| Summary: | [3.3/3.4/4.0 Regressions] Function templates, overloads, and friend name injection | ||
|---|---|---|---|
| Product: | gcc | Reporter: | Yueh-Wei Hu (J©¨°¶) <ywhu> |
| Component: | c++ | Assignee: | Mark Mitchell <mark> |
| Status: | RESOLVED FIXED | ||
| Severity: | critical | CC: | gcc-bugs, giovannibajo |
| Priority: | P2 | Keywords: | wrong-code |
| Version: | 3.3.3 | ||
| Target Milestone: | 3.4.1 | ||
| Host: | Target: | ||
| Build: | Known to work: | 2.95.3 | |
| Known to fail: | 3.0.4 3.2.3 3.3.3 3.4.0 4.0.0 | Last reconfirmed: | 2004-05-26 11:59:41 |
OK, something is really screwed up here. Take this:
-----------------
#include <iostream>
#define PRINT std::cerr << __PRETTY_FUNCTION__ << std::endl
template<int a, int b> class T;
template<int a, int b> void func(T<a, b> * t) { PRINT; }
template<int a> void func(T<a, 3> * t) { PRINT; }
template<int a, int b> struct T {
friend void func<a, b>(T<a, b> * t);
friend void func<a> (T<a, 3> * t);
void foo();
};
template<int a, int b> void T<a, b>::foo() {
func((T<2,3>*)0);
}
int main() {
func((T<2,3>*)0);
T<2,3>().foo();
}
-----------------------
Note that the call to func in main() is the same as the one in foo(), so
it should really yield the same result. Alas, with gcc3.4, we get:
g/x> /home/bangerth/bin/gcc-3.4-pre/bin/c++ x.cc ; ./a.out
void func(T<a, 3>*) [with int a = 2]
void func(T<a, b>*) [with int a = 2, int b = 3]
On the other hand, if we revert the order of the two calls in main(), we get
a different result, namely a call to the general T<a,b> template as in the
second line above. My inclination is to say that this is due to the fact that
we only instantiate T<2,3> in the second call in main(), since the cast
to (T<2,3>*)0 does not require instantiation of the template. Now, how that
can affect the result I don't know -- presumably it has something to do with
injecting the friend functions into the global namespace. This explains
why reverting the calls in main() changes the result.
What evades me, however, is why injecting the names should make any
difference? Note that if I remove the friend declarations altogether,
then we get two calls to the <a,3> template, irrespective of the call
order in main(). I tend to think that this is what we should get in all
cases, but would like to have a second opinion...
W.
Confirmed as a regression. The reduced code in comment #1 by Wolfgang emits the following with GCC 2.95 (and EDG): void func<2>(T<2,3> *) void func<2>(T<2,3> *) which is the correct behaviour. 3.0 - 3.2 even rejects this code, while from 3.3 we have the wrong-code problem (the wrong specialization is chosen). Working on a fix. Subject: Bug 15629 CVSROOT: /cvs/gcc Module name: gcc Branch: gcc-3_4-branch Changes by: mmitchel@gcc.gnu.org 2004-05-31 21:04:15 Modified files: gcc/testsuite : ChangeLog gcc/cp : ChangeLog call.c cp-tree.h cvt.c name-lookup.c pt.c tree.c typeck.c gcc/testsuite/g++.dg/ext: packed3.C packed4.C gcc/testsuite/g++.dg/template: friend.C Added files: gcc/testsuite/g++.dg/expr: ptrmem5.C gcc/testsuite/g++.dg/ext: packed6.C gcc/testsuite/g++.dg/template: friend27.C friend28.C gcc/testsuite/g++.dg/warn: Wreturn-1.C Log message: PR c++/15742 * call.c (build_over_call): Set current_function_returns_abnormally even in template functions. PR c++/15696 * cp-tree.h (invalid_nonstatic_memfn_p): New function. * cvt.c (convert_to_void): Use it. * typeck.c (invalid_nonstatic_memfn_p): New function. (decay_conversion): Use it. PR c++/15625 * pt.c (tsubst_decl): Set DECL_FRIEND_CONTEXT for instantiated templates. PR c++/15629 * name-lookup.c (arg_assoc_class): Do not find template specializations. PR c++/15209 * tree.c (lvalue_p_1): Only consider the right-hand side of "." expressions when determining whether or not an express is packed. PR c++/15742 * g++.dg/warn/Wreturn-1.C: New test. PR c++/15696 * g++.dg/expr/ptrmem5.C: New test. PR c++/15625 * g++.dg/template/friend27.C: New test. PR c++/15629 * g++.dg/template/friend28.C: New test. * g++.dg/template/friend.C: Do not depend on <iostream>. Add error message. PR c++/15209 * g++.dg/ext/packed3.C: Remove bogus error. * g++.dg/ext/packed4.C: Remove bogus check. * g++.dg/ext/packed6.C: New test. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.3389.2.187&r2=1.3389.2.188 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.3892.2.109&r2=1.3892.2.110 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/call.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.452.2.16&r2=1.452.2.17 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/cp-tree.h.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.946.4.12&r2=1.946.4.13 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/cvt.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.151.4.1&r2=1.151.4.2 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/name-lookup.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.34.2.13&r2=1.34.2.14 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/pt.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.816.2.26&r2=1.816.2.27 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/tree.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.360.4.5&r2=1.360.4.6 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/typeck.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.519.2.18&r2=1.519.2.19 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/expr/ptrmem5.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=NONE&r2=1.1.2.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/ext/packed6.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=NONE&r2=1.1.2.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/ext/packed3.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.1&r2=1.1.24.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/ext/packed4.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.1&r2=1.1.24.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/friend27.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=NONE&r2=1.1.2.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/friend28.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=NONE&r2=1.1.2.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/friend.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.5&r2=1.5.56.1 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/warn/Wreturn-1.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=NONE&r2=1.1.2.1 Subject: Bug 15629 CVSROOT: /cvs/gcc Module name: gcc Changes by: mmitchel@gcc.gnu.org 2004-05-31 21:24:31 Modified files: gcc/cp : call.c cp-tree.h cvt.c name-lookup.c pt.c tree.c typeck.c gcc/testsuite/g++.dg/ext: packed3.C packed4.C gcc/testsuite/g++.dg/template: friend.C Added files: gcc/testsuite/g++.dg/expr: ptrmem5.C gcc/testsuite/g++.dg/ext: packed6.C gcc/testsuite/g++.dg/template: friend27.C friend28.C gcc/testsuite/g++.dg/warn: Wreturn-1.C Log message: PR c++/15742 * call.c (build_over_call): Set current_function_returns_abnormally even in template functions. PR c++/15696 * cp-tree.h (invalid_nonstatic_memfn_p): New function. * cvt.c (convert_to_void): Use it. * typeck.c (invalid_nonstatic_memfn_p): New function. (decay_conversion): Use it. PR c++/15625 * pt.c (tsubst_decl): Set DECL_FRIEND_CONTEXT for instantiated templates. PR c++/15629 * name-lookup.c (arg_assoc_class): Do not find template specializations. PR c++/15209 * tree.c (lvalue_p_1): Only consider the right-hand side of "." expressions when determining whether or not an express is packed. PR c++/15742 * g++.dg/warn/Wreturn-1.C: New test. PR c++/15696 * g++.dg/expr/ptrmem5.C: New test. PR c++/15625 * g++.dg/template/friend27.C: New test. PR c++/15629 * g++.dg/template/friend28.C: New test. * g++.dg/template/friend.C: Do not depend on <iostream>. Add error message. PR c++/15209 * g++.dg/ext/packed3.C: Remove bogus error. * g++.dg/ext/packed4.C: Remove bogus check. * g++.dg/ext/packed6.C: New test. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/call.c.diff?cvsroot=gcc&r1=1.476&r2=1.477 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/cp-tree.h.diff?cvsroot=gcc&r1=1.969&r2=1.970 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/cvt.c.diff?cvsroot=gcc&r1=1.156&r2=1.157 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/name-lookup.c.diff?cvsroot=gcc&r1=1.56&r2=1.57 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/pt.c.diff?cvsroot=gcc&r1=1.856&r2=1.857 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/tree.c.diff?cvsroot=gcc&r1=1.374&r2=1.375 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/typeck.c.diff?cvsroot=gcc&r1=1.547&r2=1.548 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/expr/ptrmem5.C.diff?cvsroot=gcc&r1=1.1&r2=1.2 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/ext/packed6.C.diff?cvsroot=gcc&r1=1.1&r2=1.2 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/ext/packed3.C.diff?cvsroot=gcc&r1=1.1&r2=1.2 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/ext/packed4.C.diff?cvsroot=gcc&r1=1.1&r2=1.2 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/friend27.C.diff?cvsroot=gcc&r1=1.1&r2=1.2 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/friend28.C.diff?cvsroot=gcc&r1=1.1&r2=1.2 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/friend.C.diff?cvsroot=gcc&r1=1.5&r2=1.6 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/warn/Wreturn-1.C.diff?cvsroot=gcc&r1=1.1&r2=1.2 Fixed in GCC 3.4.1. |
Hi, When I use friend function templates in a class template, the function overloading doesn't happend. The following is the source. ============================================================== #include <iostream> template<int a, int b> class T; template<int a, int b> void func(T<a, b> const * const t) { std::cerr << "T<a, b>" << std::endl; } template<int a, int b> class T { private: friend void func<a, b>(T<a, b> const * const t); friend void func<a>(T<a, 3> const * const t); public: void ttt() const; }; template<int a> void func(T<a, 3> const * const t) { std::cerr << "T<a, 3>" << std::endl; } template<int a, int b> void T<a, b>::ttt() const { func(this); } int main() { T<2, 3> t; t.ttt(); return 0; } ============================================================== The error messages from gcc-3.2 is as following: ============================================================== eee.cpp: In member function `void T<a, b>::ttt() const [with int a = 2, int b = 3]': eee.cpp:52: instantiated from here eee.cpp:44: call of overloaded `func(const T<2, 3>* const)' is ambiguous eee.cpp:8: candidates are: void func(const T<a, b>*) [with int a = 2, int b = 3] eee.cpp:29: void func(const T<a, 3>*) [with int a = 2] eee.cpp:8: void func(const T<a, b>*) [with int a = 2, int b = 3] eee.cpp:29: void func(const T<a, 3>*) [with int a = 2] ============================================================== However, when I use gcc-3.2, gcc-3.3, gcc-3.4 to compile my code, the result is strange. Here is my result: 1) gcc-3.2: can _not_ compile, the error message is copied and pasted above. 2) gcc-3.3: can compile, but the result is T<a, b> [but I think it should be T<a, 3>] 3) gcc-3.4: can compile, but the result is T<a, b> [but I think it should be T<a, 3>] < NOTE > When I use 'struct' rather than 'class', and remove the 'friend' declarations, the function overloading works fine ! ============================================================= Question 2: ============================================================= I added one more friend function declaration, and now, even gcc-3.3 doesn't compile my code. The source code is as following: ============================================================== #include <iostream> template<int a, int b> class T; template<int a, int b> void func(T<a, b> const * const t) { std::cerr << "T<a, b>" << std::endl; } template<int a, int b> class T { private: friend void func<a, b>(T<a, b> const * const t); friend void func<a>(T<a, 3> const * const t); friend void func<b>(T<3, b> const * const t); <-- add this --> public: void ttt() const; }; template<int a> void func(T<a, 3> const * const t) { std::cerr << "T<a, 3>" << std::endl; } template<int b> <-- add this definition --> void func(T<3, b> const * const t) { std::cerr << "T<3, b>" << std::endl; } template<int a, int b> void T<a, b>::ttt() const { func(this); } int main() { T<2, 3> t; t.ttt(); return 0; } ============================================================== I can _not_ compile the code using gcc-3.2, and the error message for gcc-3.2 is like the one I posted above: ============================================================== eee.cpp: In instantiation of `T<2, 3>': eee.cpp:50: instantiated from here eee.cpp:19: ambiguous template specialization `func<3>' for `void func(const T<3, 3>*)' eee.cpp: In member function `void T<a, b>::ttt() const [with int a = 2, int b = 3]': eee.cpp:52: instantiated from here eee.cpp:44: call of overloaded `func(const T<2, 3>* const)' is ambiguous eee.cpp:8: candidates are: void func(const T<a, b>*) [with int a = 2, int b = 3] eee.cpp:29: void func(const T<a, 3>*) [with int a = 2] eee.cpp:8: void func(const T<a, b>*) [with int a = 2, int b = 3] eee.cpp:29: void func(const T<a, 3>*) [with int a = 2] ============================================================== Again, the following is the result when I compile it using gcc-3.2, gcc-3.3 and gcc-3.4: 1) gcc-3.2: can _not_ compile, the error message posted above. 2) gcc-3.3: can _not_ compile, the error message just like the one posted for gcc-3.2. 3) gcc-3.4: can compile, but the result is T<a, b> [but I think it should be T<a, 3>] ============================================================== My environment: 1) Debian unstable 2) gcc-3.4.0 (Debian 20040516) 3) gcc-3.3.3 (Debian 20040422) 4) gcc-3.2.3 5) Command line options: none 6)