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c++/10619: Instantiation through function template return type causes too cryptic error.
- From: gccbugs at contacts dot eelis dot net
- To: gcc-gnats at gcc dot gnu dot org
- Date: 4 May 2003 13:39:04 -0000
- Subject: c++/10619: Instantiation through function template return type causes too cryptic error.
- Reply-to: gccbugs at contacts dot eelis dot net
>Number: 10619
>Category: c++
>Synopsis: Instantiation through function template return type causes too cryptic error.
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: unassigned
>State: open
>Class: change-request
>Submitter-Id: net
>Arrival-Date: Sun May 04 13:46:01 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator: Eelis van der Weegen
>Release: gcc version 3.2.2 (mingw special 20030208-1)
>Organization:
>Environment:
Configured with: ../gcc/configure --with-gcc --with-gnu-ld --with-gnu-as --host=mingw32 --target=mingw32 --prefix=/mingw --enable-threads --disable-nls --enable-languages=c++,f77,objc --disable-win32-registry --disable-shared --enable-sjlj-exceptions
Thread model: win32
>Description:
When templates are instantiated through function template return types, errors during the instantiation are not always properly emitted. For example, given the following code:
template <int I> struct A;
template <int I> struct F { typename A<I>::type t; };
template <int I> typename A<I>::type f ();
Instantiating F using:
F<0> x;
causes a very clear error message:
In instantiation of 'F<0>': instantiated from here [..] invalid use of undefined type 'struct A<0>'
However, performing the same instantiation through instantiating f() using:
f<0>();
causes the following error:
no matching function for call to 'f()'
This error seems to indicate an argument or CV-qualifier mismatch or something similar. It does not indicate that the problem occurs during the instantiation of the return type. Therefore, I think this error is too cryptic and, since cryptic errors lead to more time spent debugging, needs improvement. Something like:
In instantiation of 'f<0>': instatiated from here [..] in instantiation of return type: invalid use of undefined 'struct A<0>'
would be ideal. What are your thoughts on this?
>How-To-Repeat:
Compile the code from the description.
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: