# HG changeset patch
# User Bram Moolenaar <Bram@vim.org>
# Date 1623343503 -7200
# Node ID f1a390885192d8bc2210e356b1fd8a445e1f0c2c
# Parent  97f000974cc27f7a7d46933fa4112886c28f3c0e
patch 8.2.2969: subtracting from number option fails when result is zero

Commit: https://github.com/vim/vim/commit/a42e6e0082a6d564dbfa55317d4a698ac12ae898
Author: Bram Moolenaar <Bram@vim.org>
Date:   Thu Jun 10 18:43:25 2021 +0200

    patch 8.2.2969: subtracting from number option fails when result is zero

    Problem:    Subtracting from number option fails when result is zero. (Ingo
                Karkat)
    Solution:   Reset the string value when using the numeric value.
                (closes #8351)

diff --git a/src/evalvars.c b/src/evalvars.c
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -1439,6 +1439,7 @@ ex_let_one(
 			    case '%': n = (long)num_modulus(numval, n,
 							       &failed); break;
 			}
+			s = NULL;
 		    }
 		    else if (opt_type == gov_string
 					     && stringval != NULL && s != NULL)
diff --git a/src/testdir/test_vimscript.vim b/src/testdir/test_vimscript.vim
--- a/src/testdir/test_vimscript.vim
+++ b/src/testdir/test_vimscript.vim
@@ -7083,6 +7083,15 @@ func Test_compound_assignment_operators(
     call assert_fails('let &scrolljump .= "j"', 'E734:')
     set scrolljump&vim
 
+    let &foldlevelstart = 2
+    let &foldlevelstart -= 1
+    call assert_equal(1, &foldlevelstart)
+    let &foldlevelstart -= 1
+    call assert_equal(0, &foldlevelstart)
+    let &foldlevelstart = 2
+    let &foldlevelstart -= 2
+    call assert_equal(0, &foldlevelstart)
+
     " Test for register
     let @/ = 1
     call assert_fails('let @/ += 1', 'E734:')
diff --git a/src/version.c b/src/version.c
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2969,
+/**/
     2968,
 /**/
     2967,