rust/compiler/rustc_parse
Aaron Hill ea468f4270
Allow skipping extra paren insertion during AST pretty-printing
Fixes #74616
Makes progress towards #43081
Unblocks PR #76130

When pretty-printing an AST node, we may insert additional parenthesis
to ensure that precedence is properly preserved in code we output.
However, the proc macro implementation relies on comparing a
pretty-printed AST node to the captured `TokenStream`. Inserting extra
parenthesis changes the structure of the reparsed `TokenStream`, making
the comparison fail.

This PR refactors the AST pretty-printing code to allow skipping the
insertion of additional parenthesis. Several freestanding methods are
moved to trait methods on `PrintState`, which keep track of an internal
`insert_extra_parens` flag. This flag is normally `true`, but we expose
a public method which allows pretty-printing a nonterminal with
`insert_extra_parens = false`.

To avoid changing the public interface of `rustc_ast_pretty`, the
freestanding `_to_string` methods are changed to delegate to a
newly-crated `State`. The main pretty-printing code is moved to a new
`state` module to ensure that it does not accidentally call any of these
public helper functions (instead, the internal functions with the same
name should be used).
2020-10-11 12:09:48 -04:00
..
src Allow skipping extra paren insertion during AST pretty-printing 2020-10-11 12:09:48 -04:00
Cargo.toml mv compiler to compiler/ 2020-08-30 18:45:07 +03:00