[groff] 08/10: [refer]: Fix Savannah #66078 (array comp thinko).

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 6483156146591c986948149ee55beacfd937bb12
Author: Lukas Javorsky <ljavorsk@redhat.com>
AuthorDate: Mon Aug 12 14:38:00 2024 +0200

    [refer]: Fix Savannah #66078 (array comp thinko).
    
    * src/preproc/refer/ref.cpp (same_reference): Fix array comparison
      warning by comparing elements individually.
    
    Fixes <https://savannah.gnu.org/bugs/?66078>.
    
    [One such warning is "comparison between two arrays is deprecated in
    C++20".  While groff uses C++98, if the compiler were to expand the
    array reference into a loop on its own, then it was blowing up an O(n)
    procedure to O(n^2).   And if it didn't do that, but translated the
    expressions effectively to `r1.field_index[0] != r2.field_index[0]`,
    comparing them `i` times, then it's an outright logic error.  Problem
    dates back to groff 1.02 (June 1991), and perhaps earlier.  --GBR]
---
 ChangeLog                 | 7 +++++++
 src/preproc/refer/ref.cpp | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index bd47d77ca..974c732e6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2024-08-14  Lukas Javorsky <ljavorsk@redhat.com>
+
+       * src/preproc/refer/ref.cpp (same_reference): Fix array
+       comparison warning by comparing elements individually.
+
+       Fixes <https://savannah.gnu.org/bugs/?66078>.
+
 2024-08-14  Lukas Javorsky <ljavorsk@redhat.com>
 
        * src/preproc/pic/object.cpp (object_spec::position_rectangle)
diff --git a/src/preproc/refer/ref.cpp b/src/preproc/refer/ref.cpp
index 5f6d5c63a..65b7edaf3 100644
--- a/src/preproc/refer/ref.cpp
+++ b/src/preproc/refer/ref.cpp
@@ -536,7 +536,7 @@ int same_reference(const reference &r1, const reference &r2)
     return 0;
   int i = 0; 
   for (i = 0; i < 256; i++)
-    if (r1.field_index != r2.field_index)
+    if (r1.field_index[i] != r2.field_index[i])
       return 0;
   for (i = 0; i < r1.nfields; i++)
     if (r1.field[i] != r2.field[i])