Merge pull request #23263 from mlugg/comptime-field-ptr

Sema: fix pointers to comptime fields of comptime-known aggregate pointers

test/cases/compile_errors/runtime_store_to_comptime_field.zig

@@ -0,0 +1,19 @@
+const init: u32 = 1;
+fn rt() u32 {
+    return 3;
+}
+
+var tuple_val = .{init};
+export fn tuple_field() void {
+    tuple_val[0] = rt();
+}
+
+var struct_val = .{ .x = init };
+export fn struct_field() void {
+    struct_val.x = rt();
+}
+
+// error
+//
+// :8:14: error: cannot store runtime value in compile time variable
+// :13:15: error: cannot store runtime value in compile time variable