show detailed reason of LoadError as a error message

Author: sonots

error.c

@@ -2568,7 +2568,9 @@ rb_syserr_enc_warning(int err, rb_encoding *enc, const char *fmt, ...)
 void
 rb_load_fail(VALUE path, const char *err)
 {
- VALUE mesg = rb_str_buf_new_cstr(err);
+ VALUE mesg = rb_str_buf_new_cstr("cannot load such file");
+ rb_str_cat2(mesg, " -- ");
+ rb_str_cat2(mesg, err);
  rb_str_cat2(mesg, " -- ");
  rb_str_append(mesg, path);/* should be ASCII compatible */
  raise_loaderror(path, mesg);

file.c

@@ -5813,6 +5813,9 @@ rb_find_file_ext_safe(VALUE *filep, const char *const *ext, int safe_level)
 *filep = copy_path_class(fname, *filep);
 return (int)(i+1);
  }
+ else if (errno != ENOENT) {
+ return 0;
+ }
  rb_str_set_len(fname, fnlen);
 }
 return 0;
@@ -5838,6 +5841,9 @@ rb_find_file_ext_safe(VALUE *filep, const char *const *ext, int safe_level)
 *filep = copy_path_class(tmp, *filep);
 return (int)(j+1);
  }
+ else if (errno != ENOENT) {
+ return 0;
+ }
  FL_UNSET(tmp, FL_TAINT);
 }
 rb_str_set_len(fname, fnlen);

load.c

@@ -573,7 +573,6 @@ rb_provide(const char *feature)
  rb_provide_feature(rb_fstring_cstr(feature));
 }
 
-NORETURN(static void load_failed(VALUE));
 const rb_iseq_t *rb_iseq_load_iseq(VALUE fname);
 
 static int
@@ -654,7 +653,7 @@ static VALUE
 file_to_load(VALUE fname)
 {
  VALUE tmp = rb_find_file(FilePathValue(fname));
- if (!tmp) load_failed(fname);
+ if (!tmp) rb_load_fail(fname, strerror(errno));
  return tmp;
 }
 
@@ -708,7 +707,7 @@ rb_f_load(int argc, VALUE *argv)
  path = rb_find_file(fname);
  if (!path) {
 if (!rb_file_load_ok(RSTRING_PTR(fname)))
- load_failed(orig_fname);
+ rb_load_fail(orig_fname, strerror(errno));
 path = fname;
  }
  rb_load_internal(path, RTEST(wrap));
@@ -935,12 +934,6 @@ search_required(VALUE fname, volatile VALUE *path, int safe_level)
  return type ? 's' : 'r';
 }
 
-static void
-load_failed(VALUE fname)
-{
- rb_load_fail(fname, "cannot load such file");
-}
-
 static VALUE
 load_ext(VALUE path)
 {
@@ -1048,7 +1041,7 @@ rb_require_safe(VALUE fname, int safe)
 JUMP_TAG(result);
  }
  if (result < 0) {
-load_failed(fname);
+rb_load_fail(fname, strerror(errno));
  }
 
  return result ? Qtrue : Qfalse;