[forwarded from http://bugs.debian.org/385992]
Matthias
bug submitter writes:
It appears that g++ no longer finds a dependent name when it is the
template function itself.
$cat -n test.cpp
1 template <class C> void f(C *p)
2 { f(*p); }
3
4 void f(int i)
5 { i++; }
6
7 int main(int argc, char**)
8 { f(&argc); }
$g++-4.0 -o test test.cpp
$g++-4.1 -o test test.cpp
test.cpp: In function 'void f(C*) [with C = int]':
test.cpp:8: instantiated from here
test.cpp:2: error: no matching function for call to 'f(int&)'
$
To my understanding from the C++ standard, g++-4.0 behaves correctly.
My reasoning:
In f(*p), f is a dependent name according to clause 14.6.2, para 1.
The point of instantiation is f(&argc).
In f(*p), f is an unqualified-id but not a template-id, so 14.6.4.2
applies: only functions with external linkage will be found. However,
f(int) has external linkage.
Name lookup (3.4, 3.4.2) does not distinguish between the different
contexts for the case of an instantiated instantiation.
So, the lookup of f in f(*p) should consider f<C>(C*) and f(int) together,
and select f(int) from them.
When f(int) and its call in the template are renamed to something else,
the lookup succeeds. I do not know of a reason for having template f
hide the existence of function f.
g++ -v output for upstream:
$g++-4.1 -v -o test test.cpp
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v
--enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr
--enable-shared --with-system-zlib --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --enable-nls
--program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu
--enable-libstdcxx-debug --enable-mpfr --with-tune=i686
--enable-checking=release i486-linux-gnu
Thread model: posix
gcc version 4.1.2 20060814 (prerelease) (Debian 4.1.1-11)
/usr/lib/gcc/i486-linux-gnu/4.1.2/cc1plus -quiet -v -D_GNU_SOURCE test.cpp
-quiet -dumpbase test.cpp -mtune=i686 -auxbase test -version -o
/home/vzweije/tmp/ccgs0DVY.s
ignoring nonexistent directory "/usr/local/include/i486-linux-gnu"
ignoring nonexistent directory
"/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../i486-linux-gnu/include"
ignoring nonexistent directory "/usr/include/i486-linux-gnu"
#include "..." search starts here:
#include <...> search starts here:
/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2
/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/i486-linux-gnu
/usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/backward
/usr/local/include
/usr/lib/gcc/i486-linux-gnu/4.1.2/include
/usr/include
End of search list.
GNU C++ version 4.1.2 20060814 (prerelease) (Debian 4.1.1-11)
(i486-linux-gnu)
compiled by GNU C version 4.1.2 20060814 (prerelease) (Debian
4.1.1-11).
GGC heuristics: --param ggc-min-expand=46 --param ggc-min-heapsize=31550
Compiler executable checksum: af253f4d4c50ecb6c5ed3e2466348eaf
test.cpp: In function 'void f(C*) [with C = int]':
test.cpp:8: instantiated from here
test.cpp:2: error: no matching function for call to 'f(int&)'
$
--
Summary: g++ fails to find dependent name in template from
instantiation context
Product: gcc
Version: 4.1.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: debian-gcc at lists dot debian dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29229
