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Re: Patch: stab info for const fields
- From: Mark Mitchell <mark at codesourcery dot com>
- To: Dale Johannesen <dalej at apple dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Date: Thu, 31 Oct 2002 11:04:30 -0800
- Subject: Re: Patch: stab info for const fields
--On Thursday, October 31, 2002 10:25:27 AM -0800 Dale Johannesen
<dalej@apple.com> wrote:
On Thursday, October 31, 2002, at 09:45 AM, Mark Mitchell wrote:
The right fix is to change that behavior in the C front end the same
way that I changed the C++ front end a couple of years ago.
How much of a can of worms is doing it this way?
It took me a day or two to make the changes, and there were a few bugs
that trickled in over the next couple of weeks.
OK, thanks. Given that, it's very likely that trying to do as you
suggest is going to introduce regressions. Do you say this is "right"
for some reason besides aesthetics?
Yes. The C front end is lying about the types of things. The type of
"const int a" is "const int"; the C front end is claiming that its type
is "int" and that the variable is "readonly", which is not a notion in
the C programming language.
Your patch changes the language-independent debugging output to do the
wrong thing. A front end, like C++, may set TREE_READONLY on a VAR_DECL
when it knows the variable cannot change -- independently of the
variable's type.
We certainly don't want to introduce regressions on the release branch,
but there are some parts of GCC that are a mess, and we need to bite the
bullet on cleaning them up. That will introduce some regressions, in
the short term, but it's the only path towards a more stable compiler
in the future.
--
Mark Mitchell mark@codesourcery.com
CodeSourcery, LLC http://www.codesourcery.com