10646 – [3.3/3.4 regression] non-const reference is incorrectly matched in a "const T" partial specialization (original) (raw)

| I apologize in advance if I'm not reporting this "bug" absolutely correctly. I haven't done this before. I appreciate your patience. Thank you. I believe my template should report references and functions as NOT const. Is this "pilot error" or a compiler bug? Release: gcc version 3.2 20020927 (prerelease) Environment: in bash via cygwin on windows 98 se How-To-Repeat: g++ is_const.cpp ./a.exe Comment 1 notbob 2003-05-06 22:46:00 UTC Fix: As a fix, you can add another specialization that matches references and set the result to false. Alternatively, use boost::is_const that works correctly (has workarounds). Comment 2 Giovanni Bajo 2003-05-07 00:17:50 UTC State-Changed-From-To: open->analyzed State-Changed-Why: The bug for function types is confirmed in 3.2 but it's fixed in 3.3 (20030503) and 3.4 (20030503). It might be fixed in 3.2.3 as well, I don't have that version. There still is a bug with references, though: --------------------------------- template struct is_const { typedef int type; }; template struct is_const {}; is_const<bool&>::type a; --------------------------------- This should compile (but I'm not 100% sure because this very part of the standard is still a bit misterious for me), and it does on MSVC71 and Comeau/EDG, but fails with GCC 3.3 and 3.4. Since it worked in 2.95, I rate this as a regression. Comment 4 janis187 2003-06-23 15:55:03 UTC The regression in 10646 was introduced or exposed by this patch: --- gcc/gcc/cp/ChangeLog --- > 2002-02-22 Nathan Sidwell <nathan@codesourcery.com> > > PR c++/2645, DR 295 > * cp-tree.h (tsubst_flags_t): Add tf_ignore_bad_quals, > tf_keep_type_decl. > (make_typename_type): Use tsubst_flags_t. > * decl.c (make_typename_type): Adjust. Return non-artificial > TYPE_DECLs, if required. > (grokdeclarator): Simplify CVR qualification handling. Allow bad > qualifiers on typedef types. > * decl2.c (handle_class_head): Adjust make_typename_type call. > * parse.y (nested_name_specifier): Likewise. > (typename_sub0): Likewise. > (typename_sub1): Likewise. > * pt.c (convert_template_argument): Adjust make_typename_type > return value. > (tsubst): Adjust cp_build_qualified_type_real calls. > (check_cv_quals_for_unify): Cope with alowing bad qualifications > on template type parms. > (instantiate_decl): Recheck substitutions to give warnings on bad > qualifications. > * tree.c (cp_build_qualified_type_real): Use tf_allow_bad_quals. The regression hunt used the smaller test case from comment #2. Comment 5 Nathan Sidwell 2003-07-13 14:10:48 UTC Not a bug. CV qualifiers are ignored on reference type when introduced via a typedef or template type parameter. Comment 6 Drea Pinski 2004-05-05 03:52:49 UTC Nathan, this now compiles on the mainline, this is correct right? Comment 7 Nathan Sidwell 2004-05-05 07:11:07 UTC yes this is now working | | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | |