Re: Wget2 cross-compile on iOS arm64

[Ryan Schmidt]

On Mar 23, 2021, at 04:01, Jeffrey Walton wrote:

> On Tue, Mar 23, 2021 at 12:38 AM Ryan Schmidt wrote:
>> 
>> On Mar 22, 2021, at 17:56, Jeffrey Walton wrote:
>> 
>>> It looks like  this is an Autotools problem. Autotools should test if
>>> ccp works as expected, and avoid cpp if it does not. Autotools should
>>> not break the build.
>>> 
>>> Perl works around Apple's cpp:
>>> https://github.com/Perl/perl5/blob/blead/hints/darwin.sh#L131.
>> 
>> You're referring to the part of their code that adds -no-cpp-precomp if the 
>> compiler accepts it? The last version of Apple gcc that did anything in 
>> response to -no-cpp-precomp was Apple gcc 3.1. Apple gcc 3.3 and later do 
>> nothing in response to -no-cpp-precomp. That flag is ancient history.
>> 
> Actually I was talking about the comment that says, " Avoid Apple's
> cpp precompiler".


.....this is the block of code including that comment:



# Avoid Apple's cpp precompiler, better for extensions
if [ "X`echo | ${cc} -no-cpp-precomp -E - 2>&1 >/dev/null`" = "X" ]; then
    cppflags="${cppflags} -no-cpp-precomp"

    # This is necessary because perl's build system doesn't
    # apply cppflags to cc compile lines as it should.
    ccflags="${ccflags} ${cppflags}"
fi



So they wish to avoid Apple's cpp precompiler ("cpp-precomp"), and the way that 
they do that is that they test whether the compiler supports the flag 
"-no-cpp-precomp" and if so they add that flag which instructs Apple gcc to use 
gcc's standard preprocessor instead.

cpp-precomp existed in Apple gcc 3.1 and earlier. Apple removed it in Apple gcc 
3.3 and later. In Apple gcc 3.3 and later the flag "-no-cpp-precomp", while 
still accepted, is ignored and does nothing. gcc's standard preprocessor is 
used in all cases in Apple gcc 3.3 and later. See the release notes:

https://opensource.apple.com/source/gccfast/gccfast-1626/AppleReleaseNotes.html?f=text

Apple gcc as a whole has been dead for a decade already. We use clang now.

So again, what you're talking about is ancient history and is not the cause of 
the build failure you saw. I believe the cause of the build failure you saw is 
that you weren't providing the right flags to accomplish cross-compilation. I 
showed a set of flags that worked for me and I suggest you work from there.