vim-patch:8.1.1820: using expr->FuncRef() does not work

Problem:    Using expr->FuncRef() does not work.
Solution:   Make FuncRef work as a method.
https://github.com/vim/vim/commit/761fdf01c6e307c448cec2684f8b315ba6d1f454

3 files changed, 104 insertions, 80 deletions

diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 021a9a75b8..4f934fdc70 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -3146,6 +3146,65 @@ static int pattern_match(char_u *pat, char_u *text, bool ic)
   return matches;
 }
 
+/// Handle a name followed by "(".  Both for just "name(arg)" and for
+/// "expr->name(arg)".
+//
+/// @param arg  Points to "(", will be advanced
+/// @param basetv  "expr" for "expr->name(arg)"
+//
+/// @return OK or FAIL.
+static int eval_func(char_u **const arg, char_u *const name, const int name_len,
+                     typval_T *const rettv, const bool evaluate,
+                     typval_T *const basetv)
+  FUNC_ATTR_NONNULL_ARG(1, 2, 4)
+{
+  char_u *s = name;
+  int len = name_len;
+
+  if (!evaluate) {
+    check_vars((const char *)s, len);
+  }
+
+  // If "s" is the name of a variable of type VAR_FUNC
+  // use its contents.
+  partial_T *partial;
+  s = deref_func_name((const char *)s, &len, &partial, !evaluate);
+
+  // Need to make a copy, in case evaluating the arguments makes
+  // the name invalid.
+  s = xmemdupz(s, len);
+
+  // Invoke the function.
+  funcexe_T funcexe = FUNCEXE_INIT;
+  funcexe.firstline = curwin->w_cursor.lnum;
+  funcexe.lastline = curwin->w_cursor.lnum;
+  funcexe.evaluate = evaluate;
+  funcexe.partial = partial;
+  funcexe.basetv = basetv;
+  int ret = get_func_tv(s, len, rettv, arg, &funcexe);
+
+  xfree(s);
+
+  // If evaluate is false rettv->v_type was not set in
+  // get_func_tv, but it's needed in handle_subscript() to parse
+  // what follows. So set it here.
+  if (rettv->v_type == VAR_UNKNOWN && !evaluate && **arg == '(') {
+    rettv->vval.v_string = (char_u *)tv_empty_string;
+    rettv->v_type = VAR_FUNC;
+  }
+
+  // Stop the expression evaluation when immediately
+  // aborting on error, or when an interrupt occurred or
+  // an exception was thrown but not caught.
+  if (evaluate && aborting()) {
+    if (ret == OK) {
+      tv_clear(rettv);
+    }
+    ret = FAIL;
+  }
+  return ret;
+}
+
 // TODO(ZyX-I): move to eval/expressions
 
 /*
@@ -3977,47 +4036,7 @@ static int eval7(
       ret = FAIL;
     } else {
       if (**arg == '(') {               // recursive!
-        partial_T *partial;
-
-        if (!evaluate) {
-          check_vars((const char *)s, len);
-        }
-
-        // If "s" is the name of a variable of type VAR_FUNC
-        // use its contents.
-        s = deref_func_name((const char *)s, &len, &partial, !evaluate);
-
-        // Need to make a copy, in case evaluating the arguments makes
-        // the name invalid.
-        s = xmemdupz(s, len);
-
-        // Invoke the function.
-        funcexe_T funcexe = FUNCEXE_INIT;
-        funcexe.firstline = curwin->w_cursor.lnum;
-        funcexe.lastline = curwin->w_cursor.lnum;
-        funcexe.evaluate = evaluate;
-        funcexe.partial = partial;
-        ret = get_func_tv(s, len, rettv, arg, &funcexe);
-
-        xfree(s);
-
-        // If evaluate is false rettv->v_type was not set in
-        // get_func_tv, but it's needed in handle_subscript() to parse
-        // what follows. So set it here.
-        if (rettv->v_type == VAR_UNKNOWN && !evaluate && **arg == '(') {
-          rettv->vval.v_string = (char_u *)tv_empty_string;
-          rettv->v_type = VAR_FUNC;
-        }
-
-        // Stop the expression evaluation when immediately
-        // aborting on error, or when an interrupt occurred or
-        // an exception was thrown but not caught.
-        if (evaluate && aborting()) {
-          if (ret == OK) {
-            tv_clear(rettv);
-          }
-          ret = FAIL;
-        }
+        ret = eval_func(arg, s, len, rettv, evaluate, NULL);
       } else if (evaluate) {
         ret = get_var_tv((const char *)s, len, rettv, NULL, true, false);
       } else {
@@ -4090,37 +4109,35 @@ static int eval_method(char_u **const arg, typval_T *const rettv,
 {
   // Skip over the ->.
   *arg += 2;
+  typval_T base = *rettv;
+  rettv->v_type = VAR_UNKNOWN;
 
   // Locate the method name.
-  const char_u *const name = *arg;
-  size_t len;
-  for (len = 0; eval_isnamec(name[len]); len++) {
+  char_u *name = *arg;
+  char_u *alias;
+
+  const int len
+      = get_name_len((const char **)arg, (char **)&alias, evaluate, true);
+  if (alias != NULL) {
+    name = alias;
   }
 
-  if (len == 0) {
+  int ret;
+  if (len <= 0) {
     if (verbose) {
       EMSG(_("E260: Missing name after ->"));
     }
-    return FAIL;
-  }
-
-  // Check for the "(".  Skip over white space after it.
-  if (name[len] != '(') {
-    if (verbose) {
-      EMSG2(_(e_missingparen), name);
+    ret = FAIL;
+  } else {
+    if (**arg != '(') {
+      if (verbose) {
+        EMSG2(_(e_missingparen), name);
+      }
+      ret = FAIL;
+    } else {
+      ret = eval_func(arg, name, len, rettv, evaluate, &base);
     }
-    return FAIL;
   }
-  *arg += len;
-
-  // TODO(seandewar): if "name" is a function reference, resolve it.
-
-  typval_T base = *rettv;
-  funcexe_T funcexe = FUNCEXE_INIT;
-  funcexe.evaluate = evaluate;
-  funcexe.basetv = &base;
-  rettv->v_type = VAR_UNKNOWN;
-  int ret = get_func_tv(name, len, rettv, arg, &funcexe);
 
   // Clear the funcref afterwards, so that deleting it while
   // evaluating the arguments is possible (see test55).
@@ -4128,15 +4145,6 @@ static int eval_method(char_u **const arg, typval_T *const rettv,
     tv_clear(&base);
   }
 
-  // Stop the expression evaluation when immediately aborting on
-  // error, or when an interrupt occurred or an exception was thrown
-  // but not caught.
-  if (aborting()) {
-    if (ret == OK) {
-      tv_clear(rettv);
-    }
-    ret = FAIL;
-  }
   return ret;
 }
 
diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index 3c0c0091f2..9ecde327de 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -1450,6 +1450,7 @@ call_func(
   typval_T argv[MAX_FUNC_ARGS + 1];  // used when "partial" or
                                      // "funcexe->basetv" is not NULL
   int argv_clear = 0;
+  int argv_base = 0;
   partial_T *partial = funcexe->partial;
 
   // Initialize rettv so that it is safe for caller to invoke clear_tv(rettv)
@@ -1550,8 +1551,8 @@ call_func(
           memmove(&argv[1], argvars, sizeof(typval_T) * argcount);
           argv[0] = *funcexe->basetv;
           argcount++;
-        } else {
-          memcpy(argv, argvars, sizeof(typval_T) * argcount);
+          argvars = argv;
+          argv_base = 1;
         }
 
         if (fp->uf_flags & FC_RANGE && funcexe->doesrange != NULL) {
@@ -1565,7 +1566,7 @@ call_func(
           error = ERROR_DICT;
         } else {
           // Call the user function.
-          call_user_func(fp, argcount, argv, rettv, funcexe->firstline,
+          call_user_func(fp, argcount, argvars, rettv, funcexe->firstline,
                          funcexe->lastline,
                          (fp->uf_flags & FC_DICT) ? selfdict : NULL);
           error = ERROR_NONE;
@@ -1602,9 +1603,11 @@ theend:
     user_func_error(error, (name != NULL) ? name : funcname);
   }
 
+  // clear the copies made from the partial
   while (argv_clear > 0) {
-    tv_clear(&argv[--argv_clear]);
+    tv_clear(&argv[--argv_clear + argv_base]);
   }
+
   xfree(tofree);
   xfree(name);
 
diff --git a/src/nvim/testdir/test_method.vim b/src/nvim/testdir/test_method.vim
index ef87773924..a1fbe7af28 100644
--- a/src/nvim/testdir/test_method.vim
+++ b/src/nvim/testdir/test_method.vim
@@ -1,6 +1,6 @@
 " Tests for ->method()
 
-func Test_list()
+func Test_list_method()
   let l = [1, 2, 3]
   call assert_equal([1, 2, 3, 4], [1, 2, 3]->add(4))
   eval l->assert_equal(l)
@@ -34,7 +34,7 @@ func Test_list()
   call assert_fails('eval l->values()', 'E715:')
 endfunc
 
-func Test_dict()
+func Test_dict_method()
   let d = #{one: 1, two: 2, three: 3}
 
   call assert_equal(d, d->copy())
@@ -71,7 +71,7 @@ func Test_dict()
   call assert_equal([1, 2, 3], d->values())
 endfunc
 
-func Test_string()
+func Test_string_method()
   call assert_equal(['1', '2', '3'], '1 2 3'->split())
   call assert_equal([1, 2, 3], '1 2 3'->split()->map({i, v -> str2nr(v)}))
   call assert_equal([65, 66, 67], 'ABC'->str2list())
@@ -81,7 +81,7 @@ func Test_string()
   call assert_equal('axc', 'abc'->substitute('b', 'x', ''))
 endfunc
 
-func Test_append()
+func Test_method_append()
   new
   eval ['one', 'two', 'three']->append(1)
   call assert_equal(['', 'one', 'two', 'three'], getline(1, '$'))
@@ -95,4 +95,17 @@ func Test_append()
   exe 'bwipe! ' .. bnr
 endfunc
 
+func Test_method_funcref()
+  func Concat(one, two, three)
+    return a:one .. a:two .. a:three
+  endfunc
+  let FuncRef = function('Concat')
+  eval 'foo'->FuncRef('bar', 'tail')->assert_equal('foobartail')
+
+  let Partial = function('Concat', ['two'])
+  eval 'one'->Partial('three')->assert_equal('onetwothree')
+
+  delfunc Concat
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab