BASE: ODR violations (-flto)

[lacc97]

Compilation of 2.1.2 with -flto on Gentoo Linux (GCC 10.1) generates ODR warnings.

• engines/illusions

  ./engines/illusions/bbdou/bbdou_credits.h:35:8: warning: type ‘struct CreditsItem’ violates the C++ One Definition Rule [-Wodr]
     35 | struct CreditsItem {
        |        ^
  ./engines/illusions/duckman/duckman_credits.h:32:8: note: a different type is defined in another translation unit
     32 | struct CreditsItem {
        |        ^
  ./engines/illusions/bbdou/bbdou_credits.h:36:7: note: the first difference of corresponding definitions is field ‘isUsed’
     36 |  bool isUsed;
        |       ^
  ./engines/illusions/duckman/duckman_credits.h:33:9: note: a field with different name is defined in another translation unit
     33 |  uint32 objectId;
        |
  

• audio

  audio/fmopl.cpp:42: warning: ‘create’ violates the C++ One Definition Rule [-Wodr]
     42 |  OPL *create(Config::OplType type);
        | 
  audio/alsa_opl.cpp:344: note: return value type mismatch
    344 | OPL *create(Config::OplType type) {
        | 
  audio/alsa_opl.cpp:47: note: type name ‘OPL::ALSA::OPL’ should match type name ‘OPL::OPL’
     47 | class OPL : public ::OPL::RealOPL {
        | 
  ./engines/scumm/players/player_ad.h:32:7: note: the incompatible type is defined here
     32 | class OPL;
        |       ^
  audio/alsa_opl.cpp:344: note: ‘create’ was previously declared here
    344 | OPL *create(Config::OplType type) {
        | 
  audio/alsa_opl.cpp:344: note: code may be misoptimized unless ‘-fno-strict-aliasing’ is used
  

As far as I can tell this doesn't result in runtime bugs but it is still undefined behaviour and may cause problems in the future.

[sev-]

The first one was fixed, the second one is much trickier and is basically by design.

Thanks for reporting.