From c318cf453dafbd8129203c3117d8f7be799f62ef Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Fri, 29 Apr 2022 06:52:01 +1000
Subject: [PATCH] Overhaul `MacArgs::Eq`.
The value in `MacArgs::Eq` is currently represented as a `Token`.
Because of `TokenKind::Interpolated`, `Token` can be either a token or
an arbitrary AST fragment. In practice, a `MacArgs::Eq` starts out as a
literal or macro call AST fragment, and then is later lowered to a
literal token. But this is very non-obvious. `Token` is a much more
general type than what is needed.
This commit restricts things, by introducing a new type `MacArgsEqKind`
that is either an AST expression (pre-lowering) or an AST literal
(post-lowering). The downside is that the code is a bit more verbose in
a few places. The benefit is that makes it much clearer what the
possibilities are (though also shorter in some other places). Also, it
removes one use of `TokenKind::Interpolated`, taking us a step closer to
removing that variant, which will let us make `Token` impl `Copy` and
remove many "handle Interpolated" code paths in the parser.
Things to note:
- Error messages have improved. Messages like this:
```
unexpected token: `"bug" + "found"`
```
now say "unexpected expression", which makes more sense. Although
arbitrary expressions can exist within tokens thanks to
`TokenKind::Interpolated`, that's not obvious to anyone who doesn't
know compiler internals.
- In `parse_mac_args_common`, we no longer need to collect tokens for
the value expression.
---
clippy_utils/src/ast_utils.rs | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/clippy_utils/src/ast_utils.rs b/clippy_utils/src/ast_utils.rs
index 3fce4987679..7919800483f 100644
--- a/clippy_utils/src/ast_utils.rs
+++ b/clippy_utils/src/ast_utils.rs
@@ -688,7 +688,8 @@ pub fn eq_mac_args(l: &MacArgs, r: &MacArgs) -> bool {
match (l, r) {
(Empty, Empty) => true,
(Delimited(_, ld, lts), Delimited(_, rd, rts)) => ld == rd && lts.eq_unspanned(rts),
- (Eq(_, lt), Eq(_, rt)) => lt.kind == rt.kind,
+ (Eq(_, MacArgsEq::Ast(le)), Eq(_, MacArgsEq::Ast(re))) => eq_expr(le, re),
+ (Eq(_, MacArgsEq::Hir(ll)), Eq(_, MacArgsEq::Hir(rl))) => ll.kind == rl.kind,
_ => false,
}
}