feat(sign):Allow signs to be 0 width (#13290)

Adds support for signs to be 0 cells wide. If all signs of the same
group have no width, the signcolumn will not be rendered for that group.

5 files changed, 133 insertions, 31 deletions

diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index f40ebaad90..a8cb90ff0e 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -5479,7 +5479,9 @@ int buf_signcols(buf_T *buf)
             curline = sign->lnum;
             linesum = 0;
           }
-          linesum++;
+          if (sign->has_text_or_icon) {
+            linesum++;
+          }
         }
         if (linesum > buf->b_signcols_max) {
           buf->b_signcols_max = linesum;
diff --git a/src/nvim/sign.c b/src/nvim/sign.c
index ffe51287c5..fc9f53c192 100644
--- a/src/nvim/sign.c
+++ b/src/nvim/sign.c
@@ -173,13 +173,15 @@ static void insert_sign(
     const char_u *group,    // sign group; NULL for global group
     int prio,               // sign priority
     linenr_T lnum,          // line number which gets the mark
-    int typenr              // typenr of sign we are adding
+    int typenr,             // typenr of sign we are adding
+    bool has_text_or_icon   // sign has text or icon
 )
 {
   signlist_T *newsign = xmalloc(sizeof(signlist_T));
   newsign->id = id;
   newsign->lnum = lnum;
   newsign->typenr = typenr;
+  newsign->has_text_or_icon = has_text_or_icon;
   if (group != NULL) {
     newsign->group = sign_group_ref(group);
   } else {
@@ -210,13 +212,14 @@ static void insert_sign(
 
 /// Insert a new sign sorted by line number and sign priority.
 static void insert_sign_by_lnum_prio(
-    buf_T *buf,           // buffer to store sign in
-    signlist_T *prev,     // previous sign entry
-    int id,               // sign ID
-    const char_u *group,  // sign group; NULL for global group
-    int prio,             // sign priority
-    linenr_T lnum,        // line number which gets the mark
-    int typenr            // typenr of sign we are adding
+    buf_T *buf,            // buffer to store sign in
+    signlist_T *prev,      // previous sign entry
+    int id,                // sign ID
+    const char_u *group,   // sign group; NULL for global group
+    int prio,              // sign priority
+    linenr_T lnum,         // line number which gets the mark
+    int typenr,            // typenr of sign we are adding
+    bool has_text_or_icon  // sign has text or icon
 )
 {
   signlist_T  *sign;
@@ -234,7 +237,7 @@ static void insert_sign_by_lnum_prio(
     sign = prev->next;
   }
 
-  insert_sign(buf, prev, sign, id, group, prio, lnum, typenr);
+  insert_sign(buf, prev, sign, id, group, prio, lnum, typenr, has_text_or_icon);
 }
 
 /// Get the name of a sign by its typenr.
@@ -342,12 +345,13 @@ static void sign_sort_by_prio_on_line(buf_T *buf, signlist_T *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
-    int id,         // sign ID
+    buf_T *buf,               // buffer to store sign in
+    int id,                   // sign ID
     const char_u *groupname,  // sign group
-    int prio,       // sign priority
-    linenr_T lnum,  // line number which gets the mark
-    int typenr      // typenr of sign we are adding
+    int prio,                 // sign priority
+    linenr_T lnum,            // line number which gets the mark
+    int typenr,               // typenr of sign we are adding
+    bool has_text_or_icon     // sign has text or icon
 )
 {
   signlist_T *sign;    // a sign in the signlist
@@ -363,13 +367,29 @@ void buf_addsign(
       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);
+      insert_sign_by_lnum_prio(
+          buf,
+          prev,
+          id,
+          groupname,
+          prio,
+          lnum,
+          typenr,
+          has_text_or_icon);
       return;
     }
     prev = sign;
   }
 
-  insert_sign_by_lnum_prio(buf, prev, id, groupname, prio, lnum, typenr);
+  insert_sign_by_lnum_prio(
+      buf,
+      prev,
+      id,
+      groupname,
+      prio,
+      lnum,
+      typenr,
+      has_text_or_icon);
 }
 
 // For an existing, placed sign "markId" change the type to "typenr".
@@ -786,11 +806,15 @@ static int sign_define_init_text(sign_T *sp, char_u *text)
     }
     cells += utf_ptr2cells(s);
   }
-  // Currently must be one or two display cells
-  if (s != endp || cells < 1 || cells > 2) {
+  // Currently must be empty, one or two display cells
+  if (s != endp || cells > 2) {
     EMSG2(_("E239: Invalid sign text: %s"), text);
     return FAIL;
   }
+  if (cells < 1) {
+    sp->sn_text = NULL;
+    return OK;
+  }
 
   xfree(sp->sn_text);
   // Allocate one byte more if we need to pad up
@@ -939,7 +963,15 @@ int sign_place(
   if (lnum > 0) {
     // ":sign place {id} line={lnum} name={name} file={fname}":
     // place a sign
-    buf_addsign(buf, *sign_id, sign_group, prio, lnum, sp->sn_typenr);
+    bool has_text_or_icon = sp->sn_text != NULL || sp->sn_icon != NULL;
+    buf_addsign(
+        buf,
+        *sign_id,
+        sign_group,
+        prio,
+        lnum,
+        sp->sn_typenr,
+        has_text_or_icon);
   } else {
     // ":sign place {id} file={fname}": change sign type
     lnum = buf_change_sign_type(buf, *sign_id, sign_group, sp->sn_typenr);
diff --git a/src/nvim/sign_defs.h b/src/nvim/sign_defs.h
index 687c15bbd6..c898dba890 100644
--- a/src/nvim/sign_defs.h
+++ b/src/nvim/sign_defs.h
@@ -1,6 +1,7 @@
 #ifndef NVIM_SIGN_DEFS_H
 #define NVIM_SIGN_DEFS_H
 
+#include <stdbool.h>
 #include "nvim/pos.h"
 #include "nvim/types.h"
 
@@ -22,13 +23,14 @@ typedef struct signlist signlist_T;
 
 struct signlist
 {
-    int id;              // unique identifier for each placed sign
-    linenr_T lnum;       // line number which has this sign
-    int typenr;          // typenr of sign
-    signgroup_T *group;  // sign group
-    int priority;        // priority for highlighting
-    signlist_T *next;    // next signlist entry
-    signlist_T *prev;    // previous entry -- for easy reordering
+    int id;                 // unique identifier for each placed sign
+    linenr_T lnum;          // line number which has this sign
+    int typenr;             // typenr of sign
+    bool has_text_or_icon;  // has text or icon
+    signgroup_T *group;     // sign group
+    int priority;           // priority for highlighting
+    signlist_T *next;       // next signlist entry
+    signlist_T *prev;       // previous entry -- for easy reordering
 };
 
 // Default sign priority for highlighting
diff --git a/src/nvim/testdir/test_signs.vim b/src/nvim/testdir/test_signs.vim
index 1e6c311374..4bbd722fdb 100644
--- a/src/nvim/testdir/test_signs.vim
+++ b/src/nvim/testdir/test_signs.vim
@@ -122,9 +122,9 @@ func Test_sign()
   call assert_fails("sign define Sign4 text=a\e linehl=Comment", 'E239:')
   call assert_fails("sign define Sign4 text=\ea linehl=Comment", 'E239:')
 
-  " Only 1 or 2 character text is allowed
+  " Only 0, 1 or 2 character text is allowed
   call assert_fails("sign define Sign4 text=abc linehl=Comment", 'E239:')
-  call assert_fails("sign define Sign4 text= linehl=Comment", 'E239:')
+  " call assert_fails("sign define Sign4 text= linehl=Comment", 'E239:')
   call assert_fails("sign define Sign4 text=\\ ab  linehl=Comment", 'E239:')
 
   " define sign with whitespace
@@ -306,7 +306,7 @@ func Test_sign_invalid_commands()
   call assert_fails('sign jump 1 name=', 'E474:')
   call assert_fails('sign jump 1 name=Sign1', 'E474:')
   call assert_fails('sign jump 1 line=100', '474:')
-  call assert_fails('sign define Sign2 text=', 'E239:')
+  " call assert_fails('sign define Sign2 text=', 'E239:')
   " Non-numeric identifier for :sign place
   call assert_fails("sign place abc line=3 name=Sign1 buffer=" . bufnr(''),
 								\ 'E474:')
@@ -415,7 +415,7 @@ func Test_sign_funcs()
 
   " Tests for invalid arguments to sign_define()
   call assert_fails('call sign_define("sign4", {"text" : "===>"})', 'E239:')
-  call assert_fails('call sign_define("sign5", {"text" : ""})', 'E239:')
+  " call assert_fails('call sign_define("sign5", {"text" : ""})', 'E239:')
   call assert_fails('call sign_define([])', 'E730:')
   call assert_fails('call sign_define("sign6", [])', 'E715:')
 
diff --git a/test/functional/ui/sign_spec.lua b/test/functional/ui/sign_spec.lua
index 0ed62b21b2..d1b8de5e4e 100644
--- a/test/functional/ui/sign_spec.lua
+++ b/test/functional/ui/sign_spec.lua
@@ -76,6 +76,28 @@ describe('Signs', function()
       ]])
     end)
 
+    it('allows signs with no text', function()
+      feed('ia<cr>b<cr><esc>')
+      command('sign define piet1 text= texthl=Search')
+      command('sign place 1 line=1 name=piet1 buffer=1')
+      screen:expect([[
+        a                                                    |
+        b                                                    |
+        ^                                                     |
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+                                                             |
+      ]])
+    end)
+
     it('can be called right after :split', function()
       feed('ia<cr>b<cr>c<cr><esc>gg')
       -- This used to cause a crash due to :sign using a special redraw
@@ -244,6 +266,50 @@ describe('Signs', function()
       ]]}
     end)
 
+    it('ignores signs with no icon and text when calculting the signcolumn width', function()
+      feed('ia<cr>b<cr>c<cr><esc>')
+      command('set number')
+      command('set signcolumn=auto:2')
+      command('sign define pietSearch text=>> texthl=Search')
+      command('sign define pietError text= texthl=Error')
+      command('sign place 2 line=1 name=pietError buffer=1')
+      -- no signcolumn with only empty sign
+      screen:expect([[
+        {6:  1 }a                                                |
+        {6:  2 }b                                                |
+        {6:  3 }c                                                |
+        {6:  4 }^                                                 |
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+                                                             |
+      ]])
+      -- single column with 1 sign with text and one sign without
+      command('sign place 1 line=1 name=pietSearch buffer=1')
+      screen:expect([[
+        {1:>>}{6:  1 }a                                              |
+        {2:  }{6:  2 }b                                              |
+        {2:  }{6:  3 }c                                              |
+        {2:  }{6:  ^4 }                                               |
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+                                                             |
+      ]])
+    end)
+
     it('can have 32bit sign IDs', function()
       command('sign define piet text=>> texthl=Search')
       command('sign place 100000 line=1 name=piet buffer=1')