src,doc: fix alpha tag on non-alpha releases

[lazerg]

NODE_ALPHA_MAJOR_VERSION is defined as 0 rather than left undefined, so the #ifdef guard held for every release build. That is how v26.8.0 shipped as v26.8.0-alpha.0.0.0. 26.8.1 is out and the macros are gone from v26.x, but main still carries them, so v27 can hit the same thing.

The tag now depends on the alpha version actually being set. Macros at zero, or missing entirely, both give a plain release. The cost is that the first alpha starts at 0.0.1 rather than 0.0.0.

Refs: #65566

[nodejs-github-bot]

Review requested:

• @nodejs/tsc

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.07%. Comparing base (abb365a) to head (193b5e8).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65567      +/-   ##
==========================================
- Coverage   90.07%   90.07%   -0.01%     
==========================================
  Files         751      751              
  Lines      254875   254875              
  Branches    48115    48117       +2     
==========================================
- Hits       229586   229583       -3     
- Misses      16467    16472       +5     
+ Partials     8822     8820       -2     

see 36 files with indirect coverage changes

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[aduh95]

I'm not sure this is helping, instead of having 3 macros we'd have 4 🤔 I don't think it's making it less likely to slip into a non-alpha release either

[lazerg]

Fair on the macro count, I dropped the extra one. The guard now reads the three that already exist:

#if NODE_ALPHA_MAJOR_VERSION || NODE_ALPHA_MINOR_VERSION || NODE_ALPHA_PATCH_VERSION

On the second point, I think this version does help. 26.8.0 went out alpha-tagged without anyone editing the file. The macros arrived through a backport and their presence alone was enough. Now the leftover state is all zeros, which builds a plain release, and a releaser has to put a number in to get the tag. Deleting them still works, so v26.x stays correct as it is.

The tradeoff is that the first alpha has to be 0.0.1.

[aduh95]

I’m simply not convinced any change is needed, the main branch should be in alpha state otherwise we risk the first release of Node.js 27 to not be marked as alpha.
We can revisit later if that assessment is wrong

[lazerg]

Fair enough. Leaving the macros in place on `main` is what makes the first v27 release come out alpha without anyone having to remember it, and my patch takes that default away. The 26.x slip got caught in a day and 26.8.1 is out, so nothing is pending. Thanks for the look.