[[ Bug 23234 ]] Fix iOS standalone build error when running from source

[livecodepanos]

This patch fixes the error:

Failed to open macho file at 
/../Xcodes/Xcode_12_5_0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ 
for reading: Too many levels of symbolic links

It seems there is a chance g++ is not symlinked correctly, so use the full path to clang++ instead.

Closes https://quality.livecode.com/show_bug.cgi?id=23234

[runrevmark]

Why is this only an issue when running from source?

In any case, please file a BZ issue so it has an issue number and update commit message / PR appropriately.

[livecodepanos]

@runrevmark Done :)

Does it need a release note, or is it considered "internal"?

[runrevmark]

I think its esoteric enough that it doesn't need a release note - although how is g++ not symlinked correctly? Is it something about your setup? Something one of our internals setup scripts does?

[livecodepanos]

I do not think it is my setup, since @montegoulding experienced the same issue a couple of months ago with Xcode 12.4. It might be because of a change in recent Xcodes, since I see this error with Xcode 12.5, but not with Xcode 11.3 in a different Mac.

My understanding is that somehow g++ symlinks to Xcode_12_5_0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++, but the latter is a symlink as well (to Xcode_12_5_0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang), hence the too many symbolic links error.

[runrevmark]

Okay so it sounds like it isn't necessarily a build from source issue then - isn't the modified code in code that runs in a built IDE too?

[livecodepanos]

The modified code is in the S/B, which does run in a built IDE too. It does not seem to happen with Xcode 12.1, otherwise people would have noticed. We have not released a build that supports Xcode 12.4 or Xcode 12.5 so far, so I am not entirely sure if this is a build from source issue or a general Xcode12.4+ issue. I think I will be able to tell if this is the case when #7579 is merged and we kick off a new build. So I am marking this PR as WIP until then

[runrevmark]

Ah! Okay well if it is an xcode 12.4/12.5 issue then it doesn't need a release note as it won't have affected anyone :)

[runrevmark]

@livecodepanos Is this definitely an issue we need to resolve for the new Xcode update?

[livecodepanos]

@runrevmark I have checked with a built version of 9.6.3 rc1 from staging, with Xcode 12.5, and this issue is not present. So it seems it happens only when building from source.