Add regression test for issue #100878

Author: inquisitivecrystal

src/test/ui/consts/const-eval/issue-100878.rs

@@ -0,0 +1,8 @@
+// This checks that the const-eval ICE in issue #100878 does not recur.
+//
+// build-pass
+pub fn bitshift_data(data: [u8; 1]) -> u8 {
+    data[0] << 8
+}
+
+fn main() {}