[Buildroot] [PATCH] flex: fix autobuilder failures

[Buildroot] [PATCH] flex: fix autobuilder failures

[Thomas Petazzoni]

Since fe6a9e5e9d (flex: needs M4 at runtime), the autobuilders have
been producing a number of flex related build failures. They have been
hard to track down, because even on the same machine, with the same
Git commit ID and the same configuration, the failure could not be
reproduced.

However, a close inspection of flex's config.log file allowed to find
out what the problem was. In its configure script, flex uses the
host-flex to generate a minimal example, and find out the name of the
output file of flex.

When the M4 environment is passed when building the target flex, it
also affects the *execution* of the host-flex, which tries to use
/usr/bin/m4 (which doesn't exist in the autobuilder machines) instead
of the one built in $(HOST_DIR)/usr/bin/m4. So generating the minimal
example fails. And this is where what I could reproduce and what the
autobuilders script produce differ: in my case, even though host-flex
fails to run, it creates an empty lex.yy.c, which is enough to make
the configure script happy. In the context of the autobuild scripts,
this file is apparently not created at all, for an unknown reason, and
this leads to the configure script to abort.

The fix is to set ac_cv_path_M4. This will affect the default m4 used
by the target flex, but it will not affect the m4 used by the
host-flex. It allows the test made during the configure script to work
properly, and therefore should fix the issue seen in the autobuilders.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
 package/flex/flex.mk |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/package/flex/flex.mk b/package/flex/flex.mk
index 748365b..2361536 100644
--- a/package/flex/flex.mk
+++ b/package/flex/flex.mk
@@ -11,7 +11,7 @@ FLEX_LICENSE = FLEX
 FLEX_LICENSE_FILES = COPYING
 FLEX_DEPENDENCIES = \
 	$(if $(BR2_PACKAGE_GETTEXT_IF_LOCALE),gettext) host-m4
-FLEX_CONF_ENV = M4=/usr/bin/m4
+FLEX_CONF_ENV = ac_cv_path_M4=/usr/bin/m4
 # we don't have a host-gettext/libintl
 HOST_FLEX_DEPENDENCIES = host-m4
 
-- 
1.7.9.5

[Buildroot] [PATCH] flex: fix autobuilder failures

[Peter Korsgaard]

>>>>> "Thomas" == Thomas Petazzoni <thomas.petazzoni@free-electrons.com> writes:

 Thomas> Since fe6a9e5e9d (flex: needs M4 at runtime), the autobuilders have
 Thomas> been producing a number of flex related build failures. They have been
 Thomas> hard to track down, because even on the same machine, with the same
 Thomas> Git commit ID and the same configuration, the failure could not be
 Thomas> reproduced.

 Thomas> However, a close inspection of flex's config.log file allowed to find
 Thomas> out what the problem was. In its configure script, flex uses the
 Thomas> host-flex to generate a minimal example, and find out the name of the
 Thomas> output file of flex.

 Thomas> When the M4 environment is passed when building the target flex, it
 Thomas> also affects the *execution* of the host-flex, which tries to use
 Thomas> /usr/bin/m4 (which doesn't exist in the autobuilder machines) instead
 Thomas> of the one built in $(HOST_DIR)/usr/bin/m4. So generating the minimal
 Thomas> example fails. And this is where what I could reproduce and what the
 Thomas> autobuilders script produce differ: in my case, even though host-flex
 Thomas> fails to run, it creates an empty lex.yy.c, which is enough to make
 Thomas> the configure script happy. In the context of the autobuild scripts,
 Thomas> this file is apparently not created at all, for an unknown reason, and
 Thomas> this leads to the configure script to abort.

 Thomas> The fix is to set ac_cv_path_M4. This will affect the default m4 used
 Thomas> by the target flex, but it will not affect the m4 used by the
 Thomas> host-flex. It allows the test made during the configure script to work
 Thomas> properly, and therefore should fix the issue seen in the autobuilders.

 Thomas> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Committed, thanks.

-- 
Bye, Peter Korsgaard