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(gcc-300.info)Declarations

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Declarations
============

   This section covers the various kinds of declarations that appear in
the internal representation, except for declarations of functions
(represented by `FUNCTION_DECL' nodes), which are described in Note:
Functions.

   Some macros can be used with any kind of declaration.  These include:
`DECL_NAME'
     This macro returns an `IDENTIFIER_NODE' giving the name of the
     entity.

`TREE_TYPE'
     This macro returns the type of the entity declared.

`DECL_SOURCE_FILE'
     This macro returns the name of the file in which the entity was
     declared, as a `char*'.  For an entity declared implicitly by the
     compiler (like `__builtin_memcpy'), this will be the string
     `"<internal>"'.

`DECL_SOURCE_LINE'
     This macro returns the line number at which the entity was
     declared, as an `int'.

`DECL_ARTIFICIAL'
     This predicate holds if the declaration was implicitly generated
     by the compiler.  For example, this predicate will hold of an
     implicitly declared member function, or of the `TYPE_DECL'
     implicitly generated for a class type.  Recall that in C++ code
     like:
          struct S {};

     is roughly equivalent to C code like:
          struct S {};
          typedef struct S S;
     The implicitly generated `typedef' declaration is represented by a
     `TYPE_DECL' for which `DECL_ARTIFICIAL' holds.

`DECL_NAMESPACE_SCOPE_P'
     This predicate holds if the entity was declared at a namespace
     scope.

`DECL_CLASS_SCOPE_P'
     This predicate holds if the entity was declared at a class scope.

`DECL_FUNCTION_SCOPE_P'
     This predicate holds if the entity was declared inside a function
     body.

   The various kinds of declarations include:
`LABEL_DECL'
     These nodes are used to represent labels in function bodies.  For
     more information, see Note: Functions.  These nodes only appear
     in block scopes.

`CONST_DECL'
     These nodes are used to represent enumeration constants.  The
     value of the constant is given by `DECL_INITIAL' which will be an
     `INTEGER_CST' with the same type as the `TREE_TYPE' of the
     `CONST_DECL', i.e., an `ENUMERAL_TYPE'.

`RESULT_DECL'
     These nodes represent the value returned by a function.  When a
     value is assigned to a `RESULT_DECL', that indicates that the
     value should be returned, via bitwise copy, by the function.  You
     can use `DECL_SIZE' and `DECL_ALIGN' on a `RESULT_DECL', just as
     with a `VAR_DECL'.

`TYPE_DECL'
     These nodes represent `typedef' declarations.  The `TREE_TYPE' is
     the type declared to have the name given by `DECL_NAME'.  In some
     cases, there is no associated name.

`VAR_DECL'
     These nodes represent variables with namespace or block scope, as
     well as static data members.  The `DECL_SIZE' and `DECL_ALIGN' are
     analogous to `TYPE_SIZE' and `TYPE_ALIGN'.  For a declaration, you
     should always use the `DECL_SIZE' and `DECL_ALIGN' rather than the
     `TYPE_SIZE' and `TYPE_ALIGN' given by the `TREE_TYPE', since
     special attributes may have been applied to the variable to give
     it a particular size and alignment.  You may use the predicates
     `DECL_THIS_STATIC' or `DECL_THIS_EXTERN' to test whether the
     storage class specifiers `static' or `extern' were used to declare
     a variable.

     If this variable is initialized (but does not require a
     constructor), the `DECL_INITIAL' will be an expression for the
     initializer.  The initializer should be evaluated, and a bitwise
     copy into the variable performed.  If the `DECL_INITIAL' is the
     `error_mark_node', there is an initializer, but it is given by an
     explicit statement later in the code; no bitwise copy is required.

     GCC provides an extension that allows either automatic variables,
     or global variables, to be placed in particular registers.  This
     extension is being used for a particular `VAR_DECL' if
     `DECL_REGISTER' holds for the `VAR_DECL', and if
     `DECL_ASSEMBLER_NAME' is not equal to `DECL_NAME'.  In that case,
     `DECL_ASSEMBLER_NAME' is the name of the register into which the
     variable will be placed.

`PARM_DECL'
     Used to represent a parameter to a function.  Treat these nodes
     similarly to `VAR_DECL' nodes.  These nodes only appear in the
     `DECL_ARGUMENTS' for a `FUNCTION_DECL'.

     The `DECL_ARG_TYPE' for a `PARM_DECL' is the type that will
     actually be used when a value is passed to this function.  It may
     be a wider type than the `TREE_TYPE' of the parameter; for
     example, the ordinary type might be `short' while the
     `DECL_ARG_TYPE' is `int'.

`FIELD_DECL'
     These nodes represent non-static data members.  The `DECL_SIZE' and
     `DECL_ALIGN' behave as for `VAR_DECL' nodes.  The
     `DECL_FIELD_BITPOS' gives the first bit used for this field, as an
     `INTEGER_CST'.  These values are indexed from zero, where zero
     indicates the first bit in the object.

     If `DECL_C_BIT_FIELD' holds, this field is a bit-field.

`NAMESPACE_DECL'
     Note: Namespaces.

`TEMPLATE_DECL'
     These nodes are used to represent class, function, and variable
     (static data member) templates.  The
     `DECL_TEMPLATE_SPECIALIZATIONS' are a `TREE_LIST'.  The
     `TREE_VALUE' of each node in the list is a `TEMPLATE_DECL's or
     `FUNCTION_DECL's representing specializations (including
     instantiations) of this template.  Back ends can safely ignore
     `TEMPLATE_DECL's, but should examine `FUNCTION_DECL' nodes on the
     specializations list just as they would ordinary `FUNCTION_DECL'
     nodes.

     For a class template, the `DECL_TEMPLATE_INSTANTIATIONS' list
     contains the instantiations.  The `TREE_VALUE' of each node is an
     instantiation of the class.  The `DECL_TEMPLATE_SPECIALIZATIONS'
     contains partial specializations of the class.

`USING_DECL'
     Back ends can safely ignore these nodes.