[LLVMbugs] [Bug 12459] New: False positive for call to pure virtual member function warning caused by a cast

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=12459

             Bug #: 12459
           Summary: False positive for call to pure virtual member
                    function warning caused by a cast
           Product: clang
           Version: trunk
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: l.lunak at suse.cz
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified


$ cat a.cpp
struct A { virtual void foo() = 0; };
struct B : A { B(); virtual void foo(); };
B::B() { static_cast< A* >( this )->foo(); }
void B::foo() {}
int main() { B b; }
$ clang++ -v
clang version 3.1 (trunk 153819)
Target: x86_64-unknown-linux-gnu
Thread model: posix
$ clang++ a.cpp
a.cpp:3:10: warning: call to pure virtual member function 'foo'; overrides of
'foo' in subclasses are not available in the
      constructor of 'A'
B::B() { static_cast< A* >( this )->foo(); }
         ^
a.cpp:1:12: note: 'foo' declared here                                           
struct A { virtual void foo() = 0; };
           ^
1 warning generated.                                                            
$ ./a.out
[no abort, runs fine]

Stepping through or even just running this testcase shows that B::B() calls
B::foo() and not A::foo(), despite the explicit cast and the warning. The false
warning is not generated without the explicit cast.

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