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Auto merge of #96546 - nnethercote:overhaul-MacArgs, r=petrochenkov

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Overhaul `MacArgs`

Motivation:
- Clarify some code that I found hard to understand.
- Eliminate one use of three places where `TokenKind::Interpolated` values are created.

r? `@petrochenkov`
This commit is contained in:
bors 2022-05-04 21:16:28 +00:00
commit 4c60a0ea5b
22 changed files with 193 additions and 115 deletions
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50
compiler/rustc_ast_lowering/src/lib.rs
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@ -38,8 +38,7 @@
#![recursion_limit = "256"]
#![allow(rustc::potential_query_instability)]
use rustc_ast::token::{Delimiter, Token};
use rustc_ast::tokenstream::{CanSynthesizeMissingTokens, TokenStream, TokenTree};
use rustc_ast::tokenstream::{CanSynthesizeMissingTokens, TokenStream};
use rustc_ast::visit;
use rustc_ast::{self as ast, *};
use rustc_ast_pretty::pprust;
@ -884,37 +883,24 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
)
}
// This is an inert key-value attribute - it will never be visible to macros
// after it gets lowered to HIR. Therefore, we can synthesize tokens with fake
// spans to handle nonterminals in `#[doc]` (e.g. `#[doc = $e]`).
MacArgs::Eq(eq_span, ref token) => {
// In valid code the value is always representable as a single literal token.
fn unwrap_single_token(sess: &Session, tokens: TokenStream, span: Span) -> Token {
if tokens.len() != 1 {
sess.diagnostic()
.delay_span_bug(span, "multiple tokens in key-value attribute's value");
// after it gets lowered to HIR. Therefore, we can extract literals to handle
// nonterminals in `#[doc]` (e.g. `#[doc = $e]`).
MacArgs::Eq(eq_span, MacArgsEq::Ast(ref expr)) => {
// In valid code the value always ends up as a single literal. Otherwise, a dummy
// literal suffices because the error is handled elsewhere.
let lit = if let ExprKind::Lit(lit) = &expr.kind {
lit.clone()
} else {
Lit {
token: token::Lit::new(token::LitKind::Err, kw::Empty, None),
kind: LitKind::Err(kw::Empty),
span: DUMMY_SP,
}
match tokens.into_trees().next() {
Some(TokenTree::Token(token)) => token,
Some(TokenTree::Delimited(_, delim, tokens)) => {
if delim != Delimiter::Invisible {
sess.diagnostic().delay_span_bug(
span,
"unexpected delimiter in key-value attribute's value",
);
}
unwrap_single_token(sess, tokens, span)
}
None => Token::dummy(),
}
}
let tokens = FlattenNonterminals {
parse_sess: &self.sess.parse_sess,
synthesize_tokens: CanSynthesizeMissingTokens::Yes,
nt_to_tokenstream: self.nt_to_tokenstream,
}
.process_token(token.clone());
MacArgs::Eq(eq_span, unwrap_single_token(self.sess, tokens, token.span))
};
MacArgs::Eq(eq_span, MacArgsEq::Hir(lit))
}
MacArgs::Eq(_, MacArgsEq::Hir(ref lit)) => {
unreachable!("in literal form when lowering mac args eq: {:?}", lit)
}
}
}