https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84495
Bug ID: 84495 Summary: Incorrect result for concatenation of Fortran allocatable string Product: gcc Version: 7.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: fortran Assignee: unassigned at gcc dot gnu.org Reporter: david.sagan at gmail dot com Target Milestone: --- Using gfortran 7.3.0: Davids-Mac-mini:~/Bmad> gfortran --version GNU Fortran (MacPorts gcc7 7.3.0_0) 7.3.0 Test program is: program test character(:), allocatable :: str allocate(character(3) :: str) str = '123456789' print *, str str = str(1:3) // 'A' // str(6:) print *, str end program Running gives: Davids-Mac-mini:~/Bmad> gfortran test.f90 Davids-Mac-mini:~/Bmad> ./a.out 123456789 123A678 Notice that the second line is missing a "9" at the end. That is, it should be "123A6789".