Build History for pull/2810

Rework begin match/if branch layout (review follow-up) Reworks the previous fix (e3babbb1) per review. The earlier version special-cased `ctx0=ifthenelse` in `fmt_beginend` to handle a comment before a `begin match/if … end` branch body; it glued the body (`begin if a then b`) and reindented it when a comment was added. Why the comment case now goes through the plain begin/end path: `fmt_beginend` cannot see the comment — `branch_pro` consumes it in `Params` before the expression is formatted. `get_if_then_else`, however, runs before consumption, so the decision belongs there. A special `begin match/if … end` branch with a leading comment on its body no longer takes the `begin <kw>` shortcut arm; it falls through to the existing plain begin/end machinery (`has_cmts_before` predicate). That keeps `begin` on its own line with the body (comment included) one indent in, identically across all if-then-else modes, so adding a comment no longer reindents the body. Why expr_pro is dropped for special-bodied begin/end branches: the fit-or-vertical / vertical branch `expr_pro` is `break_unless_newline 1000`, which enqueues width 1000 even as a no-op at BOL and poisons the body's `match … with` / `if … then` header box, forcing it to split over several lines. Such a body already breaks after `begin`, so it provides its own break instead of the poisoning one. Simple-bodied `begin e end` keeps the regular branch break (no header to poison). K&R additionally dropped the extra body box that indented a comment-routed body by +2. Why a ctx0 box wrap remains in fmt_beginend: the no-comment shortcut path still needs `end` aligned with `begin`. In fit-or-vertical the branch box is `hovbox 0` while the branch break indents `begin` one level in, so the body and `end` are wrapped together. This is scoped to `ctx0=ifthenelse` because wrapping unconditionally reindents application arguments (`map x begin fun … end`, exp_grouping.ml); the scope is structural (alignment), not comment-handling logic. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Fix begin match/if branch layout with fit-or-vertical With `if-then-else=fit-or-vertical`, an `else begin match … with … end` branch rendered the header split over several lines (`begin match` / scrutinee / `with`), `begin if … end` likewise, and `end` ended up less indented than `begin`. For the `begin match/try/function/if end` shortcut, `fmt_beginend` threaded the branch `pro` into the inner expression's `pro`. In fit-or-vertical (and vertical) that `pro` is a `break_unless_newline 1000`, and because the inner expression's ctx0 is the begin/end node, `match_inner_pro` places it inside the header box. `pp_print_or_newline` enqueues its full width (1000) as the token length, so the header box never fits and is forced to break. When the begin/end is an if-then-else branch, emit `pro` outside the box (the branch break already positions it) and wrap the body and `end` together so `end` lines up with `begin`. Other contexts (e.g. `map x begin fun … end`) keep `pro` inside to preserve their indentation. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>