vim-patch:9.1.0329: String interpolation fails for Dict type (#28335)

Problem:  String interpolation fails for Dict type
Solution: Support Dict data type properly, also support :put =Dict
          (without having to convert it to string() first)
          (Yegappan Lakshmanan)

fixes: vim/vim#14529
closes: vim/vim#14541

f01493c550

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

src/nvim/eval.c

@@ -969,7 +969,8 @@ int skip_expr(char **pp, evalarg_T *const evalarg)
 
 /// Convert "tv" to a string.
 ///
-/// @param convert  when true convert a List into a sequence of lines.
+/// @param convert  when true convert a List into a sequence of lines
+///                 and a Dict into a textual representation of the Dict.
 ///
 /// @return  an allocated string.
 static char *typval2string(typval_T *tv, bool convert)
@@ -985,6 +986,8 @@ static char *typval2string(typval_T *tv, bool convert)
     }
     ga_append(&ga, NUL);
     return (char *)ga.ga_data;
+  } else if (convert && tv->v_type == VAR_DICT) {
+    return encode_tv2string(tv, NULL);
   }
   return xstrdup(tv_get_string(tv));
 }

src/nvim/eval.lua

@@ -11129,10 +11129,10 @@ M.funcs = {
       for infinite and NaN floating-point values representations
       which use |str2float()|.  Strings are also dumped literally,
       only single quote is escaped, which does not allow using YAML
-      for parsing back binary strings.  |eval()| should always work for
-      strings and floats though and this is the only official
-      method, use |msgpackdump()| or |json_encode()| if you need to
-      share data with other application.
+      for parsing back binary strings.  |eval()| should always work
+      for strings and floats though, and this is the only official
+      method.  Use |msgpackdump()| or |json_encode()| if you need to
+      share data with other applications.
 
     ]=],
     name = 'string',