bjoernager/rust
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first pass at default values for const generics

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- Adds optional default values to const generic parameters in the AST
  and HIR
- Parses these optional default values
- Adds a `const_generics_defaults` feature gate
This commit is contained in:
Julian Knodt 2020-12-31 01:58:27 +01:00 • committed by Rémy Rakic
parent f8ab56bf32
commit 61f33bfd29
20 changed files with 99 additions and 32 deletions
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18
compiler/rustc_ast_passes/src/ast_validation.rs
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@ -733,7 +733,7 @@ fn validate_generic_param_order(
let (ord_kind, ident) = match &param.kind {
GenericParamKind::Lifetime => (ParamKindOrd::Lifetime, ident),
GenericParamKind::Type { default: _ } => (ParamKindOrd::Type, ident),
GenericParamKind::Const { ref ty, kw_span: _ } => {
GenericParamKind::Const { ref ty, kw_span: _, default: _ } => {
let ty = pprust::ty_to_string(ty);
let unordered = sess.features_untracked().const_generics;
(ParamKindOrd::Const { unordered }, Some(format!("const {}: {}", param.ident, ty)))
@ -775,7 +775,7 @@ fn validate_generic_param_order(
GenericParamKind::Type { default: None } => (),
GenericParamKind::Lifetime => (),
// FIXME(const_generics:defaults)
GenericParamKind::Const { ty: _, kw_span: _ } => (),
GenericParamKind::Const { ty: _, kw_span: _, default: _ } => (),
}
first = false;
}
@ -1166,6 +1166,20 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
}
}
}
if !self.session.features_untracked().const_generics_defaults {
if let GenericParamKind::Const { default: Some(ref default), .. } = param.kind {
let mut err = self.err_handler().struct_span_err(
default.value.span,
"default values for const generic parameters are unstable",
);
err.help(
"add `#![feature(const_generics_defaults)]` \
to the crate attributes to enable",
);
err.emit();
break;
}
}
}
validate_generic_param_order(