| Summary: | [3.2 regression] unhelpful error message for binding temp to reference | ||
|---|---|---|---|
| Product: | gcc | Reporter: | adelroy |
| Component: | c++ | Assignee: | Not yet assigned to anyone <unassigned> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | gcc-bugs, jbuck, mmitchel |
| Priority: | P3 | ||
| Version: | 3.2 | ||
| Target Milestone: | --- | ||
| Host: | Target: | ||
| Build: | Known to work: | ||
| Known to fail: | Last reconfirmed: | ||
| Attachments: | txt.ii.bz2 | ||
Fix: Fixed in GCC 3.3, 3.4 with: http://gcc.gnu.org/ml/gcc-patches/2003-03/msg00974.html State-Changed-From-To: open->analyzed
State-Changed-Why: Confirmed. The reason, of course, is that you try to bind
the temporary to a non-const reference. gcc2.95 actually
tells you this:
----------------------------
tmp/g> c++ -c x.cc
x.cc: In function `int main()':
x.cc:28: initialization of non-const reference type `class txt &'
x.cc:28: from rvalue of type `txt'
x.cc:13: in passing argument 1 of `operator <<<char[21]>(txt &, const char (&)[21])'
--------------------------------
The messages we get from 3.2.1 and 3.3 are incomprehensible
compared to that, which I rate as a regression, so I put
this into "high" state and leave it to others whether this
merits fixing.
From: mmitchel@gcc.gnu.org To: gcc-gnats@gcc.gnu.org Cc: Subject: c++/8700 Date: 11 Mar 2003 15:43:15 -0000 CVSROOT: /cvs/gcc Module name: gcc Changes by: mmitchel@gcc.gnu.org 2003-03-11 15:43:15 Modified files: gcc/cp : ChangeLog call.c cp-tree.h decl2.c friend.c Log message: PR c++/8700 * call.c (convert_class_to_reference): Adjust usage of splice_viable. (any_viable): Remove. (splice_viable): Combine with any_viable. (print_z_candidates): Avoid printing duplicates. (build_user_type_conversion_1): Adjust usage of splice_viable. (build_new_function_call): Likewise. (build_operator_new_call): Likewise. (build_object_call): Likewise. (build_conditional_expr): Likewise. (build_new_op): Likewise. (build_new_method_call): Likewise. (joust): Remove spurious comment. * cp-tree.h (DECL_FRIENDLIST): Correct documentation. * decl2.c (arg_assoc_class): Simplify. * friend.c (add_friend): Likewise. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/ChangeLog.diff?cvsroot=gcc&r1=1.3261&r2=1.3262 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/call.c.diff?cvsroot=gcc&r1=1.366&r2=1.367 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/cp-tree.h.diff?cvsroot=gcc&r1=1.823&r2=1.824 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/decl2.c.diff?cvsroot=gcc&r1=1.603&r2=1.604 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/friend.c.diff?cvsroot=gcc&r1=1.81&r2=1.82 From: mmitchel@gcc.gnu.org To: gcc-gnats@gcc.gnu.org Cc: Subject: c++/8700 Date: 11 Mar 2003 15:56:52 -0000 CVSROOT: /cvs/gcc Module name: gcc Branch: gcc-3_3-branch Changes by: mmitchel@gcc.gnu.org 2003-03-11 15:56:52 Modified files: gcc/cp : ChangeLog call.c Log message: PR c++/8700 * call.c (print_z_candidates): Avoid printing duplicates. Patches: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_3-branch&r1=1.3076.2.74&r2=1.3076.2.75 http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/call.c.diff?cvsroot=gcc&only_with_tag=gcc-3_3-branch&r1=1.341.2.11&r2=1.341.2.12 State-Changed-From-To: analyzed->closed State-Changed-Why: Fixed for 3.3 and in trunk, and 3.2 branch is now closed. |
Fails to match a unique operator<<, lists two copies as if they were ambiguous - but the line numbers are the same: definitely only defined once, only happens for temporary variable. Get this error compiling following code... tkrdev1:~dev/tpcc/error_contexts> g++ -o txt txt.cc txt.cc: In function `int main()': txt.cc:28: no match for `txt << const char[21]' operator txt.cc:13: candidates are: txt& operator<<(txt&, const V&) [with V = char[21]] txt.cc:13: txt& operator<<(txt&, const V&) [with V = char[21]] zsh: exit 1 g++ -o txt txt.cc tkrdev1:~dev/tpcc/error_contexts> cat txt.cc #include <iostream> #include <sstream> using namespace std; class txt { ostringstream s; public: template<typename V> friend txt& operator<<(txt& t, const V& v) { t.s << v; return t; } operator const char*() { return s.str().c_str(); } }; int main() { txt t; cout << (t << "hello world!") << endl; // ok cout << (txt() << "goodbye cruel world!") << endl; //not return 0; } --------------------------- tkrdev1:~dev/tpcc/shmew> g++ -v Reading specs from /bb/home/adelroy/lib/gcc-lib/sparc-sun-solaris2.8/3.2/specs Configured with: ../gcc-3.2/configure --prefix=/bb/home/adelroy --enable-languages=c,c++ --with-ld=/usr/ccs/bin/ld Thread model: posix gcc version 3.2 Release: gcc version 3.2 Environment: Solaris 2.8 / Sparc How-To-Repeat: Try to compile code snippet provided in description.