vim-patch:8.1.1489: sign order wrong when priority was changed

Problem:    Sign order wrong when priority was changed.
Solution:   Reorder signs when priority is changed. (Yegappan Lakshmanan,
            closes vim/vim#4502)
https://github.com/vim/vim/commit/64416127fc184b5544530afe818722679158f059

1 files changed, 76 insertions, 0 deletions

diff --git a/src/nvim/sign.c b/src/nvim/sign.c
index e81d09aa4b..baa9c6538f 100644
--- a/src/nvim/sign.c
+++ b/src/nvim/sign.c
@@ -265,6 +265,81 @@ dict_T * sign_get_info(signlist_T *sign)
   return d;
 }
 
+// Sort the signs placed on the same line as "sign" by priority.  Invoked after
+// changing the priority of an already placed sign.  Assumes the signs in the
+// buffer are sorted by line number and priority.
+static void sign_sort_by_prio_on_line(buf_T *buf, signlist_T *sign)
+  FUNC_ATTR_NONNULL_ALL
+{
+  // If there is only one sign in the buffer or only one sign on the line or
+  // the sign is already sorted by priority, then return.
+  if ((sign->prev == NULL
+       || sign->prev->lnum != sign->lnum
+       || sign->prev->priority > sign->priority)
+      && (sign->next == NULL
+          || sign->next->lnum != sign->lnum
+          || sign->next->priority < sign->priority)) {
+    return;
+  }
+
+  // One or more signs on the same line as 'sign'
+  // Find a sign after which 'sign' should be inserted
+
+  // First search backward for a sign with higher priority on the same line
+  signlist_T *p = sign;
+  while (p->prev != NULL
+         && p->prev->lnum == sign->lnum
+         && p->prev->priority <= sign->priority) {
+    p = p->prev;
+  }
+  if (p == sign) {
+    // Sign not found. Search forward for a sign with priority just before
+    // 'sign'.
+    p = sign->next;
+    while (p->next != NULL
+           && p->next->lnum == sign->lnum
+           && p->next->priority > sign->priority) {
+      p = p->next;
+    }
+  }
+
+  // Remove 'sign' from the list
+  if (buf->b_signlist == sign) {
+    buf->b_signlist = sign->next;
+  }
+  if (sign->prev != NULL) {
+    sign->prev->next = sign->next;
+  }
+  if (sign->next != NULL) {
+    sign->next->prev = sign->prev;
+  }
+  sign->prev = NULL;
+  sign->next = NULL;
+
+  // Re-insert 'sign' at the right place
+  if (p->priority <= sign->priority) {
+    // 'sign' has a higher priority and should be inserted before 'p'
+    sign->prev = p->prev;
+    sign->next = p;
+    p->prev = sign;
+    if (sign->prev != NULL) {
+      sign->prev->next = sign;
+    }
+    if (buf->b_signlist == p) {
+      buf->b_signlist = sign;
+    }
+  } else {
+    // 'sign' has a lower priority and should be inserted after 'p'
+    sign->prev = p;
+    sign->next = p->next;
+    p->next = sign;
+    if (sign->next != NULL) {
+      sign->next->prev = sign;
+    }
+  }
+}
+
+
 /// Add the sign into the signlist. Find the right spot to do it though.
 void buf_addsign(
     buf_T *buf,     // buffer to store sign in
@@ -285,6 +360,7 @@ void buf_addsign(
       // Update an existing sign
       sign->typenr = typenr;
       sign->priority = prio;
+      sign_sort_by_prio_on_line(buf, sign);
       return;
     } else if (lnum < sign->lnum) {
       insert_sign_by_lnum_prio(buf, prev, id, groupname, prio, lnum, typenr);