c++/8042: g++ rejects legal code wrt "expression" templates.

Wed Sep 25 12:06:00 GMT 2002

>Number:         8042
>Category:       c++
>Synopsis:       g++ rejects legal code wrt "expression" templates.
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Wed Sep 25 11:36:04 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Dan Johnston
>Release:        gcc 3.2
>Organization:
>Environment:
Linux yzerman.jf.intel.com 2.4.19-gentoo-r9 #2 Wed Sep 18 09:49:20 PDT 2002 i686 GenuineIntel
>Description:
g++ has problems with some advanced template code I'm writing for a high performance vector library.  Both the Intel Linux (icc) compiler and Microsoft VisualStudio.NET compiler accept this without warning. I've attatched the example .cpp file used to generate these errors (no non-std headers required).  Many of the errors generated are due to being unable to find a suitable implementation of some overloaded operators.  However, it then proceeds to list exactly one candidate that exactly matches what is required (and should be used).  Program output is as follows:

% g++ -v -save-temps -g  -ftemplate-depth-99 -o Test main.cpp
Reading specs from /usr/lib/gcc-lib/i686-pc-linux-gnu/3.2/specs
Configured with: /var/tmp/portage/gcc-3.2-r1/work/gcc-3.2/configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --host=i686-pc-linux-gnu --build=i686-pc-linux-gnu --target=i686-pc-linux-gnu --with-system-zlib --enable-languages=c,c++,ada,f77,objc,java --enable-threads=posix --enable-long-long --disable-checking --enable-cstdio=stdio --enable-clocale=generic --enable-__cxa_atexit --enable-version-specific-runtime-libs --with-gxx-include-dir=/usr/include/g++-v32 --with-local-prefix=/usr/local --enable-shared --enable-nls --without-included-gettext
Thread model: posix
gcc version 3.2
 /usr/lib/gcc-lib/i686-pc-linux-gnu/3.2/cpp0 -lang-c++ -D__GNUG__=3 -D__DEPRECATED -D__EXCEPTIONS -v -D__GNUC__=3 -D__GNUC_MINOR__=2 -D__GNUC_PATCHLEVEL__=0 -D__GXX_ABI_VERSION=102 -D__ELF__ -Dunix -D__gnu_linux__ -Dlinux -D__ELF__ -D__unix__ -D__gnu_linux__ -D__linux__ -D__unix -D__linux -Asystem=posix -D__NO_INLINE__ -D__STDC_HOSTED__=1 -D_GNU_SOURCE -Acpu=i386 -Amachine=i386 -Di386 -D__i386 -D__i386__ -D__tune_i686__ -D__tune_pentiumpro__ main.cpp main.ii
GNU CPP version 3.2 (cpplib) (i386 Linux/ELF)
ignoring nonexistent directory "/usr/local/include"
ignoring nonexistent directory "/usr/i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/include/g++-v32
 /usr/include/g++-v32/i686-pc-linux-gnu
 /usr/include/g++-v32/backward
 /usr/lib/gcc-lib/i686-pc-linux-gnu/3.2/include
 /usr/include
End of search list.
 /usr/lib/gcc-lib/i686-pc-linux-gnu/3.2/cc1plus -fpreprocessed main.ii -quiet -dumpbase main.cpp -g -version -ftemplate-depth-99 -o main.s
GNU CPP version 3.2 (cpplib) (i386 Linux/ELF)
GNU C++ version 3.2 (i686-pc-linux-gnu)
        compiled by GNU C version 3.2.
main.cpp: In function `int main(int, char**)':
main.cpp:1232: no matching function for call to `VecT<float, 4>::VecT(
   VecT<float, 4>)'
main.cpp:143: candidates are: VecT<T, D>::VecT(T*) [with T = float, int D = 4]
main.cpp:138:                 VecT<T, D>::VecT(T) [with T = float, int D = 4]
main.cpp:134:                 VecT<T, D>::VecT(VecT<T, D>&) [with T = float,
   int D = 4]
main.cpp:1232:   initializing temporary from result of `VecT<T, D>::VecT(T*)
   [with T = float, int D = 4]'
main.cpp:1233: conversion from `Expr<float, 4, BinExprOp<float, float*,
   Scalar<float>, SubOpAdd<float> > >' to non-scalar type `VecT<float, 4>'
   requested
main.cpp:1234: no match for `Expr<float, 4, BinExprOp<float, float*, float*,
   SubOpMultiply<float> > > / float' operator
main.cpp:749: candidates are: Expr<T, D, BinExprOp<T, Expr<T, D, A>, Scalar<T>,
   SubOpDivide<T> > > operator/(Expr<T, D, A>&, T) [with T = float, int D = 4,
   A = BinExprOp<float, float*, float*, SubOpMultiply<float> >]
main.cpp:1236: no match for `+ Expr<float, 4, BinExprOp<float, float*, float*,
   SubOpMultiply<float> > >' operator
main.cpp:1206: candidates are: T operator+(Expr<T, D, A>&) [with T = float, int
   D = 4, A = BinExprOp<float, float*, float*, SubOpMultiply<float> >]
main.cpp: In function `Expr<T, D, BinExprOp<T, T*, Scalar<T>, SubOpAdd<T> > >
   operator+(VecT<T, D>&, T) [with T = float, int D = 4]':
main.cpp:1233:   instantiated from here
main.cpp:532: no matching function for call to `Expr<float, 4, BinExprOp<float,
   float*, Scalar<float>, SubOpAdd<float> > >::Expr(BinExprOp<float, float*,
   Scalar<float>, SubOpAdd<float> >)'
main.cpp:76: candidates are: Expr<float, 4, BinExprOp<float, float*,
   Scalar<float>, SubOpAdd<float> > >::Expr(const Expr<float, 4,
   BinExprOp<float, float*, Scalar<float>, SubOpAdd<float> > >&)
main.cpp:82:                 Expr<T, D, A>::Expr(A&) [with T = float, int D =
   4, A = BinExprOp<float, float*, Scalar<float>, SubOpAdd<float> >]
main.cpp: In function `Expr<T, D, BinExprOp<T, T*, T*, SubOpMultiply<T> > >
   operator*(VecT<T, D>&, VecT<T, D>&) [with T = float, int D = 4]':
main.cpp:1234:   instantiated from here
main.cpp:624: no matching function for call to `Expr<float, 4, BinExprOp<float,
   float*, float*, SubOpMultiply<float> > >::Expr(BinExprOp<float, float*,
   float*, SubOpMultiply<float> >)'
main.cpp:76: candidates are: Expr<float, 4, BinExprOp<float, float*, float*,
   SubOpMultiply<float> > >::Expr(const Expr<float, 4, BinExprOp<float, float*,
   float*, SubOpMultiply<float> > >&)
main.cpp:82:                 Expr<T, D, A>::Expr(A&) [with T = float, int D =
   4, A = BinExprOp<float, float*, float*, SubOpMultiply<float> >]
>How-To-Repeat:
bnzip2 the attached file.  Run 'g++ -o Test main.cpp'
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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