[Bug debug/95041] New: gdb does not prints variables inside an equivalence statement in a module

[Bug debug/95041] New: gdb does not prints variables inside an equivalence statement in a module

[fmolina2b at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95041

            Bug ID: 95041
           Summary: gdb does not prints variables inside an equivalence
                    statement in a module
           Product: gcc
           Version: 9.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fmolina2b at gmail dot com
  Target Milestone: ---

Created attachment 48499
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48499&action=edit
Source files and temps

I found impossible to watch variables declared in equivalence statements in a
module. I could not find anything similar in bugzilla. Here follows an example
from win 10 using gcc 9.20 from equation.com, the most recent version of
gfortran that I could find (see below for linux)
***************************************************************************

c:\test>copy con m.f90
program m
use mod1
real*8 a
k=3.0
a=f(5d0)
print *,a,k,y(1)
read(*,*)
end program
^Z

c:\test>copy con mod1.f90
module mod1
real*8 y(10)
real*8 k
equivalence (y(1),k)
contains
real*8 function f(x)
real*8 x
y(1)=1d0
f=x**2
return
end function
end module
^Z

c:\test>gfortran -v
Built by Equation Solution <http://www.Equation.com>.
Using built-in specs.
COLLECT_GCC=gfortran
COLLECT_LTO_WRAPPER=c:/gcc/bin/../libexec/gcc/i686-pc-mingw32/9.2.0/lto-wrapper.exe
Target: i686-pc-mingw32
Configured with: ../gcc-9.2.0-mingw/configure --host=i686-pc-mingw32
--build=x86_64-unknown-linux-gnu --target=i686-pc-mingw32
--prefix=/home/gfortran/gcc-home/binary/mingw32/native/x86_32/gcc/9.2.0
--with-gcc --with-gnu-as --with-gnu-ld
--with-cloog=/home/gfortran/gcc-home/binary/mingw32/native/x86_32/cloog
--with-gmp=/home/gfortran/gcc-home/binary/mingw32/native/x86_32/gmp
--with-mpfr=/home/gfortran/gcc-home/binary/mingw32/native/x86_32/mpfr
--with-mpc=/home/gfortran/gcc-home/binary/mingw32/native/x86_32/mpc
--with-diagnostics-color=auto --enable-cloog-backend=isl
--with-sysroot=/home/gfortran/gcc-home/binary/mingw32/cross/x86_32/gcc/9-20190310
--disable-shared --disable-nls --disable-tls --disable-libgcc2
--disable-win32-registry --enable-build-with-cxx --enable-libquadmath-support
--enable-libquadmath --enable-languages=c,c++,fortran --disable-checking
--enable-libgomp --enable-threads=win32 --enable-lto --enable-static
--enable-shared=lto-plugin --enable-plugins --enable-ld=yes
Thread model: win32
gcc version 9.2.0 (GCC)

c:\test>gfortran mod1.f90 m.f90 -g -save-temps

c:\test>a
   25.000000000000000        1.0000000000000000        1.0000000000000000  

c:\test>gdb a.exe
This binary was built by Equation Solution <http://www.Equation.com>.
GNU gdb (GDB) 7.12
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-pc-mingw32".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.exe...done.
(gdb) b 7
Breakpoint 1 at 0x4015e1: file m.f90, line 7.
(gdb) r
Starting program: c:\test\a.exe
[New Thread 9712.0x1318]
warning: Can not parse XML library list; XML support was disabled at compile
time
   25.000000000000000        1.0000000000000000        1.0000000000000000  

Breakpoint 1, m () at m.f90:7
7       read(*,*)
(gdb) p k

c:\test>
******************************************************************************
gdb crashes silently. The same happens trying to print y or y(1)
Commenting out the equivalence statement in mod1.f90 gdb behaves correctly
******************************************************************************
[snip]
Reading symbols from a.exe...done.
(gdb) b 7
Breakpoint 1 at 0x4015e1: file m.f90, line 7.
(gdb) r
Starting program: c:\test\a.exe
[New Thread 8444.0x30b4]
warning: Can not parse XML library list; XML support was disabled at compile
time
   25.000000000000000        3.0000000000000000        1.0000000000000000  

Breakpoint 1, m () at m.f90:7
7       read(*,*)
(gdb) p k
$1 = 3
(gdb) p y
$2 = (1, 0, 0, 0, 0, 0, 0, 0, 0, 0)
(gdb)
**********************************************************************
However, gdb is rather old (7.16)
Doing the same text with gcc 8.4.0 in Mageia Linux with gdb 8.2.8 I got:
***********************************************************************
[fer@localhost test]$ gdb a.out                             
GNU gdb (GDB) 8.2-8.mga7 (Mageia release 7)
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-mageia-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...done.
(gdb) b 7
Breakpoint 1 at 0x401264: file m.f90, line 7.
(gdb) r
Starting program: /home/fer/test/a.out 
Missing separate debuginfos, use: debuginfo-install glibc-2.29-20.mga7.x86_64
   25.000000000000000        1.0000000000000000        1.0000000000000000     

Breakpoint 1, m () at m.f90:7
7       read(*,*)
Missing separate debuginfos, use: debuginfo-install
lib64zlib1-1.2.11-7.mga7.x86_64 libgcc1-8.4.0-1.mga7.x86_64
libgfortran5-8.4.0-1.mga7.x86_64 libquadmath0-8.4.0-1.mga7.x86_64
(gdb) p k
No symbol "k" in current context.
************************************************************************
Variables in modules inside an equivalence statement are not seen by gdb
I add an attachment with the files generated by gfortran 9.2.0