## Saturday, September 12, 2009

### Compiling LyX with gcc 4.4

I recently upgraded to gcc 4.4.1, and today I found that I couldn't compile LyX without fixing the source code. The reason is because gcc 4.4 has a stricter interpretation of the C standard when it comes to preprocessor syntax. The #if ... #elif ... #endif block is now either all processed or all skipped. In other words, #elif does not behave like #else #if ... #endif anymore because the conditional expression of #elif no longer enjoys deferred computation. This is documented in gcc bug #36453.

LyX failed to compile because it distributed and included boost/mpl as part of the source code. A patch for boost/mpl is readily available. I downloaded the most recent patch (0001-boost.mpl-gcc-4.4-fixes.patch), saved it under $(SRCDIR)/boost (suppose$(SRCDIR) is the source directory for LyX, e.g. lyx-1.6.4), and ran from \$(SRCDIR)/boost the command: patch -p3 < 0001-boost.mpl-gcc-4.4-fixes.patch

LyX should now compile correctly under gcc 4.4