patch 8.1.1913: not easy to compute the space on the command linev8.1.1913

Problem:    Not easy to compute the space on the command line.
Solution:   Add v:echospace. (Daniel Hahler, closes #4732)

6 files changed, 34 insertions, 1 deletions

diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 1cafba2436..aa27beac10 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -1768,6 +1768,13 @@ v:dying		Normally zero.  When a deadly signal is caught it's set to
 <		Note: if another deadly signal is caught when v:dying is one,
 		VimLeave autocommands will not be executed.
 
+					*v:echospace* *echospace-variable*
+v:echospace	Number of screen cells that can be used for an `:echo` message
+		in the last screen line before causing the |hit-enter-prompt|.
+		Depends on 'showcmd', 'ruler' and 'columns'.  You need to
+		check 'cmdheight' for whether there are full-width lines
+		available above the last line.
+
 					*v:errmsg* *errmsg-variable*
 v:errmsg	Last given error message.  It's allowed to set this variable.
 		Example: >
diff --git a/src/eval.c b/src/eval.c
index 5c5fd2f10d..9a2642cbe8 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -201,6 +201,7 @@ static struct vimvar
     {VV_NAME("termblinkresp",	 VAR_STRING), VV_RO},
     {VV_NAME("event",		 VAR_DICT), VV_RO},
     {VV_NAME("versionlong",	 VAR_NUMBER), VV_RO},
+    {VV_NAME("echospace",	 VAR_NUMBER), VV_RO},
 };
 
 /* shorthand */
@@ -389,6 +390,8 @@ eval_init(void)
     set_vim_var_nr(VV_TYPE_CHANNEL, VAR_TYPE_CHANNEL);
     set_vim_var_nr(VV_TYPE_BLOB,    VAR_TYPE_BLOB);
 
+    set_vim_var_nr(VV_ECHOSPACE,    sc_col - 1);
+
     set_reg_var(0);  /* default for v:register is not 0 but '"' */
 
 #ifdef EBCDIC
diff --git a/src/option.c b/src/option.c
index 6d3a059cca..215d48a092 100644
--- a/src/option.c
+++ b/src/option.c
@@ -10881,6 +10881,9 @@ comp_col(void)
     sc_col = Columns;
     ru_col = Columns;
 #endif
+#ifdef FEAT_EVAL
+    set_vim_var_nr(VV_ECHOSPACE, sc_col - 1);
+#endif
 }
 
 #if defined(FEAT_PYTHON) || defined(FEAT_PYTHON3) || defined(PROTO)
diff --git a/src/testdir/test_messages.vim b/src/testdir/test_messages.vim
index 8c6c854fab..f122917ba7 100644
--- a/src/testdir/test_messages.vim
+++ b/src/testdir/test_messages.vim
@@ -155,3 +155,20 @@ func Test_mode_message_at_leaving_insert_with_esc_mapped()
   exe buf . 'bwipe!'
   call delete(testfile)
 endfunc
+
+func Test_echospace()
+  set noruler noshowcmd laststatus=1
+  call assert_equal(&columns - 1, v:echospace)
+  split
+  call assert_equal(&columns - 1, v:echospace)
+  set ruler
+  call assert_equal(&columns - 1, v:echospace)
+  close
+  call assert_equal(&columns - 19, v:echospace)
+  set showcmd noruler
+  call assert_equal(&columns - 12, v:echospace)
+  set showcmd ruler
+  call assert_equal(&columns - 29, v:echospace)
+
+  set ruler& showcmd&
+endfunc
diff --git a/src/version.c b/src/version.c
index dfe1438bff..ee4c964ec5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1913,
+/**/
     1912,
 /**/
     1911,
diff --git a/src/vim.h b/src/vim.h
index 254d3efbe6..dca8748179 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -1981,7 +1981,8 @@ typedef int sock_T;
 #define VV_TERMBLINKRESP 89
 #define VV_EVENT	90
 #define VV_VERSIONLONG	91
-#define VV_LEN		92	// number of v: vars
+#define VV_ECHOSPACE	92
+#define VV_LEN		93	// number of v: vars
 
 // used for v_number in VAR_SPECIAL
 #define VVAL_FALSE	0L