Subject: Re: bug#59426: 29.0.50; [tree-sitter] Some functions exceed maximum recursion limit

From: Mattias Engdegård <[email-masked]>
Date: Wed, 23 Nov 2022 21:01:49 +0100

23 nov. 2022 kl. 19.46 skrev Yuan Fu <[email-masked]>:

> It shouldn’t, but tree-sitter thinks some closing brackets are erroneous and skips them when parsing (it skips erroneous tokens in the hope to parse the rest of the file despite local errors). So a 10k wide tree becomes 10k tall.
> 
> We can submit a bug repot to tree-sitter-c (“maybe don’t skip closing brackets even there is error, or somthing”), but that’s another story.

Thanks for the explanation. In this case it seems that it's the #line directive that throws a spanner in the works. You probably already discovered that, but for the record, here is a cut-down example:

static hf_register_info hf[] = {
#line 1 "./asn1/rrc/packet-rrc-hfarr.c"
    { &hf_rrc_DL_DCCH_Message_PDU,
      { "DL-DCCH-Message", "rrc.DL_DCCH_Message_element",
        FT_NONE, BASE_NONE, NULL, 0,
        NULL, HFILL }},
    { &hf_rrc_cellIdentity_c_id,
       {"Cell Identifier", "rrc.cellIdentity.c_id",
       FT_UINT32, BASE_DEC, NULL, 0,
       "The Cell Identifier (C-Id) part of the Cell Identity", HFILL }}
  };

Note how the warning colour of the curly brackets vanishes once the #line line is removed.
Even if this snag is corrected, there will always be cases where preprocessor use causes trouble of this or a similar kind. It seems quite convincing that we should void C recursion in favour of explicit stacks where possible.