https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97592
Bug ID: 97592 Summary: Incorrectly set pointer remapping with array pointer argument to CONTIGUOUS dummy Product: gcc Version: og10 (devel/omp/gcc-10) Status: UNCONFIRMED Severity: normal Priority: P3 Component: fortran Assignee: unassigned at gcc dot gnu.org Reporter: reubendb at gmail dot com Target Milestone: --- Hi, The following code produces an incorrect results with GCC 10.1.0, 10.2.0. The code works as expected with GCC/6.4.0,7.4.0,8.1.0,8.1.1 program RemappingTest implicit none real, dimension ( :, : ), pointer :: & B_2D real, dimension ( :, :, : ), pointer :: & B_3D !-- Prepare B_2D allocate ( B_2D ( 16, 3 ) ) B_2D = - huge ( 1.0 ) !-- Point B_3D to Storage call SetPointer ( B_2D, 4, 4, 3, B_3D ) !-- Set B_3D B_3D = 2.0 !-- See if the result is reflected in Storage print* print*, "B_2D = ", B_2D !-- expect 2.0 for all elements contains subroutine SetPointer ( C_2D, n1, n2, n3, C_3D ) real, dimension ( :, : ), intent ( inout ), target, contiguous :: & C_2D integer :: & n1, n2, n3 real, dimension ( :, :, : ), intent ( inout ), pointer :: & C_3D C_3D ( 1 : n1, 1 : n2, 1 : n3 ) => C_2D end subroutine SetPointer end program RemappingTest ]$ gfortran --version GNU Fortran (GCC) 10.2.0 Copyright (C) 2020 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. ]$ gfortran -Wall -Wextra -fno-strict-aliasing -fwrapv -Warray-temporaries PointerRemapTest.f90 PointerRemapTest.f90:13:20: 13 | call SetPointer ( B_2D, 4, 4, 3, B_3D ) | 1 Warning: Creating array temporary at (1) [-Warray-temporaries] ]$ ./a.out B_2D = -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 -3.40282347E+38 It seems to be issue is because inside the subroutine SetPointer, a new array `C_2D` is created. So `C_3D` points to this new array instead. Outside of subroutine, this pointer (now `B_3D`) actually points to an invalid memory location. In some cases I can trigger a segfault with the code with GCC-10.2.0