vim-patch:8.2.2343: Vim9: return type of readfile() is any (#20896)

Problem:    Vim9: return type of readfile() is any.
Solution:   Add readblob() so that readfile() can be expected to always
            return a list of strings. (closes vim/vim#7671)

c423ad77ed

Co-authored-by: Bram Moolenaar <Bram@vim.org>

src/nvim/eval.lua

@@ -291,6 +291,7 @@ return {
     perleval={args=1, base=1},
     rand={args={0, 1}, base=1},
     range={args={1, 3}, base=1},
+    readblob={args=1, base=1},
     readdir={args={1, 2}, base=1},
     readfile={args={1, 3}, base=1},
     reduce={args={2, 3}, base=1},

src/nvim/eval/funcs.c

@@ -5872,11 +5872,11 @@ static void f_readdir(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
   ga_clear_strings(&ga);
 }
 
-/// "readfile()" function
-static void f_readfile(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
+/// "readfile()" or "readblob()" function
+static void read_file_or_blob(typval_T *argvars, typval_T *rettv, bool always_blob)
 {
   bool binary = false;
-  bool blob = false;
+  bool blob = always_blob;
   FILE *fd;
   char buf[(IOSIZE/256) * 256];    // rounded to avoid odd + 1
   int io_size = sizeof(buf);
@@ -6011,8 +6011,8 @@ static void f_readfile(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
             int adjust_prevlen = 0;
 
             if (dest < buf) {  // -V782
-              adjust_prevlen = (int)(buf - dest);  // -V782
               // adjust_prevlen must be 1 or 2.
+              adjust_prevlen = (int)(buf - dest);  // -V782
               dest = buf;
             }
             if (readlen > p - buf + 1) {
@@ -6055,6 +6055,18 @@ static void f_readfile(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
   fclose(fd);
 }
 
+/// "readblob()" function
+static void f_readblob(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
+{
+  read_file_or_blob(argvars, rettv, true);
+}
+
+/// "readfile()" function
+static void f_readfile(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
+{
+  read_file_or_blob(argvars, rettv, false);
+}
+
 /// "getreginfo()" function
 static void f_getreginfo(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 {

src/nvim/testdir/test_mksession.vim

@@ -851,9 +851,7 @@ func Test_mksession_shortmess_with_A()
   edit Xtestfile
   write
   let fname = swapname('%')
-  " readblob() needs patch 8.2.2343
-  " let cont = readblob(fname)
-  let cont = readfile(fname, 'B')
+  let cont = readblob(fname)
   set sessionoptions-=options
   mksession Xtestsession
   bwipe!