Const qualifier is not applied to structs or unions

[thk123]

Const qualifiers seem to be lost on tagged structs and unions. Consider the following code:

struct struct_tag_name
{
  int x;
  float y;
};

int main()
{
  const struct struct_tag_name my_struct_var = {.x =  1, .y = 3.15};
  const double z = 4;
  return 0;
}

In the symbol table for the compiled GOTO program, you get the following symbols for the two variables in main:

Symbol......: main::1::my_struct_var
Pretty name.: main::1::my_struct_var
Module......: main
Base name...: my_struct_var
Mode........: C
Type........: struct struct_tag_name
Value.......: { .x=1, .y=(float)3.150000e+0 }
Flags.......: lvalue thread_local file_local
Location....: file main.c line 10 function main

Symbol......: main::1::z
Pretty name.: main::1::z
Module......: main
Base name...: z
Mode........: C
Type........: const double
Value.......: (const double)4
Flags.......: lvalue thread_local file_local
Location....: file main.c line 11 function main

Note z's type is correctly marked as a const double but my_struct_var only has type struct struct_tag_name.

This happens independently of whether you run goto-cc then goto-instrument or run the file straight through cbmc.

[thk123]

This comment appears to point to where the fix needs to be applied:

#345 (review)

[thk123]

Got something working for this, need to test the following cases:

• unions
• anonymous structs
• make the tests checked in in Added a regression to demonstrate const structs #356 actually fail pre this fix (they were marked as KNOWBUG but weren't checking the correct output but instead validating the incorrect output
• check what Store the typedef identifier in the symbol_type (cleaned up) #358 is doing (i.e. does it check for const typedef'd structs correctly) - there exists KNOWNBUG tests, assuming it gets merged first, I will check this fixes them and mark them as CORE as part of this PR) (if this get's merged first, I'll mark them as CORE in the other one)
• other non-const qualifiers