vim-patch:9.0.0691: lalloc(0) error in listchars test

Problem:    lalloc(0) error in listchars test.
Solution:   Skip generating text for tab if tab_len is zero.

https://github.com/vim/vim/commit/2b7b4f7670f607704307f7715ce56752757c22e3

Co-authored-by: Bram Moolenaar <Bram@vim.org>

1 files changed, 35 insertions, 33 deletions

diff --git a/src/nvim/drawline.c b/src/nvim/drawline.c
index 6b24fe6b46..e2a0895fff 100644
--- a/src/nvim/drawline.c
+++ b/src/nvim/drawline.c
@@ -2103,43 +2103,45 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
               tab_len += n_extra - tab_len;
             }
 
-            // If n_extra > 0, it gives the number of chars
-            // to use for a tab, else we need to calculate the width
-            // for a tab.
-            int tab2_len = utf_char2len(wp->w_p_lcs_chars.tab2);
-            int len = tab_len * tab2_len;
-            if (wp->w_p_lcs_chars.tab3) {
-              len += utf_char2len(wp->w_p_lcs_chars.tab3) - tab2_len;
-            }
-            if (n_extra > 0) {
-              len += n_extra - tab_len;
-            }
-            c = wp->w_p_lcs_chars.tab1;
-            p = xmalloc((size_t)len + 1);
-            memset(p, ' ', (size_t)len);
-            p[len] = NUL;
-            xfree(p_extra_free);
-            p_extra_free = p;
-            for (int i = 0; i < tab_len; i++) {
-              if (*p == NUL) {
-                tab_len = i;
-                break;
+            if (tab_len > 0) {
+              // If n_extra > 0, it gives the number of chars
+              // to use for a tab, else we need to calculate the
+              // width for a tab.
+              int tab2_len = utf_char2len(wp->w_p_lcs_chars.tab2);
+              int len = tab_len * tab2_len;
+              if (wp->w_p_lcs_chars.tab3) {
+                len += utf_char2len(wp->w_p_lcs_chars.tab3) - tab2_len;
               }
-              int lcs = wp->w_p_lcs_chars.tab2;
+              if (n_extra > 0) {
+                len += n_extra - tab_len;
+              }
+              c = wp->w_p_lcs_chars.tab1;
+              p = xmalloc((size_t)len + 1);
+              memset(p, ' ', (size_t)len);
+              p[len] = NUL;
+              xfree(p_extra_free);
+              p_extra_free = p;
+              for (int i = 0; i < tab_len; i++) {
+                if (*p == NUL) {
+                  tab_len = i;
+                  break;
+                }
+                int lcs = wp->w_p_lcs_chars.tab2;
 
-              // if tab3 is given, use it for the last char
-              if (wp->w_p_lcs_chars.tab3 && i == tab_len - 1) {
-                lcs = wp->w_p_lcs_chars.tab3;
+                // if tab3 is given, use it for the last char
+                if (wp->w_p_lcs_chars.tab3 && i == tab_len - 1) {
+                  lcs = wp->w_p_lcs_chars.tab3;
+                }
+                p += utf_char2bytes(lcs, p);
+                n_extra += utf_char2len(lcs) - (saved_nextra > 0 ? 1 : 0);
               }
-              p += utf_char2bytes(lcs, p);
-              n_extra += utf_char2len(lcs) - (saved_nextra > 0 ? 1 : 0);
-            }
-            p_extra = p_extra_free;
+              p_extra = p_extra_free;
 
-            // n_extra will be increased by FIX_FOX_BOGUSCOLS
-            // macro below, so need to adjust for that here
-            if (vcol_off > 0) {
-              n_extra -= vcol_off;
+              // n_extra will be increased by FIX_FOX_BOGUSCOLS
+              // macro below, so need to adjust for that here
+              if (vcol_off > 0) {
+                n_extra -= vcol_off;
+              }
             }
           }