allow unordered const/ty params if any cg feature is active

Author: lcnr

Diff for: compiler/rustc_ast/src/ast.rs

@@ -332,8 +332,8 @@ pub type GenericBounds = Vec<GenericBound>;
 pub enum ParamKindOrd {
     Lifetime,
     Type,
-    // `unordered` is only `true` if `sess.has_features().const_generics_defaults`
-    // is active. Specifically, if it's only `min_const_generics`, it will still require
+    // `unordered` is only `true` if `sess.unordered_const_ty_params()`
+    // returns true. Specifically, if it's only `min_const_generics`, it will still require
     // ordering consts after types.
     Const { unordered: bool },
     // `Infer` is not actually constructed directly from the AST, but is implicitly constructed

Diff for: compiler/rustc_ast_passes/src/ast_validation.rs

@@ -1351,7 +1351,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
     }
 
     fn visit_generics(&mut self, generics: &'a Generics) {
-        let cg_defaults = self.session.features_untracked().const_generics_defaults;
+        let cg_defaults = self.session.features_untracked().unordered_const_ty_params();
 
         let mut prev_param_default = None;
         for param in &generics.params {

Diff for: compiler/rustc_feature/src/active.rs

@@ -71,7 +71,7 @@ macro_rules! declare_features {
             }
 
             pub fn unordered_const_ty_params(&self) -> bool {
-                self.const_generics_defaults
+                self.const_generics_defaults || self.generic_const_exprs || self.const_param_types
             }
 
             /// Some features are known to be incomplete and using them is likely to have

Diff for: src/test/ui/const-generics/params-in-ct-in-ty-param-lazy-norm.full.stderr

@@ -3,8 +3,6 @@ error: generic parameters with a default must be trailing
    |
 LL | struct Bar<T = [u8; N], const N: usize>(T);
    |            ^
-   |
-   = note: using type defaults and const parameters in the same parameter list is currently not permitted
 
 error[E0128]: generic parameters with a default cannot use forward declared identifiers
   --> $DIR/params-in-ct-in-ty-param-lazy-norm.rs:8:21