toolchain/60000: split debug data rules broke ${.TARGET}-dependent flags

["campbell+netbsd%mumble.net@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         60000
>Category:       toolchain
>Synopsis:       split debug data rules broke ${.TARGET}-dependent flags
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Feb 13 08:05:00 +0000 2026
>Originator:     Taylor R Campbell
>Release:        current, 11?
>Organization:
The ${.TARGET}BSD Foundation
>Environment:
>Description:

	Once upon a time, we built program foo and its debug data
	foo.debug by two recipes, which roughly reduce to:

foo: foo.o bar.o baz.o
	ld -o foo foo.o bar.o baz.o ${LDFLAGS}

foo.debug: foo
	objcopy --only-keep-debug foo foo.debug
	objcopy --strip-debug \
	    -p -R .gnu_debuglink --add-gnu-debuglink=foo.debug \
	    foo

	The foo.debug rule is troublesome, though, because it
	overwrites foo in place -- this breaks parallel runs and
	changes the mtime of foo.debug's own prerequisite foo.

	To fix this, I split it into three recipes with appropriate
	dependencies:

foo.link: foo.o bar.o baz.o
	ld -o foo foo.o bar.o baz.o ${LDFLAGS}

foo.debug: foo.link
	objcopy --only-keep-debug foo.link foo.debug

foo: foo.link
	objcopy --strip-debug \
	    -p -R .gnu_debuglink --add-gnu-debuglink=foo.debug \
	    foo.link foo

	Unfortunately, this change had a side effect: any
	${.TARGET}-dependent expansion in LDFLAGS is now different,
	because previously ${.TARGET} was `foo' and now ${.TARGET} is
	`foo.link'.  So logic like this changed:

LDFLAGS+=	${"${LDSTATIC.${.TARGET}}" == "-static" :? : ${PIE_LDFLAGS}}

https://nxr.netbsd.org/xref/src/share/mk/bsd.prog.mk?r=1.361#41

	Before, if you defined LDSTATIC.foo=-static, it would prevent
	LDFLAGS from having `-pie' added.  But after the change, you
	would have to define LDSTATIC.foo.link=-static to have the same
	effect.

>How-To-Repeat:

	cd src/tests/lib/csu && nbmake-$MACHINE h_initfini2

	This should be a static _non-pie_ because LDSTATIC.h_initfini2
	is set to `-static', but instead it is built as a static pie.

>Fix:

	1. Audit all the .TARGET-dependent variables.
	2. In this case, consider instead using:

.for _P in ${PROGS}
LDFLAGS.${_P}+=	${"${LDSTATIC.${_P}}" == "-static" :? : ${PIE_LDFLAGS}}
.endfor