26 Jan 2008

Bug: Glew and Mesa Glut

There is a macro definition clash between Glew's glew.h and Mesa Glut's glut.h on Unix. Any program using Glew fails to compile. The problem does NOT occur with other Glut implementations (freeglut, Kilgard glut).

I am using Slackware Linux 12.0, Mesa 6.5.2 and Glew 1.5.0. However, the problem is present in all recent versions of Glew, including svn, and all recent versions of Mesa Glut, including git.

Other people have had the same problem:

I first encountered this problem when trying to compile enblend, but even the following trivial test program is sufficient to demonstrate the problem (thanks Philippe Després). It doesn't compile.

#include <GL/glew.h>
#include <GL/glut.h>
int main()
return 0;
  • First, the application #includes glew.h
  • glew.h #defines GLAPIENTRY -- for Unix this is line 209 of glew.h, and GLAPIENTRY is defined to be empty
  • Then glew.h #includes glu.h at line 1137
  • Then glu.h #includes gl.h which redefines GLAPIENTRY (consistently with glew.h)
  • Then glew.h uses GLAPIENTRY (successfully), and eventually #undefs GLAPIENTRY at line 10767
  • Then the application #includes glut.h
  • Then glut.h #includes glu.h at line 11
  • But glu.h has already been included, so glu.h does nothing (it checks __glu_h__ in the usual way)
  • Then glut.h uses GLAPIENTRY at line 196
    In other words, glut.h expects to get GLAPIENTRY from glu.h, but glew.h undefined it.
  • So GLUTAPIENTRY now contains the string "GLAPIENTRY" instead of being empty. This causes compilation errors throughout the rest of glut.h, starting on line 531
    GLUTAPI void GLUTAPIENTRY glutInit(int *argcp, char **argv);
    which produces these errors
    /usr/include/GL/glut.h:531: error: expected initializer before 'glutInit'
    /usr/include/GL/glut.h:539: error: expected initializer before 'glutInitDisplayMode'
    /usr/include/GL/glut.h:541: error: expected initializer before 'glutInitDisplayString'
    /usr/include/GL/glut.h:543: error: expected initializer before 'glutInitWindowPosition'
    /usr/include/GL/glut.h:544: error: expected initializer before 'glutInitWindowSize'

    etc etc...

The obvious solution is to delete the #undef at line 10767 of glew.h. Here's the trivial patch:
--- glew-1.5.0/include/GL/glew.h        2007-12-28 03:09:49.000000000 +0000
+++ glew-patched/include/GL/glew.h 2008-01-26 11:45:27.000000000 +0000
@@ -10764,7 +10764,6 @@


9 Jan 2008

Musical Maxtor

Well it's been a typical Christmas and New Year. Phone line down (rainwater in cable splice), one bereavement, one separation, and four PCs worked on at friends and family rate (ie, £nil and intolerable working conditions).

One of the PCs had been reported to me as 'playing a ringtone when you turn it on'. This wasn't 'Für Elise' (which some bioses play on low voltage or failed CPU fan). It was a nine-note quick beep pattern, consisting of a rising tritone repeated three times.

On opening the case, it became apparent that the beeping was coming from the disk drive (*boggle!*), a notorious Maxtor 6Y120L0 Diamondmax 9. Uhh?! A beeping disk drive! And it was being detected, but it wasn't spinning up. So, it deserved Punishment. Power was applied and I gave it a good clonk, and Lo! It was Healed!

The next step was to get a replacement. The household I was visiting is a desolate unwired backwater in the wasteland of South Wales, so the only recourse was to pick a local PC emporium from the yellow pages. There was but one, which turned out to be a slightly seedy repair biz above a betting shop, but they did have a Hitachi 160Gb Deathstar. Took it back, booted Knoppix from CD and dd'ed the whole of the old disk to the new. Worked perfectly (fsvo, this being Win XP on NTFS).

Back home, I researched the musical Maxtor phenomenon. There's nothing on the official site about beep codes, and in particular the so-called troubleshooter admits no possibility of beeps or failure to spin up. No. Can't possibly happen. What a bunch of useless lying corporatist bastards. There are even some old forum posts out there citing an official denial that Maxtor drives ever beep, and pig headed dismissiveness at the risibly misnamed Experts Exchange (motto: pay dollars, read bollocks!) Nevertheless, there are plenty of other folk reporting exactly the same experience - that a triple-tritone beep from a Maxtor Diamondmax drive means spin-up failure. It's not a fantasy, it's real.