ASN.1 definitions with C reserved words cause faulty generated code

[swthorn]

Hi,

first of all, very cool project. Some ASN.1 specifications define reserved words as part of an enum. e.g, this is from cellular network specs (RRC):

TimingMaintainedSynchInd ::= ENUMERATED { false }

This generates code with asn1scc --field-prefix AUTO that looks something like this:

typedef enum {
    false = 0
} TimingMaintainedSynchInd;

If you try to compile this, you'll get an error like this:

file.c:11:
file.h:1312:5: error: expected identifier
 1312 |     false = 0
      |     ^
/usr/lib/llvm-17/lib/clang/17/include/stdbool.h:22:15: note: expanded from macro 'false'
   22 | #define false 0
      |               ^
In file included from /data/asn1scc_DL-DataToUL-ACK-DCI-1-2-r17_uper.c:12:
file.h:1312:5: error: expected identifier

I think this issue may expand to other named values in enums that are reserved words, but I did not test. I suggest making the field prefix CLI argument also prefix enum values to resolve the issue, but this may cause backward compatibility problems.

The full list of reserved words for C is here: https://en.cppreference.com/w/c/keyword.html