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Subject: Re: ABI compatibility between versions
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On Tue, Feb 26, 2019 at 10:58:38AM +0100, Szabolcs Nagy wrote:
> other than the bug compatibility, a difference between the
> two approaches is that glibc may do certain abi breaking
> changes while keeping old binaries work, that musl cant do.

I feel this statement is unfair to musl.

AFAICS symbol versioning does not allow "breaking" the ABI, but
*extending* it with new entry points (made to look like the old ones in
the API, which makes the old ones inaccessible via the API).

This is also exactly what musl can do, extend the ABI.
The difference is how to reflect those changes in the API.

Keeping the old API on top of a subset of the occasionally extended ABI
is what glibc does and musl does not.

Regarding old binaries API stability is irrelevant.

Rune