I'm trying to debug a fortran90 application, using vscode with gdb. In one particular function:

subroutine get_hamiltonian(...)
    real :: list(:)
    ...
end subroutine get_hamiltonian

I can not print the value of variable list. Specifically, I get this error:

(gdb) list
-var-create: unable to create variable object

I have checked that list is actually correctly instantiated and I have managed to print the list too, and it works. Somehow, inside gdb, printing the value of list doesn't work. Why?

I'm trying to debug a fortran90 application, using vscode with gdb. In one particular function:

subroutine get_hamiltonian(...)
    real :: list(:)
    ...
end subroutine get_hamiltonian

I can not print the value of variable list. Specifically, I get this error:

(gdb) list
-var-create: unable to create variable object

I have checked that list is actually correctly instantiated and I have managed to print the list too, and it works. Somehow, inside gdb, printing the value of list doesn't work. Why?

• fortran
• gdb
• vscode-debugger

• Why not print list? – Vladimir F Героям слава Commented Mar 31 at 13:47
• print, with or without any args also gives a '-var-create: unable...'. I assume it is also reserved in gdb. – tornikeo Commented Mar 31 at 14:00
• If you mean print within the code, I've tried that, and it works. But debugging with GDB just makes my current task a bit easier. – tornikeo Commented Mar 31 at 14:02

2 Answers 2

The problem is that inside GDB, keyword list is reserved. Specifically:

list linenum

    Print lines centered around line number linenum in the current source file.

So, the quickest solution to read the value of that variable is to rename it. For example, if you rename the variable list -> alist, then printing alist will work. For the purposes of debugging the application this should suffice.

Just use print to print variables using GDB. Having to rename to rename variables in your code just to be able to debug it is absurd.

(gdb) print list
$2 = (1, 2, 3, 4, 5)