feat(lua): allow `:=expr` as a shorter version of `:lua =expr`

existing behavior of
  :=
and
  :[range]=

are unchanged. `|` is still allowed with this usage.

However,
   :=p
and similar are changed in a way which could be construed as a breaking
change. Allowing |ex-flags| for := in the first place was a mistake as
any form of := DOES NOT MOVE THE CURSOR. So it would print one line number
and then print a completely different line contents after that.

1 files changed, 5 insertions, 4 deletions

diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 3616f1f69f..7e331a097f 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -1621,14 +1621,15 @@ void ex_lua(exarg_T *const eap)
     xfree(code);
     return;
   }
-  // When =expr is used transform it to print(vim.inspect(expr))
-  if (code[0] == '=') {
-    len += sizeof("vim.print()") - sizeof("=");
+  // When =expr is used transform it to vim.print(expr)
+  if (eap->cmdidx == CMD_equal || code[0] == '=') {
+    size_t off = (eap->cmdidx == CMD_equal) ? 0 : 1;
+    len += sizeof("vim.print()") - 1 - off;
     // code_buf needs to be 1 char larger then len for null byte in the end.
     // lua nlua_typval_exec doesn't expect null terminated string so len
     // needs to end before null byte.
     char *code_buf = xmallocz(len);
-    vim_snprintf(code_buf, len + 1, "vim.print(%s)", code + 1);
+    vim_snprintf(code_buf, len + 1, "vim.print(%s)", code + off);
     xfree(code);
     code = code_buf;
   }