[Bug c/85361] New: Variable length array allowed in c89/90

[whh8b at virginia dot edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85361

            Bug ID: 85361
           Summary: Variable length array allowed in c89/90
           Product: gcc
           Version: 5.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: whh8b at virginia dot edu
  Target Milestone: ---

Created attachment 43914
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43914&action=edit
Code to trigger behavior.

In an attempt to fix bug 44209, I was investigating warning messages about
variable length arrays. 

The c89/90 standard appears to forbid VLAs but GCC treats their presence as
something only to warn the user about. Should this be an error instead of a
warning?

Depending on how you invoke GCC on the code attached to this report, it either
compiles with no complaints:

$ gcc -std=c89 /tmp/vla.c
$

or with a simple warning:
$  gcc -std=c89 -Wpedantic /tmp/vla.c 
/tmp/vla.c:1:13: warning: ISO C90 does not support ‘[*]’ array declarators
[-Wpedantic]
 void f(int a[*]);
$

Since gcc gives the user the option to specify which version of the c standard
to adhere to, shouldn't gcc be a little more strict when the user is explicit? 

I absolutely appeal to the wiser counsel of all the experts, but I thought I
would ask. 

Thank you!