Re: Lua on Ubuntu - again

[Hans-Bernhard B. <HBB...@t-...>]

On 18.02.2011 21:42, Ethan A Merritt wrote:

>> In practice this means that the variable LUA_LIBS will be set to "-llua"
>> even if it was explicitly overridden on the command line.
>
> That's not what the AC_SEARCH_LIBS macro is supposed to do,
> according to its documentation.

I don't think the problem is what AC_SEARCH_LIBS does by itself.  It's 
what we do with the result in our call of it.  In our ACTION-IF-FOUND we 
explicitly set LUA_LIBS='-llua' if AC_SEARCH_LIBS succeeded, even though 
we don't know if -llua actually was the library that fulfilled the test. 
  Then later we append $(LUA_LIBS) to TERMLIBS.

> That's because it had already constructed a correct environment by
> executing pkgconfig.

But we don't trust it, and thus decide to override the result.  That's 
where the problem is.

We need to check the result variable ac_cv_search_luaL_openlibs.  If it 
contains "none_needed", we should leave alone LUA_LIBS, otherweise 
append $(ac_cv_search_luaL_openlibs) instead of a hardcoded value.

> The intent is that even if we failed to find or invoke pkgconfig, we can
> still test if -llua is sufficient to pull in the library.

But as-is we unconditionally pull in -llua, even if the actual library 
name is a different one.

> OK.  That line
>      LUA_LIBS='-llua'
> is quite possibly wrong.  But if you remove it, then you also have to
> also remove the fourth line below it:
>      LIBS='$_libs"

It should suffice to move the line into the ACTION-IF-NOT-FOUND branch 
of the AC_SEARCH_LIBS call.

Or maybe just move the entire AC_SEARCH_LIBS call into the else branch 
of the PKG_CHECK_MODULES one.