bug#20894: make libgnu.a doesn't generate everything it requires

bug#20894: make libgnu.a doesn't generate everything it requires

[Glenn Morris]

Package: emacs
Version: 25.0.50

Current master on x86_64 RHEL7:

make maintainer-clean
configure
cd lib
make libgnu.a

Fails with:

  In file included from binary-io.c:3:0:
  binary-io.h: In function 'set_binary_mode':
  binary-io.h:57:10: error: 'O_BINARY' undeclared (first use in this function)

'make libgnu.a' doesn't generate the lib/ version of fcntl.h, which is
what defines O_BINARY.

In contrast, 'make all' (in lib) does.

I noticed this because src/temacs depends on libgnu.a and calls 'make
libgnu.a' to create it (I would like 'make -C src emacs' to work).

Perhaps it should call 'make -C lib all' instead (an Emacs issue);
or perhaps 'make libgnu.a' should generate the files it requires
(a gnulib issue?).

bug#20894: make libgnu.a doesn't generate everything it requires

[Glenn Morris]

Glenn Morris wrote:

> Perhaps it should call 'make -C lib all' instead (an Emacs issue);

Same thing for lib-src/Makefile.

bug#20894: make libgnu.a doesn't generate everything it requires

[Paul Eggert]

> 'make libgnu.a' doesn't generate the lib/ version of fcntl.h, which is
> what defines O_BINARY.
>
> In contrast, 'make all' (in lib) does.

That's a known problem with Automake, when dependency checking is turned on. 
The short version is that it can't compute dependencies until it has the .h 
files, and it can't make the .h files until it knows the dependencies.  The 
usual workaround is BUILT_SOURCES, but as the Automake manual says in 
<http://www.gnu.org/software/automake/manual/html_node/Sources.html>:

=====
It might be important to emphasize that BUILT_SOURCES is honored only by ‘make 
all’, ‘make check’ and ‘make install’. This means you cannot build a specific 
target (e.g., ‘make foo’) in a clean tree if it depends on a built source. 
However it will succeed if you have run ‘make all’ earlier, because accurate 
dependencies are already available.
=====

Ways to work around this issue are described in 
<http://www.gnu.org/software/automake/manual/html_node/Built-Sources-Example.html>. 
  They are all a bit of a pain, though, and the simplest thing is probably to 
say “don't try to make libgnu.a by hand without doing an ordinary make first”....

> (I would like 'make -C src emacs' to work).

*That* we can arrange.

> Perhaps it should call 'make -C lib all' instead (an Emacs issue);

Yes, that's an easy way to arrange things.  I installed that as part of commit 
319eeeb0fb154a0cd1d36ec33c68029ff9d6c290.  Good enough?

bug#20894: make libgnu.a doesn't generate everything it requires

[Glenn Morris]

Paul Eggert wrote:

>> (I would like 'make -C src emacs' to work).
>
> *That* we can arrange.
>
>> Perhaps it should call 'make -C lib all' instead (an Emacs issue);
>
> Yes, that's an easy way to arrange things.  I installed that as part
> of commit 319eeeb0fb154a0cd1d36ec33c68029ff9d6c290.  Good enough?

'make -C src emacs' now works, but 'make -j8 -C src emacs' fails in lib with

  GEN      stddef.h
  mv: cannot stat 'alloca.h-t': No such file or directory
  make[2]: *** [alloca.h] Error 1

bug#20894: make libgnu.a doesn't generate everything it requires

[Paul Eggert]

[-- Attachment #1: Type: text/plain, Size: 321 bytes --]

Glenn Morris wrote:
> 'make -C src emacs' now works, but 'make -j8 -C src emacs' fails in lib with
>
>    GEN      stddef.h
>    mv: cannot stat 'alloca.h-t': No such file or directory

Hmm, well, I'm sure there are other dependency bugs like that in the makefiles 
somewhere.  Anyway I fixed this bug with the attached.

[-- Attachment #2: 0001-Fix-submake-dependency-bug-with-.h-files.patch --]
[-- Type: text/x-diff, Size: 976 bytes --]

From 1dbeff026f3dd8244d648501cfcb84621dc3a655 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Thu, 25 Jun 2015 13:31:18 -0700
Subject: [PATCH] Fix submake dependency bug with .h files

* src/Makefile.in ($(libsrc)/make-docfile$(EXEEXT)):
Depend on $(lib)/libgnu.a, so that we build $(lib)/*/*.h
before the submake in $(libsrc) would spin off a subsubmake
for $(lib) in parallel with our submake for $(lib) (Bug#20894).
---
 src/Makefile.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Makefile.in b/src/Makefile.in
index bfb911e..1fb770d 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -529,7 +529,7 @@ $(etc)/DOC: lisp.mk $(libsrc)/make-docfile$(EXEEXT) $(obj) $(lisp)
 	$(AM_V_at)$(libsrc)/make-docfile -a $(etc)/DOC -d $(lispsource) \
 	  $(shortlisp)
 
-$(libsrc)/make-docfile$(EXEEXT):
+$(libsrc)/make-docfile$(EXEEXT): $(lib)/libgnu.a
 	$(MAKE) -C $(libsrc) make-docfile$(EXEEXT)
 
 buildobj.h: Makefile
-- 
2.1.4

bug#20894: make libgnu.a doesn't generate everything it requires

[Glenn Morris]

Thanks, it works now.