[llvm-bugs] [Bug 39191] New: UBSan vptr false positive with -fvisibility=hidden

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=39191

            Bug ID: 39191
           Summary: UBSan vptr false positive with -fvisibility=hidden
           Product: new-bugs
           Version: 7.0
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: nok.raven at gmail.com
                CC: llvm-bugs at lists.llvm.org

There is a report on GCC bug tracker about the similar problem
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80963

// foo.cpp
#include "foo.h"

void call_foo(Foo const& obj)
{
    obj.foo();
}

// foo.h
struct Foo
{
    virtual void foo() const = 0;
};

__attribute__((visibility("default"))) void call_foo(Foo const&);

// main.cpp
#include "foo.h"

struct Bar : Foo
{
    void foo() const override {}
};

int main()
{
    call_foo(Bar());
}


// run command
clang++-7 -fPIC -o libfoo.so -shared foo.cpp -fvisibility=hidden -Wall -Wextra
-pedantic -fsanitize=undefined && \
  clang++-7 -o main main.cpp ./libfoo.so -fvisibility=hidden -Wall -Wextra
-pedantic -fsanitize=undefined && \
  ./main

// output
foo.cpp:5:9: runtime error: member call on address 0x7ffd9212cb28 which does
not point to an object of type 'Foo'
0x7ffd9212cb28: note: object is of type 'Bar'
 fd 7f 00 00  08 69 43 00 00 00 00 00  50 e1 42 00 00 00 00 00  e1 82 2b 52 9c
7f 00 00  00 1c 01 00
              ^~~~~~~~~~~~~~~~~~~~~~~
              vptr for 'Bar'

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