Change how preview=in is detected

This is a minor internal change, but will allow us to deprecate in ref at the parser level.
dlang · Feb 28, 2023 · 2e8f217 · 2e8f217
1 parent 6d647c5
commit 2e8f217
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/std/format/internal/write.d b/std/format/internal/write.d
@@ -1829,7 +1829,8 @@ enum HasToStringResult
     customPutWriterFormatSpec,
 }
 
-private enum hasPreviewIn = !is(typeof(mixin(q{(in ref int a) => a})));
+private alias DScannerBug895 = int[256];
+private immutable bool hasPreviewIn = ((in DScannerBug895 a) { return __traits(isRef, a); })(DScannerBug895.init);
 
 template hasToString(T, Char)
 {