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Re: archive of archives

Hi NightStrike,

$ x86_64-w64-mingw32-ar  cru liba.a libb.a
$ x86_64-w64-mingw32-ranlib liba.a

The resulting liba.a doesn't work too well:

$ x86_64-w64-mingw32-nm liba.a
x86_64-w64-mingw32-nm: liba.a: File format not recognized

No, it's not supposed to work.

We use an MRI linker script to combine 3 libX.a files into a single
libZ.a file.  It seems to work.

This is because you can put any file you like into an archive, including other archives. BUT - you cannot construct a symbol index for this sort of nested archive[1] and it will not be recognised by other tools that are expecting an archive consisting solely of object files.

For example:

  % echo "first" > f1
  % echo "second" > f2
  % ar cr libfoo.a f1 f2

You can print and extract files from this non-object-file archive:

  % ar t libfoo.a
  % mv f1 f1.saved
  % ar x libfoo.a f1
  % cmp f1 f1.saved

But try to run a binary tool on it and:

  % nm libfoo.a
  nm: f1: File format not recognized
  nm: f2: File format not recognized

Based on what you are saying, are we
doing something that will not be supported in the future?

I know of no plans to add support for this kind of feature. If you want to merge multiple libraries into a single big library, either make the new library a thin library or else extract and add the contents of each input library one by one. This is free software however, so if you feel the need, please do create a patch to handle nested archives and submit it for review... :-)


[1] Actually you can use the 's' option to ar or run ranlib, and it will appear to work, but nothing will happen. No symbol table will be constructed. This could be considered to be a bug.

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