loading: bugfix: try specified path before suffixes.

This is a partial revert of the May 1, 2019 commit
065dde19dfbe50e91e313e5b3ccc033cfbe47f74,
titled "loading: try unsuffixed files directly last".

Test cases added in prior commit now pass.

* parser.c (open_txr_file); Like before the 2019 commit, we
try the exact path that is specified first. Only if that is
not found do we try adding suffixes to a file which has no
recognizable suffix. This does mean that (load "foo") will
probe the filesystem twice in order to find "foo.tl" or
"foo.tlo" there is no obvious way around that that doesn't
cause a problem.

* txr.1: Update documentation that is outdated, incomplete,
incorrect, or that is has become incorrect because of this
fix.

1 files changed, 27 insertions, 21 deletions

diff --git a/parser.c b/parser.c
index ee2ab6df..dbb7e481 100644
--- a/parser.c
+++ b/parser.c
@@ -534,6 +534,33 @@ void open_txr_file(val spec_file, val *txr_lisp_p, val *name, val *stream,
     val spec_file_try = nil;
     FILE *in = 0;
 
+    {
+      spec_file_try = spec_file;
+      errno = 0;
+      in = w_fopen(c_str(spec_file_try, self), L"r");
+      if (in != 0) {
+        switch (suffix) {
+        case tl:
+          *txr_lisp_p = t;
+          break;
+        case tlo:
+          *txr_lisp_p = chr('o');
+          break;
+        case txr:
+          *txr_lisp_p = nil;
+          break;
+        default:
+          break;
+        }
+        goto found;
+       } else {
+#ifdef ENOENT
+        if (errno != ENOENT)
+          goto except;
+#endif
+       }
+    }
+
     if (suffix == none && !*txr_lisp_p) {
       spec_file_try = scat(lit("."), spec_file, lit("txr"), nao);
       if ((in = w_fopen(c_str(spec_file_try, nil), L"r")) != 0)
@@ -571,27 +598,6 @@ void open_txr_file(val spec_file, val *txr_lisp_p, val *name, val *stream,
       }
     }
 
-    {
-      spec_file_try = spec_file;
-      errno = 0;
-      in = w_fopen(c_str(spec_file_try, self), L"r");
-      if (in != 0) {
-        switch (suffix) {
-        case tl:
-          *txr_lisp_p = t;
-          break;
-        case tlo:
-          *txr_lisp_p = chr('o');
-          break;
-        case txr:
-          *txr_lisp_p = nil;
-          break;
-        default:
-          break;
-        }
-      }
-    }
-
     if (in == 0) {
 #ifdef ENOENT
 except: