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* Re: c++/9298: [3.4 regression] [new parser] ICE with function-pointer-type template args
@ 2003-01-15 20:46 Volker Reichelt
0 siblings, 0 replies; 6+ messages in thread
From: Volker Reichelt @ 2003-01-15 20:46 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR c++/9298; it has been noted by GNATS.
From: Volker Reichelt <reichelt@igpm.rwth-aachen.de>
To: bangerth@ticam.utexas.edu
Cc: gcc-bugs@gcc.gnu.org, gcc-gnats@gcc.gnu.org
Subject: Re: c++/9298: [3.4 regression] [new parser] ICE with function-pointer-type template args
Date: Wed, 15 Jan 2003 22:39:56 +0100
Hi Wolfgang,
sorry for the confusion, I was *quite* wrong.
Let's have another look at the code:
The declaration of foo as a static template function is of course legal.
But I disagree with you when you say
> It's illegal, though, to use its address as a template parameter!
Why should it be illegal? You can use the address of a static variable as
a template parameter, too:
------------snip here-------------
int i;
template <int*> void foo() {}
template void foo<&i> ();
----------------------------------
You're right, there's only one bug in the following line:
> template int CPU::dispatch<&template foo<2> > ();
^^^^^^^^
And then, there's one more bug in the whole file:
We only have declarations for "foo" and "dispatch", but we need
definitions for the explicit instantiation of dispatch and its
template parameter.
Given that, the following code should compile IMHO (the EDG front-end
thinks so, too):
----------------------snip here-------------------
struct A
{
typedef void (*pfun)();
template <pfun> static void bar() {}
};
template <int> static void foo() {}
template void A::bar< &foo<0> >();
----------------------snip here-------------------
Alas, each gcc version since 2.95.x rejects the code with a message similar to
bug.cc:10: `&foo<0>' is not a valid template argument
bug.cc:10: template-id `bar<(&foo<0>)>' for `void A::bar()' does not match any
template declaration
(That's probably why I ended up changing random things in the code to make
it compile and came up with the bogus errors from my first message.)
That leaves us with an additional rejects-legal bug.
I'll open an additional PR for that one, if you agree.
Regards,
Volker
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: c++/9298: [3.4 regression] [new parser] ICE with function-pointer-type template args
@ 2003-01-22 22:25 mmitchel
0 siblings, 0 replies; 6+ messages in thread
From: mmitchel @ 2003-01-22 22:25 UTC (permalink / raw)
To: bangerth, gcc-bugs, gcc-prs, nobody
Synopsis: [3.4 regression] [new parser] ICE with function-pointer-type template args
State-Changed-From-To: analyzed->closed
State-Changed-By: mmitchel
State-Changed-When: Wed Jan 22 22:25:48 2003
State-Changed-Why:
Fixed in GCC 3.4.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9298
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: c++/9298: [3.4 regression] [new parser] ICE with function-pointer-type template args
@ 2003-01-15 22:16 Volker Reichelt
0 siblings, 0 replies; 6+ messages in thread
From: Volker Reichelt @ 2003-01-15 22:16 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR c++/9298; it has been noted by GNATS.
From: Volker Reichelt <reichelt@igpm.rwth-aachen.de>
To: bangerth@ticam.utexas.edu
Cc: gcc-bugs@gcc.gnu.org, gcc-gnats@gcc.gnu.org
Subject: Re: c++/9298: [3.4 regression] [new parser] ICE with function-pointer-type template args
Date: Thu, 16 Jan 2003 00:12:15 +0100
On 15 Jan, Wolfgang Bangerth wrote:
> Values for pointer- or reference-type template arguments need to have
> _external_ linkage. "int i" does have that, "static void foo()" doesn't.
Argghh! Sorry again! You're right, of course. ISO-standard 14.3.2.
Regards,
Volker
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: c++/9298: [3.4 regression] [new parser] ICE with function-pointer-type template args
@ 2003-01-15 21:36 Wolfgang Bangerth
0 siblings, 0 replies; 6+ messages in thread
From: Wolfgang Bangerth @ 2003-01-15 21:36 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR c++/9298; it has been noted by GNATS.
From: Wolfgang Bangerth <bangerth@ticam.utexas.edu>
To: Volker Reichelt <reichelt@igpm.rwth-aachen.de>
Cc: gcc-bugs@gcc.gnu.org, <gcc-gnats@gcc.gnu.org>
Subject: Re: c++/9298: [3.4 regression] [new parser] ICE with function-pointer-type
template args
Date: Wed, 15 Jan 2003 15:35:39 -0600 (CST)
> sorry for the confusion, I was *quite* wrong.
No problem :-) You're hereby sentenced to three days in the C++ testcase
diction jail:
struct bars {
bool behind ();
};
...
if (bars().behind())
printf("foo :-)");
> Let's have another look at the code:
>
> The declaration of foo as a static template function is of course legal.
> But I disagree with you when you say
>
> > It's illegal, though, to use its address as a template parameter!
>
> Why should it be illegal? You can use the address of a static variable as
> a template parameter, too:
>
> ------------snip here-------------
> int i;
> template <int*> void foo() {}
> template void foo<&i> ();
> ----------------------------------
Values for pointer- or reference-type template arguments need to have
_external_ linkage. "int i" does have that, "static void foo()" doesn't.
> Given that, the following code should compile IMHO (the EDG front-end
> thinks so, too):
>
> ----------------------snip here-------------------
> struct A
> {
> typedef void (*pfun)();
>
> template <pfun> static void bar() {}
> };
>
> template <int> static void foo() {}
>
> template void A::bar< &foo<0> >();
> ----------------------snip here-------------------
>
> Alas, each gcc version since 2.95.x rejects the code with a message similar to
>
> bug.cc:10: `&foo<0>' is not a valid template argument
> bug.cc:10: template-id `bar<(&foo<0>)>' for `void A::bar()' does not match any
> template declaration
EDG is wrong (surprisingly), and gcc is right: foo has internal linkage,
and its address is therefore not a valid one for a template parameter.
Once you remove the static from the declaration of foo, it compiles
cleanly.
It's just too bad that here the error message is not really good:
GCC2.96:
tmp/g> gcc -c x.cc
x.cc:10: `&foo<0>' is not a valid template argument
x.cc:10: template-id `bar<(&foo<0>)>' for `A::bar ()' does not match
any template declaration
PRESENT CVS:
tmp/g> ../build-gcc/gcc-install/bin/gcc -c x.cc
x.cc:10: error: template-id `bar<(&foo<0>)>' for `void A::bar()' does not match
any template declaration
It's particularly bad since gcc-CVS knows about this. If I take your
example from above, and make it invalid by adding "static" to the
declaration of "int i", then I get:
x.cc:3: error: address of non-extern `i' cannot be used as template argument
x.cc:3: error: template-id `foo<(&i)>' for `void foo()' does not match any
template declaration
Regards
Wolfgang
-------------------------------------------------------------------------
Wolfgang Bangerth email: bangerth@ticam.utexas.edu
www: http://www.ticam.utexas.edu/~bangerth/
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: c++/9298: [3.4 regression] [new parser] ICE with function-pointer-type template args
@ 2003-01-15 17:16 Wolfgang Bangerth
0 siblings, 0 replies; 6+ messages in thread
From: Wolfgang Bangerth @ 2003-01-15 17:16 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR c++/9298; it has been noted by GNATS.
From: Wolfgang Bangerth <bangerth@ticam.utexas.edu>
To: Volker Reichelt <reichelt@igpm.rwth-aachen.de>, <gcc-bugs@gcc.gnu.org>,
<gcc-gnats@gcc.gnu.org>
Cc:
Subject: Re: c++/9298: [3.4 regression] [new parser] ICE with function-pointer-type
template args
Date: Wed, 15 Jan 2003 11:11:32 -0600 (CST)
> BTW, the code is illegal (there are three bugs):
Of course the code is illegal, but I can really only spot one error :-)
> template<int> static int foo();
> ^^^^^^
Why shouldn't a template not be a static function? It's illegal, though,
to use its address as a template parameter!
> template int CPU::dispatch<&template foo<2> > ();
> ^^ ^^^^^^^^
The one at the left: That's an explicit instantiation, not specialization,
so this is legal syntax. The syntax at the right should be wrong, though
(well, not quite sure, should it?).
W.
-------------------------------------------------------------------------
Wolfgang Bangerth email: bangerth@ticam.utexas.edu
www: http://www.ticam.utexas.edu/~bangerth/
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: c++/9298: [3.4 regression] [new parser] ICE with function-pointer-type template args
@ 2003-01-15 9:48 reichelt
0 siblings, 0 replies; 6+ messages in thread
From: reichelt @ 2003-01-15 9:48 UTC (permalink / raw)
To: bangerth, gcc-bugs, gcc-prs, nobody
Synopsis: [3.4 regression] [new parser] ICE with function-pointer-type template args
State-Changed-From-To: open->analyzed
State-Changed-By: reichelt
State-Changed-When: Wed Jan 15 01:48:42 2003
State-Changed-Why:
Confirmed.
BTW, the code is illegal (there are three bugs):
template<int> static int foo();
^^^^^^
template int CPU::dispatch<&template foo<2> > ();
^^ ^^^^^^^^
The correct verion would be
template<int> int foo();
template<> int CPU::dispatch<&foo<2> > ();
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9298
^ permalink raw reply [flat|nested] 6+ messages in thread
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2003-01-15 20:46 c++/9298: [3.4 regression] [new parser] ICE with function-pointer-type template args Volker Reichelt
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2003-01-22 22:25 mmitchel
2003-01-15 22:16 Volker Reichelt
2003-01-15 21:36 Wolfgang Bangerth
2003-01-15 17:16 Wolfgang Bangerth
2003-01-15 9:48 reichelt
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