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fix #21714 by using discriminant_value in #[derive(Hash)] 

This is the same approach taken in #24270, except that this
should not be a breaking change because it only changes the output
of hash functions, which nobody should be relying on.
This commit is contained in:
Alex Burka 2016-03-07 13:05:12 -05:00
parent 01c0723ef2
commit c480b6a75d
1 changed files with 12 additions and 9 deletions
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21
src/libsyntax_ext/deriving/hash.rs
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@ -12,7 +12,7 @@ use deriving;
use deriving::generic::*;
use deriving::generic::ty::*;
use syntax::ast::{MetaItem, Expr, Mutability};
use syntax::ast::{self, MetaItem, Expr, Mutability};
use syntax::codemap::Span;
use syntax::ext::base::{ExtCtxt, Annotatable};
use syntax::ext::build::AstBuilder;
@ -81,15 +81,18 @@ fn hash_substructure(cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure)
let fields = match *substr.fields {
Struct(_, ref fs) => fs,
EnumMatching(index, variant, ref fs) => {
// Determine the discriminant. We will feed this value to the byte
// iteration function.
let discriminant = match variant.node.disr_expr {
Some(ref d) => d.clone(),
None => cx.expr_usize(trait_span, index)
};
EnumMatching(_, _, ref fs) => {
let path = cx.std_path(&["intrinsics", "discriminant_value"]);
let call = cx.expr_call_global(
trait_span, path, vec![cx.expr_self(trait_span)]);
let variant_value = cx.expr_block(P(ast::Block {
stmts: vec![],
expr: Some(call),
id: ast::DUMMY_NODE_ID,
rules: ast::BlockCheckMode::Unsafe(ast::CompilerGenerated),
span: trait_span }));
stmts.push(call_hash(trait_span, discriminant));
stmts.push(call_hash(trait_span, variant_value));
fs
}