[Bug c++/60239] New: False positive maybe-uninitialized in for loop

[lcid-fire at gmx dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60239

            Bug ID: 60239
           Summary: False positive maybe-uninitialized in for loop
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: lcid-fire at gmx dot net

The code in
https://github.com/RobertBeckebans/RBDOOM-3-BFG/blob/dd9b8a8710dd7f8c1376eb245ee31fc740eae6eb/neo/renderer/tr_backend_rendertools.cpp
triggers a false positive maybe-uninitialized warning.

The code in question begins at line 1971:

    static void RB_DrawText( const char* text, const idVec3& origin, float
scale, const idVec4& color, const idMat3& viewAxis, const int align )
    {

    // <snip/>

    idVec3 org, p1, p2;

    // <snip/>

    for( i = 0; i < len; i++ )
    {
      if( i == 0 || text[i] == '\n' )
      {
        org = origin - viewAxis[2] * ( line * 36.0f * scale );
        // <snip/>
      }

      org -= viewAxis[1] * ( spacing * scale );
    }


The error message is:
idlib/../idlib/math/Vector.h: In function 'void RB_DrawText(const char*, const
idVec3&, float, const idVec4&, const idMat3&, int)':
idlib/../idlib/math/Vector.h:567:10: error: 'org.idVec3::x' may be used
uninitialized in this function [-Werror=maybe-uninitialized]
/home/andreas/Projects/bfg/neo/renderer/tr_backend_rendertools.cpp:1971:9:
note: 'org.idVec3::x' was declared here
  idVec3 org, p1, p2;


I tried to create a simple version that triggers that false positive but
everything I tried analyzes the code correctly.