bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/mbe/src/expander/transcriber.rs')
-rw-r--r--crates/mbe/src/expander/transcriber.rs57
1 files changed, 53 insertions, 4 deletions
diff --git a/crates/mbe/src/expander/transcriber.rs b/crates/mbe/src/expander/transcriber.rs
index 7bcc84740f..cbb59ab8e6 100644
--- a/crates/mbe/src/expander/transcriber.rs
+++ b/crates/mbe/src/expander/transcriber.rs
@@ -6,7 +6,7 @@ use tt::{Delimiter, Subtree};
use crate::{
expander::{Binding, Bindings, Fragment},
- parser::{Op, RepeatKind, Separator},
+ parser::{MetaVarKind, Op, RepeatKind, Separator},
ExpandError, ExpandResult, MetaTemplate,
};
@@ -15,7 +15,7 @@ impl Bindings {
self.inner.contains_key(name)
}
- fn get(&self, name: &str, nesting: &mut [NestingState]) -> Result<&Fragment, ExpandError> {
+ fn get(&self, name: &str, nesting: &mut [NestingState]) -> Result<Fragment, ExpandError> {
macro_rules! binding_err {
($($arg:tt)*) => { ExpandError::binding_error(format!($($arg)*)) };
}
@@ -26,6 +26,7 @@ impl Bindings {
nesting_state.hit = true;
b = match b {
Binding::Fragment(_) => break,
+ Binding::Missing(_) => break,
Binding::Nested(bs) => bs.get(nesting_state.idx).ok_or_else(|| {
nesting_state.at_end = true;
binding_err!("could not find nested binding `{name}`")
@@ -37,7 +38,55 @@ impl Bindings {
};
}
match b {
- Binding::Fragment(it) => Ok(it),
+ Binding::Fragment(it) => Ok(it.clone()),
+ // emit some reasonable default expansion for missing bindings,
+ // this gives better recovery than emitting the `$fragment-name` verbatim
+ Binding::Missing(it) => Ok(match it {
+ MetaVarKind::Stmt => {
+ Fragment::Tokens(tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct {
+ id: tt::TokenId::unspecified(),
+ char: ';',
+ spacing: tt::Spacing::Alone,
+ })))
+ }
+ MetaVarKind::Block => Fragment::Tokens(tt::TokenTree::Subtree(tt::Subtree {
+ delimiter: Some(tt::Delimiter {
+ id: tt::TokenId::unspecified(),
+ kind: tt::DelimiterKind::Brace,
+ }),
+ token_trees: vec![],
+ })),
+ // FIXME: Meta and Item should get proper defaults
+ MetaVarKind::Meta | MetaVarKind::Item | MetaVarKind::Tt | MetaVarKind::Vis => {
+ Fragment::Tokens(tt::TokenTree::Subtree(tt::Subtree {
+ delimiter: None,
+ token_trees: vec![],
+ }))
+ }
+ MetaVarKind::Path
+ | MetaVarKind::Ty
+ | MetaVarKind::Pat
+ | MetaVarKind::PatParam
+ | MetaVarKind::Expr
+ | MetaVarKind::Ident => {
+ Fragment::Tokens(tt::TokenTree::Leaf(tt::Leaf::Ident(tt::Ident {
+ text: SmolStr::new_inline("missing"),
+ id: tt::TokenId::unspecified(),
+ })))
+ }
+ MetaVarKind::Lifetime => {
+ Fragment::Tokens(tt::TokenTree::Leaf(tt::Leaf::Ident(tt::Ident {
+ text: SmolStr::new_inline("'missing"),
+ id: tt::TokenId::unspecified(),
+ })))
+ }
+ MetaVarKind::Literal => {
+ Fragment::Tokens(tt::TokenTree::Leaf(tt::Leaf::Ident(tt::Ident {
+ text: SmolStr::new_inline("\"missing\""),
+ id: tt::TokenId::unspecified(),
+ })))
+ }
+ }),
Binding::Nested(_) => {
Err(binding_err!("expected simple binding, found nested binding `{name}`"))
}
@@ -157,7 +206,7 @@ fn expand_var(ctx: &mut ExpandCtx<'_>, v: &SmolStr, id: tt::TokenId) -> ExpandRe
} else {
ctx.bindings.get(v, &mut ctx.nesting).map_or_else(
|e| ExpandResult { value: Fragment::Tokens(tt::TokenTree::empty()), err: Some(e) },
- |b| ExpandResult::ok(b.clone()),
+ |it| ExpandResult::ok(it),
)
}
}