[review v4] Add static_asserts for the sizes of space-critical structs

[Christian Biesinger (Code Review)]

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/306
......................................................................

Add static_asserts for the sizes of space-critical structs

Specifically the three structs mentioned in symtab.h:
- general_symbol_info
- symbol
- partial_symbol

This ensures that those structs won't accidentally get bigger.

gdb/ChangeLog:

2019-10-25  Christian Biesinger  <cbiesinger@google.com>

	* psympriv.h: Add static_asserts for sizeof (general_symbol_info)
	and sizeof (symbol).
	* symtab.h: Add a static_assert for sizeof (partial_symbol).

Change-Id: Idd68320aa3e79ee7cc749019724636a58ce4b9c6
---
M gdb/psympriv.h
M gdb/symtab.h
2 files changed, 19 insertions(+), 0 deletions(-)



diff --git a/gdb/psympriv.h b/gdb/psympriv.h
index 19d692b..c81261a 100644
--- a/gdb/psympriv.h
+++ b/gdb/psympriv.h
@@ -82,6 +82,12 @@
   ENUM_BITFIELD(address_class) aclass : SYMBOL_ACLASS_BITS;
 };
 
+/* This struct is size-critical (see comment at the to of symtab.h), so this
+   assert makes sure the size doesn't change accidentally.  Be careful when
+   purposely increasing the size.  */
+gdb_static_assert ((sizeof (void *) == 8 && sizeof (partial_symbol) == 40)
+		   || (sizeof (void *) == 4 && sizeof (partial_symbol) == 24));
+
 /* A convenience enum to give names to some constants used when
    searching psymtabs.  This is internal to psymtab and should not be
    used elsewhere.  */
diff --git a/gdb/symtab.h b/gdb/symtab.h
index eac44ae..83b75d1 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -446,6 +446,13 @@
   short section;
 };
 
+/* This struct is size-critical (see comment at the top), so this assert
+   makes sure the size doesn't change accidentally.  Be careful when
+   purposely increasing the size.  */
+gdb_static_assert ((sizeof (void *) == 8 && sizeof (general_symbol_info) == 32)
+		   || (sizeof (void *) == 4 &&
+		       sizeof (general_symbol_info) == 20));
+
 extern void symbol_set_demangled_name (struct general_symbol_info *,
 				       const char *,
                                        struct obstack *);
@@ -1187,6 +1194,12 @@
   struct symbol *hash_next;
 };
 
+/* This struct is size-critical (see comment at the top), so this assert
+   makes sure the size doesn't change accidentally.  Be careful when
+   purposely increasing the size.  */
+gdb_static_assert ((sizeof (void *) == 8 && sizeof (symbol) == 72)
+		   || (sizeof (void *) == 4 && sizeof (symbol) == 40));
+
 /* Several lookup functions return both a symbol and the block in which the
    symbol is found.  This structure is used in these cases.  */
 

-- 
Gerrit-Project: binutils-gdb
Gerrit-Branch: master
Gerrit-Change-Id: Idd68320aa3e79ee7cc749019724636a58ce4b9c6
Gerrit-Change-Number: 306
Gerrit-PatchSet: 4
Gerrit-Owner: Christian Biesinger <cbiesinger@google.com>
Gerrit-Reviewer: Tom Tromey <tromey@sourceware.org>
Gerrit-MessageType: newpatchset