Avoid "const uses param" error

Author: camelid

compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs

@@ -3250,7 +3250,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         obligation: &PredicateObligation<'tcx>,
         span: Span,
     ) -> Result<Diag<'a>, ErrorGuaranteed> {
-        if !self.tcx.features().generic_const_exprs() {
+        if !self.tcx.features().generic_const_exprs()
+            && !self.tcx.features().min_generic_const_args()
+        {
             let guar = self
                 .dcx()
                 .struct_span_err(span, "constant expression depends on a generic parameter")

tests/ui/const-generics/mgca/assoc-const.rs

@@ -0,0 +1,15 @@
+//@ check-pass
+
+#![feature(min_generic_const_args)]
+#![allow(incomplete_features)]
+
+pub trait Tr {
+    const SIZE: usize;
+}
+
+fn mk_array<T: Tr>(_x: T) -> [(); T::SIZE] {
+    [(); T::SIZE]
+}
+
+fn main() {}
+