39 lines
933 B
Rust
39 lines
933 B
Rust
// Test an example where we fail to infer the type parameter H. This
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// is because there is really nothing constraining it. At one time, we
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// would infer based on the where clauses in scope, but that no longer
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// works.
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trait Hash<H> {
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fn hash2(&self, hasher: &H) -> u64;
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}
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trait Stream {
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fn input(&mut self, bytes: &[u8]);
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fn result(&self) -> u64;
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}
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trait StreamHasher {
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type S : Stream;
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fn stream(&self) -> Self::S;
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}
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trait StreamHash<H: StreamHasher>: Hash<H> {
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fn input_stream(&self, stream: &mut H::S);
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}
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impl<H: StreamHasher> Hash<H> for u8 {
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fn hash2(&self, hasher: &H) -> u64 {
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let mut stream = hasher.stream();
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self.input_stream(&mut stream); //~ ERROR type annotations needed
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Stream::result(&stream)
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}
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}
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impl<H: StreamHasher> StreamHash<H> for u8 {
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fn input_stream(&self, stream: &mut H::S) {
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Stream::input(stream, &[*self]);
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}
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}
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fn main() {}
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