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

[maxime-esa]

You may use the -renamePolicy 3 flag to avoid issues with enumerants in a consistent way:

    --rename-policy, -renamePolicy <int>
                          Specify rename policy for Enumerated values. Allowed values are:
                              0 perform no rename (Ada default).
                              1 rename only conflicting enumerants (C default).
                                E.g. In a grammar that contains
                                  RGB ::= ENUMERATED {red, green, blue}
                                  FavColors = ENUMERATED {red, yellow}
                                only the red enumerant will be renamed to
                                RGB_red and FavColors_red.
                              2 rename all enumerants of an enumerated type
                                that has least one conflicting enumerant.
                              3 all enumerants of all of an enumerated types
                                are renamed.

With this option the enumerants are prefixed with the typename:

typedef enum {
    TimingMaintainedSynchInd_false = 0
} TimingMaintainedSynchInd;