Make "v:errmsg", "v:shell_error" and "v:this_session" distinct

4 files changed, 19 insertions, 7 deletions

diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index c460e65c64..a306c77829 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -1508,7 +1508,6 @@ v:errmsg	Last given error message.  It's allowed to set this variable.
 	:silent! next
 	:if v:errmsg != ""
 	:  ... handle error
-<		"errmsg" also works, for backwards compatibility.
 
 					*v:errors* *errors-variable*
 v:errors	Errors found by assert functions, such as |assert_true()|.
@@ -1813,8 +1812,7 @@ v:shell_error	Result of the last shell command.  When non-zero, the last
 	:if v:shell_error
 	:  echo 'could not rename "foo" to "bar"!'
 	:endif
-<		"shell_error" also works, for backwards compatibility.
-
+<
 					*v:statusmsg* *statusmsg-variable*
 v:statusmsg	Last given status message.  It's allowed to set this variable.
 
@@ -1888,7 +1886,6 @@ v:testing	Must be set before using `test_garbagecollect_now()`.
 v:this_session	Full filename of the last loaded or saved session file.  See
 		|:mksession|.  It is allowed to set this variable.  When no
 		session file has been saved, this variable is empty.
-		"this_session" also works, for backwards compatibility.
 
 					*v:throwpoint* *throwpoint-variable*
 v:throwpoint	The point where the exception most recently caught and not
diff --git a/runtime/doc/vim_diff.txt b/runtime/doc/vim_diff.txt
index 8bda114639..ef0b54fa33 100644
--- a/runtime/doc/vim_diff.txt
+++ b/runtime/doc/vim_diff.txt
@@ -352,6 +352,9 @@ TUI:
 
 VimL (Vim script) compatibility:
   `count` does not alias to |v:count|
+  `errmsg` does not alias to |v:errmsg|
+  `shell_error` does not alias to |v:shell_error|
+  `this_session` does not alias to |v:this_session|
 
 ==============================================================================
 5. Missing legacy features				 *nvim-features-missing*
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index e6880f58e7..36662b2a39 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -344,11 +344,11 @@ static struct vimvar {
   VV(VV_COUNT,          "count",            VAR_NUMBER, VV_RO),
   VV(VV_COUNT1,         "count1",           VAR_NUMBER, VV_RO),
   VV(VV_PREVCOUNT,      "prevcount",        VAR_NUMBER, VV_RO),
-  VV(VV_ERRMSG,         "errmsg",           VAR_STRING, VV_COMPAT),
+  VV(VV_ERRMSG,         "errmsg",           VAR_STRING, 0),
   VV(VV_WARNINGMSG,     "warningmsg",       VAR_STRING, 0),
   VV(VV_STATUSMSG,      "statusmsg",        VAR_STRING, 0),
-  VV(VV_SHELL_ERROR,    "shell_error",      VAR_NUMBER, VV_COMPAT+VV_RO),
-  VV(VV_THIS_SESSION,   "this_session",     VAR_STRING, VV_COMPAT),
+  VV(VV_SHELL_ERROR,    "shell_error",      VAR_NUMBER, VV_RO),
+  VV(VV_THIS_SESSION,   "this_session",     VAR_STRING, 0),
   VV(VV_VERSION,        "version",          VAR_NUMBER, VV_COMPAT+VV_RO),
   VV(VV_LNUM,           "lnum",             VAR_NUMBER, VV_RO_SBX),
   VV(VV_TERMRESPONSE,   "termresponse",     VAR_STRING, VV_RO),
diff --git a/test/functional/eval/special_vars_spec.lua b/test/functional/eval/special_vars_spec.lua
index b5773a5529..97a12d490d 100644
--- a/test/functional/eval/special_vars_spec.lua
+++ b/test/functional/eval/special_vars_spec.lua
@@ -174,5 +174,17 @@ describe('Special values', function()
       command('let count = []') -- v:count is readonly
       eq(1, eval('count is# g:["count"]'))
     end)
+    it('v:errmsg is distinct from errmsg', function()
+      command('let errmsg = 1')
+      eq(1, eval('errmsg is# g:["errmsg"]'))
+    end)
+    it('v:shell_error is distinct from shell_error', function()
+      command('let shell_error = []') -- v:shell_error is readonly
+      eq(1, eval('shell_error is# g:["shell_error"]'))
+    end)
+    it('v:this_session is distinct from this_session', function()
+      command('let this_session = []')
+      eq(1, eval('this_session is# g:["this_session"]'))
+    end)
   end)
 end)