Change vectorlike from struct to union

* src/lisp.h (vectorlike_headed): Change from struct to union.
All uses changed.  Since it has only one member, this does not
change semantics.  This is designed to simplify future changes
needed to fix bugs like Bug#29040.  All uses changed.

1 files changed, 14 insertions, 14 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 015346858b5..1d6fd5a4fe2 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -796,11 +796,11 @@ struct Lisp_Symbol
 /* Header of vector-like objects.  This documents the layout constraints on
    vectors and pseudovectors (objects of PVEC_xxx subtype).  It also prevents
    compilers from being fooled by Emacs's type punning: XSETPSEUDOVECTOR
-   and PSEUDOVECTORP cast their pointers to struct vectorlike_header *,
+   and PSEUDOVECTORP cast their pointers to union vectorlike_header *,
    because when two such pointers potentially alias, a compiler won't
    incorrectly reorder loads and stores to their size fields.  See
    Bug#8546.  */
-struct vectorlike_header
+union vectorlike_header
   {
     /* The only field contains various pieces of information:
        - The MSB (ARRAY_MARK_FLAG) holds the gcmarkbit.
@@ -1094,10 +1094,10 @@ INLINE bool
 		       | ((restsize) << PSEUDOVECTOR_SIZE_BITS) \
 		       | (lispsize)))
 
-/* The cast to struct vectorlike_header * avoids aliasing issues.  */
+/* The cast to union vectorlike_header * avoids aliasing issues.  */
 #define XSETPSEUDOVECTOR(a, b, code) \
   XSETTYPED_PSEUDOVECTOR (a, b,					\
-			  (((struct vectorlike_header *)	\
+			  (((union vectorlike_header *)	\
 			    XUNTAG (a, Lisp_Vectorlike))	\
 			   ->size),				\
 			  code)
@@ -1399,7 +1399,7 @@ STRING_SET_CHARS (Lisp_Object string, ptrdiff_t newsize)
 
 struct Lisp_Vector
   {
-    struct vectorlike_header header;
+    union vectorlike_header header;
     Lisp_Object contents[FLEXIBLE_ARRAY_MEMBER];
   };
 
@@ -1456,7 +1456,7 @@ PSEUDOVECTOR_TYPE (struct Lisp_Vector *v)
 
 /* Can't be used with PVEC_NORMAL_VECTOR.  */
 INLINE bool
-PSEUDOVECTOR_TYPEP (struct vectorlike_header *a, enum pvec_type code)
+PSEUDOVECTOR_TYPEP (union vectorlike_header *a, enum pvec_type code)
 {
   /* We don't use PSEUDOVECTOR_TYPE here so as to avoid a shift
    * operation when `code' is known.  */
@@ -1472,8 +1472,8 @@ PSEUDOVECTORP (Lisp_Object a, int code)
     return false;
   else
     {
-      /* Converting to struct vectorlike_header * avoids aliasing issues.  */
-      struct vectorlike_header *h = XUNTAG (a, Lisp_Vectorlike);
+      /* Converting to union vectorlike_header * avoids aliasing issues.  */
+      union vectorlike_header *h = XUNTAG (a, Lisp_Vectorlike);
       return PSEUDOVECTOR_TYPEP (h, code);
     }
 }
@@ -1484,7 +1484,7 @@ struct Lisp_Bool_Vector
   {
     /* HEADER.SIZE is the vector's size field.  It doesn't have the real size,
        just the subtype information.  */
-    struct vectorlike_header header;
+    union vectorlike_header header;
     /* This is the size in bits.  */
     EMACS_INT size;
     /* The actual bits, packed into bytes.
@@ -1697,7 +1697,7 @@ struct Lisp_Char_Table
        pseudovector type information.  It holds the size, too.
        The size counts the defalt, parent, purpose, ascii,
        contents, and extras slots.  */
-    struct vectorlike_header header;
+    union vectorlike_header header;
 
     /* This holds a default value,
        which is used whenever the value for a specific character is nil.  */
@@ -1739,7 +1739,7 @@ struct Lisp_Sub_Char_Table
   {
     /* HEADER.SIZE is the vector's size field, which also holds the
        pseudovector type information.  It holds the size, too.  */
-    struct vectorlike_header header;
+    union vectorlike_header header;
 
     /* Depth of this sub char-table.  It should be 1, 2, or 3.  A sub
        char-table of depth 1 contains 16 elements, and each element
@@ -1814,7 +1814,7 @@ CHAR_TABLE_SET (Lisp_Object ct, int idx, Lisp_Object val)
 
 struct Lisp_Subr
   {
-    struct vectorlike_header header;
+    union vectorlike_header header;
     union {
       Lisp_Object (*a0) (void);
       Lisp_Object (*a1) (Lisp_Object);
@@ -2026,7 +2026,7 @@ struct hash_table_test
 struct Lisp_Hash_Table
 {
   /* This is for Lisp; the hash table code does not refer to it.  */
-  struct vectorlike_header header;
+  union vectorlike_header header;
 
   /* Nil if table is non-weak.  Otherwise a symbol describing the
      weakness of the table.  */
@@ -3929,7 +3929,7 @@ typedef emacs_value (*emacs_subr) (emacs_env *, ptrdiff_t,
 
 struct Lisp_Module_Function
 {
-  struct vectorlike_header header;
+  union vectorlike_header header;
 
   /* Fields traced by GC; these must come first.  */
   Lisp_Object documentation;