[LLVMbugs] [Bug 10126] New: Class accessed before it is constructed not warned about

bugzilla-daemon at llvm.org bugzilla-daemon at llvm.org
Sun Jun 12 09:51:02 PDT 2011


           Summary: Class accessed before it is constructed not warned
           Product: clang
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: C++
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: overminddl1 at gmail.com
                CC: llvmbugs at cs.uiuc.edu, dgregor at apple.com

There is an article on GOTW listed on: http://www.gotw.ca/gotw/080.htm
It details a program bug that is not caught be almost every compiler.  Here is
the example program:
#include <string>
using namespace std;

class A
  A( const string& s ) { /* ... */ }
  string f() { return "hello, world"; }

class B : public A
  B() : A( s = f() ) {} // The bug is on this line
  string s;

int main()
  B b;
The bug is in the A( s = f() ) call, it calls f() (which is in A and 'this' is
not constructed yet), and it sets s to it (which is in B and not constructed
yet since A is not yet constructed), then passes the result on to A.

clang++ currently issues no warning about the code even with -Wall on the trunk
as of r132876.  As an enhancement, this kind of access should be warned about
on some level.

Configure bugmail: http://llvm.org/bugs/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.

More information about the llvm-bugs mailing list