patch 8.2.0339: Vim9: function return type may depend on arguments

Problem:    Vim9: function return type may depend on arguments.
Solution:   Instead of a fixed return type use a function to figure out the
            return type.

src/evalbuffer.c

@@ -752,6 +752,12 @@ f_getbufline(typval_T *argvars, typval_T *rettv)
     get_buffer_lines(buf, lnum, end, TRUE, rettv);
 }
 
+    type_T *
+ret_f_getline(int argcount, type_T **argtypes UNUSED)
+{
+    return argcount == 1 ? &t_string : &t_list_string;
+}
+
 /*
  * "getline(lnum, [end])" function
  */

src/proto/evalbuffer.pro

@@ -16,6 +16,7 @@ void f_bufwinnr(typval_T *argvars, typval_T *rettv);
 void f_deletebufline(typval_T *argvars, typval_T *rettv);
 void f_getbufinfo(typval_T *argvars, typval_T *rettv);
 void f_getbufline(typval_T *argvars, typval_T *rettv);
+type_T *ret_f_getline(int argcount, type_T **argtypes);
 void f_getline(typval_T *argvars, typval_T *rettv);
 void f_setbufline(typval_T *argvars, typval_T *rettv);
 void f_setline(typval_T *argvars, typval_T *rettv);

src/proto/evalfunc.pro

@@ -4,7 +4,7 @@ char_u *get_expr_name(expand_T *xp, int idx);
 int find_internal_func(char_u *name);
 int has_internal_func(char_u *name);
 char *internal_func_name(int idx);
-type_T *internal_func_ret_type(int idx, int argcount);
+type_T *internal_func_ret_type(int idx, int argcount, type_T **argtypes);
 int check_internal_func(int idx, int argcount);
 int call_internal_func(char_u *name, int argcount, typval_T *argvars, typval_T *rettv);
 void call_internal_func_by_idx(int idx, typval_T *argvars, typval_T *rettv);

src/testdir/test_vim9_script.vim

@@ -55,7 +55,12 @@ def Test_assignment()
 
   if has('channel')
     let chan1: channel
+    let job1: job
   endif
+  if has('float')
+    let float1: float = 3.4
+  endif
+  let party: partial = funcref('Test_syntax')
 
   g:newvar = 'new'
   assert_equal('new', g:newvar)

src/version.c

@@ -738,6 +738,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    339,
 /**/
     338,
 /**/

src/vim9compile.c

@@ -992,6 +992,8 @@ generate_BCALL(cctx_T *cctx, int func_idx, int argcount)
 {
     isn_T	*isn;
     garray_T	*stack = &cctx->ctx_type_stack;
+    type_T	*argtypes[MAX_FUNC_ARGS];
+    int		i;
 
     if (check_internal_func(func_idx, argcount) == FAIL)
 	return FAIL;
@@ -1001,11 +1003,14 @@ generate_BCALL(cctx_T *cctx, int func_idx, int argcount)
     isn->isn_arg.bfunc.cbf_idx = func_idx;
     isn->isn_arg.bfunc.cbf_argcount = argcount;
 
+    for (i = 0; i < argcount; ++i)
+	argtypes[i] = ((type_T **)stack->ga_data)[stack->ga_len - argcount + i];
+
     stack->ga_len -= argcount; // drop the arguments
     if (ga_grow(stack, 1) == FAIL)
 	return FAIL;
     ((type_T **)stack->ga_data)[stack->ga_len] =
-				    internal_func_ret_type(func_idx, argcount);
+			  internal_func_ret_type(func_idx, argcount, argtypes);
     ++stack->ga_len;	    // add return value
 
     return OK;
@@ -1374,7 +1379,7 @@ parse_type(char_u **arg, garray_T *type_list)
 	    }
 	    break;
 	case 'p':
-	    if (len == 4 && STRNCMP(*arg, "partial", len) == 0)
+	    if (len == 7 && STRNCMP(*arg, "partial", len) == 0)
 	    {
 		*arg += len;
 		// TODO: arguments and return type