822805 - Support building NSS with OBJDIRs completely outside the source directory

Status: RESOLVED INACTIVE

(NSS :: Build, enhancement, P5)

Description

[Brian Smith (:briansmith, :bsmith, use NEEDINFO?)]

Gecko contains this workaround to build with the OBJDIR outside of the source dirctory:

http://mxr.mozilla.org/mozilla-central/source/security/build/Makefile.in?rev=6a0ed6484811#151

# Hack to force NSS build system to use "normal" object directories
DEFAULT_GMAKE_FLAGS += BUILD='$(MOZ_BUILD_ROOT)/security/$$(subst $(ABS_topsrcdir)/security/,,$$(CURDIR))'
DEFAULT_GMAKE_FLAGS += BUILD_TREE='$$(BUILD)' OBJDIR='$$(BUILD)' DEPENDENCIES='$$(BUILD)/.deps' SINGLE_SHLIB_DIR='$$(BUILD)'
DEFAULT_GMAKE_FLAGS += SOURCE_XP_DIR=$(ABS_DIST)

We should build support for this into the NSS build system, and make it the default.

Currently, our workflow is something like this:
   cvs co NSPR NSS
   cd mozilla/security/nss
   make nss_build_all

which puts output files in mozilla/dist/$(OBJDIR_NAME) and throughout mozilla/security/nss/.../$(OBJDIR_NAME)

With the proposed Mercurial layout, we will have a workflow like this:

   # "mozilla" could actually be any name
   export BASEDIR=mozilla
   mkdir $BASEDIR
   cd $BASEDIR
   hg clone http://hg.mozilla.org/nspr
   hg clone http://hg.mozilla.org/nss
   cd nss
   make nss_build_all

I propose that the dist directory should be $BASEDIR/dist/$(OBJDIR_NAME) and that all intermediate files are generated Gecko-style under that directory.

We can test this is working by verifying that the build succeeds when the source directory is read-only.