* experimental test for #39758

tests/webtbs/tw39758.pp

@@ -0,0 +1,41 @@
+{ %OPT=-O4 -Sg }
+{$mode objfpc} {$h+}
+label A0, A1, B0, B1, C0, C1, D0, D1;
+
+var
+	x, y: single;
+	dontDrop: string;
+    size: ptrint;
+
+begin
+	x := random;
+A0:
+	y := x + 1 + 2 + 3 + 4 + 5 + 6; // folds
+A1:
+	writestr(dontDrop, y);
+    size:=CodePointer(@A1) - CodePointer(@A0);
+	writeln('x + 1 + 2 + 3 + 4 + 5 + 6 = ', y, ' ', CodePointer(@A1) - CodePointer(@A0), ' b');
+
+B0:
+	y := x + 1 - 2 + 3 - 4 + 5 - 6; // doesn’t fold
+B1:
+	writestr(dontDrop, y);
+    if CodePointer(@B1) - CodePointer(@B0) > size then
+      halt(1);
+	writeln('x + 1 - 2 + 3 - 4 + 5 - 6 = ', y, ' ', CodePointer(@B1) - CodePointer(@B0), ' b');
+
+C0:
+	y := x - 1 - 2 - 3 - 4 - 5 - 6; // didn't fold at the time of making the issue, now folds
+C1:
+	writestr(dontDrop, y);
+    if CodePointer(@C1) - CodePointer(@C0) > size then
+      halt(1);
+	writeln('x - 1 - 2 - 3 - 4 - 5 - 6 = ', y, ' ', CodePointer(@C1) - CodePointer(@C0), ' b');
+D0:
+	y := x - 1 + 2 - 3 + 4 - 5 + 6; // didn't fold at the time of making the issue, now folds
+D1:
+	writestr(dontDrop, y);
+    if CodePointer(@D1) - CodePointer(@D0) > size then
+      halt(1);
+	writeln('x - 1 + 2 - 3 + 4 - 5 + 6 = ', y, ' ', CodePointer(@D1) - CodePointer(@D0), ' b');
+end.