patch 9.0.0407: matchstr() does match column offset

Problem:    matchstr() does match column offset. (Yasuhiro Matsumoto)
Solution:   Accept line number zero. (closes #10938)

src/regexp_bt.c

@@ -3444,7 +3444,7 @@ regmatch(
 		linenr_T    lnum = rex.reg_firstlnum + rex.lnum;
 		long_u	    vcol = 0;
 
-		if (lnum > 0 && lnum <= wp->w_buffer->b_ml.ml_line_count)
+		if (lnum >= 0 && lnum <= wp->w_buffer->b_ml.ml_line_count)
 		    vcol = (long_u)win_linetabsize(wp, lnum, rex.line,
 					      (colnr_T)(rex.input - rex.line));
 		if (!re_num_cmp(vcol + 1, scan))

src/regexp_nfa.c

@@ -6778,7 +6778,7 @@ nfa_regmatch(
 			linenr_T    lnum = rex.reg_firstlnum + rex.lnum;
 			long_u	    vcol = 0;
 
-			if (lnum > 0
+			if (lnum >= 0
 				   && lnum <= wp->w_buffer->b_ml.ml_line_count)
 			    vcol = (long_u)win_linetabsize(wp, lnum,
 								rex.line, col);

src/testdir/test_regexp_latin.vim

@@ -30,11 +30,13 @@ endfunc
 func Test_equivalence_re1()
   set re=1
   call s:equivalence_test()
+  set re=0
 endfunc
 
 func Test_equivalence_re2()
   set re=2
   call s:equivalence_test()
+  set re=0
 endfunc
 
 func Test_recursive_substitute()
@@ -67,6 +69,7 @@ func Test_eow_with_optional()
     let actual = matchlist('abc def', '\(abc\>\)\?\s*\(def\)')
     call assert_equal(expected, actual)
   endfor
+  set re=0
 endfunc
 
 func Test_backref()
@@ -1141,4 +1144,14 @@ def Test_compare_columns()
   prop_type_delete('name')
 enddef
 
+def Test_compare_column_matchstr()
+  enew
+  set re=1
+  call assert_equal('aaa', matchstr('aaaaaaaaaaaaaaaaaaaa', '.*\%<5v'))
+  set re=2
+  call assert_equal('aaa', matchstr('aaaaaaaaaaaaaaaaaaaa', '.*\%<5v'))
+  set re=0
+enddef
+
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -703,6 +703,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    407,
 /**/
     406,
 /**/