Further fix for MAYBE_NUM values used as array subscripts.

2 files changed, 17 insertions, 9 deletions

diff --git a/ChangeLog b/ChangeLog
index ee6ff430..4b6e88db 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,10 @@
 	* awk.h [fatal]: Make parentheses and use of indirection
 	consistent with warning and lintwarn. Thanks to Andrew Schorr
 	for pointing this out.
+	* str_array.c (str_lookup): Move test for MAYBE_NUM to where
+	we duplicate the subscript. Removing it across the board is
+	wrong if there are multiple references to the value. Thanks
+	to Andrew Schorr for discussion and test case.
 
 2016-05-26         Andrew J. Schorr     <aschorr@telemetry-investments.com>
 
diff --git a/str_array.c b/str_array.c
index 9514d515..1de432c7 100644
--- a/str_array.c
+++ b/str_array.c
@@ -137,7 +137,18 @@ str_lookup(NODE *symbol, NODE *subs)
 		hash1 = code1 % (unsigned long) symbol->array_size;
 	}
 
-	if (subs->stfmt != -1) {
+
+	/*
+	 * Repeat after me: "Array indices are always strings."
+	 * "Array indices are always strings."
+	 * "Array indices are always strings."
+	 * "Array indices are always strings."
+	 * ....
+	 * If subs is a STRNUM, copy it; don't clear the MAYBE_NUM
+	 * flag on it since other variables could be using the same
+	 * reference-counted value.
+	 */
+	if (subs->stfmt != -1 || (subs->flags & MAYBE_NUM) != 0) {
 		NODE *tmp;
 
 		/*
@@ -168,14 +179,7 @@ str_lookup(NODE *symbol, NODE *subs)
 		subs = dupnode(subs);
 	}
 
-	/*
-	 * Repeat after me: "Array indices are always strings."
-	 * "Array indices are always strings."
-	 * "Array indices are always strings."
-	 * "Array indices are always strings."
-	 * ....
-	 */
-	subs->flags &= ~MAYBE_NUM;
+	assert((subs->flags & MAYBE_NUM) == 0);
 
 	getbucket(b);
 	b->ahnext = symbol->buckets[hash1];