[Bug d/95155] New: d: wrong vtable offset in virtual function call

[Bug d/95155] New: d: wrong vtable offset in virtual function call

[ibuclaw at gdcproject dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95155

            Bug ID: 95155
           Summary: d: wrong vtable offset in virtual function call
           Product: gcc
           Version: 9.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: d
          Assignee: ibuclaw at gdcproject dot org
          Reporter: ibuclaw at gdcproject dot org
  Target Milestone: ---

Seen when compiling self-hosted D compiler.

release/gcc-9 compiles:

isBaseOf (struct TypeClass * const this, struct Type * t, int * poffset)
{
  if (t != 0B && t->ty == 7)
    {
      {
        struct ClassDeclaration * cd;

        cd = ((struct TypeClass *) t)->sym;
        if (MEM[(bool (*<T1704>) (struct ClassDeclaration *, struct
ClassDeclaration *, int *))this->sym->__vptr + 704B] (this->sym, cd, poffset))
          {
            return <retval> = 1;
          }
      }
    }
  return <retval> = 0;
}


release/gcc-10 compiles:

isBaseOf (struct TypeClass * const this, struct Type * t, int * poffset)
{
  if (t != 0B && t->ty == 7)
    {
      {
        struct ClassDeclaration * cd;

        cd = ((struct TypeClass *) t)->sym;
        if (MEM[(bool (*<T171b>) (struct ClassDeclaration *, struct
ClassDeclaration *, int *))this->sym->__vptr + 736B] (this->sym, cd, poffset))
          {
            return <retval> = 1;
          }
      }
    }
  return <retval> = 0;
}


Applied all changes to gcc/d to the gcc-9 branch, and the problem gets
resolved, so will have to comb through the diff to find out what missing change
is causing gdc-9 to miscompile.

[Bug d/95155] d: wrong vtable offset in virtual function call

[ibuclaw at gdcproject dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95155

--- Comment #1 from Iain Buclaw <ibuclaw at gdcproject dot org> ---
Looks like fix was in r10-7280, taken from the upstream backport in
https://github.com/dlang/dmd/pull/10913

[Bug d/95155] d: wrong vtable offset in virtual function call

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95155

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Iain Buclaw
<ibuclaw@gcc.gnu.org>:

https://gcc.gnu.org/g:7d505b0ed8565b8c120ddd2b0b4630c93eecdec5

commit r9-8599-g7d505b0ed8565b8c120ddd2b0b4630c93eecdec5
Author: Iain Buclaw <ibuclaw@gdcproject.org>
Date:   Sat May 16 23:33:15 2020 +0200

    d: Fix wrong vtable offset in virtual function call

    The Semantic (pass 1) analysis for classes is handled by
    ClassDeclaration::semantic.  For a given class, this method may be ran
    multiple times in order to resolve forward references.  The method
    incrementally tries to resolve the types referred to by the members of
    the class.

    The subsequent calls to this method are short-circuited if the class
    members have been fully analyzed.  For this the code tests that it is
    not the first/main call to the method (semanticRun == PASS.init else
    branch), scx is not set, and that the this->symtab is already set.  If
    all these conditions are met, the method returns.  But before returning,
    the method was setting this->semanticRun to PASSsemanticdone.  It should
    not set semanticRun since the class has not been fully analyzed yet.
    The base class analysis for this class could be pending and as a result
    vtable may not have been fully created.

    This fake setting of semanticRun results in the semantic analyzer to
    believe that the class has been fully analyzed.  As exposed by the
    issues in upstream, it may result in compile time errors when a derived
    type class is getting analyzed and because of this fake semanticdone on
    the base class, the semantic analysis construes that an overriden method
    is not defined in the base class.  PR95155 exposes anoter scenario where
    a buggy vtable may be created and a call to a class method may result in
    execution of some adhoc code.

    gcc/d/ChangeLog:

            PR d/95155
            * dmd/dclass.c (ClassDeclaration::semantic): Don't prematurely
            set done on semantic analysis.

    gcc/testsuite/ChangeLog:

            PR d/95155
            * gdc.test/compilable/imports/pr9471a.d: New test.
            * gdc.test/compilable/imports/pr9471b.d: New test.
            * gdc.test/compilable/imports/pr9471c.d: New test.
            * gdc.test/compilable/imports/pr9471d.d: New test.
            * gdc.test/compilable/pr9471.d: New test.

[Bug d/95155] d: wrong vtable offset in virtual function call

[ibuclaw at gdcproject dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95155

Iain Buclaw <ibuclaw at gdcproject dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #3 from Iain Buclaw <ibuclaw at gdcproject dot org> ---
Fixed.