Commits on Oct 3, 2018

1. abolish ICE when pretty-printing async block …

   Joshua Netterfield reported an ICE when the unused-parentheses lint
   triggered around an async block (rust-lang#54752). In order to compose an
   autofixable suggestion, the lint invokes the pretty-printer on the
   unnecessarily-parenthesized expression. (One wonders why the lint
   doesn't just use `SourceMap::span_to_snippet` instead, to preserve the
   formatting of the original source?—but for that, you'd have to ask the
   author of 5c9f806.)
   
   But then the pretty-printer panics when trying to call `<pprust::State
   as PrintState>::end` when `State.boxes` is empty. Empirically, the
   problem would seem to be solved if we start some "boxes" beforehand in
   the `ast::ExprKind::Async` arm of the big match in
   `print_expr_outer_attr_style`, exactly like we do in the
   immediately-preceding match arm for `ast::ExprKind::Block`—it would
   seem pretty ("pretty") reasonable for the pretty-printing of async
   blocks to work a lot like the pretty-printing of ordinary non-async
   blocks, right??
   
   Of course, it would be shamefully cargo-culty to commit code on the
   basis of this kind of mere reasoning-by-analogy (in contrast to
   understanding the design of the pretty-printer in such detail that the
   correctness of the patch is comprehended with all the lucid certainty
   of mathematical proof, rather than being merely surmised by
   intuition). But maybe we care more about fixing the bug with high
   probability today, than with certainty in some indefinite hypothetical
   future?  Maybe the effort is worth a fifth of a shirt??
   
   Humbly resolves rust-lang#54752.

   

   zackmdavis committed Oct 3, 2018
   Configuration menu

   • View commit details
   • Copy full SHA for 1081bbb
   • Browse repository at this point

   Copy the full SHA

   1081bbb View commit details

   Browse the repository at this point in the history