http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53015
Bug #: 53015 Summary: free_pi_tree(): Unresolved fixup is back Classification: Unclassified Product: gcc Version: 4.8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: fortran AssignedTo: unassig...@gcc.gnu.org ReportedBy: brainsch...@gmx.de Bug 47546 was fixed some time ago, but I get "Internal error - free_pi_tree(): Unresolved fixup" all over the place again, with versions 4.6.2, 4.7.0 and 4.8.0 of gfortran from svn. I have a project that uses many Fortran 2003 features, like polymorphism, type-bound procedures etc. Some sub-classes are in different modules, which did not cause problems before and is supported by the standard. I also use OpenMPI and PETSc, so there are some preprocessor macros. The code compiles and runs fine withe the Intel Fortran compiler, which is the only other Fortran compiler I have access to. Like in 47546 , the issue is very elusive: Sometimes it happens when compiling the modules themselves, sometimes when compiling a program that uses the modules. Sometimes commenting out one arbitrary line of code fixes the error, and it remains fixed after putting the line in again. Sometimes removing all modules and object files and re-compiling (even files that remain unchanged) fixes the error. On some days, I cannot compile my code at all, but using an different version of gfortran works. But then the issue pops up again after adding a new line of code. Because of this, I am not able to provide a test case as I have no clue what the error means and the rest of the case seems non-deterministic. Maybe someone can assist me in narrowing down the possibilities.