workaround codegen error for `Base10.decode`

[etan-status]

Calling Base10.decode may lead to different structures being generated for use with uint64.

The one normally generated is:

struct tyObject_Result__559ckyoL0ZZBsNFIYXjaoeg {NIM_BOOL o;
union{
struct {NCSTRING e;
} _o_1;
struct {unsigned long long v;
} _o_2;
};

But sometimes, it may be generated as:

struct tyObject_Result__xZhi1m1g75ioXsKjx9bN5bg {NIM_BOOL o;
union{
struct {NCSTRING e;
} _o_1;
struct {NU64 v;
} _o_2;
};

When the latter is generated, the compiler throws with:

error: passing 'tyObject_Result__xZhi1m1g75ioXsKjx9bN5bg' (aka 'struct tyObject_Result__xZhi1m1g75ioXsKjx9bN5bg') to parameter of incompatible type 'tyObject_Result__559ckyoL0ZZBsNFIYXjaoeg' (aka 'struct tyObject_Result__559ckyoL0ZZBsNFIYXjaoeg')

for

proc getInt*(ht: HttpTables, key: string): uint64 =
  let res = Base10.decode(uint64, ht.getString(key))
  if res.isOk():
    res.get()    # This line may lead to the compiler error above
  else:
    0'u64

By passing the type as a generic param, the unsigned long long version gets consistently generated / used regardless of include order.

Minimal POC to trigger the bug, from nimbus-eth2 root:

echo 'import beacon_chain/conf, beacon_chain/sync/sync_manager' >x.nim
nim c -d:"libp2p_pki_schemes=secp256k1" -r x

Swapping include order (conf after sync_manager) works.

[arnetheduck]

rebasing should help clear the CI failures here

[arnetheduck]

is there an upstream bug for this?

[etan-status]

is there an upstream bug for this?

Not yet, I have not found the time to minimize this to a reproducible example.

[arnetheduck]

@etan-status is this still relevant after the latest Result fixes?

[etan-status]

Yep, just tried it again and it is still broken.

From nimbus-eth2 repo root:

echo 'import beacon_chain/conf, beacon_chain/sync/sync_manager' >x.nim
nim c -d:"libp2p_pki_schemes=secp256k1" -r x

/Users/etan/Documents/Repos/nimbus-eth2/vendor/nim-chronos/chronos/apps/http/httptable.nim:82:73: error: passing 'tyObject_Result__wclb9c9bJbd6rJAwn3uS2nPg' (aka 'struct tyObject_Result__wclb9c9bJbd6rJAwn3uS2nPg') to parameter of incompatible type 'tyObject_Result__v9aWRrNLc0mAO9a315N8TSpA' (aka 'struct tyObject_Result__v9aWRrNLc0mAO9a315N8TSpA')
                result = value__vendorZnim45chronosZchronosZappsZhttpZhttpserver_1477(res);     }
                                                                                      ^~~
/Users/etan/Documents/Repos/nimbus-eth2/vendor/nim-results/results.nim:796:127: note: passing argument to parameter 'self' here
static N_INLINE(NU64, value__vendorZnim45chronosZchronosZappsZhttpZhttpserver_1477)(tyObject_Result__v9aWRrNLc0mAO9a315N8TSpA self) {   
                                                                                                                              ^
1 error generated.

And no, still couldn't find the time to minimize this example for upstream reporting.

[tersec]

https://github.com/nim-lang/Nim/issues/23765