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preprocessor/9689: Number: 9688 update : pasting "<" and "ValidStruct" does not give a valid preprocessing token
- From: ediaz at veridis dot com
- To: gcc-gnats at gcc dot gnu dot org
- Date: 13 Feb 2003 10:00:14 -0000
- Subject: preprocessor/9689: Number: 9688 update : pasting "<" and "ValidStruct" does not give a valid preprocessing token
- Reply-to: ediaz at veridis dot com
>Number: 9689
>Category: preprocessor
>Synopsis: Number: 9688 update : pasting "<" and "ValidStruct" does not give a valid preprocessing token
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: rejects-legal
>Submitter-Id: net
>Arrival-Date: Thu Feb 13 10:06:01 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator: ediaz@veridis.com
>Release: g++ (GCC) 3.3 20030212 (prerelease)
>Organization:
>Environment:
SuSE 7.3/Linux
>Description:
c&p of the #9688 descripton :
When I try to compile a file using macros of templates, I get a 'MyFileStruct.h:541:67: pasting "<" and "MyStruct" does not give a valid preprocessing token' message.
It worked perfectly with the 2.95.x serie and with the 3.2.1 version.
I've tryied to do it in two passes, with a --save-temps and a g++ thefile.ii -c and it worked. Like if the processed code was not the same as the preprocessor's output.
-----------
I've made a better & cleaner example and attached it :
>How-To-Repeat:
Explanations in test2.cpp
>Fix:
Use the two passes trick.
>Release-Note:
>Audit-Trail:
>Unformatted:
----gnatsweb-attachment----
Content-Type: text/plain; name="test2.cpp"
Content-Disposition: inline; filename="test2.cpp"
/*
This is a better example of the problem (cleaner too)
How to fail :
sh-2.05$ g++ test2.cpp -o test2_fail
test2.cpp:46:11: pasting "<" and "Field" does not give a valid preprocessing token
How to success :
sh-2.05$ g++ test2.cpp --save-temps
test2.cpp:46:11: pasting "<" and "Field" does not give a valid preprocessing token
sh-2.05$ g++ test2.ii -o test2_success
sh-2.05$
I hope it will helps.
Regards,
Eric Diaz
*/
#include<stdlib.h>
#include<stdio.h>
#include<string.h>
template <class T>
class C
{
T hold;
public:
C(T to_hold)
{
hold=to_hold;
}
static void process(T a_value)
{
puts("Generic");
return 0;
}
};
#define CM(x) \
template<> \
class C < ##x > \
{ \
public: \
static void process(x a_value) \
{ \
puts("Not Generic (" #x ")"); \
} \
};
struct Field
{
};
struct Field2
{
};
// The following will fail :
CM( Field )
// The following, being a copy&paste of the .ii output for the CM( Field ) (with Field replaced by Field2) will work.
template<> class C < Field2 > { public: static void process(Field2 a_value) { puts("Not Generic (" "Field2" ")"); } };
int main(int argc,char* argv[])
{
Field f1;
Field2 f2;
C<Field>::process(f1);
C<Field2>::process(f2);
return 0;
}