From 19fad65511484261b44a1f73381f71262315610c Mon Sep 17 00:00:00 2001
From: Bryan Drewery <bdrewery@FreeBSD.org>
Date: Thu, 22 Jun 2017 21:03:27 +0000
Subject: [PATCH] Support cached linker values in environment.

This is similar to r289659 for bsd.compiler.mk.

MFC after:	2 weeks
Reviewed by:	emaste
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D11310
---
 share/mk/bsd.linker.mk | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/share/mk/bsd.linker.mk b/share/mk/bsd.linker.mk
index db554ef3e40d..7a6502012689 100644
--- a/share/mk/bsd.linker.mk
+++ b/share/mk/bsd.linker.mk
@@ -19,6 +19,27 @@ __<bsd.linker.mk>__:
 
 .for ld X_ in LD $${_empty_var_} XLD X_
 .if ${ld} == "LD" || !empty(XLD)
+# Try to import LINKER_TYPE and LINKER_VERSION from parent make.
+# The value is only used/exported for the same environment that impacts
+# LD and LINKER_* settings here.
+_exported_vars=	${X_}LINKER_TYPE ${X_}LINKER_VERSION
+${X_}_ld_hash=	${${ld}}${MACHINE}${PATH}
+${X_}_ld_hash:=	${${X_}_ld_hash:hash}
+# Only import if none of the vars are set somehow else.
+_can_export=	yes
+.for var in ${_exported_vars}
+.if defined(${var})
+_can_export=	no
+.endif
+.endfor
+.if ${_can_export} == yes
+.for var in ${_exported_vars}
+.if defined(${var}.${${X_}_ld_hash})
+${var}=	${${var}.${${X_}_ld_hash}}
+.endif
+.endfor
+.endif
+
 .if ${ld} == "LD" || (${ld} == "XLD" && ${XLD} != ${LD})
 
 _ld_version!=	${${ld}} --version 2>/dev/null | head -n 1 || echo none
@@ -40,6 +61,14 @@ ${X_}LINKER_VERSION!=	echo "${_v:M[1-9].[0-9]*}" | \
 .undef _v
 .endif	# ${ld} == "LD" || (${ld} == "XLD" && ${XLD} != ${LD})
 
+# Export the values so sub-makes don't have to look them up again, using the
+# hash key computed above.
+.for var in ${_exported_vars}
+${var}.${${X_}_ld_hash}:=	${${var}}
+.export-env ${var}.${${X_}_ld_hash}
+.undef ${var}.${${X_}_ld_hash}
+.endfor
+
 .endif	# ${ld} == "LD" || !empty(XLD)
 .endfor	# .for ld in LD XLD