diff options
Diffstat (limited to 'src/backend/parser')
| -rw-r--r-- | src/backend/parser/Makefile | 17 |
1 files changed, 11 insertions, 6 deletions
diff --git a/src/backend/parser/Makefile b/src/backend/parser/Makefile index fdd8485cec5..161251a2f91 100644 --- a/src/backend/parser/Makefile +++ b/src/backend/parser/Makefile @@ -28,12 +28,17 @@ endif # There is no correct way to write a rule that generates two files. # Rules with two targets don't have that meaning, they are merely -# shorthand for two otherwise separate rules. To be safe for parallel -# make, we must chain the dependencies like this. The semicolon is -# important, otherwise make will choose the built-in rule for -# gram.y=>gram.c. - -gram.h: gram.c ; +# shorthand for two otherwise separate rules. If we have an action +# that in fact generates two or more files, we must choose one of them +# as primary and show it as the action's output, then make all of the +# other output files dependent on the primary, like this. Furthermore, +# the "touch" action is essential, because it ensures that gram.h is +# marked as newer than (or at least no older than) gram.c. Without that, +# make is likely to try to rebuild gram.h in subsequent runs, which causes +# failures in VPATH builds from tarballs. + +gram.h: gram.c + touch $@ gram.c: BISONFLAGS += -d gram.c: BISON_CHECK_CMD = $(PERL) $(srcdir)/check_keywords.pl $< $(top_srcdir)/src/include/parser/kwlist.h |