From 081db1a66d17e46ac3b03b7514f11a004a35009a Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Thu, 22 Oct 2020 20:09:43 +0200
Subject: [PATCH] patch 8.2.1890: Vim9: strange error for subtracting from a
 list

Problem:    Vim9: strange error for subtracting from a list.
Solution:   Check getting a number, not a string. (closes #7167)
---
 src/eval.c                     | 14 ++++++++++++--
 src/testdir/test_vim9_expr.vim | 14 +++++++++++++-
 src/version.c                  |  2 ++
 3 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/src/eval.c b/src/eval.c
index 9ef312863..bb402dee9 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -2679,6 +2679,9 @@ eval4(char_u **arg, typval_T *rettv, evalarg_T *evalarg)
     return OK;
 }
 
+/*
+ * Make a copy of blob "tv1" and append blob "tv2".
+ */
     void
 eval_addblob(typval_T *tv1, typval_T *tv2)
 {
@@ -2699,6 +2702,9 @@ eval_addblob(typval_T *tv1, typval_T *tv2)
     }
 }
 
+/*
+ * Make a copy of list "tv1" and append list "tv2".
+ */
     int
 eval_addlist(typval_T *tv1, typval_T *tv2)
 {
@@ -2777,8 +2783,10 @@ eval5(char_u **arg, typval_T *rettv, evalarg_T *evalarg)
 #ifdef FEAT_FLOAT
 		&& (op == '.' || rettv->v_type != VAR_FLOAT)
 #endif
-		)
+		&& evaluate)
 	{
+	    int		error = FALSE;
+
 	    // For "list + ...", an illegal use of the first operand as
 	    // a number cannot be determined before evaluating the 2nd
 	    // operand: if this is also a list, all is ok.
@@ -2786,7 +2794,9 @@ eval5(char_u **arg, typval_T *rettv, evalarg_T *evalarg)
 	    // we know that the first operand needs to be a string or number
 	    // without evaluating the 2nd operand.  So check before to avoid
 	    // side effects after an error.
-	    if (evaluate && tv_get_string_chk(rettv) == NULL)
+	    if (op != '.')
+		tv_get_number_chk(rettv, &error);
+	    if ((op == '.' && tv_get_string_chk(rettv) == NULL) || error)
 	    {
 		clear_tv(rettv);
 		return FAIL;
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 9b5b4ff2e..568c3bf6a 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -1128,7 +1128,19 @@ def Test_expr5_vim9script()
       vim9script
       echo {} - 22
   END
-  CheckScriptFailure(lines, 'E731:', 2)
+  CheckScriptFailure(lines, 'E728:', 2)
+
+  lines =<< trim END
+      vim9script
+      echo [] - 33
+  END
+  CheckScriptFailure(lines, 'E745:', 2)
+
+  lines =<< trim END
+      vim9script
+      echo 0z1234 - 44
+  END
+  CheckScriptFailure(lines, 'E974:', 2)
 
   lines =<< trim END
       vim9script
diff --git a/src/version.c b/src/version.c
index 97f9cba2f..2340ab8d1 100644
--- a/src/version.c
+++ b/src/version.c
@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1890,
 /**/
     1889,
 /**/
-- 
2.50.1