[Guile-commits] 01/01: Fix errors introduced when giving multiple-values objects a tc7

[Andy Wingo]

wingo pushed a commit to branch master
in repository guile.

commit e6461cf1b2b63e3ec9a2867731742db552b61b71
Author: Andy Wingo <address@hidden>
Date:   Mon Jul 16 12:16:58 2018 +0200

    Fix errors introduced when giving multiple-values objects a tc7
    
    * libguile/values.c (scm_c_value_ref): Fix a case in which a request for
      the 0th value of a zero-valued object would return the object instead
      of erroring.
    * libguile/vm-engine.c (halt): Fix construction of a multiple-valued
      return (off-by-one error).  Fixes a crash introduced in
      4a2d78b4d463cd29226f3eee776dcad9f64e6152.
---
 libguile/values.c    | 14 ++++++++++----
 libguile/vm-engine.c |  2 +-
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/libguile/values.c b/libguile/values.c
index 4fd9b54..8603aa3 100644
--- a/libguile/values.c
+++ b/libguile/values.c
@@ -59,10 +59,16 @@ scm_c_nvalues (SCM obj)
 SCM
 scm_c_value_ref (SCM obj, size_t idx)
 {
-  if (SCM_LIKELY (scm_is_values (obj) && idx < scm_i_nvalues (obj)))
-    return scm_i_value_ref (obj, idx);
-  else if (idx == 0)
-    return obj;
+  if (scm_is_values (obj))
+    {
+      if (idx < scm_i_nvalues (obj))
+        return scm_i_value_ref (obj, idx);
+    }
+  else
+    {
+      if (idx == 0)
+        return obj;
+    }
 
   scm_error (scm_out_of_range_key,
             "scm_c_value_ref",
diff --git a/libguile/vm-engine.c b/libguile/vm-engine.c
index d08ebbb..7305bee 100644
--- a/libguile/vm-engine.c
+++ b/libguile/vm-engine.c
@@ -335,7 +335,7 @@ VM_NAME (scm_thread *thread)
           VM_ASSERT (nvals <= (UINTPTR_MAX >> 8), abort ());
           ret = scm_words ((nvals << 8) | scm_tc7_values, nvals + 1);
           for (n = 0; n < nvals; n++)
-            SCM_SET_CELL_OBJECT (ret, n+1, FP_REF (4 + n - 1));
+            SCM_SET_CELL_OBJECT (ret, n+1, FP_REF (4 + n));
         }
 
       VP->ip = SCM_FRAME_RETURN_ADDRESS (VP->fp);