vim-patch:8.2.3766: converting a funcref to a string leaves out "g:"

Problem:    Converting a funcref to a string leaves out "g:", causing the
            meaning of the name depending on the context.
Solution:   Prepend "g:" for a global function.

c4ec338fb8

Co-authored-by: Bram Moolenaar <Bram@vim.org>
Co-authored-by: Jan Edmund Lazo <jan.lazo@mail.utoronto.ca>

src/nvim/api/private/converter.c

@@ -74,7 +74,7 @@ static Object typval_cbuf_to_obj(EncodedData *edata, const char *data, size_t le
     kvi_push(edata->stack, typval_cbuf_to_obj(edata, len_ ? blob_->bv_ga.ga_data : "", len_)); \
   } while (0)
 
-#define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun) \
+#define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun, prefix) \
   do { \
     ufunc_T *fp = find_func(fun); \
     if (fp != NULL && (fp->uf_flags & FC_LUAREF)) { \

src/nvim/eval/encode.c

@@ -295,7 +295,7 @@ int encode_read_from_list(ListReaderState *const state, char *const buf, const s
 #define TYPVAL_ENCODE_CONV_STRING(tv, buf, len) \
   do { \
     const char *const buf_ = (buf); \
-    if ((buf) == NULL) { \
+    if (buf_ == NULL) { \
       ga_concat(gap, "''"); \
     } else { \
       const size_t len_ = (len); \
@@ -370,15 +370,21 @@ int encode_read_from_list(ListReaderState *const state, char *const buf, const s
     } \
   } while (0)
 
-#define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun) \
+#define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun, prefix) \
   do { \
     const char *const fun_ = (fun); \
     if (fun_ == NULL) { \
       internal_error("string(): NULL function name"); \
       ga_concat(gap, "function(NULL"); \
     } else { \
+      const char *const prefix_ = (prefix); \
       ga_concat(gap, "function("); \
+      const int name_off = gap->ga_len; \
+      ga_concat(gap, prefix_); \
       TYPVAL_ENCODE_CONV_STRING(tv, fun_, strlen(fun_)); \
+      /* <prefix>'<fun>' -> '<prefix><fun>'. */ \
+      ((char *)gap->ga_data)[name_off] = '\''; \
+      memcpy((char *)gap->ga_data + name_off + 1, prefix_, strlen(prefix_)); \
     } \
   } while (0)
 
@@ -748,7 +754,7 @@ static inline int convert_to_json_string(garray_T *const gap, const char *const
   } while (0)
 
 #undef TYPVAL_ENCODE_CONV_FUNC_START
-#define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun) \
+#define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun, prefix) \
   return conv_error(_("E474: Error while dumping %s, %s: " \
                       "attempt to dump function reference"), \
                     mpstack, objname)
@@ -932,7 +938,7 @@ char *encode_tv2json(typval_T *tv, size_t *len)
 #define TYPVAL_ENCODE_CONV_FLOAT(tv, flt) \
   mpack_float8(&packer->ptr, (double)(flt))
 
-#define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun) \
+#define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun, prefix) \
   return conv_error(_("E5004: Error while dumping %s, %s: " \
                       "attempt to dump function reference"), \
                     mpstack, objname)

src/nvim/eval/typval.c

@@ -3436,7 +3436,7 @@ static inline int _nothing_conv_func_start(typval_T *const tv, char *const fun)
   }
   return NOTDONE;
 }
-#define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun) \
+#define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun, prefix) \
   do { \
     if (_nothing_conv_func_start(tv, fun) != NOTDONE) { \
       return OK; \

src/nvim/eval/typval_encode.c.h

@@ -102,6 +102,7 @@
 ///
 /// @param  tv  Pointer to typval where value is stored. May not be NULL.
 /// @param  fun  Function name. May be NULL.
+/// @param  prefix  Prefix for converting to a string.
 
 /// @def TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS
 /// @brief Macros used before starting to convert partial arguments
@@ -344,15 +345,19 @@ static int TYPVAL_ENCODE_CONVERT_ONE_VALUE(
                             tv_blob_len(tv->vval.v_blob));
     break;
   case VAR_FUNC:
-    TYPVAL_ENCODE_CONV_FUNC_START(tv, tv->vval.v_string);
+    TYPVAL_ENCODE_CONV_FUNC_START(tv, tv->vval.v_string, "");
     TYPVAL_ENCODE_CONV_FUNC_BEFORE_ARGS(tv, 0);
     TYPVAL_ENCODE_CONV_FUNC_BEFORE_SELF(tv, -1);
     TYPVAL_ENCODE_CONV_FUNC_END(tv);
     break;
   case VAR_PARTIAL: {
     partial_T *const pt = tv->vval.v_partial;
-    (void)pt;
-    TYPVAL_ENCODE_CONV_FUNC_START(tv, (pt == NULL ? NULL : partial_name(pt)));
+    char *const fun = pt == NULL ? NULL : partial_name(pt);
+    // When using uf_name prepend "g:" for a global function.
+    const char *const prefix = fun != NULL && pt->pt_name == NULL
+                               && ASCII_ISUPPER(fun[0]) ? "g:" : "";
+    (void)prefix;
+    TYPVAL_ENCODE_CONV_FUNC_START(tv, fun, prefix);
     kvi_push(*mpstack, ((MPConvStackVal) {
         .type = kMPConvPartial,
         .tv = tv,

src/nvim/lua/converter.c

@@ -453,7 +453,7 @@ static bool typval_conv_special = false;
     lua_pushlstring(lstate, blob_ != NULL ? blob_->bv_ga.ga_data : "", (size_t)(len)); \
   } while (0)
 
-#define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun) \
+#define TYPVAL_ENCODE_CONV_FUNC_START(tv, fun, prefix) \
   do { \
     ufunc_T *fp = find_func(fun); \
     if (fp != NULL && fp->uf_flags & FC_LUAREF) { \

test/old/testdir/test_functions.vim

@@ -3719,6 +3719,11 @@ func Test_builtin_check()
   unlet bar
 endfunc
 
+func Test_funcref_to_string()
+  let Fn = funcref('g:Test_funcref_to_string')
+  call assert_equal("function('g:Test_funcref_to_string')", string(Fn))
+endfunc
+
 " Test for isabsolutepath()
 func Test_isabsolutepath()
   call assert_false(isabsolutepath(''))