fp.bugs 3809 loop variables not seen as initialized?

From: ###@###.### (Norm Morrison)
This does not look like form output to me.


When I try to compile Test.java, I get the following three strange errors (see
compilation attempt below). The first is the strangest, as `x' is clearly the
loop variable, so it must be initialized. Still stranger, if one removes the
`if (false) {}', the class compiles fine!

Obviously I have distilled this code from a much larger chunk of an algorthim.
Also of note, when I tried to compile the whole algorthim, I received a
`statement not reached' error in the middle of a block, such that it said
the equivalent of `b=2;' in the next block was not reachable. If this not
a known problem, I can probably send a code fragment that demonstrates this
bug as well.

   { a=1; b=2; c=3 }

   -Norm

-- compilation attempt of Test.java under Solaris 2.5 and 2.4, Linux 1.2.3 --

sol1:~/tmp% /pkg/java/bin/javac Test.java
Test.java:28: Variable x may not have been initialized.
    for (x=g_rbx; x<g_rbx+g_rbw; x++, dpi+=1) {
                                 ^
Test.java:39: Variable results may not have been initialized.
        results[dpi] = (255 << 24);
        ^
Test.java:39: Variable dpi may not have been initialized.
        results[dpi] = (255 << 24);
                ^


------- Test.java -------
public class Test {
    
   double g_xf, g_yf;
   int g_rbx, g_rby, g_rbw, g_rbh;

public int[] RotatePixelGrid(int[] pic24, int w, int h, int selx, int sely,
                    int selw, int selh, double rotval)
{
  double a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11;
  int ppi,dpi;
  int i, j, x, y, ox,oy, ox1,oy1;
  int i1,i2,i3,i4,i5,i6,i7,i8;
  int i9, i10;

  if (false) return null;

  g_rbx=0;
  g_rby=0;
  g_rbw=100;
  g_rbh=100;

  int[] results = new int [g_rbw * g_rbh];

  for (y=g_rby; y<g_rby+g_rbh; y++) {

    dpi = (y * w + g_rbx) ;

    for (x=g_rbx; x<g_rbx+g_rbw; x++, dpi+=1) {

      if (true) {

        int p0r,p0g,p0b, p1r,p1g,p1b, p2r,p2g,p2b, p3r,p3g,p3b;
        int rv,gv,bv;
        double rd,gd,bd, p0wgt, p1wgt, p2wgt, p3wgt;

        if (false) {
        }

        results[dpi] = (255 << 24);
       }
    }
  }

  return results;
}

}