vim-patch:8.1.1816: cannot use a user defined function as a method

Problem:    Cannot use a user defined function as a method.
Solution:   Pass the base as the first argument to the user defined function
            after "->". (partly by FUJIWARA Takuya)
fcfe1a9b89

src/nvim/eval.c

@@ -4031,7 +4031,7 @@ static int eval7(
   *arg = skipwhite(*arg);
 
   // Handle following '[', '(' and '.' for expr[expr], expr.name,
-  // expr(expr).
+  // expr(expr), expr->name(expr)
   if (ret == OK) {
     ret = handle_subscript((const char **)arg, rettv, evaluate, true);
   }
@@ -4094,7 +4094,7 @@ static int eval_method(char_u **const arg, typval_T *const rettv,
   // Locate the method name.
   const char_u *const name = *arg;
   size_t len;
-  for (len = 0; ASCII_ISALNUM(name[len]) || name[len] == '_'; len++) {
+  for (len = 0; eval_isnamec(name[len]); len++) {
   }
 
   if (len == 0) {
@@ -4113,6 +4113,8 @@ static int eval_method(char_u **const arg, typval_T *const rettv,
   }
   *arg += len;
 
+  // TODO(seandewar): if "name" is a function reference, resolve it.
+
   typval_T base = *rettv;
   funcexe_T funcexe = FUNCEXE_INIT;
   funcexe.evaluate = evaluate;

src/nvim/eval/userfunc.c

@@ -1447,7 +1447,8 @@ call_func(
   int argcount = argcount_in;
   typval_T *argvars = argvars_in;
   dict_T *selfdict = funcexe->selfdict;
-  typval_T argv[MAX_FUNC_ARGS + 1];  // used when "partial" is not NULL
+  typval_T argv[MAX_FUNC_ARGS + 1];  // used when "partial" or
+                                     // "funcexe->basetv" is not NULL
   int argv_clear = 0;
   partial_T *partial = funcexe->partial;
 
@@ -1514,10 +1515,7 @@ call_func(
       }
     } else if (fp != NULL || !builtin_function((const char *)rfname, -1)) {
       // User defined function.
-      if (funcexe->basetv != NULL) {
-        // TODO(seandewar): support User function: base->Method()
-        fp = NULL;
-      } else if (fp == NULL) {
+      if (fp == NULL) {
         fp = find_func(rfname);
       }
 
@@ -1546,6 +1544,16 @@ call_func(
           argcount = funcexe->argv_func(argcount, argvars, argv_clear,
                                         fp->uf_args.ga_len);
         }
+
+        if (funcexe->basetv != NULL) {
+          // Method call: base->Method()
+          memmove(&argv[1], argvars, sizeof(typval_T) * argcount);
+          argv[0] = *funcexe->basetv;
+          argcount++;
+        } else {
+          memcpy(argv, argvars, sizeof(typval_T) * argcount);
+        }
+
         if (fp->uf_flags & FC_RANGE && funcexe->doesrange != NULL) {
           *funcexe->doesrange = true;
         }
@@ -1557,14 +1565,15 @@ call_func(
           error = ERROR_DICT;
         } else {
           // Call the user function.
-          call_user_func(fp, argcount, argvars, rettv, funcexe->firstline,
+          call_user_func(fp, argcount, argv, rettv, funcexe->firstline,
                          funcexe->lastline,
                          (fp->uf_flags & FC_DICT) ? selfdict : NULL);
           error = ERROR_NONE;
         }
       }
     } else if (funcexe->basetv != NULL) {
-      // Find the method name in the table, call its implementation.
+      // expr->method(): Find the method name in the table, call its
+      // implementation with the base as one of the arguments.
       error = call_internal_method(fname, argcount, argvars, rettv,
                                    funcexe->basetv);
     } else {

src/nvim/testdir/sautest/autoload/foo.vim

@@ -5,3 +5,7 @@ let foo#bar = {}
 func foo#bar.echo()
   let g:called_foo_bar_echo += 1
 endfunc
+
+func foo#addFoo(head)
+  return a:head .. 'foo'
+endfunc

src/nvim/testdir/test_autoload.vim

@@ -8,6 +8,8 @@ func Test_autoload_dict_func()
   call g:foo#bar.echo()
   call assert_equal(1, g:loaded_foo_vim)
   call assert_equal(1, g:called_foo_bar_echo)
+
+  eval 'bar'->g:foo#addFoo()->assert_equal('barfoo')
 endfunc
 
 func Test_source_autoload()

src/nvim/testdir/test_user_func.vim

@@ -47,7 +47,7 @@ func FuncWithRef(a)
 endfunc
 
 func Test_user_func()
-  let g:FuncRef=function("FuncWithRef")
+  let g:FuncRef = function("FuncWithRef")
   let g:counter = 0
   inoremap <expr> ( ListItem()
   inoremap <expr> [ ListReset()
@@ -62,6 +62,14 @@ func Test_user_func()
   call assert_equal(9, g:retval)
   call assert_equal(333, g:FuncRef(333))
 
+  let g:retval = "nop"
+  call assert_equal('xxx4asdf', "xxx"->Table(4, "asdf"))
+  call assert_equal('fail', 45->Compute(0, "retval"))
+  call assert_equal('nop', g:retval)
+  call assert_equal('ok', 45->Compute(5, "retval"))
+  call assert_equal(9, g:retval)
+  " call assert_equal(333, 333->g:FuncRef())
+
   enew
 
   normal oXX+-XX
@@ -150,6 +158,14 @@ func Test_default_arg()
 	\ execute('func Args2'))
 endfunc
 
+func s:addFoo(lead)
+  return a:lead .. 'foo'
+endfunc
+
+func Test_user_method()
+  eval 'bar'->s:addFoo()->assert_equal('barfoo')
+endfunc
+
 func Test_failed_call_in_try()
   try | call UnknownFunc() | catch | endtry
 endfunc