40de350c7aff82babf54c7a7eea41ff5c354bafc
chmalee
  Tue Jul 14 11:15:31 2026 -0700
Build shared objects once before parallel sub-makes in userAppMulti.mk. refs #37809

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

diff --git src/inc/userAppMulti.mk src/inc/userAppMulti.mk
index 14c8027adc3..d37bef1f13e 100644
--- src/inc/userAppMulti.mk
+++ src/inc/userAppMulti.mk
@@ -1,45 +1,55 @@
 ########################################################################
 # Additional rules to use when build multiple programs with userApps.mk
 #
 # Due the way many rules do use patterns, it is necessary to recursively
 # call make to build multiple user apps or CGI loaders in the same directory.
 # Do this using this idiom:
 #
 #   kentSrc = ../..
 #   ifeq $({PROGS},)
 #   PROGS = one two three
 #   include ${kentSrc}/inc/userAppMulti.mk
 #   else
 #   A = ${PROG}
 #   include ${kentSrc}/inc/userApp.mk
 #   endif
 
 
 # Note MAKECMDGOALS is used to set variables, so
 # can not any make magic to combine these names
 
 default:: ${PROGS:%=%_default}
-%_default:
+%_default: sharedObjectsBuilt
 	${MAKE} default PROG=$*
 compile:: ${PROGS:%=%_compile}
-%_compile:
+%_compile: sharedObjectsBuilt
 	${MAKE} compile PROG=$*
 clean:: ${PROGS:%=%_clean}
 %_clean::
 	${MAKE} clean PROG=$*
 install: ${PROGS:%=%_}
 %_install:
 	${MAKE} install PROG=$*
 cgi::  ${PROGS:%=%_cgi}
-%_cgi:
+%_cgi: sharedObjectsBuilt
 	${MAKE} cgi PROG=$*
 alpha:: ${PROGS:%=%_alpha}
-%_alpha:
+%_alpha: sharedObjectsBuilt
 	${MAKE} alpha PROG=$*
 beta::  ${PROGS:%=%_beta}
-%_beta:
+%_beta: sharedObjectsBuilt
 	${MAKE} beta PROG=$*
 
+# When the programs share a compiled object (an extraObjects entry used by more
+# than one program), build it once here before the per-program sub-makes fan
+# out. Otherwise parallel make lets two sub-makes compile the same object at
+# once, and one truncates the .o while the other links it.
+# Set sharedObjects in the PROGS branch of the directory makefile.
+sharedObjectsBuilt:
+ifneq (${sharedObjects},)
+	${MAKE} ${sharedObjects} PROG=$(firstword ${PROGS})
+endif
+
 # fake name useds to get pass recurise ifeq
 test::
 	${MAKE} test PROG=testing