patch 9.1.1943: Memory leak with :breakadd expr

Problem:  Memory leak with :breakadd expr
Solution: Free debug_oldval and debug_newval before assigning to them.
          Verify the existing (though confusing) :breakadd expr behavior
          (zeertzjq).

It seems that :breakadd expr doesn't work as documented at all. This PR
only fixes the memory leak. The tests are for the existing behavior.

closes: #18844

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/debugger.c

@@ -1111,8 +1111,10 @@ debuggy_find(
 	    {
 		if (bp->dbg_val == NULL)
 		{
+		    vim_free(debug_oldval);
 		    debug_oldval = typval_tostring(NULL, TRUE);
 		    bp->dbg_val = tv;
+		    vim_free(debug_newval);
 		    debug_newval = typval_tostring(bp->dbg_val, TRUE);
 		    line = TRUE;
 		}
@@ -1129,10 +1131,12 @@ debuggy_find(
 			typval_T *v;
 
 			line = TRUE;
+			vim_free(debug_oldval);
 			debug_oldval = typval_tostring(bp->dbg_val, TRUE);
 			// Need to evaluate again, typval_compare() overwrites
 			// "tv".
 			v = eval_expr_no_emsg(bp);
+			vim_free(debug_newval);
 			debug_newval = typval_tostring(v, TRUE);
 			free_tv(bp->dbg_val);
 			bp->dbg_val = v;
@@ -1142,7 +1146,9 @@ debuggy_find(
 	    }
 	    else if (bp->dbg_val != NULL)
 	    {
+		vim_free(debug_oldval);
 		debug_oldval = typval_tostring(bp->dbg_val, TRUE);
+		vim_free(debug_newval);
 		debug_newval = typval_tostring(NULL, TRUE);
 		free_tv(bp->dbg_val);
 		bp->dbg_val = NULL;

src/testdir/test_debugger.vim

@@ -361,34 +361,73 @@ func Test_Debugger_breakadd()
 endfunc
 
 " Test for expression breakpoint set using ":breakadd expr <expr>"
+" FIXME: This doesn't seem to work as documented. The breakpoint is not
+" triggered until the next function call.
 func Test_Debugger_breakadd_expr()
   CheckCWD
 
   let lines =<< trim END
+    func Foo()
+      eval 1
+      eval 2
+    endfunc
+
     let g:Xtest_var += 1
+    call Foo()
+    let g:Xtest_var += 1
+    call Foo()
   END
-  call writefile(lines, 'XdebugBreakExpr.vim', 'D')
+  call writefile(lines, 'XbreakExpr.vim', 'D')
 
   " Start Vim in a terminal
-  let buf = RunVimInTerminal('XdebugBreakExpr.vim', {})
+  let buf = RunVimInTerminal('XbreakExpr.vim', {})
   call s:RunDbgCmd(buf, ':let g:Xtest_var = 10')
   call s:RunDbgCmd(buf, ':breakadd expr g:Xtest_var')
-  call s:RunDbgCmd(buf, ':source %')
   let expected =<< trim eval END
     Oldval = "10"
     Newval = "11"
-    {fnamemodify('XdebugBreakExpr.vim', ':p')}
-    line 1: let g:Xtest_var += 1
+    {fnamemodify('XbreakExpr.vim', ':p')}[7]..function Foo
+    line 1: eval 1
   END
   call s:RunDbgCmd(buf, ':source %', expected)
-  call s:RunDbgCmd(buf, 'cont')
   let expected =<< trim eval END
     Oldval = "11"
     Newval = "12"
-    {fnamemodify('XdebugBreakExpr.vim', ':p')}
-    line 1: let g:Xtest_var += 1
+    {fnamemodify('XbreakExpr.vim', ':p')}[9]..function Foo
+    line 1: eval 1
+  END
+  call s:RunDbgCmd(buf, 'cont', expected)
+  call s:RunDbgCmd(buf, 'cont')
+
+  " Check the behavior without the g: prefix.
+  " FIXME: The Oldval and Newval don't look right here.
+  call s:RunDbgCmd(buf, ':breakdel *')
+  call s:RunDbgCmd(buf, ':breakadd expr Xtest_var')
+  let expected =<< trim eval END
+    Oldval = "13"
+    Newval = "(does not exist)"
+    {fnamemodify('XbreakExpr.vim', ':p')}[7]..function Foo
+    line 1: eval 1
   END
   call s:RunDbgCmd(buf, ':source %', expected)
+  let expected =<< trim eval END
+    {fnamemodify('XbreakExpr.vim', ':p')}[7]..function Foo
+    line 2: eval 2
+  END
+  call s:RunDbgCmd(buf, 'cont', expected)
+  let expected =<< trim eval END
+    Oldval = "14"
+    Newval = "(does not exist)"
+    {fnamemodify('XbreakExpr.vim', ':p')}[9]..function Foo
+    line 1: eval 1
+  END
+  call s:RunDbgCmd(buf, 'cont', expected)
+  let expected =<< trim eval END
+    {fnamemodify('XbreakExpr.vim', ':p')}[9]..function Foo
+    line 2: eval 2
+  END
+  call s:RunDbgCmd(buf, 'cont', expected)
+  call s:RunDbgCmd(buf, 'cont')
 
   call StopVimInTerminal(buf)
 endfunc

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1943,
 /**/
     1942,
 /**/