*>  > > > > > > > > > > > > > > > > > > > > > > >
>::D& {aka R<27, R<26, R<25, R<24, R<23,  R<22,  R<21,  R<20,  R<19,  R<18,
R<17,  R<16,  R<15,  R<14, R<13, R<12, R<11, R<10, R<9, R<8, R<7, R<6, R<5,
R<4, R<3, R<2, R<1, float, float>, R<1, float, float> >, R<2,  R<1,  float,
float>,  R<1,  float, float> > >, R<3, R<2, R<1, float, float>, R<1, float,
float> >, R<2, R<1, float, float>, R<1, float, float> > > >, R<4, 
...
, R<1, float, float>, R<1, float, float> > >, R<3, R<2, R<1, float, float>,
R<1, float, float> >, R<2, R<1, float, float>, R<1, float, float> > > > > >
>  >  >  >  >  >  > > > > > > > > > > > > > > >&}’ from an rvalue of type
‘int’
    template<int    i,class   S,class   T>struct   R{typedef   R<i,typename
R<i-1,S,S>::D,typename  R<i-1,S,S>::D>D;};template<class  S,class  T>struct
R<0,S,T>{typedef                         S                         D;};void
f(){R<27,float,R<24,int*const*,int>::D>::D&E=4;}


                                                        ^
compilation terminated due to -fmax-errors=1.

2,139,390,572 bytes / 211 bytes = 10,139,291.8

Answer 9

SmileBASIC, 1/1 = 1

A

Generates the error Syntax Error in 0:1