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Remove filter no longer necessary for rustc >=1.7

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David Tolnay 2016-07-01 22:34:15 -07:00
parent 831802adc8
commit dc8d209f29
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1 changed files with 0 additions and 42 deletions
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serde_codegen/src/bound.rs
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@ -1,5 +1,3 @@
use std::collections::HashSet;
use aster::AstBuilder;
use syntax::ast;
@ -63,8 +61,6 @@ pub fn with_bound<F>(
item.body.all_fields()
.filter(|&field| filter(&field.attrs))
.map(|field| &field.ty)
// TODO this filter can be removed later, see comment on function
.filter(|ty| contains_generic(ty, generics))
.filter(|ty| !contains_recursion(ty, item.ident))
.map(|ty| strip_reference(ty))
.map(|ty| builder.where_predicate()
@ -76,44 +72,6 @@ pub fn with_bound<F>(
.build()
}
// Rust <1.7 enforces that `where` clauses involve generic type parameters. The
// corresponding compiler error is E0193. It is no longer enforced in Rust >=1.7
// so this filtering can be removed in the future when we stop supporting <1.7.
//
// E0193 means we must not generate a `where` clause like `i32: Serialize`
// because even though i32 implements Serialize, i32 is not a generic type
// parameter. Clauses like `T: Serialize` and `Option<T>: Serialize` are okay.
// This function decides whether a given type references any of the generic type
// parameters in the input `Generics`.
fn contains_generic(ty: &ast::Ty, generics: &ast::Generics) -> bool {
struct FindGeneric<'a> {
generic_names: &'a HashSet<ast::Name>,
found_generic: bool,
}
impl<'a, 'v> visit::Visitor<'v> for FindGeneric<'a> {
fn visit_path(&mut self, path: &'v ast::Path, _id: ast::NodeId) {
if !path.global
&& path.segments.len() == 1
&& self.generic_names.contains(&path.segments[0].identifier.name) {
self.found_generic = true;
} else {
visit::walk_path(self, path);
}
}
}
let generic_names: HashSet<_> = generics.ty_params.iter()
.map(|ty_param| ty_param.ident.name)
.collect();
let mut visitor = FindGeneric {
generic_names: &generic_names,
found_generic: false,
};
visit::walk_ty(&mut visitor, ty);
visitor.found_generic
}
// We do not attempt to generate any bounds based on field types that are
// directly recursive, as in:
//