MT#61993 build: Force recursive variables into simple ones

Starting with GNU make 4.4, build time have massively regressed
where before they would take 5m on amd64 now can take 2h40m. While this
seems clearly broken, the release notes are filled with notices for
breaking changes, and in particular the one for passing all make
variables down to the invoked programs executed via the «shell» GNU make
function, so it is not clear what is expected breakage and what is not.

This has been reported in Debian, but not yet upstream, and while it
seems like a clear regression, it's not clear what will be the upstream
take on it. For now apply workarounds that do not change semantics, and
which do not regress with older GNU make versions.

Use the GNU make «origin» function instead of «?=» which defaults to
defining a variable as a recursive one. Coerce already defined variables
into simple ones to avoid GNU make re-evaluating these variables for
each «shell» function invocation.

Ref: https://bugs.debian.org/1092051
Change-Id: I076fc05dd616918473a22e7e942fecfdc9851d47
(cherry picked from commit 887fb40f3f)
(cherry picked from commit 67a2b222c7)

Makefile

@@ -3,7 +3,11 @@ with_transcoding ?= yes
 
 ifeq ($(DO_ASAN_FLAGS),1)
 ASAN_FLAGS = -ggdb -O0 -fsanitize=address -fsanitize=leak -fsanitize=undefined
-CFLAGS ?= -Wall -Wextra -Wno-sign-compare -Wno-unused-parameter -Wstrict-prototypes
+ifeq ($(origin CFLAGS),undefined)
+CFLAGS := -Wall -Wextra -Wno-sign-compare -Wno-unused-parameter -Wstrict-prototypes
+else
+CFLAGS := $(CFLAGS)
+endif
 CFLAGS += $(ASAN_FLAGS)
 CFLAGS += -DASAN_BUILD
 LDFLAGS += $(ASAN_FLAGS)

daemon/Makefile

@@ -3,9 +3,12 @@ TARGET=		rtpengine
 with_iptables_option ?= yes
 with_transcoding ?= yes
 
-
-CFLAGS?=	-g -Wall -Wextra -Wno-sign-compare -Wno-unused-parameter -Wstrict-prototypes -Werror=return-type \
+ifeq ($(origin CFLAGS),undefined)
+CFLAGS:=	-g -Wall -Wextra -Wno-sign-compare -Wno-unused-parameter -Wstrict-prototypes -Werror=return-type \
 		-Wshadow
+else
+CFLAGS:=	$(CFLAGS)
+endif
 CFLAGS+=	-pthread -fno-strict-aliasing
 CFLAGS+=	-std=c11
 CFLAGS+=	$(shell pkg-config --cflags glib-2.0)
@@ -49,7 +52,7 @@ endif
 #CFLAGS+=	-DSRTCP_KEY_DERIVATION_RFC_COMPLIANCE
 #CFLAGS+=	-DSTRICT_SDES_KEY_LIFETIME
 
-LDLIBS=		-lm -ldl
+LDLIBS:=	-lm -ldl
 LDLIBS+=	$(shell pkg-config --libs glib-2.0)
 LDLIBS+=	$(shell pkg-config --libs gthread-2.0)
 LDLIBS+=	$(shell pkg-config --libs zlib)

debian/rules

@@ -21,7 +21,7 @@ endif
 
 export FIXTURES_PATH = /usr/share/rtpengine-perftest
 
-export deb_systemdsystemunitdir = $(shell pkg-config --variable=systemdsystemunitdir systemd)
+export deb_systemdsystemunitdir := $(shell pkg-config --variable=systemdsystemunitdir systemd)
 
 %:
 	dh $@

kernel-module/Makefile

@@ -4,12 +4,12 @@ KBUILD := $(KSRC)
 M      ?= $(PWD)
 
 ifeq ($(RTPENGINE_VERSION),)
-  DPKG_PRSCHNGLG= $(shell which dpkg-parsechangelog 2>/dev/null)
-  DEB_CHANGELOG=$(shell test -f $(M)/../debian/changelog && echo $(M)/../debian/changelog || echo $(M)/debian/changelog)
+  DPKG_PRSCHNGLG := $(shell which dpkg-parsechangelog 2>/dev/null)
+  DEB_CHANGELOG := $(shell test -f $(M)/../debian/changelog && echo $(M)/../debian/changelog || echo $(M)/debian/changelog)
   ifneq ($(DPKG_PRSCHNGLG),)
-    DPKG_PRSCHNGLG=$(shell dpkg-parsechangelog -l$(DEB_CHANGELOG) | awk '/^Version: / {print $$2}')
+    DPKG_PRSCHNGLG := $(shell dpkg-parsechangelog -l$(DEB_CHANGELOG) | awk '/^Version: / {print $$2}')
   endif
-  GIT_BR_COMMIT=git-$(shell cd $(M) && git rev-parse --abbrev-ref --symbolic-full-name HEAD 2> /dev/null)-$(shell cd $(M) && git rev-parse --short HEAD 2> /dev/null)
+  GIT_BR_COMMIT := git-$(shell cd $(M) && git rev-parse --abbrev-ref --symbolic-full-name HEAD 2> /dev/null)-$(shell cd $(M) && git rev-parse --short HEAD 2> /dev/null)
 
   ifneq ($(DPKG_PRSCHNGLG),)
     RTPENGINE_VERSION+=$(DPKG_PRSCHNGLG)

lib/g729.Makefile

@@ -1,8 +1,8 @@
 ifeq (,$(filter pkg.ngcp-rtpengine.nobcg729,${DEB_BUILD_PROFILES}))
 # look for bcg729
 # system pkg-config
-ifeq ($(shell pkg-config --exists libbcg729 && echo yes),yes)
-have_bcg729 := yes
+have_bcg729 := $(shell pkg-config --exists libbcg729 && echo yes)
+ifeq ($(have_bcg729),yes)
 bcg729_inc := $(shell pkg-config --cflags libbcg729)
 bcg729_lib := $(shell pkg-config --libs libbcg729)
 else

lib/lib.Makefile

@@ -5,22 +5,22 @@ ifeq ($(RTPENGINE_ROOT_DIR),)
 	RTPENGINE_ROOT_DIR=..
 endif
 
-HAVE_DPKG_PARSECHANGELOG?=$(shell which dpkg-parsechangelog 2>/dev/null)
+HAVE_DPKG_PARSECHANGELOG := $(shell which dpkg-parsechangelog 2>/dev/null)
 
 ifeq ($(RELEASE_DATE),)
   ifneq ($(HAVE_DPKG_PARSECHANGELOG),)
-    RELEASE_DATE=$(shell date -u -d "@$$(dpkg-parsechangelog -l$(RTPENGINE_ROOT_DIR)/debian/changelog -STimestamp)" '+%F')
+    RELEASE_DATE := $(shell date -u -d "@$$(dpkg-parsechangelog -l$(RTPENGINE_ROOT_DIR)/debian/changelog -STimestamp)" '+%F')
   endif
   ifeq ($(RELEASE_DATE),)
-    RELEASE_DATE=undefined
+    RELEASE_DATE := undefined
   endif
 endif
 
 ifeq ($(RTPENGINE_VERSION),)
   ifneq ($(HAVE_DPKG_PARSECHANGELOG),)
-    DPKG_PRSCHNGLG=$(shell dpkg-parsechangelog -l$(RTPENGINE_ROOT_DIR)/debian/changelog | awk '/^Version: / {print $$2}')
+    DPKG_PRSCHNGLG := $(shell dpkg-parsechangelog -l$(RTPENGINE_ROOT_DIR)/debian/changelog | awk '/^Version: / {print $$2}')
   endif
-  GIT_BR_COMMIT=git-$(shell git rev-parse --abbrev-ref --symbolic-full-name HEAD 2> /dev/null)-$(shell git rev-parse --short HEAD 2> /dev/null)
+  GIT_BR_COMMIT := git-$(shell git rev-parse --abbrev-ref --symbolic-full-name HEAD 2> /dev/null)-$(shell git rev-parse --short HEAD 2> /dev/null)
 
   ifneq ($(DPKG_PRSCHNGLG),)
     RTPENGINE_VERSION+=$(DPKG_PRSCHNGLG)
@@ -36,9 +36,7 @@ endif
 CFLAGS+=	-DRTPENGINE_VERSION="\"$(RTPENGINE_VERSION)\""
 
 # look for libsystemd
-ifeq ($(shell pkg-config --exists libsystemd && echo yes),yes)
-have_libsystemd := yes
-endif
+have_libsystemd := $(shell pkg-config --exists libsystemd && echo yes)
 ifeq ($(have_libsystemd),yes)
 CFLAGS+=	$(shell pkg-config --cflags libsystemd)
 CFLAGS+=	-DHAVE_LIBSYSTEMD
@@ -47,9 +45,7 @@ endif
 
 # look for liburing
 ifeq (,$(filter pkg.ngcp-rtpengine.nouring,${DEB_BUILD_PROFILES}))
-ifeq ($(shell pkg-config --atleast-version=2.3 liburing && echo yes),yes)
-have_liburing := yes
-endif
+have_liburing := $(shell pkg-config --atleast-version=2.3 liburing && echo yes)
 ifeq ($(have_liburing),yes)
 CFLAGS+=	$(shell pkg-config --cflags liburing)
 CFLAGS+=	-DHAVE_LIBURING
@@ -66,7 +62,7 @@ LDFLAGS += -rdynamic
 
 ifneq ($(DBG),yes)
   ifeq (,$(filter $(CFLAGS),-O0))
-    DPKG_BLDFLGS=	$(shell which dpkg-buildflags 2>/dev/null)
+    DPKG_BLDFLGS := $(shell which dpkg-buildflags 2>/dev/null)
     ifneq ($(DPKG_BLDFLGS),)
       # support http://wiki.debian.org/Hardening for >=wheezy
       CFLAGS+=	$(shell dpkg-buildflags --get CFLAGS)

lib/mqtt.Makefile

@@ -1,10 +1,7 @@
-ifeq ($(shell pkg-config --exists libmosquitto && echo yes),yes)
-have_mqtt := yes
+have_mqtt := $(shell pkg-config --exists libmosquitto && echo yes)
+ifeq ($(have_mqtt),yes)
 mqtt_inc := $(shell pkg-config --cflags libmosquitto)
 mqtt_lib := $(shell pkg-config --libs libmosquitto)
-endif
-
-ifeq ($(have_mqtt),yes)
 CFLAGS+=	-DHAVE_MQTT
 CFLAGS+=	$(mqtt_inc)
 endif

perf-tester/Makefile

@@ -2,8 +2,12 @@ TARGET = rtpengine-perftest
 
 FIXTURES_PATH ?= ../fixtures
 
+ifeq ($(origin CFLAGS),undefined)
 CFLAGS ?= -g -Wall -Wextra -Wno-sign-compare -Wno-unused-parameter -Wstrict-prototypes -Werror=return-type \
 		-Wshadow
+else
+CFLAGS := $(CFLAGS)
+endif
 
 CFLAGS += -pthread
 CFLAGS += -std=c11
@@ -23,7 +27,7 @@ CFLAGS += $(shell pkg-config --cflags ncursesw)
 CFLAGS += -DWITH_TRANSCODING
 CFLAGS += $(shell pkg-config --cflags openssl)
 
-LDLIBS = -lm -ldl
+LDLIBS := -lm -ldl
 LDLIBS += $(shell pkg-config --libs glib-2.0)
 LDLIBS += $(shell pkg-config --libs gthread-2.0)
 LDLIBS += $(shell pkg-config --libs libavcodec)

recording-daemon/Makefile

@@ -1,7 +1,11 @@
 TARGET=		rtpengine-recording
 
+ifeq ($(origin CFLAGS),undefined)
 CFLAGS?=	-g -Wall -Wextra -Wno-sign-compare -Wno-unused-parameter -Wstrict-prototypes -Werror=return-type \
 		-Wshadow
+else
+CFLAGS:=	$(CFLAGS)
+endif
 CFLAGS+=	-pthread -I. -I../lib/ -I../kernel-module/
 CFLAGS+=	-std=c11 -fno-strict-aliasing
 CFLAGS+=	-D_GNU_SOURCE -D_POSIX_SOURCE -D_POSIX_C_SOURCE
@@ -17,7 +21,7 @@ CFLAGS+=	$(shell mysql_config --cflags)
 CFLAGS+=	$(shell pkg-config --cflags openssl)
 CFLAGS+=	$(shell pkg-config --cflags libcurl)
 
-LDLIBS=		-lm -ldl
+LDLIBS:=	-lm -ldl
 LDLIBS+=	$(shell pkg-config --libs glib-2.0)
 LDLIBS+=	$(shell pkg-config --libs gthread-2.0)
 LDLIBS+=	$(shell pkg-config --libs libavcodec)

t/Makefile

@@ -2,8 +2,12 @@ TARGET=		all-tests
 
 with_transcoding ?= yes
 
+ifeq ($(origin CFLAGS),undefined)
 CFLAGS?=	-g -Wall -Wextra -Wno-sign-compare -Wno-unused-parameter -Wstrict-prototypes -Werror=return-type \
 		-Wshadow
+else
+CFLAGS:=	$(CFLAGS)
+endif
 PRELOAD_CFLAGS := $(CFLAGS)
 CFLAGS+=	-pthread -fno-strict-aliasing
 CFLAGS+=	-std=c11
@@ -38,7 +42,7 @@ else
 CFLAGS+=	-DWITHOUT_CODECLIB
 endif
 
-LDLIBS=		-lm -ldl
+LDLIBS:=	-lm -ldl
 LDLIBS+=	$(shell pkg-config --libs glib-2.0)
 LDLIBS+=	$(shell pkg-config --libs gthread-2.0)
 LDLIBS+=	$(shell pkg-config --libs libcrypto)