Fix crash at startup related to GC of font entities

* src/font.h (GC_FONT_SPEC_P, GC_FONT_ENTITY_P)
(GC_FONT_OBJECT_P, GC_XFONT_SPEC, GC_XFONT_ENTITY)
(GC_XFONT_OBJECT): New macros, for use in garbage collector.
* src/alloc.c (compact_font_cache_entry, compact_font_caches):
Don't ifdef away font cache compaction on NT_GUI, as the problems
which led to that seem to have been solved.
(compact_font_cache_entry): Use GC_FONT_SPEC_P, GC_XFONT_SPEC,
GC_XFONT_ENTITY, and GC_XFONT_OBJECT, instead of their non-GC_
cousins.  (Bug#21999)

2 files changed, 48 insertions, 13 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 99f5cdcdea2..e83b3836aa4 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -5317,10 +5317,6 @@ total_bytes_of_live_objects (void)
 
 #ifdef HAVE_WINDOW_SYSTEM
 
-/* This code has a few issues on MS-Windows, see Bug#15876 and Bug#16140.  */
-
-#if !defined (HAVE_NTGUI)
-
 /* Remove unmarked font-spec and font-entity objects from ENTRY, which is
    (DRIVER-TYPE NUM-FRAMES FONT-CACHE-DATA ...), and return changed entry.  */
 
@@ -5335,11 +5331,12 @@ compact_font_cache_entry (Lisp_Object entry)
       Lisp_Object obj = XCAR (tail);
 
       /* Consider OBJ if it is (font-spec . [font-entity font-entity ...]).  */
-      if (CONSP (obj) && FONT_SPEC_P (XCAR (obj))
-          && !VECTOR_MARKED_P (XFONT_SPEC (XCAR (obj)))
+      if (CONSP (obj) && GC_FONT_SPEC_P (XCAR (obj))
+          && !VECTOR_MARKED_P (GC_XFONT_SPEC (XCAR (obj)))
           && VECTORP (XCDR (obj)))
         {
           ptrdiff_t i, size = gc_asize (XCDR (obj));
+          Lisp_Object obj_cdr = XCDR (obj);
 
           /* If font-spec is not marked, most likely all font-entities
              are not marked too.  But we must be sure that nothing is
@@ -5348,14 +5345,14 @@ compact_font_cache_entry (Lisp_Object entry)
             {
               Lisp_Object objlist;
 
-              if (VECTOR_MARKED_P (XFONT_ENTITY (AREF (XCDR (obj), i))))
+              if (VECTOR_MARKED_P (GC_XFONT_ENTITY (AREF (obj_cdr, i))))
                 break;
 
-              objlist = AREF (AREF (XCDR (obj), i), FONT_OBJLIST_INDEX);
+              objlist = AREF (AREF (obj_cdr, i), FONT_OBJLIST_INDEX);
               for (; CONSP (objlist); objlist = XCDR (objlist))
                 {
                   Lisp_Object val = XCAR (objlist);
-                  struct font *font = XFONT_OBJECT (val);
+                  struct font *font = GC_XFONT_OBJECT (val);
 
                   if (!NILP (AREF (val, FONT_TYPE_INDEX))
                       && VECTOR_MARKED_P(font))
@@ -5383,8 +5380,6 @@ compact_font_cache_entry (Lisp_Object entry)
   return entry;
 }
 
-#endif /* not HAVE_NTGUI */
-
 /* Compact font caches on all terminals and mark
    everything which is still here after compaction.  */
 
@@ -5396,7 +5391,6 @@ compact_font_caches (void)
   for (t = terminal_list; t; t = t->next_terminal)
     {
       Lisp_Object cache = TERMINAL_FONT_CACHE (t);
-#if !defined (HAVE_NTGUI)
       if (CONSP (cache))
         {
           Lisp_Object entry;
@@ -5404,7 +5398,6 @@ compact_font_caches (void)
           for (entry = XCDR (cache); CONSP (entry); entry = XCDR (entry))
             XSETCAR (entry, compact_font_cache_entry (XCAR (entry)));
         }
-#endif /* not HAVE_NTGUI */
       mark_object (cache);
     }
 }
diff --git a/src/font.h b/src/font.h
index 1d13e1cb6b0..24c058dd88b 100644
--- a/src/font.h
+++ b/src/font.h
@@ -427,6 +427,13 @@ FONT_SPEC_P (Lisp_Object x)
   return FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_SPEC_MAX;
 }
 
+/* Like FONT_SPEC_P, but can be used in the garbage collector.  */
+INLINE bool
+GC_FONT_SPEC_P (Lisp_Object x)
+{
+  return FONTP (x) && (gc_asize (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_SPEC_MAX;
+}
+
 /* True iff X is font-entity.  */
 INLINE bool
 FONT_ENTITY_P (Lisp_Object x)
@@ -434,6 +441,13 @@ FONT_ENTITY_P (Lisp_Object x)
   return FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_ENTITY_MAX;
 }
 
+/* Like FONT_ENTITY_P, but can be used in the garbage collector.  */
+INLINE bool
+GC_FONT_ENTITY_P (Lisp_Object x)
+{
+  return FONTP (x) && (gc_asize (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_ENTITY_MAX;
+}
+
 /* True iff X is font-object.  */
 INLINE bool
 FONT_OBJECT_P (Lisp_Object x)
@@ -441,6 +455,13 @@ FONT_OBJECT_P (Lisp_Object x)
   return FONTP (x) && (ASIZE (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_OBJECT_MAX;
 }
 
+/* Like FONT_OBJECT_P, but can be used in the garbage collector.  */
+INLINE bool
+GC_FONT_OBJECT_P (Lisp_Object x)
+{
+  return FONTP (x) && (gc_asize (x) & PSEUDOVECTOR_SIZE_MASK) == FONT_OBJECT_MAX;
+}
+
 /* Type checking functions for various font-related objects.  */
 
 INLINE void
@@ -476,6 +497,13 @@ XFONT_SPEC (Lisp_Object p)
   return XUNTAG (p, Lisp_Vectorlike);
 }
 
+INLINE struct font_spec *
+GC_XFONT_SPEC (Lisp_Object p)
+{
+  eassert (GC_FONT_SPEC_P (p));
+  return XUNTAG (p, Lisp_Vectorlike);
+}
+
 INLINE struct font_entity *
 XFONT_ENTITY (Lisp_Object p)
 {
@@ -483,6 +511,13 @@ XFONT_ENTITY (Lisp_Object p)
   return XUNTAG (p, Lisp_Vectorlike);
 }
 
+INLINE struct font_entity *
+GC_XFONT_ENTITY (Lisp_Object p)
+{
+  eassert (GC_FONT_ENTITY_P (p));
+  return XUNTAG (p, Lisp_Vectorlike);
+}
+
 INLINE struct font *
 XFONT_OBJECT (Lisp_Object p)
 {
@@ -490,6 +525,13 @@ XFONT_OBJECT (Lisp_Object p)
   return XUNTAG (p, Lisp_Vectorlike);
 }
 
+INLINE struct font *
+GC_XFONT_OBJECT (Lisp_Object p)
+{
+  eassert (GC_FONT_OBJECT_P (p));
+  return XUNTAG (p, Lisp_Vectorlike);
+}
+
 #define XSETFONT(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_FONT))
 
 INLINE struct font *