zstd_legacy.h is missing - include attempted when ZSTD_LEGACY_SUPPORT is defined about zstd

[Cyan4973]

It is present in the legacy folder

The provided Makefile is supposed to automatically include this directory.

[TurtleSimos]

Ah, my mistake - I was updating ZStd in lzbench, which doesn't have the folder.

How about defaulting ZSTD_LEGACY_SUPPORT to 0, so that the legacy folder is only required if specifically desired?

[Cyan4973]

It's a matter of preference.
I'm not sure whichever option is better "by default".
So I opted for the "safer" one, so that people / projects having used Zstd prior version don't get accidentally blocked.

[TurtleSimos]

Sure, understood. I was assuming from the major version being zero, that api changes were assumed to be okay at any time. That is minor issue with semantic versioning before the first major release.
Thank you.

[Cyan4973]

Actually, thinking again about it, something I could do and feels logical :

• when built using the default provided Makefile : set ZSTD_LEGACY_SUPPORT to 1
• when file is just being copy pasted into another project and no ZSTD_LEGACY_SUPPORT value is provided, set it to 0

This way, when including zstd into another project, the expectation, in general, is to not need additional legacy files.

[TurtleSimos]

That looks to be a very good solution to me. It is difficult to balance having the code out there for people to use and report bugs etc, before committing to a major version. Keeping the main lib folder as current and self sufficient would make adoption easy, while minimizing the penalty for early adoptors to migrate to changes.

[Cyan4973]

pushed into dev branch