--- /dev/null
+2004-11-04 Jim Blandy <jimb@redhat.com>
+
+ * gdbtypes.c (make_qualified_type): Doc fix. Add assertion to
+ prevent cross-objfile references.
+ (make_cv_type): Doc fix. Don't create cross-objfile references,
+ even for stub types.
+ (replace_type): Add assertion to prevent cross-objfile references.
+ (check_typedef): Never resolve a stub type by copying over a type
+ from another file.
+
+Index: src/gdb/gdbtypes.c
+===================================================================
+RCS file: /big/fsf/rsync/src-cvs/src/gdb/gdbtypes.c,v
+retrieving revision 1.92
+retrieving revision 1.93
+diff -u -p -r1.92 -r1.93
+--- src/gdb/gdbtypes.c 8 Aug 2004 17:18:16 -0000 1.92
++++ src/gdb/gdbtypes.c 4 Nov 2004 17:50:16 -0000 1.93
+@@ -433,7 +433,9 @@ address_space_int_to_name (int space_fla
+ }
+
+ /* Create a new type with instance flags NEW_FLAGS, based on TYPE.
+- If STORAGE is non-NULL, create the new type instance there. */
++
++ If STORAGE is non-NULL, create the new type instance there.
++ STORAGE must be in the same obstack as TYPE. */
+
+ static struct type *
+ make_qualified_type (struct type *type, int new_flags,
+@@ -453,6 +455,12 @@ make_qualified_type (struct type *type,
+ ntype = alloc_type_instance (type);
+ else
+ {
++ /* If STORAGE was provided, it had better be in the same objfile as
++ TYPE. Otherwise, we can't link it into TYPE's cv chain: if one
++ objfile is freed and the other kept, we'd have dangling
++ pointers. */
++ gdb_assert (TYPE_OBJFILE (type) == TYPE_OBJFILE (storage));
++
+ ntype = storage;
+ TYPE_MAIN_TYPE (ntype) = TYPE_MAIN_TYPE (type);
+ TYPE_CHAIN (ntype) = ntype;
+@@ -501,11 +509,12 @@ make_type_with_address_space (struct typ
+ CNST is a flag for setting the const attribute
+ VOLTL is a flag for setting the volatile attribute
+ TYPE is the base type whose variant we are creating.
+- TYPEPTR, if nonzero, points
+- to a pointer to memory where the reference type should be stored.
+- If *TYPEPTR is zero, update it to point to the reference type we return.
+- We allocate new memory if needed. */
+
++ If TYPEPTR and *TYPEPTR are non-zero, then *TYPEPTR points to
++ storage to hold the new qualified type; *TYPEPTR and TYPE must be
++ in the same objfile. Otherwise, allocate fresh memory for the new
++ type whereever TYPE lives. If TYPEPTR is non-zero, set it to the
++ new type we construct. */
+ struct type *
+ make_cv_type (int cnst, int voltl, struct type *type, struct type **typeptr)
+ {
+@@ -524,20 +533,19 @@ make_cv_type (int cnst, int voltl, struc
+
+ if (typeptr && *typeptr != NULL)
+ {
+- /* Objfile is per-core-type. This const-qualified type had best
+- belong to the same objfile as the type it is qualifying, unless
+- we are overwriting a stub type, in which case the safest thing
+- to do is to copy the core type into the new objfile. */
+-
+- gdb_assert (TYPE_OBJFILE (*typeptr) == TYPE_OBJFILE (type)
+- || TYPE_STUB (*typeptr));
+- if (TYPE_OBJFILE (*typeptr) != TYPE_OBJFILE (type))
+- {
+- TYPE_MAIN_TYPE (*typeptr)
+- = TYPE_ALLOC (*typeptr, sizeof (struct main_type));
+- *TYPE_MAIN_TYPE (*typeptr)
+- = *TYPE_MAIN_TYPE (type);
+- }
++ /* TYPE and *TYPEPTR must be in the same objfile. We can't have
++ a C-V variant chain that threads across objfiles: if one
++ objfile gets freed, then the other has a broken C-V chain.
++
++ This code used to try to copy over the main type from TYPE to
++ *TYPEPTR if they were in different objfiles, but that's
++ wrong, too: TYPE may have a field list or member function
++ lists, which refer to types of their own, etc. etc. The
++ whole shebang would need to be copied over recursively; you
++ can't have inter-objfile pointers. The only thing to do is
++ to leave stub types as stub types, and look them up afresh by
++ name each time you encounter them. */
++ gdb_assert (TYPE_OBJFILE (*typeptr) == TYPE_OBJFILE (type));
+ }
+
+ ntype = make_qualified_type (type, new_flags, typeptr ? *typeptr : NULL);
+@@ -562,6 +570,12 @@ replace_type (struct type *ntype, struct
+ {
+ struct type *chain;
+
++ /* These two types had better be in the same objfile. Otherwise,
++ the assignment of one type's main type structure to the other
++ will produce a type with references to objects (names; field
++ lists; etc.) allocated on an objfile other than its own. */
++ gdb_assert (TYPE_OBJFILE (ntype) == TYPE_OBJFILE (ntype));
++
+ *TYPE_MAIN_TYPE (ntype) = *TYPE_MAIN_TYPE (type);
+
+ /* The type length is not a part of the main type. Update it for each
+@@ -1416,8 +1430,24 @@ check_typedef (struct type *type)
+ return type;
+ }
+ newtype = lookup_transparent_type (name);
++
+ if (newtype)
+- make_cv_type (is_const, is_volatile, newtype, &type);
++ {
++ /* If the resolved type and the stub are in the same objfile,
++ then replace the stub type with the real deal. But if
++ they're in separate objfiles, leave the stub alone; we'll
++ just look up the transparent type every time we call
++ check_typedef. We can't create pointers between types
++ allocated to different objfiles, since they may have
++ different lifetimes. Trying to copy NEWTYPE over to TYPE's
++ objfile is pointless, too, since you'll have to move over any
++ other types NEWTYPE refers to, which could be an unbounded
++ amount of stuff. */
++ if (TYPE_OBJFILE (newtype) == TYPE_OBJFILE (type))
++ make_cv_type (is_const, is_volatile, newtype, &type);
++ else
++ type = newtype;
++ }
+ }
+ /* Otherwise, rely on the stub flag being set for opaque/stubbed types */
+ else if (TYPE_STUB (type) && !currently_reading_symtab)
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