The basics of this framework is INSTALL_TARGETS is a list of values (e.g., XPIDL_MODULE) such that all $1_FILES get installed to $1_DEST in $1_TARGET. This is basically added by bug 784262 and bug 773202. It's not necessary for cc-rework, but it eliminates a lot of extra rules in Makefiles. Assuming that the install:: rules are useless these days, then this means we have no rules in the mailnews/ tree excepting mapi's MIDL generation and mailnews' xpcshell-tests kludge.
Created attachment 762830 [details] [diff] [review] Part 1: Add the INSTALL_TARGETS to rules.mk
Created attachment 762837 [details] [diff] [review] Part 2: Use INSTALL_TARGETS internally to rules.mk This isn't strictly necessary, but it brings us closer to mozilla-central's rules.mk. This patch was largely constructed by using vimdiff between the two copies, though I tried to avoid excessive changes to the comm-central copy. It also serves as a litmus test for part 1.
I've just backed out part 2 of this, as my analysis on via try server was that this caused the Linux & Windows mailbloat failures. https://hg.mozilla.org/comm-central/rev/7307fb151f1d
Also backed out on aurora: https://hg.mozilla.org/releases/comm-aurora/rev/b3a387b1b1c3