[FFmpeg-user] Unable to configure ffmpeg on FreeBSD

[Tom Evans]

On Wed, Nov 7, 2012 at 10:16 AM, Tom Evans <tevans.uk at googlemail.com> wrote:
> On Tue, Nov 6, 2012 at 5:21 PM, Tom Evans <tevans.uk at googlemail.com> wrote:
>> Hi all
>>
>> I have a problem getting ffmpeg's configure to work properly when
>> specifying "--cc" and "--as" on the configure line.
>>
>> What seems to happen is that configure thinks that the "--as" argument
>> supplied is actually a c compiler, and tests to see if it is LLVM etc.
>>
>> This hangs, because 'as -v' prints the version and then waits for
>> input ('cc -v' prints the version and exits).
>>
>> Eg:
>>
>>> $ ./configure --as=/usr/local/bin/as --cc=/usr/local/bin/gcc46 --extra-libs=-L/usr/local/lib --extra-cflags="-I/usr/local/include"
>>
>>
>>> $ pstree 43143
>> -+= 43143 tom /bin/sh ./configure --as=/usr/local/bin/as
>> --cc=/usr/local/bin/gcc46 --extra-libs=-L/usr/local/lib
>> --extra-cflags=-I/usr/local/include
>>  |--- 43280 tom /usr/local/bin/as -v
>>  \--- 43281 tom grep -q ^gcc.*LLVM
>>
>> This check is around line 2486 in my current sources (pulled today):
>>
>>> $ grep -A 4 -B 1 -n gcc\.\*LLVM configure
>> 2485-
>> 2486:    if $_cc -v 2>&1 | grep -q '^gcc.*LLVM'; then
>> 2487-        _type=llvm_gcc
>> 2488-        gcc_extra_ver=$(expr "$($_cc --version | head -n1)" : '.*\((.*)\)')
>> 2489-        _ident="llvm-gcc $($_cc -dumpversion) $gcc_extra_ver"
>> 2490-        _depflags='-MMD -MF $(@:.o=.d) -MT $@'
>>
>>
>> I've tried re-ordering where --cc and --as appear, with no effect.
>> There are no CC or AS environment variables set.
>>
>> Cheers
>>
>> Tom
>
> Having done a git bisect, the error was introduced in:
>
>
> a758c5e2594893c0e7e1c5d966d6e486e2a77bb3 is the first bad commit
> commit a758c5e2594893c0e7e1c5d966d6e486e2a77bb3
> Author: Mans Rullgard <mans at mansr.com>
> Date:   Fri Jul 20 13:43:07 2012 +0100
>
>     build: do full flag handling for all compiler-type tools
>
>     This adds a full identification probe of CC, AS, LD and HOSTCC,
>     and sets up correct flags and dependency tracking for each.
>
>     Signed-off-by: Mans Rullgard <mans at mansr.com>
>
> :100644 100644 478ffcab4b2bc3fe98fd62e852ef6f765bcd1796
> 90b90fc18406b284db463c5e4e7019ce4d0bd4cf M      Makefile
> :100755 100755 c91b5f1ef2c057775d85b2d16884b3aab6c20db0
> fd903692122baf0b3e16234974554e6987ab1dd8 M      configure
>
> I've not yet looked at the commit..
>
> Cheers
>
> Tom

So this commit abstracted out testing $cc to a function, probe_cc().
For some reason, configure also calls probe_cc with $as and $ld, but
the tests inside probe_cc are solely testing the compiler.

The aim of calling probe_cc with $as arguments seems to be to set
$as_type and $as_ident (also $ld_type and $ld_ident), which don't seem
to be used elsewhere in the configure script at all. It just looks
entirely bogus to me.

Commenting out calls to 'probe_cc as "$as"' and 'probe_cc ld "$ld"'
allow current git to configure correctly when supplied --as argument.

Cheers

Tom