* [PATCH] uchar.h: define char16_t and char32_t for old c++
@ 2018-07-08 13:19 Szabolcs Nagy
2018-07-09 9:20 ` Joakim Sindholt
0 siblings, 1 reply; 3+ messages in thread
From: Szabolcs Nagy @ 2018-07-08 13:19 UTC (permalink / raw)
To: musl
including uchar.h in c++ code is only well defined in c++11 onwards
where char16_t and char32_t type definitions must be hidden since they
are keywords. however some c++ code compiled for older c++ standard
include uchar.h too and they need the typedefs, this fix makes such
code work.
---
include/uchar.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/include/uchar.h b/include/uchar.h
index 8dabf1ed..7e5c4d40 100644
--- a/include/uchar.h
+++ b/include/uchar.h
@@ -3,7 +3,9 @@
#ifdef __cplusplus
extern "C" {
-#else
+#endif
+
+#if __cplusplus < 201103L
typedef unsigned short char16_t;
typedef unsigned char32_t;
#endif
--
2.16.3
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] uchar.h: define char16_t and char32_t for old c++
2018-07-08 13:19 [PATCH] uchar.h: define char16_t and char32_t for old c++ Szabolcs Nagy
@ 2018-07-09 9:20 ` Joakim Sindholt
2018-07-09 12:58 ` Szabolcs Nagy
0 siblings, 1 reply; 3+ messages in thread
From: Joakim Sindholt @ 2018-07-09 9:20 UTC (permalink / raw)
To: musl
On Sun, Jul 08, 2018 at 03:19:03PM +0200, Szabolcs Nagy wrote:
> including uchar.h in c++ code is only well defined in c++11 onwards
> where char16_t and char32_t type definitions must be hidden since they
> are keywords. however some c++ code compiled for older c++ standard
> include uchar.h too and they need the typedefs, this fix makes such
> code work.
> ---
> include/uchar.h | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/include/uchar.h b/include/uchar.h
> index 8dabf1ed..7e5c4d40 100644
> --- a/include/uchar.h
> +++ b/include/uchar.h
> @@ -3,7 +3,9 @@
>
> #ifdef __cplusplus
> extern "C" {
> -#else
> +#endif
> +
> +#if __cplusplus < 201103L
> typedef unsigned short char16_t;
> typedef unsigned char32_t;
> #endif
> --
> 2.16.3
Isn't this a bit ill advised? I just did a little test to see how GCC
mangles the names and it looks troublesome:
char16_t func(char32_t *s); becomes _Z4funcPDi when -std=c++11
and when we add
typedef unsigned short char16_t;
typedef unsigned char32_t;
and compile it with -std=c++03 it becomes _Z4funcPj
Did I do something egregiously wrong? Because this seems like a recipe
for ABI incompatibility.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] uchar.h: define char16_t and char32_t for old c++
2018-07-09 9:20 ` Joakim Sindholt
@ 2018-07-09 12:58 ` Szabolcs Nagy
0 siblings, 0 replies; 3+ messages in thread
From: Szabolcs Nagy @ 2018-07-09 12:58 UTC (permalink / raw)
To: musl
* Joakim Sindholt <opensource@zhasha.com> [2018-07-09 11:20:05 +0200]:
> On Sun, Jul 08, 2018 at 03:19:03PM +0200, Szabolcs Nagy wrote:
> > including uchar.h in c++ code is only well defined in c++11 onwards
> > where char16_t and char32_t type definitions must be hidden since they
> > are keywords. however some c++ code compiled for older c++ standard
> > include uchar.h too and they need the typedefs, this fix makes such
> > code work.
> > ---
> > include/uchar.h | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/uchar.h b/include/uchar.h
> > index 8dabf1ed..7e5c4d40 100644
> > --- a/include/uchar.h
> > +++ b/include/uchar.h
> > @@ -3,7 +3,9 @@
> >
> > #ifdef __cplusplus
> > extern "C" {
> > -#else
> > +#endif
> > +
> > +#if __cplusplus < 201103L
> > typedef unsigned short char16_t;
> > typedef unsigned char32_t;
> > #endif
> > --
> > 2.16.3
>
> Isn't this a bit ill advised? I just did a little test to see how GCC
> mangles the names and it looks troublesome:
> char16_t func(char32_t *s); becomes _Z4funcPDi when -std=c++11
> and when we add
> typedef unsigned short char16_t;
> typedef unsigned char32_t;
> and compile it with -std=c++03 it becomes _Z4funcPj
>
> Did I do something egregiously wrong? Because this seems like a recipe
> for ABI incompatibility.
yes, same thing happens with glibc, if a project uses pre-c++11
compilation setting and includes uchar.h then it will have
different abi.
this is a problem if it uses or provides extern C++ interfaces
with these types.
i would normally say that we shouldn't support such broken code,
but this is c++ where things are broken no matter what.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-07-08 13:19 [PATCH] uchar.h: define char16_t and char32_t for old c++ Szabolcs Nagy
2018-07-09 9:20 ` Joakim Sindholt
2018-07-09 12:58 ` Szabolcs Nagy
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