bjoernager/rust
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Split MacArgs in two.

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`MacArgs` is an enum with three variants: `Empty`, `Delimited`, and `Eq`. It's
used in two ways:
- For representing attribute macro arguments (e.g. in `AttrItem`), where all
  three variants are used.
- For representing function-like macros (e.g. in `MacCall` and `MacroDef`),
  where only the `Delimited` variant is used.

In other words, `MacArgs` is used in two quite different places due to them
having partial overlap. I find this makes the code hard to read. It also leads
to various unreachable code paths, and allows invalid values (such as
accidentally using `MacArgs::Empty` in a `MacCall`).

This commit splits `MacArgs` in two:
- `DelimArgs` is a new struct just for the "delimited arguments" case. It is
  now used in `MacCall` and `MacroDef`.
- `AttrArgs` is a renaming of the old `MacArgs` enum for the attribute macro
  case. Its `Delimited` variant now contains a `DelimArgs`.

Various other related things are renamed as well.

These changes make the code clearer, avoids several unreachable paths, and
disallows the invalid values.
This commit is contained in:
Nicholas Nethercote 2022-11-18 11:24:21 +11:00
parent 1cbc45942d
commit 3e3a4192d8
33 changed files with 252 additions and 248 deletions
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65
compiler/rustc_parse/src/parser/mod.rs
View file

@ -25,8 +25,8 @@ use rustc_ast::tokenstream::{TokenStream, TokenTree};
use rustc_ast::util::case::Case;
use rustc_ast::AttrId;
use rustc_ast::DUMMY_NODE_ID;
use rustc_ast::{self as ast, AnonConst, AttrStyle, AttrVec, Const, Extern};
use rustc_ast::{Async, Expr, ExprKind, MacArgs, MacArgsEq, MacDelimiter, Mutability, StrLit};
use rustc_ast::{self as ast, AnonConst, AttrStyle, AttrVec, Const, DelimArgs, Extern};
use rustc_ast::{Async, AttrArgs, AttrArgsEq, Expr, ExprKind, MacDelimiter, Mutability, StrLit};
use rustc_ast::{HasAttrs, HasTokens, Unsafe, Visibility, VisibilityKind};
use rustc_ast_pretty::pprust;
use rustc_data_structures::fx::FxHashMap;
@ -1249,39 +1249,40 @@ impl<'a> Parser<'a> {
}
}
fn parse_mac_args(&mut self) -> PResult<'a, P<MacArgs>> {
self.parse_mac_args_common(true).map(P)
fn parse_delim_args(&mut self) -> PResult<'a, P<DelimArgs>> {
if let Some(args) = self.parse_delim_args_inner() { Ok(P(args)) } else { self.unexpected() }
}
fn parse_attr_args(&mut self) -> PResult<'a, MacArgs> {
self.parse_mac_args_common(false)
}
fn parse_mac_args_common(&mut self, delimited_only: bool) -> PResult<'a, MacArgs> {
Ok(
if self.check(&token::OpenDelim(Delimiter::Parenthesis))
|| self.check(&token::OpenDelim(Delimiter::Bracket))
|| self.check(&token::OpenDelim(Delimiter::Brace))
{
match self.parse_token_tree() {
TokenTree::Delimited(dspan, delim, tokens) =>
// We've confirmed above that there is a delimiter so unwrapping is OK.
{
MacArgs::Delimited(dspan, MacDelimiter::from_token(delim).unwrap(), tokens)
}
_ => unreachable!(),
}
} else if !delimited_only {
if self.eat(&token::Eq) {
let eq_span = self.prev_token.span;
MacArgs::Eq(eq_span, MacArgsEq::Ast(self.parse_expr_force_collect()?))
} else {
MacArgs::Empty
}
fn parse_attr_args(&mut self) -> PResult<'a, AttrArgs> {
Ok(if let Some(args) = self.parse_delim_args_inner() {
AttrArgs::Delimited(args)
} else {
if self.eat(&token::Eq) {
let eq_span = self.prev_token.span;
AttrArgs::Eq(eq_span, AttrArgsEq::Ast(self.parse_expr_force_collect()?))
} else {
return self.unexpected();
},
)
AttrArgs::Empty
}
})
}
fn parse_delim_args_inner(&mut self) -> Option<DelimArgs> {
if self.check(&token::OpenDelim(Delimiter::Parenthesis))
|| self.check(&token::OpenDelim(Delimiter::Bracket))
|| self.check(&token::OpenDelim(Delimiter::Brace))
{
match self.parse_token_tree() {
// We've confirmed above that there is a delimiter so unwrapping is OK.
TokenTree::Delimited(dspan, delim, tokens) => Some(DelimArgs {
dspan,
delim: MacDelimiter::from_token(delim).unwrap(),
tokens,
}),
_ => unreachable!(),
}
} else {
None
}
}
fn parse_or_use_outer_attributes(