Ensure link commands list *.o files before LDFLAGS.

It's important for link commands to list *.o input files before -l
switches for libraries, as library code may not get pulled into the link
unless referenced by an earlier command-line entry.  This is certainly
necessary for static libraries (.a style).  Apparently on some platforms
it is also necessary for shared libraries, as reported by Donald Dong.

We often put -l switches for within-tree libraries into LDFLAGS, meaning
that link commands that list *.o files after LDFLAGS are hazardous.
Most of our link commands got this right, but a few did not.  In
particular, places that relied on gmake's default implicit link rule
failed, because that puts LDFLAGS first.  Fix that by overriding the
built-in rule with our own.  The implicit link rules in
src/makefiles/Makefile.* for single-.o-file shared libraries mostly
got this wrong too, so fix them.  I also changed the link rules for the
backend and a couple of other places for consistency, even though they
are not (currently) at risk because they aren't adding any -l switches
to LDFLAGS.

Arguably, the real problem here is that we're abusing LDFLAGS by
putting -l switches in it and we should stop doing that.  But changing
that would be quite invasive, so I'm not eager to do so.

Perhaps this is a candidate for back-patching, but so far it seems
that problems can only be exhibited in test code we don't normally
build, and at least some of the problems are new in HEAD anyway.
So I'll refrain for now.

Donald Dong and Tom Lane

Discussion: https://postgr.es/m/CAKABAquXn-BF-vBeRZxhzvPyfMqgGuc74p8BmQZyCFDpyROBJQ@mail.gmail.com

src/Makefile.global.in

@@ -742,6 +742,13 @@ endif
 # tracking (see below) is used.
 %: %.c
 
+# Replace gmake's default rule for linking a single .o file to produce an
+# executable.  The main point here is to put LDFLAGS after the .o file,
+# since we put -l switches into LDFLAGS and those are order-sensitive.
+# In addition, include CFLAGS and LDFLAGS_EX per project conventions.
+%: %.o
+	$(CC) $(CFLAGS) $< $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@$(X)
+
 ifndef PGXS
 
 # Remake Makefile.global from Makefile.global.in if the latter

src/backend/Makefile

@@ -60,7 +60,7 @@ ifneq ($(PORTNAME), win32)
 ifneq ($(PORTNAME), aix)
 
 postgres: $(OBJS)
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_EX) $(export_dynamic) $(call expand_subsys,$^) $(LIBS) -o $@
+	$(CC) $(CFLAGS) $(call expand_subsys,$^) $(LDFLAGS) $(LDFLAGS_EX) $(export_dynamic) $(LIBS) -o $@
 
 endif
 endif
@@ -69,7 +69,7 @@ endif
 ifeq ($(PORTNAME), cygwin)
 
 postgres: $(OBJS)
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_EX) $(export_dynamic) -Wl,--stack,$(WIN32_STACK_RLIMIT) -Wl,--export-all-symbols -Wl,--out-implib=libpostgres.a $(call expand_subsys,$^) $(LIBS) -o $@
+	$(CC) $(CFLAGS) $(call expand_subsys,$^) $(LDFLAGS) $(LDFLAGS_EX) $(export_dynamic) -Wl,--stack,$(WIN32_STACK_RLIMIT) -Wl,--export-all-symbols -Wl,--out-implib=libpostgres.a $(LIBS) -o $@
 
 # libpostgres.a is actually built in the preceding rule, but we need this to
 # ensure it's newer than postgres; see notes in src/backend/parser/Makefile
@@ -82,7 +82,7 @@ ifeq ($(PORTNAME), win32)
 LIBS += -lsecur32
 
 postgres: $(OBJS) $(WIN32RES)
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_EX) -Wl,--stack=$(WIN32_STACK_RLIMIT) -Wl,--export-all-symbols -Wl,--out-implib=libpostgres.a $(call expand_subsys,$(OBJS)) $(WIN32RES) $(LIBS) -o $@$(X)
+	$(CC) $(CFLAGS) $(call expand_subsys,$(OBJS)) $(WIN32RES) $(LDFLAGS) $(LDFLAGS_EX) -Wl,--stack=$(WIN32_STACK_RLIMIT) -Wl,--export-all-symbols -Wl,--out-implib=libpostgres.a $(LIBS) -o $@$(X)
 
 # libpostgres.a is actually built in the preceding rule, but we need this to
 # ensure it's newer than postgres; see notes in src/backend/parser/Makefile
@@ -94,7 +94,7 @@ endif # win32
 ifeq ($(PORTNAME), aix)
 
 postgres: $(POSTGRES_IMP)
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_EX) $(call expand_subsys,$(OBJS)) -Wl,-bE:$(top_builddir)/src/backend/$(POSTGRES_IMP) $(LIBS) -Wl,-brtllib -o $@
+	$(CC) $(CFLAGS) $(call expand_subsys,$(OBJS)) $(LDFLAGS) $(LDFLAGS_EX) -Wl,-bE:$(top_builddir)/src/backend/$(POSTGRES_IMP) $(LIBS) -Wl,-brtllib -o $@
 
 $(POSTGRES_IMP): $(OBJS)
 	$(LD) $(LDREL) $(LDOUT) SUBSYS.o $(call expand_subsys,$^)
@@ -117,7 +117,7 @@ $(top_builddir)/src/port/libpgport_srv.a: | submake-libpgport
 # The postgres.o target is needed by the rule in Makefile.global that
 # creates the exports file when MAKE_EXPORTS = true.
 postgres.o: $(OBJS)
-	$(CC) $(LDREL) $(LDFLAGS) $(LDFLAGS_EX) $(call expand_subsys,$^) $(LIBS) -o $@
+	$(CC) $(LDREL) $(call expand_subsys,$^) $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@
 
 
 # The following targets are specified in make commands that appear in
@@ -319,4 +319,4 @@ maintainer-clean: distclean
 # are up to date.  It saves the time of doing all the submakes.
 .PHONY: quick
 quick: $(OBJS)
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_EX) $(export_dynamic) $(call expand_subsys,$^) $(LIBS) -o postgres
+	$(CC) $(CFLAGS) $(call expand_subsys,$^) $(LDFLAGS) $(LDFLAGS_EX) $(export_dynamic) $(LIBS) -o postgres

src/interfaces/ecpg/preproc/Makefile

@@ -37,7 +37,7 @@ endif
 all: ecpg
 
 ecpg: $(OBJS) | submake-libpgport
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_EX) $^ $(LIBS) $(PTHREAD_LIBS) -o $@$(X)
+	$(CC) $(CFLAGS) $^ $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) $(PTHREAD_LIBS) -o $@$(X)
 
 # We symlink typename.c from ecpglib and recompile it here
 typename.c: % : $(top_srcdir)/src/interfaces/ecpg/ecpglib/%

src/interfaces/ecpg/test/Makefile

@@ -49,7 +49,7 @@ clean distclean maintainer-clean:
 all: pg_regress$(X)
 
 pg_regress$(X): pg_regress_ecpg.o $(WIN32RES) $(top_builddir)/src/test/regress/pg_regress.o
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_EX) $^ $(LIBS) -o $@
+	$(CC) $(CFLAGS) $^ $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@
 
 $(top_builddir)/src/test/regress/pg_regress.o:
 	$(MAKE) -C $(dir $@) $(notdir $@)

src/interfaces/ecpg/test/Makefile.regress

@@ -21,9 +21,6 @@ ECPG_TEST_DEPENDENCIES = ../../preproc/ecpg$(X) \
 	$(srcdir)/../../include/sqltypes.h \
 	$(srcdir)/../../include/sql3types.h
 
-%: %.o
-	$(CC) $(CFLAGS) $< $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@
-
 # Caution: this build rule is overridden in some child Makefiles
 # where it's necessary to use nondefault switches to ecpg;
 # make sure those rules match except for the extra switches.

src/makefiles/Makefile.aix

@@ -40,4 +40,4 @@ MKLDEXPORT=$(top_srcdir)/$(MKLDEXPORT_DIR)/mkldexport.sh
 
 # Rule for building a shared library from a single .o file
 %$(DLSUFFIX): %.o %.exp
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_SL) -o $@ $*.o -Wl,-bE:$*.exp $(BE_DLLLIBS)
+	$(CC) $(CFLAGS) $*.o $(LDFLAGS) $(LDFLAGS_SL) -o $@ -Wl,-bE:$*.exp $(BE_DLLLIBS)

src/makefiles/Makefile.darwin

@@ -10,4 +10,4 @@ endif
 
 # Rule for building a shared library from a single .o file
 %.so: %.o
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_SL) -bundle $(BE_DLLLIBS) -o $@ $<
+	$(CC) $(CFLAGS) $< $(LDFLAGS) $(LDFLAGS_SL) -bundle $(BE_DLLLIBS) -o $@

src/makefiles/Makefile.freebsd

@@ -13,7 +13,7 @@ CFLAGS_SL = -fPIC -DPIC
 # Rule for building a shared library from a single .o file
 %.so: %.o
 ifdef ELF_SYSTEM
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@ $<
+	$(CC) $(CFLAGS) $< $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@
 else
 	$(LD) $(LDREL) $(LDOUT) $<.obj -x $<
 	@echo building shared object $@

src/makefiles/Makefile.hpux

@@ -40,13 +40,13 @@ endif
 %$(DLSUFFIX): %.o
 ifeq ($(GCC), yes)
   ifeq ($(with_gnu_ld), yes)
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@ $< `$(CC) $(LDFLAGS) -print-libgcc-file-name`
+	$(CC) $(CFLAGS) $< $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@ `$(CC) $(LDFLAGS) -print-libgcc-file-name`
   else
 	$(LD) -b -o $@ $< `$(CC) $(LDFLAGS) -print-libgcc-file-name`
   endif
 else
   ifeq ($(with_gnu_ld), yes)
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@ $<
+	$(CC) $(CFLAGS) $< $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@
   else
 	$(LD) -b -o $@ $<
   endif

src/makefiles/Makefile.linux

@@ -12,4 +12,4 @@ CFLAGS_SL = -fPIC
 
 # Rule for building a shared library from a single .o file
 %.so: %.o
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@ $<
+	$(CC) $(CFLAGS) $< $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@

src/makefiles/Makefile.netbsd

@@ -15,7 +15,7 @@ CFLAGS_SL = -fPIC -DPIC
 # Rule for building a shared library from a single .o file
 %.so: %.o
 ifdef ELF_SYSTEM
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@ $<
+	$(CC) $(CFLAGS) $< $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@
 else
 	$(LD) $(LDREL) $(LDOUT) $<.obj -x $<
 	@echo building shared object $@

src/makefiles/Makefile.openbsd

@@ -13,7 +13,7 @@ CFLAGS_SL = -fPIC -DPIC
 # Rule for building a shared library from a single .o file
 %.so: %.o
 ifdef ELF_SYSTEM
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@ $<
+	$(CC) $(CFLAGS) $< $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@
 else
 	$(LD) $(LDREL) $(LDOUT) $<.obj -x $<
 	@echo building shared object $@

src/makefiles/Makefile.solaris

@@ -19,9 +19,9 @@ endif
 # Rule for building a shared library from a single .o file
 %.so: %.o
 ifeq ($(GCC), yes)
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@ $<
+	$(CC) $(CFLAGS) $< $(LDFLAGS) $(LDFLAGS_SL) -shared -o $@
 else
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_SL) -G -o $@ $<
+	$(CC) $(CFLAGS) $< $(LDFLAGS) $(LDFLAGS_SL) -G -o $@
 endif
 
 sqlmansect = 5sql

src/test/thread/Makefile

@@ -18,7 +18,7 @@ all: thread_test
 
 thread_test: thread_test.o
 # no need for $LIBS, might not be compiled yet
-	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_EX) $^ $(PTHREAD_LIBS) -o $@
+	$(CC) $(CFLAGS) $^ $(LDFLAGS) $(LDFLAGS_EX) $(PTHREAD_LIBS) -o $@$(X)
 
 clean distclean maintainer-clean:
 	rm -f thread_test$(X) thread_test.o