A /usr/src/Makefile.inc1 question for its MK_SYSTEM_COMPILER=no MK_SYSTEM_LINKER=no usage

[Mark Millard]

Is the following as intended?

In /usr/src/Makefile.inc1 there is:

# If all targets are disabled for system llvm then don't expect it to work
# for cross-builds.
.if !defined(TOOLS_PREFIX) && ${MK_LLVM_TARGET_ALL} == "no" && \
    ${MACHINE} != ${TARGET} && ${MACHINE_ARCH} != ${TARGET_ARCH} && \
    !make(showconfig)
MK_SYSTEM_COMPILER=     no
MK_SYSTEM_LINKER=       no
.endif

Take an example context of:

MACHINE=arm64        TARGET=arm
MACHINE_ARCH=aarch64 TARGET_ARCH=armv7

This would potentially allow the MK_SYSTEM_COMPILER
and MK_SYSTEM_LINKER assignments to "no".
(As an example use: MK_SYSTEM_COMPILER=="yes" is
required to set to disable the bootstrap compiler
via MK_CLANG_BOOTSTRAP and MK_GCC_BOOTSTRAP being
set to "no".)

Note: Any time ${MACHINE} != ${TARGET} then
${MACHINE_ARCH} != ${TARGET_ARCH} for the
existing/supported combinations (if I understand
right). This is probably a requirement on any
future combinations as well in order to avoid
_ARCH's being ambiguous.

But both the contrasting example contexts of:

MACHINE=arm        TARGET=arm
MACHINE_ARCH=armv6 TARGET_ARCH=armv7

and:

MACHINE=arm        TARGET=arm
MACHINE_ARCH=armv7 TARGET_ARCH=armv7

would prevent the MK_SYSTEM_COMPILER and
MK_SYSTEM_LINKER assignments to "no" based
on (at least) ${MACHINE} == ${TARGET}.

Note: Any time ${MACHINE_ARCH} == ${TARGET_ARCH}
then ${MACHINE} == ${TARGET} for the
existing/supported combinations (if I understand
right). This is probably a requirement on any
future combinations as well in order to avoid
_ARCH's being ambiguous.

So overall it seems the code is effectively (for
valid combinations):

.if !defined(TOOLS_PREFIX) && ${MK_LLVM_TARGET_ALL} == "no" && \
    ${MACHINE} != ${TARGET} && \
    !make(showconfig)
MK_SYSTEM_COMPILER=     no
MK_SYSTEM_LINKER=       no
.endif

Is that the intent?

(I avoided powerpc combinations because of the
current problematical status of clang/llvm materials
when powerpc family members are involved for
FreeBSD. Hopefully some year this will have proved
temporary.)


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)