Use PCH

[Olaf van der Spek]

To decrease build times, A PCH should be used. A PCH (pch.h.gch) can be build with "g++ pch.h". Since I've no experience with the build system, could someone help me to add this bit?
A depedency on pch.h.gch should also be added to config.h.

http://gcc.gnu.org/onlinedocs/gcc/Precompiled-Headers.html

[Olaf van der Spek (olafvdspek)]

In a Hello World app, this suffices:
BUILT_SOURCES = config.h.gch

config.h.gch: config.h
 ${CXXCOMPILE} -o $@ $<

But in Drizzle this doesn't work.
It seems the GCC invocations don't match and the PCH is ignored.

PCH compile:
g++ -DHAVE_CONFIG_H -I. -I. -g -pipe -std=gnu++98 -O2 -fvisibility=hidden -fvisibility-inlines-hidden -Werror -pedantic -Wall -Wundef -Wshadow -fdiagnostics-show-option -floop-parallelize-all -fno-strict-aliasing -Wno-strict-aliasing -Wextra -Wformat -Wno-format-nonliteral -Wno-format-security -Woverloaded-virtual -Wnon-virtual-dtor -Wctor-dtor-privacy -Wno-long-long -Wmissing-declarations -Wframe-larger-than=32768 -Wno-redundant-decls -c config.h

Normal compile:
  CXX drizzled/message/drizzled_message_libdrizzledmessage_la-statement_transform.lo

Monty, could you look into this?

BTW, why does it use .lo instead of .o?

[Monty Taylor (mordred)]

In reverse order:

.lo is a libtool object description file, and it's used because we use libtool. Libtool then uses these at link time to help build the libraries. (you'll also note that .la files are the in-tree libraries - which allow things be able to be used in-tree and then things get re-linked at install time so that all of the rpath info is correct)

That being said - you need to use LTCXXCOMPILE instead of CXXCOMPILE