Re: [PATCH 1/1] configure.ac: attempt mysql_config to find the MySQL headers.

[Heinrich Schuchardt]

On 3/6/20 10:38 PM, Michael Orlitzky wrote:
> When building with MySQL support, the configure script guesses that
> the path to the MySQL headers is /usr/include/mysql. That is usually
> correct, but when people install MySQL to a nonstandard location such
> as /home/mjo/usr, it falls over. Fortunately, MySQL usually provides
> an executable called "mysql_config" that can output the location of
> its headers.
>
> In such a "local" installation, if I prepend /home/mjo/usr/bin to my
> PATH, then running "mysql_config" will execute the mysql_config from
> /home/mjo/usr/bin and will therefore output -I/home/mjo/usr/include as
> the preprocessor flag that glpk needs. That's the right thing to do,
> and it works just as well for a system install under /usr or
> /usr/local.
>
> This commit attempts to find the headers using mysql_config first,
> and falls back to the location /usr/include/mysql.
>
> Gentoo-bug: https://bugs.gentoo.org/597620
> ---
>   configure.ac | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/configure.ac b/configure.ac
> index 96c4cc5..d20a6ef 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -145,7 +145,10 @@ if test "$enable_mysql" = "yes"; then
>         AC_MSG_ERROR([--enable-mysql requires --enable-dl])
>      fi
>      AC_MSG_RESULT([yes])
> -   CPPFLAGS="-I/usr/include/mysql $CPPFLAGS"
> +   # Guess at the include directory if mysql_config isn't in our PATH.
> +   MYSQL_INCLUDE=$(mysql_config --include 2>/dev/null)
> +   test -z "${MYSQL_INCLUDE}" && MYSQL_INCLUDE="-I/usr/include/mysql"
> +   CPPFLAGS="${MYSQL_INCLUDE} $CPPFLAGS"

Thanks for your suggestion.

Should we only use 'mysql_config --include' or the more comprehensive
'mysql_config --cflags'?

In the scenario that you describe wouldn't the library also be installed
in a user path. So would we have to consider 'mysql_config --libs'?

Of cause you already can pass CPPFLAGS and LDFLAGS to ./configure to
specify your special directories.

On my computer I get:

$ mysql_config --include
-I/usr/include/mysql

$ mysql_config --cflags
-I/usr/include/mysql -g -g -fabi-version=2 -fno-omit-frame-pointer
-fno-strict-aliasing

$ mysql_config --libs
-L/usr/lib/arm-linux-gnueabihf -lmysqlclient -lpthread -lz -lm -ldl

Best regards

Heinrich

>      AC_DEFINE_UNQUOTED([MYSQL_DLNAME], ["$LIBMYSQL"], [N/A])
>   else
>      AC_MSG_RESULT([no])