libstdc++/3552: missing hash function for std::string

Matthias Klose doko@klose.in-berlin.de
Tue Jul 3 15:27:00 GMT 2001


>Number:         3552
>Category:       libstdc++
>Synopsis:       missing hash function for std::string
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 03 15:26:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Goswin Brederlow <goswin.brederlow@student.uni-tuebingen.de>
>Release:        3.0 (Debian GNU/Linux)
>Organization:
The Debian project
>Environment:
System: Debian GNU/Linux (testing/unstable)
Architecture: i686
	
host: i386-linux
build: i386-linux
target: i386-linux
configured with: ../src/configure -v --enable-languages=c,c++,java,f77,proto,objc --prefix=/usr --infodir=/share/info --mandir=/share/man --enable-shared --with-gnu-as --with-gnu-ld --with-system-zlib --enable-long-long --enable-nls --without-included-gettext --disable-checking --enable-threads=posix --enable-java-gc=boehm --with-cpp-install-dir=bin --enable-objc-gc i386-linux
>Description:
[ Reported to the Debian BTS as report #87063.
  Please CC 87063-quiet@bugs.debian.org on replies.
  Log of report can be found at http://bugs.debian.org/87063 ]
 	

The STL hash_map does not work with strings. This is because no
hash<string> spezialisation is defined. The code for char* should be
used for strings also.

Heres a testcase:
----------------------------------------------------------------------
#include <ext/hash_map>
#include <string>

using namespace std;

int main() {
        hash_map<string, int> myHashMap;
        myHashMap["Hallo"] = 42;
}
----------------------------------------------------------------------

[commented by Laurent Bonnaud <Laurent.Bonnaud@inpg.fr>:]

This one is clearly a bug.  In the Stroustrup book v3 (not the
definitive reference, but it's the closest thing I have) §17.6.1
explicitely uses a hash_map<string, int> class.  Furthermore, §17.6.2.3
discusses about hashing strings.

>How-To-Repeat:
	
>Fix:
	
>Release-Note:
>Audit-Trail:
>Unformatted:



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