From: Mark Wooding <mdw@distorted.org.uk>
Date: Wed, 21 Oct 2015 23:46:28 +0000 (+0100)
Subject: src/frontend.lisp: Report an error if no output types are requested.
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/sod/commitdiff_plain/ca0c10c49568d1d340296ae9e613f32a6a31bfc9

src/frontend.lisp: Report an error if no output types are requested.

Silently not doing anything is sort of unhelpful.
---

diff --git a/src/frontend.lisp b/src/frontend.lisp
index 0336d1a..f1694ab 100644
--- a/src/frontend.lisp
+++ b/src/frontend.lisp
@@ -169,6 +169,10 @@     (define-program
 					     reason))
 			   nil)))))
 
+	      ;; If there are no output types then there's nothing to do.
+	      (unless output-reasons
+		(error "No output types given: nothing to do"))
+
 	      ;; If we're writing the builtin module then now seems like a
 	      ;; good time to do that.
 	      (when builtinsp