The comment for DECL_SIZE makes it clear it may be non-constant
but not that it may be null. The comment for TYPE_SIZE mentions
neither.
The attached update adds a few sentences to make these caveats
clear. If no one has any suggestions I'll commit it as obvious
today or tomorrow.
Thanks
Martin
gcc/ChangeLog:
* tree.def (TYPE_SIZE): Clarify.
* tree.h (TYPE_SIZE, TYPE_SIZE_UNIT, DECL_SIZE): Add comments.
Index: gcc/tree.def
===================================================================
--- gcc/tree.def (revision 274541)
+++ gcc/tree.def (working copy)
@@ -77,7 +77,10 @@ DEFTREECODE (BLOCK, "block", tcc_exceptional, 0)
/* Each data type is represented by a tree node whose code is one of
the following: */
/* Each node that represents a data type has a component TYPE_SIZE
- containing a tree that is an expression for the size in bits.
+ that evaluates either to a tree that is a (potentially non-constant)
+ expression representing the type size in bits, or to a null pointer
+ when the size of the type is unknown (for example, for incomplete
+ types such as arrays of unspecified bound).
The TYPE_MODE contains the machine mode for values of this type.
The TYPE_POINTER_TO field contains a type for a pointer to this type,
or zero if no such has been created yet.
Index: gcc/tree.h
===================================================================
--- gcc/tree.h (revision 274541)
+++ gcc/tree.h (working copy)
@@ -1952,7 +1952,10 @@ class auto_suppress_location_wrappers
so they must be checked as well. */
#define TYPE_UID(NODE) (TYPE_CHECK (NODE)->type_common.uid)
+/* Type size in bits as a tree expression. Need not be constant
+ and may be null. */
#define TYPE_SIZE(NODE) (TYPE_CHECK (NODE)->type_common.size)
+/* Likewise, type size in bytes. */
#define TYPE_SIZE_UNIT(NODE) (TYPE_CHECK (NODE)->type_common.size_unit)
#define TYPE_POINTER_TO(NODE) (TYPE_CHECK (NODE)->type_common.pointer_to)
#define TYPE_REFERENCE_TO(NODE) (TYPE_CHECK (NODE)->type_common.reference_to)
@@ -2480,7 +2483,7 @@ extern machine_mode vector_type_mode (const_tree);
#define DECL_INITIAL(NODE) (DECL_COMMON_CHECK (NODE)->decl_common.initial)
/* Holds the size of the datum, in bits, as a tree expression.
- Need not be constant. */
+ Need not be constant and may be null. */
#define DECL_SIZE(NODE) (DECL_COMMON_CHECK (NODE)->decl_common.size)
/* Likewise for the size in bytes. */
#define DECL_SIZE_UNIT(NODE) (DECL_COMMON_CHECK (NODE)->decl_common.size_unit)
