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Re: C++ nested classes, namespaces, structs, and compound statements
- From: Jim Blandy <jimb at redhat dot com>
- To: Daniel Jacobowitz <drow at mvista dot com>
- Cc: gdb at sources dot redhat dot com, Benjamin Kosnik <bkoz at redhat dot com>,Daniel Berlin <dan at dberlin dot org>
- Date: 08 Apr 2002 19:19:14 -0500
- Subject: Re: C++ nested classes, namespaces, structs, and compound statements
- References: <20020406044204.245E45EA11@zwingli.cygnus.com><20020406013408.A4570@nevyn.them.org>
Daniel Jacobowitz <email@example.com> writes:
> How about -containing- `struct fields', instead of replacing? i.e. let
> the name search happen in the `struct environment', as before, but the
> data items would be fields (could be indicated in a flag in the
> environment, with a pointer to the type or symbol for the enclosing
> structure). I don't think turning members into symbols is a good idea.
I admit the idea of using `struct symbol' for fields as well as
variables is pretty weird. Here's the rationale:
First, keep in mind that `struct symbol' is sort of a `messy union':
it's used for a lot of distinct purposes, and it contains all the
members any of those purposes might need. The `struct symbol'
representing a declaration like `struct A' doesn't need its
ginfo.value field. The `struct symbol' representing a local variable
doesn't need its `bfd_section' field. (I'm not saying this is a great
way to do things; but it is the way it's done now.)
Now, when we're debugging a C++ program, if we have a class A, think
about what sorts of objects A::x could represent:
- It could be a member.
- It could be a static member, which is really a global variable
with a qualified name.
- It could be a typedef.
- It could be a nested class.
When the user says `ptype A::x', we should be able to just look up A,
then look up x in A's environment, and see what it is.
It needs to have an `enum address_class' to distinguish members from
If it's a static member, it'll need to have a bfd_section.
`struct field' is slowly acquiring the equivalent of `enum
address_class', but badly: here's the comment for the `bitsize'
/* Size of this field, in bits, or zero if not packed.
For an unpacked field, the field's type's length
says how many bytes the field occupies.
A value of -1 or -2 indicates a static field; -1 means the location
is specified by the label loc.physname; -2 means that loc.physaddr
specifies the actual address. */
How would you suggest we represent nested typedefs and classes?