Convert Doxygen comments that reference parameters

[jserv]

Transform 2 aborted a whole comment if any whitespace-delimited "@word" that is not @param/@return appeared anywhere in it. Real Doxygen prose cross-references its arguments ("need not be a multiple of @align", "Pointer to at least @SiZe bytes"), so essentially every such comment bailed and never converted. That is the common case, not a corner.

A "@name"/"\name" is now a cross-reference rather than a foreign tag when the same comment declares that parameter and the name is not a DOXY_TAGS keyword in its own right. Line position looks like the sharper discriminator and is not, because reflow owns line position: a comment this aborts on is still re-wrapped, the line-leading "@file" merges into the line above, and a position test then reads it mid-line and converts what the run before refused. A name-only test cannot move under the packer. Declarations come from the tag region only, read as one word stream so a "@PARAM" ending a line still declares the name that opens the next one. One-character C escapes are excluded after trailing punctuation is trimmed, so "\n" and "\n." agree.

A parameter named after a convertible tag keyword is refused outright: "@PARAM return desc" emitted "@return : desc", which the next run read as a return tag and rewrote again.

Entries then hang their continuations under the description column, the way a @PARAM entry already did, so the two forms match once one comment in a file converts and its neighbor aborts. A nonzero hang made a latent packer bug reachable: classify_lines has always split a paragraph at a "@name :" line, but while entries wrapped flush the regrouping moved no bytes. Three rules close it. The packer will not forge that shape by joining a lone "@name" to a ":"-led word on a continuation line, which has to be caught at the append because is_kernel_doc_tag reads the line start and no later word can clear it. It will not split a paragraph's opening line between "@name" and its colon, overflowing instead. And the end-of-paragraph borrow no longer hands a tag word down to open a continuation line.

That borrow also had a pre-existing data-loss bug the hang exposed: the fold arm sat inside the "there is a word to borrow" case, so a one-word line above fell through and emitted a bare rule alone, which transform 1 deletes on the next run.

Comments across the repo are reflowed by the tool itself.

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Summary by cubic

Converts Doxygen comments that reference their own parameters instead of aborting on unknown “@word” tokens. Previously any non-@param/@return “@word” aborted the comment; now “@name”/“\name” that matches a declared param is treated as prose, while real foreign tags still abort. Kernel-doc entries now hang their continuations under the description column, which may rewrap many comments. A param named after a convertible keyword (for example “return”) forces pass-through to keep rewrites idempotent.

New Features

• Treat “@name”/“\name” as a param cross-reference when the name is declared in the same tag block and not a known tag.
• Accept trailing punctuation and collect param names across line breaks in the tag region.
• Exclude one-character C escapes (for example “\n”) from cross-reference detection.
• Hang kernel-doc entry continuations under the description column.

Bug Fixes

• Do not forge a kernel-doc tag by joining a lone “@name” with a “:”-led word on a continuation line.
• Do not split an entry between “@name” and its colon; overflow instead.
• End-of-paragraph borrow no longer moves a tag to the start of a continuation line.
• Fix a data-loss case where a trailing rule after a one-word line emitted a bare rule that a later pass deleted.

^{Written for commit e4ccd2b. Summary will update on new commits.}