Struct HygieneEncodeContext 

pub struct HygieneEncodeContext {
    serialized_ctxts: FxHashSet<SyntaxContext>,
    latest_ctxts: Vec<(u32, SyntaxContext)>,
    serialized_expns: FxHashSet<ExpnId>,
    latest_expns: Vec<ExpnId>,
    encoding_indices: FxHashMap<SyntaxContext, u32>,
}

Fields

serialized_ctxts: FxHashSet<SyntaxContext>

All SyntaxContexts for which we have written SyntaxContextData into crate metadata.

latest_ctxts: Vec<(u32, SyntaxContext)>

The SyntaxContexts that we have serialized (e.g. as a result of encoding Spans) in the most recent ‘round’ of serializing. Serializing SyntaxContextData may cause us to serialize more SyntaxContexts, so serialize in a loop until we reach a fixed point.

serialized_expns: FxHashSet<ExpnId>

latest_expns: Vec<ExpnId>

encoding_indices: FxHashMap<SyntaxContext, u32>

Maps every SyntaxContext into its encoding index. Earlier the ctxt.0 was used when writing metadata, however, this results into non-deterministic metadata (see #129094). The non-determinism is encountered when decoding syntax contexts in decode_syntax_context function below. The syntax contexts from other crate metadata can be decoded in different order, which results into different ids assigned to decoded syntax contexts. First invocation: (ALLOC - syntax context id, ORIG - original id of decoded syntax context: raw_id in decode_syntax_context) ALLOC: #3, ORIG: 1 ALLOC: #9, ORIG: 18769 ALLOC: #10, ORIG: 25868 ALLOC: #11, ORIG: 18822 ALLOC: #12, ORIG: 23092

Second invocation: ALLOC: #3, ORIG: 1 ALLOC: #9, ORIG: 25868 ALLOC: #10, ORIG: 18769 ALLOC: #11, ORIG: 18822 ALLOC: #12, ORIG: 23092

We see that 18769 and 25868 assigned different syntax context ids, however, the order of encoding is deterministic, so we can remap allocated syntax context ids into encoding indices and use them, thus outputting same metadata.

Implementations

impl HygieneEncodeContext

fn get_encoding_index(&mut self, ctxt: SyntaxContext) -> u32

pub fn schedule_expn_data_for_encoding(&mut self, expn: ExpnId)

Record the fact that we need to serialize the corresponding ExpnData.

pub fn encode<T>( h_ctxt: &RefCell<HygieneEncodeContext>, encoder: &mut T, encode_ctxt: impl FnMut(&mut T, u32, &SyntaxContextKey), encode_expn: impl FnMut(&mut T, ExpnId, Option<&ExpnData>, ExpnHash), )

pub fn get_syntax_ctxt_encoding_index(&mut self, ctxt: SyntaxContext) -> u32

Trait Implementations

impl Default for HygieneEncodeContext

fn default() -> HygieneEncodeContext

Returns the “default value” for a type.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 144 bytes