#35 Berkeley db module configure error

[Jerry James]

The berkeley-db module's configure script adds -Werror to CFLAGS. With recent versions of GCC, this code triggers a warning (and therefore an error) about the use of an uninitialized variable:

DB_ENV dbe; dbe.set_errcall(&dbe,&my_callback);

There are multiple possible fixes. I chose to also add -Wno-uninitialized to CFLAGS in this patch. Not adding -Werror is another option.

[Jerry James]

Patch to add -Wno-uninitialized to CFLAGS

[Sam Steingold]

the configure check is there for a good reason.
this works fine with clang-900.0.38 on x86_64-apple-darwin16.7.0,

[Jerry James]

I'm not sure what "works fine" means, as this depends on which warning flags you pass to the compiler. With the default flags used by Fedora, namely "-Wall", the configure script incorrectly says:

checking whether DB_ENV->set_errcall() accepts DBE... no

It does, in fact, accept DBE. In config.log I see:

configure:5749: checking whether DB_ENV->set_errcall() accepts DBE
configure:5769: gcc -c -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic -Wa,--noexecstack -Werror -I/usr/include/libsvm conftest.c >&5
conftest.c: In function 'main':
conftest.c:51:16: error: 'dbe.set_errcall' is used uninitialized in this function [-Werror=uninitialized]
DB_ENV dbe; dbe.set_errcall(&dbe,&my_callback);
~~~^~~~~~~~~~~~
cc1: all warnings being treated as errors
configure:5769: $? = 1
configure: failed program was:
| / confdefs.h /
...

When building with clang, do you have -Wall in CFLAGS? Is DB_ENV->set_errcall() detected as accepting DBE?

[Sam Steingold]

Yes, DB_ENV->set_errcall() is correctly detected:

configure:5749: checking whether DB_ENV->set_errcall() accepts DBE
configure:5769: gcc -c -g -O2 -Werror -I/usr/local/include conftest.c >&5
configure:5769: $? = 0
configure:5777: result: yes

if your system passes "unusual" options to gcc, this is probably not the right place to discuss this.
Either autoconf should handle this, or the system should not modify gcc command line options.
At any rate, please discuss this with the autoconf maintainers and bring back their verdict on how this issue is to be handled.
Thanks.