From 50010c982776ae62233f577f74a8e92e02c5b190 Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adam@chlipala.net>
Date: Sun, 3 Jun 2018 15:05:39 -0400
Subject: Fail when requesting a file cache with a database engine that won't
 do SHA512

---
 src/settings.sml | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/settings.sml b/src/settings.sml
index 47a88932..cfbe98a5 100644
--- a/src/settings.sml
+++ b/src/settings.sml
@@ -727,7 +727,12 @@ fun setSigFile v = sigFile := v
 fun getSigFile () = !sigFile
 
 val fileCache = ref (NONE : string option)
-fun setFileCache v = fileCache := v
+fun setFileCache v =
+    (if Option.isSome v andalso not (#supportsSHA512 (currentDbms ())) then
+         ErrorMsg.error "The selected database engine is incompatible with file caching."
+     else
+        ();
+     fileCache := v)
 fun getFileCache () = !fileCache
 
 structure SS = BinarySetFn(struct
-- 
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