fix compilation of x[y,]

Oh boy.  I do not pretend to totally understand what is going on, but
what seemed to be happening is that somehow when walking the parse
tree to adjust srcrefs to the real file position rather than the
string position, the `empty' space in x[y,] was turning from a
zero-element name to a missing object, and then subsequent attempts to
evaluate the missing object (or even return it) were failing.

The workaround is to short-circuit the process for name objects, which
are atomic and (empirically) do not have srcrefs attached anyway and
so can be returned without modification.

diff --git a/swank.R b/swank.R
index 99012ec57ec4bc7ed9b6d80010145476d40f108d..757e2430752b00ce87724f82ccfbd0d6dfbb5dbe 100644 (file)
--- a/swank.R
+++ b/swank.R
@@ -514,6 +514,17 @@ computeRestartsForEmacs <- function (sldbState) {
                     ifelse(x[3]==1, x[6]+colOffset-1, x[6]))))
   }
   transformSrcrefs <- function(s) {
+    ## horrendous KLUDGE: we need to short-circuit here for "name"
+    ## objects, rather than having a nice uniform behaviour, because
+    ## for expressions of the form x[y,] there is an empty "name"
+    ## which ends up becoming a `missing' object when passed through
+    ## the switch; why, I do not know, but it is then impossible to
+    ## return it, because returning it attempts to evaluate it and
+    ## evaluating it is an error.  Fortunately it appears that names
+    ## don't have srcrefs attached.
+    if(mode(s) == "name") {
+      return(s)
+    }
     srcrefs <- attr(s, "srcref")
     attribs <- attributes(s)
     new <-