feat(lua): make =expr print result of expr

1 files changed, 13 insertions, 1 deletions

diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 7d43d21d53..334fb91576 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -1115,11 +1115,23 @@ void ex_lua(exarg_T *const eap)
   FUNC_ATTR_NONNULL_ALL
 {
   size_t len;
-  char *const code = script_get(eap, &len);
+  char *code = script_get(eap, &len);
   if (eap->skip) {
     xfree(code);
     return;
   }
+  // When =expr is used transform it to print(vim.inspect(expr))
+  if (code[0] == '=') {
+    len += sizeof("print(vim.inspect())") - sizeof("=");
+    // 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, "print(vim.inspect(%s))", code+1);
+    xfree(code);
+    code = code_buf;
+  }
+
   nlua_typval_exec(code, len, ":lua", NULL, 0, false, NULL);
 
   xfree(code);