P3371R5 Fix C++26 by making the rank-1, rank-2, rank-k, and rank-2k updates consistent with the BLAS

[eisenwave]

Fixes #8479
Fixes NB US 168-277 (C++26 CD).

Also fixes cplusplus/papers#2028
Also fixes https://github.com/cplusplus/nbballot/issues/852

[jwakely]

Too late now, but this would have been much less difficult to review as two commits, one doing all the inout sub-word edits, and another adding and removing blocks of text 😢

Edit: three commits, even. One changing inout to in, one adding/removing blocks of text, and then one changing every "class Scalar" to "scalar Scalar", which needs to be done after adding the new functions.

[jwakely]

@mhoemmen please confirm that the new class Scalar template parameters being added by this paper should actually be scalar Scalar instead, since that's part of this paper, right?

Edit: yes, the editor's note at https://wiki.edg.com/pub/Wg21kona2025/StrawPolls/P3371R5.html#constrain-all-class-scalar-template-parameters says to rename all class Scalar to scalar Scalar after applying the changes from the paper. So the wording in the paper is "wrong" but the paper gives instructions for fixing it.

[jwakely]

The paper has these line breaks in template parameter lists but they're unnecessary IMHO.

[jwakely]

[Editorial Note: The changes proposed here are rebased atop the changes proposed in [LWG4137], “Fix Mandates, Preconditions, and Complexity elements of [linalg] algorithms.” – end note]

Are we going to get conflicts when the LWG issues from Kona are applied?

[eisenwave]

Everything should be ready to merge now.

Are we going to get conflicts when the LWG issues from Kona are applied?

I'm not sure. It looks like the paper makes the exact same changes as LWG4137, so in theory, they will just be identical during merging, which git shouldn't see as a conflict.