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proc_macro: Move subspan to be a method on Span in the bridge

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This method is still only used for Literal::subspan, however the
implementation only depends on the Span component, so it is simpler and
more efficient for now to pass down only the information that is needed.
In the future, if more information about the Literal is required in the
implementation (e.g. to validate that spans line up as expected with
source text), that extra information can be added back with extra
arguments.
This commit is contained in:
Nika Layzell 2022-07-09 11:34:06 -04:00
parent b34c79f8f1
commit c4acac6443
3 changed files with 38 additions and 44 deletions
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73
compiler/rustc_expand/src/proc_macro_server.rs
View File

@ -436,43 +436,6 @@ fn literal_from_str(&mut self, s: &str) -> Result<Literal<Self::Span, Self::Symb
span: self.call_site,
})
}
fn literal_subspan(
&mut self,
literal: Literal<Self::Span, Self::Symbol>,
start: Bound<usize>,
end: Bound<usize>,
) -> Option<Self::Span> {
let span = literal.span;
let length = span.hi().to_usize() - span.lo().to_usize();
let start = match start {
Bound::Included(lo) => lo,
Bound::Excluded(lo) => lo.checked_add(1)?,
Bound::Unbounded => 0,
};
let end = match end {
Bound::Included(hi) => hi.checked_add(1)?,
Bound::Excluded(hi) => hi,
Bound::Unbounded => length,
};
// Bounds check the values, preventing addition overflow and OOB spans.
if start > u32::MAX as usize
|| end > u32::MAX as usize
|| (u32::MAX - start as u32) < span.lo().to_u32()
|| (u32::MAX - end as u32) < span.lo().to_u32()
|| start >= end
|| end > length
{
return None;
}
let new_lo = span.lo() + BytePos::from_usize(start);
let new_hi = span.lo() + BytePos::from_usize(end);
Some(span.with_lo(new_lo).with_hi(new_hi))
}
}
impl server::TokenStream for Rustc<'_, '_> {
@ -697,6 +660,42 @@ fn join(&mut self, first: Self::Span, second: Self::Span) -> Option<Self::Span>
Some(first.to(second))
}
fn subspan(
&mut self,
span: Self::Span,
start: Bound<usize>,
end: Bound<usize>,
) -> Option<Self::Span> {
let length = span.hi().to_usize() - span.lo().to_usize();
let start = match start {
Bound::Included(lo) => lo,
Bound::Excluded(lo) => lo.checked_add(1)?,
Bound::Unbounded => 0,
};
let end = match end {
Bound::Included(hi) => hi.checked_add(1)?,
Bound::Excluded(hi) => hi,
Bound::Unbounded => length,
};
// Bounds check the values, preventing addition overflow and OOB spans.
if start > u32::MAX as usize
|| end > u32::MAX as usize
|| (u32::MAX - start as u32) < span.lo().to_u32()
|| (u32::MAX - end as u32) < span.lo().to_u32()
|| start >= end
|| end > length
{
return None;
}
let new_lo = span.lo() + BytePos::from_usize(start);
let new_hi = span.lo() + BytePos::from_usize(end);
Some(span.with_lo(new_lo).with_hi(new_hi))
}
fn resolved_at(&mut self, span: Self::Span, at: Self::Span) -> Self::Span {
span.with_ctxt(at.ctxt())
}

2
library/proc_macro/src/bridge/mod.rs
View File

@ -57,7 +57,6 @@ macro_rules! with_api {
fn track_env_var(var: &str, value: Option<&str>);
fn track_path(path: &str);
fn literal_from_str(s: &str) -> Result<Literal<$S::Span, $S::Symbol>, ()>;
fn literal_subspan(lit: Literal<$S::Span, $S::Symbol>, start: Bound<usize>, end: Bound<usize>) -> Option<$S::Span>;
},
TokenStream {
fn drop($self: $S::TokenStream);
@ -114,6 +113,7 @@ fn sub(
fn before($self: $S::Span) -> $S::Span;
fn after($self: $S::Span) -> $S::Span;
fn join($self: $S::Span, other: $S::Span) -> Option<$S::Span>;
fn subspan($self: $S::Span, start: Bound<usize>, end: Bound<usize>) -> Option<$S::Span>;
fn resolved_at($self: $S::Span, at: $S::Span) -> $S::Span;
fn source_text($self: $S::Span) -> Option<String>;
fn save_span($self: $S::Span) -> usize;

7
library/proc_macro/src/lib.rs
View File

@ -1379,12 +1379,7 @@ pub fn set_span(&mut self, span: Span) {
// was 'c' or whether it was '\u{63}'.
#[unstable(feature = "proc_macro_span", issue = "54725")]
pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
bridge::client::FreeFunctions::literal_subspan(
self.0.clone(),
range.start_bound().cloned(),
range.end_bound().cloned(),
)
.map(Span)
self.0.span.subspan(range.start_bound().cloned(), range.end_bound().cloned()).map(Span)
}
fn with_symbol_and_suffix<R>(&self, f: impl FnOnce(&str, &str) -> R) -> R {