Bug: IBackCommit must remove dynamic captures, too

Like a fail, a IBackCommit instruction must remove any dynamic capture
made inside an 'and' pattern. (The added test for this problem
needs assertions on to detect the bug.)

3 files changed, 14 insertions, 1 deletions

diff --git a/lpvm.c b/lpvm.c
index dbe1a8e..af9e617 100644
--- a/lpvm.c
+++ b/lpvm.c
@@ -320,6 +320,8 @@ const char *match (lua_State *L, const char *o, const char *s, const char *e,
       case IBackCommit: {
         assert(stack > getstackbase(L, ptop) && (stack - 1)->s != NULL);
         s = (--stack)->s;
+        if (ndyncap > 0)  /* are there matchtime captures? */
+          ndyncap -= removedyncap(L, capture, stack->caplevel, captop);
         captop = stack->caplevel;
         p += getoffset(p);
         continue;
diff --git a/lpvm.h b/lpvm.h
index 9fde967..ca625f9 100644
--- a/lpvm.h
+++ b/lpvm.h
@@ -27,7 +27,7 @@ typedef enum Opcode {
   IOpenCall,  /* call rule number 'key' (must be closed to a ICall) */
   ICommit,  /* pop choice and jump to 'offset' */
   IPartialCommit,  /* update top choice to current position and jump */
-  IBackCommit,  /* "fails" but jump to its own 'offset' */
+  IBackCommit,  /* backtrack like "fail" but jump to its own 'offset' */
   IFailTwice,  /* pop one choice and then fail */
   IFail,  /* go back to saved state on choice and jump to saved offset */
   IGiveup,  /* internal use */
diff --git a/test.lua b/test.lua
index 403aa09..4263ff4 100755
--- a/test.lua
+++ b/test.lua
@@ -1032,6 +1032,17 @@ local function id (s, i, ...)
   return true, ...
 end
 
+do   -- run-time capture in an end predicate (should discard its value)
+  local x = 0
+  function foo (s, i)
+      x = x + 1
+      return true, x
+  end
+
+  local p = #(m.Cmt("", foo) * "xx") * m.Cmt("", foo)
+  assert(p:match("xx") == 2)
+end
+
 assert(m.Cmt(m.Cs((m.Cmt(m.S'abc' / { a = 'x', c = 'y' }, id) +
               m.R'09'^1 /  string.char +
               m.P(1))^0), id):match"acb98+68c" == "xyb\98+\68y")