Eliminate parallel-make hazard in ecpg/preproc.

tglsfdc · tglsfdc · commit 29180e5d78e5 · 2018-12-01T17:19:51.000-05:00
Re-making ecpglib's typename.o is dangerous because another make thread could be doing that at the same time. While we've not heard field complaints traceable to this, it seems inevitable that it'd bite someone eventually. Instead, symlink typename.c into the preproc directory and recompile it there. That file is small enough that compiling it twice isn't much of a penalty. Furthermore, this way we get a .o file that's made without shlib CFLAGS, which seems cleaner. This requires adding more stuff to the module's -I list. The MSVC aspect of that is untested, but I'm sure the buildfarm will tell me if I got it wrong. Per a suggestion from Peter Eisentraut. Although this is theoretically a bug fix, the lack of field reports makes me feel we needn't back-patch. Discussion: https://postgr.es/m/31364.1543511708@sss.pgh.pa.us
diff --git a/src/interfaces/ecpg/preproc/.gitignore b/src/interfaces/ecpg/preproc/.gitignore
@@ -2,5 +2,5 @@
 /preproc.c
 /preproc.h
 /pgc.c
-
+/typename.c
 /ecpg
diff --git a/src/interfaces/ecpg/preproc/Makefile b/src/interfaces/ecpg/preproc/Makefile
@@ -16,13 +16,16 @@ top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
 override CPPFLAGS := -I../include -I$(top_srcdir)/src/interfaces/ecpg/include \
-	-I. -I$(srcdir) -DECPG_COMPILE \
-	 $(CPPFLAGS)
+	-I. -I$(srcdir) \
+	-I$(top_srcdir)/src/interfaces/ecpg/ecpglib \
+	-I$(libpq_srcdir) \
+	-DECPG_COMPILE \
+	$(CPPFLAGS)
 
 override CFLAGS += $(PTHREAD_CFLAGS)
 
 OBJS=	preproc.o pgc.o type.o ecpg.o output.o parser.o \
-	keywords.o c_keywords.o ecpg_keywords.o ../ecpglib/typename.o descriptor.o variable.o \
+	keywords.o c_keywords.o ecpg_keywords.o typename.o descriptor.o variable.o \
 	$(WIN32RES)
 
 # Suppress parallel build to avoid a bug in GNU make 3.82
@@ -36,8 +39,9 @@ all: ecpg
 ecpg: $(OBJS) | submake-libpgport
 	$(CC) $(CFLAGS) $(LDFLAGS) $(LDFLAGS_EX) $^ $(LIBS) $(PTHREAD_LIBS) -o $@$(X)
 
-../ecpglib/typename.o: ../ecpglib/typename.c
-	$(MAKE) -C $(dir $@) $(notdir $@)
+# We symlink typename.c from ecpglib and recompile it here
+typename.c: % : $(top_srcdir)/src/interfaces/ecpg/ecpglib/%
+	rm -f $@ && $(LN_S) $< .
 
 # See notes in src/backend/parser/Makefile about the following two rules
 preproc.h: preproc.c
@@ -64,6 +68,7 @@ uninstall:
 
 clean distclean:
 	rm -f *.o ecpg$(X)
+	rm -f typename.c
 
 # `make distclean' must not remove preproc.y, preproc.c, preproc.h, or pgc.c
 # since we want to ship those files in the distribution for people with
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
@@ -291,6 +291,7 @@ sub mkvcbuild
 	my $ecpg = $solution->AddProject('ecpg', 'exe', 'interfaces',
 		'src/interfaces/ecpg/preproc');
 	$ecpg->AddIncludeDir('src/interfaces/ecpg/include');
+	$ecpg->AddIncludeDir('src/interfaces/ecpg/ecpglib');
 	$ecpg->AddIncludeDir('src/interfaces/libpq');
 	$ecpg->AddPrefixInclude('src/interfaces/ecpg/preproc');
 	$ecpg->AddFiles('src/interfaces/ecpg/preproc', 'pgc.l', 'preproc.y');
