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(gcc-300.info)Functions

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Functions
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   A function is represented by a `FUNCTION_DECL' node.  A set of
overloaded functions is sometimes represented by a `OVERLOAD' node.

   An `OVERLOAD' node is not a declaration, so none of the `DECL_'
macros should be used on an `OVERLOAD'.  An `OVERLOAD' node is similar
to a `TREE_LIST'.  Use `OVL_CURRENT' to get the function associated
with an `OVERLOAD' node; use `OVL_NEXT' to get the next `OVERLOAD' node
in the list of overloaded functions.  The macros `OVL_CURRENT' and
`OVL_NEXT' are actually polymorphic; you can use them to work with
`FUNCTION_DECL' nodes as well as with overloads.  In the case of a
`FUNCTION_DECL', `OVL_CURRENT' will always return the function itself,
and `OVL_NEXT' will always be `NULL_TREE'.

   To determine the scope of a function, you can use the
`DECL_REAL_CONTEXT' macro.  This macro will return the class (either a
`RECORD_TYPE' or a `UNION_TYPE') or namespace (a `NAMESPACE_DECL') of
which the function is a member.  For a virtual function, this macro
returns the class in which the function was actually defined, not the
base class in which the virtual declaration occurred.  If a friend
function is defined in a class scope, the `DECL_CLASS_CONTEXT' macro
can be used to determine the class in which it was defined.  For
example, in
     class C { friend void f() {} };
   the `DECL_REAL_CONTEXT' for `f' will be the `global_namespace', but
the `DECL_CLASS_CONTEXT' will be the `RECORD_TYPE' for `C'.

   The `DECL_REAL_CONTEXT' and `DECL_CLASS_CONTEXT' are not available
in C; instead you should simply use `DECL_CONTEXT'.  In C, the
`DECL_CONTEXT' for a function maybe another function.  This
representation indicates that the GNU nested function extension is in
use.  For details on the semantics of nested functions, see the GCC
Manual.  The nested function can refer to local variables in its
containing function.  Such references are not explicitly marked in the
tree structure; back ends must look at the `DECL_CONTEXT' for the
referenced `VAR_DECL'.  If the `DECL_CONTEXT' for the referenced
`VAR_DECL' is not the same as the function currently being processed,
and neither `DECL_EXTERNAL' nor `DECL_STATIC' hold, then the reference
is to a local variable in a containing function, and the back end must
take appropriate action.

Function Basics

Function names, linkage, and so forth.

Function Bodies

The statements that make up a function body.