eval.c: factor out eval/funcs.c #11828

close #11828
ref #5081
cf. vim patch 7.4.2063

src/nvim/eval/funcs.h

@@ -0,0 +1,24 @@
+#ifndef NVIM_EVAL_FUNCS_H
+#define NVIM_EVAL_FUNCS_H
+
+#include "nvim/buffer_defs.h"
+#include "nvim/eval/typval.h"
+
+typedef void (*FunPtr)(void);
+
+/// Prototype of C function that implements VimL function
+typedef void (*VimLFunc)(typval_T *args, typval_T *rvar, FunPtr data);
+
+/// Structure holding VimL function definition
+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.
+  VimLFunc func;     ///< Function implementation.
+  FunPtr data;       ///< Userdata for function implementation.
+} VimLFuncDef;
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "eval/funcs.h.generated.h"
+#endif
+#endif  // NVIM_EVAL_FUNCS_H