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Re: [PATCH/WIP] C/C++ wchar_t/Unicode printing support
- From: Tom Tromey <tromey at redhat dot com>
- To: Julian Brown <julian at codesourcery dot com>
- Cc: gdb-patches at sourceware dot org
- Date: Thu, 15 Jan 2009 13:59:51 -0700
- Subject: Re: [PATCH/WIP] C/C++ wchar_t/Unicode printing support
- References: <20090115202411.5f154657@rex.config>
- Reply-to: Tom Tromey <tromey at redhat dot com>
>>>>> "Julian" == Julian Brown <julian@codesourcery.com> writes:
Julian> 3. Types which are literally called "wchar_t" are assumed to
Julian> be wide characters.
I did something similar -- my patch looks at TYPE_NAME to see if it is
"wchar_t". In C, this is a typedef, and so I needed the appended to
make it work. Without this patch, lookup_typename will find a
"wchar_t" symbol whose type has a TYPE_NAME which is not "wchar_t".
That seemed odd. The patch changes the dwarf reader so that the
wchar_t symbol points to a type whose name is "wchar_t".
I think the failing case here was "p L'a'", so I suppose it would not
necessarily show up with your patch.
Anyway I'd appreciate comments on the appended.
Julian> $3 = (wchar_t *) 0x85c4 "Sch\x00f6ne Gr\x00fc\x00dfe"
It should probably print L"..." :-)
Julian> 2. I've probably broken building with iconv disabled (actually I
Julian> couldn't figure out how to build without iconv() support -- even for
Julian> e.g. a mingw32 host which shouldn't support it).
FWIW, my patch goes even further -- I deleted all the existing
conversion code in charset.c. I thin it is reasonable to require a
working iconv; folks on hosts without iconv can use the capable GNU
libiconv.
This does make it a little harder to build gdb, but we can write a
script to download libiconv and drop it into the src build
infrastructure.
Julian> Tom Tromey is working on a patch related to this.
Yeah. Mine:
* Handles input and output of wide characters and strings, and also
the new C0X u"" and U"" syntax.
* Adds "%ls" and "%lc" to the gdb printf.
* Handles all target character sets, in particular variable length
encodings are handled.
* Auto-selects the appropriate endianness for wide characters on the
target.
Mine also has a few limitations:
* Like your patch, mine doesn't deal with non-C-family languages.
I'll probably fix up Java at some point, but I just don't know the
others.
* I got rid of the apparently undocumented gdb extension '\^c'.
The plain form could probably be restored, but the form '\^\242' is
a real pain, and IMO not useful enough anyhow.
* Getting the list of character sets support by iconv is a pain.
Right now I just have a list of dubious provenance (read: iconv -l | sed).
Perhaps we can invoke "iconv -l" at startup... eww.
Also there is no good way, that I know of, to distinguish between
character sets suitable for "target-wide-charset" and the others.
Another difference is that I have the intermediate step go through the
host wchar_t rather than UCS-4. This is nice because it means we can
use iswprint to decide if something is printable. But, it may have
limitations, I suppose, on a host where wchar_t is less capable.
Julian> OK to apply, or any comments?
If you wouldn't mind holding off, my patch is nearing completion. It
is feature complete, and at the moment I am writing test cases.
I'm happy to send what I have now, if you want to see it. Or it is
all in the archer git repository on the tromey-archer-charset branch.
I've lifted stuff -- ideas and code -- from your patch, but the result
is pretty different. Perhaps we could discuss the areas where we made
different decisions and try to plot the best route forward.
Tom
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 4f2f7fb..0d30abc 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -2809,6 +2809,7 @@ process_die (struct die_info *die, struct dwarf2_cu *cu)
case DW_TAG_base_type:
case DW_TAG_subrange_type:
+ case DW_TAG_typedef:
/* Add a typedef symbol for the type definition, if it has a
DW_AT_name. */
new_symbol (die, read_type_die (die, cu), cu);
diff --git a/gdb/eval.c b/gdb/eval.c
index 78d03f5..804e9c4 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -2475,7 +2475,17 @@ evaluate_subexp_standard (struct type *expect_type,
if (noside == EVAL_SKIP)
goto nosideret;
else if (noside == EVAL_AVOID_SIDE_EFFECTS)
- return allocate_value (exp->elts[pc + 1].type);
+ {
+ struct type *type = exp->elts[pc + 1].type;
+ /* If this is a typedef, then find its immediate target. We
+ use check_typedef to resolve stubs, but we ignore its
+ result because we do not want to dig past all
+ typedefs. */
+ check_typedef (type);
+ if (TYPE_CODE (type) == TYPE_CODE_TYPEDEF)
+ type = TYPE_TARGET_TYPE (type);
+ return allocate_value (type);
+ }
else
error (_("Attempt to use a type name as an expression"));