build_bg should also respect users Makevars

[jimhester]

E.g. the code from

pkgbuild/R/compile-dll.R

Lines 41 to 50 in 01898ad

	# If the user has a makevars file just use that
	if (length(makevars_user()) > 0) {
	install_min(
	path,
	dest = install_dir,
	components = "libs",
	args = if (needs_clean(path)) "--preclean",
	quiet = quiet
	)
	} else {

should also be in build-bg.R

[gaborcsardi]

@jimhester I don't get this. Seemingly compile_dll() is not called by build(). Or anywhere in the package, actually.

[gaborcsardi]

OK, I think I understand now. There are three cases:

• pkgload::load_all(), this calls pkgbuild::compile_dll(), and that uses the user Makevars, as above.
• pkgbuild::build() just calls R CMD build without doing anything about Makevars, and R CMD build uses it automatically.
• pkgbuild::pkgbuild_process sets up the compiler flags, and uses a temporary user Makevars, so the user's Makevars is ignored.

So in the spirit of pkgbuild::build(), pkgbuild_process should just rely on R CMD build and the user's Makevars, and not touch the compiler flags.