https://gcc.gnu.org/g:f89e3c8acdc3a0e12aa8eaaec1bc9c67ea6fde98

commit r16-6861-gf89e3c8acdc3a0e12aa8eaaec1bc9c67ea6fde98
Author: Jose E. Marchesi <[email protected]>
Date:   Sat Jan 17 21:56:20 2026 +0100

    a68: add explicative comment to are_packs_equivalent
    
    While fixing PR algol68/123653 I noticed that there was a struct mode
    interned in the compiler with the form `struct (ref int)'.  This is
    odd because fields are supposed to have names in struct modes.
    
    Turns out that the culprit is:
    
        (void) a68_add_mode_to_pack (&z, M_REF_INT, NO_TEXT, NO_NODE);
    
        EQUIVALENT (M_SEMA) = a68_add_mode (&TOP_MOID (&A68_JOB),
                                            STRUCT_SYMBOL,
                                            a68_count_pack_members (z),
                                            NO_NODE, NO_MOID, z);
    
    i.e. it is the standard mode `sema'.  The report says that it is a
    struct that hold a reference to int within, but you are not allowed to
    access it.
    
    This patch adds a comment to are_packs_equivalent explaining why the
    name of a pack may be NULL.
    
    Signed-off-by: Jose E. Marchesi <[email protected]>
    
    gcc/algol68/ChangeLog
    
            * a68-parser-moids-equivalence.cc (are_packs_equivalent): Add
            explicative comment.

Diff:
---
 gcc/algol68/a68-parser-moids-equivalence.cc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/gcc/algol68/a68-parser-moids-equivalence.cc 
b/gcc/algol68/a68-parser-moids-equivalence.cc
index 260eb4209a6a..f97dcafc694b 100644
--- a/gcc/algol68/a68-parser-moids-equivalence.cc
+++ b/gcc/algol68/a68-parser-moids-equivalence.cc
@@ -49,6 +49,10 @@ are_packs_equivalent (PACK_T *s, PACK_T *t,
        return false;
       if (compare_names)
        {
+         /* Note that a name in a pack of a struct may be NULL if the
+            corresponding field is supposed to not be accessible by the user.
+            There is at present one instance of this: the standard prelude
+          */
          if (TEXT (s) != TEXT (t)
              && !(TEXT (s) != NO_TEXT
                   && TEXT (t) != NO_TEXT

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