]> git.ipfire.org Git - thirdparty/gcc.git/commitdiff
C: Fix type compatibility for structs with variable sized fields.
authorMartin Uecker <uecker@tugraz.at>
Fri, 22 Dec 2023 16:32:34 +0000 (17:32 +0100)
committerMartin Uecker <uecker@tugraz.at>
Sat, 30 Dec 2023 21:32:51 +0000 (22:32 +0100)
This fixes the test gcc.dg/gnu23-tag-4.c introduced by commit 23fee88f
which fails for -march=... because the DECL_FIELD_BIT_OFFSET are set
inconsistently for types with and without variable-sized field.  This
is fixed by testing for DECL_ALIGN instead.  The code is further
simplified by removing some unnecessary conditions, i.e. anon_field is
set unconditionaly and all fields are assumed to be DECL_FIELDs.

gcc/c:
* c-typeck.cc (tagged_types_tu_compatible_p): Revise.

gcc/testsuite:
* gcc.dg/c23-tag-9.c: New test.

gcc/c/c-typeck.cc
gcc/testsuite/gcc.dg/c23-tag-9.c [new file with mode: 0644]

index 2d9139d09d24902aabcd9f85b76833d4dad4aefb..84ddda1ebab6609da1a276f5748f3389b7ade6dd 100644 (file)
@@ -1511,8 +1511,6 @@ tagged_types_tu_compatible_p (const_tree t1, const_tree t2,
   if (!data->anon_field && TYPE_STUB_DECL (t1) != TYPE_STUB_DECL (t2))
     data->different_types_p = true;
 
-  data->anon_field = false;
-
   /* Incomplete types are incompatible inside a TU.  */
   if (TYPE_SIZE (t1) == NULL || TYPE_SIZE (t2) == NULL)
     return false;
@@ -1592,22 +1590,21 @@ tagged_types_tu_compatible_p (const_tree t1, const_tree t2,
             s1 && s2;
             s1 = DECL_CHAIN (s1), s2 = DECL_CHAIN (s2))
          {
-           if (TREE_CODE (s1) != TREE_CODE (s2)
-               || DECL_NAME (s1) != DECL_NAME (s2))
+           gcc_assert (TREE_CODE (s1) == FIELD_DECL);
+           gcc_assert (TREE_CODE (s2) == FIELD_DECL);
+
+           if (DECL_NAME (s1) != DECL_NAME (s2))
+             return false;
+
+           if (DECL_ALIGN (s1) != DECL_ALIGN (s2))
              return false;
 
-           if (!DECL_NAME (s1) && RECORD_OR_UNION_TYPE_P (TREE_TYPE (s1)))
-             data->anon_field = true;
+           data->anon_field = !DECL_NAME (s1);
 
            data->cache = &entry;
            if (!comptypes_internal (TREE_TYPE (s1), TREE_TYPE (s2), data))
              return false;
 
-           if (TREE_CODE (s1) == FIELD_DECL
-               && simple_cst_equal (DECL_FIELD_BIT_OFFSET (s1),
-                                    DECL_FIELD_BIT_OFFSET (s2)) != 1)
-             return false;
-
            tree st1 = TYPE_SIZE (TREE_TYPE (s1));
            tree st2 = TYPE_SIZE (TREE_TYPE (s2));
 
diff --git a/gcc/testsuite/gcc.dg/c23-tag-9.c b/gcc/testsuite/gcc.dg/c23-tag-9.c
new file mode 100644 (file)
index 0000000..1d32560
--- /dev/null
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-std=c23" } */
+
+struct foo { int x; } x;
+struct foo { alignas(128) int x; } y;  /* { dg-error "redefinition" } */
+static_assert(alignof(y) == 128);
+
+