[Bug fortran/69304] New: Fortran logical common block equivalence lto

[physiker at toast2 dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69304

            Bug ID: 69304
           Summary: Fortran logical common block equivalence lto
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: physiker at toast2 dot net
  Target Milestone: ---

Compiling m.f90 and f.f90 into a shared library with the -flto opion active
causes a strange "warning: type of 'l' does not match original declaration".
The definition of the common block is identical in both input files (include
'l.inc'), though. The same message occurs when the files are compiled with
gcc-5.3 on osx or on linux. 


l.inc

      COMMON /L/ F
      LOGICAL(4)      F
      SAVE /L/
!===========================================================================

m.f90

     SUBROUTINE A

      IMPLICIT NONE

      INCLUDE 'l.inc'
      LOGICAL(4) :: M(12) 
      EQUIVALENCE (M(1),F)

      END SUBROUTINE A
!===========================================================================

t.f90

     SUBROUTINE B

      IMPLICIT NONE

      INCLUDE 'l.inc'

      END SUBROUTINE B
!===========================================================================

bash-3.2$ gfortran-6 -v -c -flto -fPIC -W -Wall -pedantic t.f90 
Using built-in specs.
COLLECT_GCC=gfortran-6
Target: x86_64-apple-darwin13.4.0
Configured with: ../gcc/configure --enable-languages=c,c++,fortran,lto
--with-gmp=/sw --with-libiconv-prefix=/sw --with-isl=/sw --with-mpc=/sw
--with-system-zlib --program-suffix=-6
Thread model: posix
gcc version 6.0.0 20160114 (experimental) (GCC) 
COLLECT_GCC_OPTIONS='-v' '-c' '-flto' '-fPIC' '-Wextra' '-Wall' '-Wpedantic'
'-mmacosx-version-min=10.9.4' '-mtune=core2'
 /usr/local/libexec/gcc/x86_64-apple-darwin13.4.0/6.0.0/f951 t.f90 -fPIC -quiet
-dumpbase t.f90 -mmacosx-version-min=10.9.4 -mtune=core2 -auxbase t -Wextra
-Wall -Wpedantic -version -flto -fPIC -fintrinsic-modules-path
/usr/local/lib/gcc/x86_64-apple-darwin13.4.0/6.0.0/finclude -o
/var/folders/97/4qnhjhtn25s86s9hkz0h37_m0000gn/T//ccHS2R6E.s
GNU Fortran (GCC) version 6.0.0 20160114 (experimental)
(x86_64-apple-darwin13.4.0)
        compiled by GNU C version 6.0.0 20160114 (experimental), GMP version
6.1.0, MPFR version 3.1.3, MPC version 1.0.3, isl version 0.14 or 0.13
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
GNU Fortran2008 (GCC) version 6.0.0 20160114 (experimental)
(x86_64-apple-darwin13.4.0)
        compiled by GNU C version 6.0.0 20160114 (experimental), GMP version
6.1.0, MPFR version 3.1.3, MPC version 1.0.3, isl version 0.14 or 0.13
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
COLLECT_GCC_OPTIONS='-v' '-c' '-flto' '-fPIC' '-Wextra' '-Wall' '-Wpedantic'
'-mmacosx-version-min=10.9.4' '-mtune=core2'
 as -arch x86_64 -force_cpusubtype_ALL -o t.o
/var/folders/97/4qnhjhtn25s86s9hkz0h37_m0000gn/T//ccHS2R6E.s
COMPILER_PATH=/usr/local/libexec/gcc/x86_64-apple-darwin13.4.0/6.0.0/:/usr/local/libexec/gcc/x86_64-apple-darwin13.4.0/6.0.0/:/usr/local/libexec/gcc/x86_64-apple-darwin13.4.0/:/usr/local/lib/gcc/x86_64-apple-darwin13.4.0/6.0.0/:/usr/local/lib/gcc/x86_64-apple-darwin13.4.0/
LIBRARY_PATH=/usr/local/lib/gcc/x86_64-apple-darwin13.4.0/6.0.0/:/usr/local/lib/gcc/x86_64-apple-darwin13.4.0/6.0.0/../../../
COLLECT_GCC_OPTIONS='-v' '-c' '-flto' '-fPIC' '-Wextra' '-Wall' '-Wpedantic'
'-mmacosx-version-min=10.9.4' '-mtune=core2'
bash-3.2$ gfortran-6 -v -c -flto -fPIC -W -Wall -pedantic m.f90 
Using built-in specs.
COLLECT_GCC=gfortran-6
Target: x86_64-apple-darwin13.4.0
Configured with: ../gcc/configure --enable-languages=c,c++,fortran,lto
--with-gmp=/sw --with-libiconv-prefix=/sw --with-isl=/sw --with-mpc=/sw
--with-system-zlib --program-suffix=-6
Thread model: posix
gcc version 6.0.0 20160114 (experimental) (GCC) 
COLLECT_GCC_OPTIONS='-v' '-c' '-flto' '-fPIC' '-Wextra' '-Wall' '-Wpedantic'
'-mmacosx-version-min=10.9.4' '-mtune=core2'
 /usr/local/libexec/gcc/x86_64-apple-darwin13.4.0/6.0.0/f951 m.f90 -fPIC -quiet
-dumpbase m.f90 -mmacosx-version-min=10.9.4 -mtune=core2 -auxbase m -Wextra
-Wall -Wpedantic -version -flto -fPIC -fintrinsic-modules-path
/usr/local/lib/gcc/x86_64-apple-darwin13.4.0/6.0.0/finclude -o
/var/folders/97/4qnhjhtn25s86s9hkz0h37_m0000gn/T//ccJqlXsY.s
GNU Fortran (GCC) version 6.0.0 20160114 (experimental)
(x86_64-apple-darwin13.4.0)
        compiled by GNU C version 6.0.0 20160114 (experimental), GMP version
6.1.0, MPFR version 3.1.3, MPC version 1.0.3, isl version 0.14 or 0.13
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
GNU Fortran2008 (GCC) version 6.0.0 20160114 (experimental)
(x86_64-apple-darwin13.4.0)
        compiled by GNU C version 6.0.0 20160114 (experimental), GMP version
6.1.0, MPFR version 3.1.3, MPC version 1.0.3, isl version 0.14 or 0.13
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
COLLECT_GCC_OPTIONS='-v' '-c' '-flto' '-fPIC' '-Wextra' '-Wall' '-Wpedantic'
'-mmacosx-version-min=10.9.4' '-mtune=core2'
 as -arch x86_64 -force_cpusubtype_ALL -o m.o
/var/folders/97/4qnhjhtn25s86s9hkz0h37_m0000gn/T//ccJqlXsY.s
COMPILER_PATH=/usr/local/libexec/gcc/x86_64-apple-darwin13.4.0/6.0.0/:/usr/local/libexec/gcc/x86_64-apple-darwin13.4.0/6.0.0/:/usr/local/libexec/gcc/x86_64-apple-darwin13.4.0/:/usr/local/lib/gcc/x86_64-apple-darwin13.4.0/6.0.0/:/usr/local/lib/gcc/x86_64-apple-darwin13.4.0/
LIBRARY_PATH=/usr/local/lib/gcc/x86_64-apple-darwin13.4.0/6.0.0/:/usr/local/lib/gcc/x86_64-apple-darwin13.4.0/6.0.0/../../../
COLLECT_GCC_OPTIONS='-v' '-c' '-flto' '-fPIC' '-Wextra' '-Wall' '-Wpedantic'
'-mmacosx-version-min=10.9.4' '-mtune=core2'
bash-3.2$ gfortran-6  -shared -o lib.dylib -W -Wall -pedantic m.o t.o
l.inc:2:0: warning: type of 'l' does not match original declaration
[-Wlto-type-mismatch]
       COMMON /L/ F


l.inc:2:0: note: 'l' was previously declared here
       COMMON /L/ F


l.inc:2:0: note: code may be misoptimized unless -fno-strict-aliasing is used