vim-patch:8.1.1803: all builtin functions are global

Problem:    All builtin functions are global.
Solution:   Add the method call operator ->.  Implemented for a limited number
            of functions.
https://github.com/vim/vim/commit/ac92e25a33c37ec5becbfffeccda136c73b761ac

- Note that to *exactly* port hunk @@ -7376,18 +7444,19 from
  handle_subscript(), we need the :scriptversion patches (I have an open
  PR for those, but this patch works fine without them anyway).
- Port call_internal_func() from v7.4.2058.
- Adjust some error messages in tests, as they rely on the Blob patches.
- Add a modeline to test_method.vim.

Ignore the global_functions and base_method tables and prefer the
current GPerf implementation. Instead, add an extra base_arg field to
VimLFuncDef that holds the number of the argument to use as the base
(1-indexed, so that 0 may be used to refer to functions that cannot be
used as methods).

This also means we support using any argument as a base from the get-go,
rather than just the first (Vim includes this ability in future patches,
however).

To mark a function as usable as a method, use the "base" key as
described in eval.lua.

4 files changed, 57 insertions, 14 deletions

diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 363640adc5..787d5aaf78 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -175,6 +175,50 @@ const VimLFuncDef *find_internal_func(const char *const name)
   return find_internal_func_gperf(name, len);
 }
 
+int call_internal_func(const char_u *const fname, const int argcount,
+                       typval_T *const argvars, typval_T *const rettv)
+  FUNC_ATTR_NONNULL_ALL
+{
+  const VimLFuncDef *const fdef = find_internal_func((const char *)fname);
+  if (fdef == NULL) {
+    return ERROR_UNKNOWN;
+  } else if (argcount < fdef->min_argc) {
+    return ERROR_TOOFEW;
+  } else if (argcount > fdef->max_argc) {
+    return ERROR_TOOMANY;
+  }
+  argvars[argcount].v_type = VAR_UNKNOWN;
+  fdef->func(argvars, rettv, fdef->data);
+  return ERROR_NONE;
+}
+
+/// Invoke a method for base->method().
+int call_internal_method(const char_u *const fname, const int argcount,
+                         typval_T *const argvars, typval_T *const rettv,
+                         typval_T *const basetv)
+  FUNC_ATTR_NONNULL_ALL
+{
+  const VimLFuncDef *const fdef = find_internal_func((const char *)fname);
+  if (fdef == NULL || fdef->base_arg == 0) {
+    return ERROR_UNKNOWN;
+  } else if (argcount + 1 < fdef->min_argc) {
+    return ERROR_TOOFEW;
+  } else if (argcount + 1 > fdef->max_argc) {
+    return ERROR_TOOMANY;
+  }
+
+  typval_T argv[MAX_FUNC_ARGS + 1];
+  const ptrdiff_t base_index = fdef->base_arg - 1;
+  memcpy(argv, argvars, base_index * sizeof(typval_T));
+  argv[base_index] = *basetv;
+  memcpy(argv + base_index + 1, argvars + base_index,
+         (argcount - base_index) * sizeof(typval_T));
+  argv[argcount + 1].v_type = VAR_UNKNOWN;
+
+  fdef->func(argv, rettv, fdef->data);
+  return ERROR_NONE;
+}
+
 /*
  * Return TRUE for a non-zero Number and a non-empty String.
  */
diff --git a/src/nvim/eval/funcs.h b/src/nvim/eval/funcs.h
index a343290734..3ad0b8282a 100644
--- a/src/nvim/eval/funcs.h
+++ b/src/nvim/eval/funcs.h
@@ -14,6 +14,7 @@ typedef struct fst {
   char *name;        ///< Name of the function.
   uint8_t min_argc;  ///< Minimal number of arguments.
   uint8_t max_argc;  ///< Maximal number of arguments.
+  uint8_t base_arg;  ///< Method base arg # (1-indexed), or 0 if not a method.
   VimLFunc func;     ///< Function implementation.
   FunPtr data;       ///< Userdata for function implementation.
 } VimLFuncDef;
diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index 516f7a1d53..ec43987b07 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -1514,7 +1514,10 @@ call_func(
       }
     } else if (fp != NULL || !builtin_function((const char *)rfname, -1)) {
       // User defined function.
-      if (fp == NULL) {
+      if (funcexe->basetv != NULL) {
+        // TODO(seandewar): support User function: base->Method()
+        fp = NULL;
+      } else if (fp == NULL) {
         fp = find_func(rfname);
       }
 
@@ -1560,20 +1563,13 @@ call_func(
           error = ERROR_NONE;
         }
       }
+    } else if (funcexe->basetv != NULL) {
+      // Find the method name in the table, call its implementation.
+      error = call_internal_method(fname, argcount, argvars, rettv,
+                                   funcexe->basetv);
     } else {
       // Find the function name in the table, call its implementation.
-      const VimLFuncDef *const fdef = find_internal_func((const char *)fname);
-      if (fdef != NULL) {
-        if (argcount < fdef->min_argc) {
-          error = ERROR_TOOFEW;
-        } else if (argcount > fdef->max_argc) {
-          error = ERROR_TOOMANY;
-        } else {
-          argvars[argcount].v_type = VAR_UNKNOWN;
-          fdef->func(argvars, rettv, fdef->data);
-          error = ERROR_NONE;
-        }
-      }
+      error = call_internal_func(fname, argcount, argvars, rettv);
     }
     /*
      * The function call (or "FuncUndefined" autocommand sequence) might
@@ -2937,7 +2933,7 @@ void ex_call(exarg_T *eap)
   rettv.v_type = VAR_UNKNOWN;  // tv_clear() uses this.
 
   if (*startarg != '(') {
-    EMSG2(_("E107: Missing parentheses: %s"), eap->arg);
+    EMSG2(_(e_missingparen), eap->arg);
     goto end;
   }
 
diff --git a/src/nvim/eval/userfunc.h b/src/nvim/eval/userfunc.h
index 9af35e0411..513473449a 100644
--- a/src/nvim/eval/userfunc.h
+++ b/src/nvim/eval/userfunc.h
@@ -44,6 +44,7 @@ typedef struct {
   bool evaluate;       ///< actually evaluate expressions
   partial_T *partial;  ///< for extra arguments
   dict_T *selfdict;    ///< Dictionary for "self"
+  typval_T *basetv;    ///< base for base->method()
 } funcexe_T;
 
 #define FUNCEXE_INIT (funcexe_T) { \
@@ -54,6 +55,7 @@ typedef struct {
   .evaluate = false, \
   .partial = NULL, \
   .selfdict = NULL, \
+  .basetv = NULL, \
 }
 
 #define FUNCARG(fp, j)  ((char_u **)(fp->uf_args.ga_data))[j]