From 1fea5f8e3f019532321d9fc30f51533e37f4e473 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Wed, 27 Jan 2021 14:47:58 -0700
Subject: [PATCH] cs: don't display via prop:exn:srclocs when context length is
 0

It's not clear that supressing source locations with the context
length is set to 0 is the right choie, but it's consistent with BC.
---
 pkgs/racket-test-core/tests/racket/srcloc.rktl | 5 +++++
 racket/src/cs/rumble/error.ss                  | 5 +++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/pkgs/racket-test-core/tests/racket/srcloc.rktl b/pkgs/racket-test-core/tests/racket/srcloc.rktl
index a79f6618df..d4289e4673 100644
--- a/pkgs/racket-test-core/tests/racket/srcloc.rktl
+++ b/pkgs/racket-test-core/tests/racket/srcloc.rktl
@@ -336,6 +336,11 @@
   (test #t regexp-match? #rx"listof srcloc[?]" (go (a "msg" (current-continuation-marks)
                                                       'oops)
                                                    #:catch? #t))
+  (parameterize ([error-print-context-length 0])
+    (test #f regexp-match? #rx"here" (go (a "msg" (current-continuation-marks)
+                                            (list (srcloc "here" 1 2 3 4)
+                                                  (srcloc "there" 10 20 30 40))))))
+
   (void))
 
 (report-errs)
diff --git a/racket/src/cs/rumble/error.ss b/racket/src/cs/rumble/error.ss
index 5a952bf1e7..8879691b06 100644
--- a/racket/src/cs/rumble/error.ss
+++ b/racket/src/cs/rumble/error.ss
@@ -701,9 +701,10 @@
             (and (exn? v)
                  (not (exn:fail:user? v))))
     (let* ([n (|#%app| error-print-context-length)]
-           [locs (if (exn:srclocs? v)
+           [locs (if (and (exn:srclocs? v)
+                          (not (zero? n)))
                      ((exn:srclocs-accessor* v) v)
-                     null)]
+                     '())]
            [l (if (zero? n)
                   '()
                   (traces->context