If a -include pch_name is given while compiling a C File included with QT4 
beta2, gcc segfaults. Here is the command line  
gcc-3.4 -c -include QtGui_debug -fno-exceptions -g -Wall -W -D_REENTRANT -fPIC 
-DQT_SHARED -DQT_BUILD_GUI_LIB -DQT_NO_CAST_TO_ASCII -DQT3_SUPPORT_WARNINGS 
-DQT_MOC_COMPAT -DQT_RASTER_IMAGEENGINE -DQT_HAVE_FREETYPE -DQT_CORE_LIB 
-I/home/parag/qt-x11-opensource-4.0.0-b2/mkspecs/linux-g++ -I. 
-I../../include/QtCore -I../../include -I../../include/QtGui 
-I../3rdparty/libpng -I../3rdparty/zlib -I../3rdparty/opentype 
-I/usr/X11R6/include -I/usr/include/freetype2 -I.moc/debug-shared -I. 
-o .obj/debug-shared/pngrtran.o ../3rdparty/libpng/pngrtran.c 
It compiles fine if the PCH include is removed. (no -include) 
 
Here is gcc-3.4 -v output - 
Reading specs from /usr/lib/gcc/i486-linux/3.4.4/specs 
Configured with: ../src/configure -v 
--enable-languages=c,c++,java,f77,pascal,objc,ada,treelang --prefix=/usr 
--libexecdir=/usr/lib --with-gxx-include-dir=/usr/include/c++/3.4 
--enable-shared --with-system-zlib --enable-nls --without-included-gettext 
--program-suffix=-3.4 --enable-__cxa_atexit --enable-libstdcxx-allocator=mt 
--enable-clocale=gnu --enable-libstdcxx-debug --enable-java-gc=boehm 
--enable-java-awt=gtk --disable-werror i486-linux 
Thread model: posix 
gcc version 3.4.4 20050209 (prerelease) (Debian 3.4.3-9ubuntu4) 
 
Also attached is the relevant .i file.