Re: [lmi] [PATCH] Add script allowing to install any wxWidgets version from Git

[Greg Chicares]

On 2018-04-06 22:42, Vadim Zeitlin wrote:
> On Fri, 6 Apr 2018 13:31:31 +0000 Greg Chicares <address@hidden> wrote:
> 
> [...]
> GC> > Should we do it like this?
> GC> 
> GC> If I've understood this correctly, then yes, please.
> 
>  I think https://github.com/vadz/lmi/pull/80 should do it, at least it
> seems to work for me both when cloning from the GitHub wxWidgets repository
> and when cloning from a local mirror.

Let me ask a couple questions about 'skip_update'.

(1) It occurs only on these three lines:

$grep skip_update install_wx.sh 
        skip_update=1
    [ -n "$skip_update" ] || git checkout "$wx_commit_sha"
if [ "$skip_update" != 1 ]

so it can only be either null or 1, but the tests differ. Can I replace the
last line as follows, just for uniformity, or am I missing some nuance?

-if [ "$skip_update" != 1 ]
+if [ -n "$skip_update" ]

Oh, wait: '-n" doesn't test whether it's null: it tests whether it's nonnull.
So '-z' would be the appropriate alternative there. But because I obviously
can't make sense of '-n' without extreme effort, let me ask instead whether
the middle line could be replaced thus:
-   [ -n "$skip_update" ] || git checkout "$wx_commit_sha"
+   [ "$skip_update" = 1 ] || git checkout "$wx_commit_sha"

(2) Wouldn't the following be a pure refactoring (and simpler)?

    if [ $(git rev-parse HEAD) = "$wx_commit_sha" ]
    then
+       git checkout "$wx_commit_sha"
        # Don't bother updating anything if we already had the correct version
        # of the tree.
        skip_update=1
    else
        # Get the missing commit from the upstream repository if we don't have
        # it yet.
        if ! git rev-parse --quiet --verify "$wx_commit_sha^{commit}" >/dev/null
        then
            git fetch "$wx_git_url"
        fi
[or move the '+' line here if I still don't understand 'test -n']
    fi

-   [ -n "$skip_update" ] || git checkout "$wx_commit_sha"

>  Please note that if you use a local mirror in some/where/wxWidgets, you
> need to set up the submodule mirrors under some/where directory and use
> the last component of their URLs, _not_ paths, as the repositories names
> (which is confusing because they're similar, or even identical, for zlib,
> but not the same). I.e. you need to have Catch.git, libexpat.lib,
> libpng.git and zlib.git (and not "catch", "expat", "png" and "zlib"). Also
> note that while they can (and arguably should) be bare repositories, you
> can also just use symlinks to the existing subdirectories of your wxWidgets
> working tree, e.g. I just did
> 
>       $ cd some/where
>       $ ln -s wxWidgets/3rdparty/catch Catch.git
>       $ ln -s wxWidgets/src/expat libexpat.git
>       $ ln -s wxWidgets/src/png libpng.git
>       $ ln -s wxWidgets/src/zlib zlib.git
> 
> here. And, of course, if you want to make the "real" bare repositories, you
> can clone from these existing directories too, in order to avoid
> re-downloading everything from GitHub.

I feel certain that I want a local mirror, and I imagine I want it to
contain "real" bare repositories.

Let's take libpng as an example.
- Do I mirror "git://git.code.sf.net/p/libpng/code"? Or does wx git
  contain its own libpng git repository that I can mirror instead?
  And if so, would you please tell me the command to do that?
  [Unless you already did tell me--see my confusion below.]
- If I can mirror a bare libpng repository from wx, then does that
  avoid the
    
https://github.com/wxWidgets/wxWidgets/blob/master/docs/contributing/how-to-update-third-party-library.md
    "We use a special hack for libpng"
  issues, or do I have to implement that special hack myself?

I ran './install_wx.sh' before PR #80, which executed this line:
  git clone "$wx_git_url" ${wx_dir##*/}
and I ran
  wx_skip_clean=1 ./install_wx.sh
after applying PR #80. Now the clone is up to date:
  /opt/lmi/third_party/src/wxWidgets[0]$git rev-parse HEAD                      
     
  41045df7ea5f93e4c07c1bd846d7127a372705bd
and, if I understand the 'skip_update' logic correctly, there's
nothing more that the script should do--the new PR #80 section
is skipped. If that's right, then I should have all the submodules
I need. But I seem to have none, because there's no '.gitmodules':
  /opt/lmi/third_party/src/wxWidgets[0]$ls -a .git/       
  .  ..  HEAD  branches  config  description  hooks  index  info  logs  objects 
 packed-refs  refs
And I had hoped that maybe wxWidgets/src/png would contain its
own '.git' subdirectory, but it doesn't. Is this merely because
41045df7ea didn't yet use submodules?