regsub: fix substitution with a trailing backslash

Should just replace with the bare backslash, not backslash '\0'

Signed-off-by: Steve Bennett <steveb@workware.net.au>

2 files changed, 9 insertions, 1 deletions

diff --git a/jim-regexp.c b/jim-regexp.c
index 25ffd21..25e05a3 100644
--- a/jim-regexp.c
+++ b/jim-regexp.c
@@ -496,7 +496,10 @@ int Jim_RegsubCmd(Jim_Interp *interp, int argc, Jim_Obj *const *argv)
                     continue;
                 }
                 else {
-                    Jim_AppendString(interp, resultObj, replace_str + j - 1, 2);
+                    /* If the replacement is a trailing backslash, just replace with a backslash, otherwise
+                     * with the literal backslash and the following character
+                     */
+                    Jim_AppendString(interp, resultObj, replace_str + j - 1, (j == replace_len) ? 1 : 2);
                     continue;
                 }
             }
diff --git a/tests/regexp.test b/tests/regexp.test
index 7fa3ee0..a4e3f73 100644
--- a/tests/regexp.test
+++ b/tests/regexp.test
@@ -644,6 +644,11 @@ test regexp-21.14 {Literal newline in pattern} {
     regexp -all -inline "\n(\[ \t\]+)" "\n\t\t# This  is  a test"
 } "{\n\t\t} {\t\t}"
 
+test regexp-21.15 {Replace literal backslash} {
+    regsub -all <bs> {<bs>abc<bs>def} \\ value
+    set value
+} "\\abc\\def"
+
 test regexp-22.1 {effect of caching} jim {
 
     set filedata {BEGIN_TABLE ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; END_TABLE}