fix missleading error for tuple ctor

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -2465,7 +2465,13 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 let parent_did = tcx.parent(*def_id);
                 (tcx.adt_def(parent_did), fn_args, parent_did)
             }
-            _ => return non_adt_or_variant_res(),
+            _ => {
+                let e = self.dcx().span_err(
+                    span,
+                    "complex const arguments must be placed inside of a `const` block",
+                );
+                return Const::new_error(tcx, e);
+            }
         };
 
         let variant_def = adt_def.variant_with_id(variant_did);

tests/ui/const-generics/mgca/size-of-generic-ptr-in-array-len.rs

@@ -4,9 +4,10 @@
 
 fn foo<T>() {
     [0; size_of::<*mut T>()];
-    //~^ ERROR: tuple constructor with invalid base path
+    //~^ ERROR: complex const arguments must be placed inside of a `const` block
     [0; const { size_of::<*mut T>() }];
     //~^ ERROR: generic parameters may not be used in const operations
+    [0; const { size_of::<*mut i32>() }];
 }
 
 fn main() {}

tests/ui/const-generics/mgca/size-of-generic-ptr-in-array-len.stderr

@@ -1,4 +1,4 @@
-error: tuple constructor with invalid base path
+error: complex const arguments must be placed inside of a `const` block
   --> $DIR/size-of-generic-ptr-in-array-len.rs:6:9
    |
 LL |     [0; size_of::<*mut T>()];

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

@@ -32,7 +32,7 @@ fn test_errors<const N: usize>() {
     //~| ERROR tuple constructor with invalid base path
 
     accepts_point::<{ non_ctor(N, N) }>();
-    //~^ ERROR tuple constructor with invalid base path
+    //~^ ERROR complex const arguments must be placed inside of a `const` block
 
     accepts_point::<{ CONST_ITEM(N, N) }>();
     //~^ ERROR tuple constructor with invalid base path

tests/ui/const-generics/mgca/tuple_ctor_erroneous.stderr

@@ -27,7 +27,7 @@ error: tuple constructor with invalid base path
 LL |     accepts_point::<{ UnresolvedIdent(N, N) }>();
    |                       ^^^^^^^^^^^^^^^^^^^^^
 
-error: tuple constructor with invalid base path
+error: complex const arguments must be placed inside of a `const` block
   --> $DIR/tuple_ctor_erroneous.rs:34:23
    |
 LL |     accepts_point::<{ non_ctor(N, N) }>();