Re: [RFA] Patch for supportinf DW_TAG_module / FORTRAN modules

Jim Blandy
2002-08-15T21:41:20Z

If I understand this patch correctly, it stores a Fortran module in
GDB's symbol table as if it were a C++ structure type, full of static
data and function members. A Fortran module gets stored in GDB's
symbol table as a LOC_TYPEDEF symbol. Is that right?

I'd like to hear other folks' opinions on this.

It seems to me like it would work, since a class establishes a scope
that behaves very much like a module. Isn't Class::member, where
member is a static thingy, very much like Module::member (or whatever
the Fortran syntax is)? We already have logic for resolving class
scopes; I don't immediately see why module scopes need to behave any
differently.

But I think a module should be represented by something that calls
itself a module, not a typedef. How will people feel reading a
comment explaining that a LOC_TYPEDEF for a type with TYPE_CODE_CLASS
is how we represent Fortran modules? I'm not sure that counts as good
maintenance.

Perhaps we should introduce LOC_MODULE, or TYPE_CODE_MODULE.

Or maybe this is okay for now. When we provide better support for C++
namespaces, Fortran modules can become a variant of that, which feels
like a better fit.

But without a better sense of how people feel about this issue,
I don't think I can comment specifically on this patch.

Petr Sorfa <petrs@caldera.com> writes:

> Hi,
>
> The patch below provides support for DW_TAG_module which is used to
> represent FORTRAN modules, and possibly other language constructs, such
> as C++ namespaces. The patch basically provides support for a module as
> a C++ class with static members and functions.
>
> 2002-07-16 Petr Sorfa <petrs@caldera.com>
>
> * dwarf2read.c (dwarf2_update_pc_bounds): New function
> that updates a die's low and high pc bound. Used to
> remedy possible inconsistencies between ELF and DWARF
> information.
> (dwarf2_get_child_pc_bounds): New function that
> calculates the scope bounds of a die's children.
> (dwarf2_add_member_fn): Added a new argument that holds
> a parent die's tag type. Used to determine whether
> a child die's parent is a module and treat the child
> die as a static.
> (scan_partial_symbol): Support the DW_TAG_module tag.
> (add_partial_symbol): Support the DW_TAG_module tag.
> (process_die): Supports the DW_TAG_module tag by
> treating it as a structure scope.
> (read_file_scope): Moved and enhanced some of the code
> to create the new dwarf2_get_child_pc_bounds()
> function.
> (read_structure_scope): Now supports the DW_TAG_module
> tag as a class and handles module variables and
> functions/subroutines as static members.
> (new_symbol): Now supports the DW_TAG_module tag and
> adds a module symbol to the global symbol list.
> (read_die_type): Now supports the DW_TAG_module tag
> as a structure scope.Index: dwarf2read.c