Autogenerated source file causes stack overflow

Parsing this file:

https://docs.rs/crate/softcore-rv64/latest/source/src/raw.rs

crashes about 5000 calls deep:

```
frame #0: 0x000100aa82a4 `_$LT$syn..bigint..BigInt$u20$as$u20$core..ops..arith..MulAssign$LT$u8$GT$$GT$::mul_assign::h5bf6493d6ea58638(self=0x0000000177210058, base='\n') at bigint.rs:0:6 [opt]
frame #1: 0x000100acc5a0 `syn::lit::value::parse_lit_int::h666d81687a2469df(s=(data_ptr = "6", length = 1)) at lit.rs:1748:13 [opt]
frame #2: 0x000100ac8984 `syn::lit::value::_$LT$impl$u20$syn..lit..Lit$GT$::new::h90f87a4f01c4400f(token=Literal @ 0x0000000177210208) at lit.rs:1182:53 [opt]
frame #3: 0x000100a72b78 `syn::lit::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..lit..Lit$GT$::parse::_$u7b$$u7b$closure$u7d$$u7d$::h5e9a3635775a9480((null)=, cursor=StepCursor @ 0x0000600000485f30) at lit.rs:870:32 [opt]
frame #4: 0x000100a729dc `syn::parse::ParseBuffer::step::hcc8898b82eaf104c(self=0x0000000177210330, function=) at parse.rs:1075:28 [opt]
frame #5: 0x000100a6e8f4 `syn::lit::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..lit..Lit$GT$::parse::hf1e8201a74f1ebf5(input=) at lit.rs:868:19 [opt]
frame #6: 0x000100a6e8ec `syn::lit::parsing::_$LT$impl$u20$syn..token..Token$u20$for$u20$syn..lit..Lit$GT$::peek::peek::h513a04e2e963957b(input=) at lit.rs:1036:25 [opt]
frame #7: 0x000100ac9c94 `syn::lit::parsing::peek_impl::h6ea94d8ac3addaed(cursor=, peek=) at lit.rs:1028:9 [opt]
frame #8: 0x000100ac9c5c `syn::lit::parsing::_$LT$impl$u20$syn..token..Token$u20$for$u20$syn..lit..Lit$GT$::peek::hbaf240f9dfcf2b16(cursor=Cursor @ 0x00006000004c82b0) at lit.rs:1038:21 [opt]
frame #9: 0x000100a8a99c `syn::parse::ParseBuffer::peek::hfc4723e5025fd383(self=0x00000001772118f0) at parse.rs:583:9 [opt]
frame #10: 0x000100a8a998 `syn::path::parsing::const_argument::h75ade8dd3568802a(input=0x00000001772118f0) at path.rs:412:18 [opt]
frame #11: 0x000100aa014c `syn::path::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..path..GenericArgument$GT$::parse::h7e1c5669b965b30a(input=0x00000001772118f0) at path.rs:323:24 [opt]
frame #12: 0x000100aa0b98 `core::ptr::drop_in_place$LT$$u5b$$LP$syn..path..PathSegment$C$syn..token..PathSep$RP$$u5d$$GT$::h990c0446db09731d((null)=) - 18446744069403440231 [opt]
frame #13: 0x000100aa129c `syn::path::parsing::_$LT$impl$u20$syn..path..PathSegment$GT$::parse_helper::h48b2b5cae2af4992(input=, expr_style=) at path.rs:539:68 [opt]
frame #14: 0x000100aa1754 `syn::path::parsing::_$LT$impl$u20$syn..path..Path$GT$::parse_helper::hdb9bbb34acda19bf(input=0x00000001772118f0, expr_style=true) at path.rs:616:33 [opt]
frame #15: 0x000100a8ad14 `syn::path::parsing::qpath::h0e857d154ce7187d(input=, expr_style=) at path.rs:693:24 [opt]
frame #16: 0x000100a57a90 `syn::expr::parsing::path_or_macro_or_struct::h9bc758670d31cdd6(input=0x00000001772118f0, allow_struct=(__0 = true)) at expr.rs:1947:29 [opt]
frame #17: 0x000100a55688 `syn::expr::parsing::atom_expr::h0e64037f795e3aa1(input=0x00000001772118f0, allow_struct=) at expr.rs:1825:13 [opt]
frame #18: 0x000100a553a0 `syn::expr::parsing::trailer_expr::he832baaba910f330(begin=, attrs=, input=, allow_struct=) at expr.rs:1597:20 [opt]
frame #19: 0x000100a54510 `syn::expr::parsing::unary_expr::h359e981c04fe104a(input=0x00000001772118f0, allow_struct=(__0 = true)) at expr.rs:0 [opt]
frame #20: 0x000100a53ac4 `syn::expr::parsing::parse_binop_rhs::hfa21d20e657bcf80(input=, allow_struct=, precedence=) at expr.rs:1438:23 [opt]
frame #21: 0x000100a52fcc `core::ptr::drop_in_place$LT$syn..pat..Pat$GT$::h2ebbd378394b5dad((null)=) at mod.rs:804:1 [opt]
frame #22: 0x000100a57f34 `syn::expr::parsing::ambiguous_expr::hecaab7e4d4e2ae58(input=, allow_struct=(__0 = true)) at expr.rs:1492:9 [opt]
frame #23: 0x000100a57ed8 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..Expr$GT$::parse::h1be490d1cb678742(input=) at expr.rs:1230:13 [opt]
frame #24: 0x000100a57ed8 `syn::parse::ParseBuffer::parse::h7e764d05607492c1(self=) at parse.rs:466:9 [opt]
frame #25: 0x000100a57ed8 `syn::expr::parsing::paren_or_tuple::hbc439bc255d99e55(input=) at expr.rs:2015:35 [opt]
frame #26: 0x000100a556e4 `syn::expr::parsing::atom_expr::h0e64037f795e3aa1(input=0x00000001772120b0, allow_struct=) at expr.rs:1827:13 [opt]
frame #27: 0x000100a553a0 `syn::expr::parsing::trailer_expr::he832baaba910f330(begin=, attrs=, input=, allow_struct=) at expr.rs:1597:20 [opt]
frame #28: 0x000100a54510 `syn::expr::parsing::unary_expr::h359e981c04fe104a(input=0x00000001772120b0, allow_struct=(__0 = true)) at expr.rs:0 [opt]
frame #29: 0x000100a57e74 `syn::expr::parsing::ambiguous_expr::hecaab7e4d4e2ae58(input=0x00000001772120b0, allow_struct=(__0 = true)) at expr.rs:1487:19 [opt]
frame #30: 0x000100a57e64 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..Expr$GT$::parse::h1be490d1cb678742(input=0x00000001772120b0) at expr.rs:1230:13 [opt]
frame #31: 0x000100a57e64 `syn::parse::ParseBuffer::parse::h7e764d05607492c1(self=0x00000001772120b0) at parse.rs:466:9 [opt]
frame #32: 0x000100a57e64 `syn::expr::parsing::paren_or_tuple::hbc439bc255d99e55(input=) at expr.rs:2015:35 [opt]
frame #33: 0x000100a556e4 `syn::expr::parsing::atom_expr::h0e64037f795e3aa1(input=0x0000000177212d00, allow_struct=) at expr.rs:1827:13 [opt]
frame #34: 0x000100a553a0 `syn::expr::parsing::trailer_expr::he832baaba910f330(begin=, attrs=, input=, allow_struct=) at expr.rs:1597:20 [opt]
frame #35: 0x000100a54510 `syn::expr::parsing::unary_expr::h359e981c04fe104a(input=0x0000000177212d00, allow_struct=(__0 = true)) at expr.rs:0 [opt]
frame #36: 0x000100a53ac4 `syn::expr::parsing::parse_binop_rhs::hfa21d20e657bcf80(input=, allow_struct=, precedence=) at expr.rs:1438:23 [opt]
frame #37: 0x000100a52fcc `core::ptr::drop_in_place$LT$syn..pat..Pat$GT$::h2ebbd378394b5dad((null)=) at mod.rs:804:1 [opt]
frame #38: 0x000100a57f34 `syn::expr::parsing::ambiguous_expr::hecaab7e4d4e2ae58(input=, allow_struct=(__0 = true)) at expr.rs:1492:9 [opt]
frame #39: 0x000100a57ed8 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..Expr$GT$::parse::h1be490d1cb678742(input=) at expr.rs:1230:13 [opt]
frame #40: 0x000100a57ed8 `syn::parse::ParseBuffer::parse::h7e764d05607492c1(self=) at parse.rs:466:9 [opt]
frame #41: 0x000100a57ed8 `syn::expr::parsing::paren_or_tuple::hbc439bc255d99e55(input=) at expr.rs:2015:35 [opt]
frame #42: 0x000100a556e4 `syn::expr::parsing::atom_expr::h0e64037f795e3aa1(input=0x0000000177213fd0, allow_struct=) at expr.rs:1827:13 [opt]
frame #43: 0x000100a553a0 `syn::expr::parsing::trailer_expr::he832baaba910f330(begin=, attrs=, input=, allow_struct=) at expr.rs:1597:20 [opt]
frame #44: 0x000100a54510 `syn::expr::parsing::unary_expr::h359e981c04fe104a(input=0x0000000177213fd0, allow_struct=(__0 = true)) at expr.rs:0 [opt]
frame #45: 0x000100a52898 `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1273:13 [opt]
frame #46: 0x000100a8d228 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x0000000177213fd0) at expr.rs:891:9 [opt]
frame #47: 0x000100a8d220 `syn::stmt::parsing::stmt_expr::h95834f2229d821e9(input=0x0000000177213fd0, allow_nosemi=(__0 = true), attrs=Vec @ 0x0000000177213a40) at stmt.rs:339:21 [opt]
frame #48: 0x000100a8c7b4 `syn::stmt::parsing::parse_stmt::h83bee592433198de(input=0x0000000177213fd0, allow_nosemi=(__0 = true)) at stmt.rs:262:13 [opt]
frame #49: 0x000100abfc4c `syn::stmt::parsing::_$LT$impl$u20$syn..stmt..Block$GT$::parse_within::h274ba139e2cd8d35(input=) at stmt.rs:160:28 [opt]
frame #50: 0x000100a979d8 `syn::parse::ParseBuffer::call::h6f4746d1b03313be(self=0x0000000177213fd0, function=) at parse.rs:506:9 [opt]
frame #51: 0x000100a979cc `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprBlock$GT$::parse::h88f314481c78322e(input=0x0000000177214a70) at expr.rs:2862:33 [opt]
frame #52: 0x000100a55bc8 `syn::parse::ParseBuffer::parse::h49018e8ac92277eb(self=0x0000000177214a70) at parse.rs:466:9 [opt]
frame #53: 0x000100a55bbc `syn::expr::parsing::atom_expr::h0e64037f795e3aa1(input=0x0000000177214a70, allow_struct=) at expr.rs:1857:19 [opt]
frame #54: 0x000100a55a50 `syn::expr::parsing::trailer_expr::he832baaba910f330(begin=, attrs=, input=, allow_struct=) at expr.rs:1597:20 [opt]
frame #55: 0x000100a54510 `syn::expr::parsing::unary_expr::h359e981c04fe104a(input=0x0000000177214a70, allow_struct=(__0 = true)) at expr.rs:0 [opt]
frame #56: 0x000100a98478 `syn::expr::parsing::ambiguous_expr::hecaab7e4d4e2ae58(input=0x0000000177214a70, allow_struct=(__0 = true)) at expr.rs:1487:19 [opt]
frame #57: 0x000100a98468 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..Expr$GT$::parse::h1be490d1cb678742(input=0x0000000177214a70) at expr.rs:1230:13 [opt]
frame #58: 0x000100a98468 `syn::parse::ParseBuffer::parse::h7e764d05607492c1(self=0x0000000177214a70) at parse.rs:466:9 [opt]
frame #59: 0x000100a98468 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..Arm$GT$::parse::h813388a49c3e6446(input=) at expr.rs:3008:49 [opt]
frame #60: 0x000100a95dfc `syn::parse::ParseBuffer::call::h72a48f48372db5e0(self=, function=) at parse.rs:506:9 [opt]
frame #61: 0x000100a95df0 `syn::expr::parsing::_$LT$impl$u20$syn..expr..Arm$GT$::parse_multiple::hfbd825a8cd189a1c(input=0x0000000177214a70) at expr.rs:2991:33 [opt]
frame #62: 0x000100a95d70 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprMatch$GT$::parse::h1ff6afd9ecea7f46(input=) at expr.rs:2356:24 [opt]
frame #63: 0x000100a55a74 `syn::parse::ParseBuffer::parse::h2334be4fa706c19f(self=0x0000000177215fe0) at parse.rs:466:9 [opt]
frame #64: 0x000100a55a68 `syn::expr::parsing::atom_expr::h0e64037f795e3aa1(input=0x0000000177215fe0, allow_struct=) at expr.rs:1849:19 [opt]
frame #65: 0x000100a55a50 `syn::expr::parsing::trailer_expr::he832baaba910f330(begin=, attrs=, input=, allow_struct=) at expr.rs:1597:20 [opt]
frame #66: 0x000100a54510 `syn::expr::parsing::unary_expr::h359e981c04fe104a(input=0x0000000177215fe0, allow_struct=(__0 = false)) at expr.rs:0 [opt]
frame #67: 0x000100a95bc0 `syn::expr::parsing::ambiguous_expr::hecaab7e4d4e2ae58(input=0x0000000177215fe0, allow_struct=(__0 = false)) at expr.rs:1487:19 [opt]
frame #68: 0x000100a95bb0 `syn::expr::Expr::parse_without_eager_brace::hd9f223fb4db82a11(input=0x0000000177215fe0) at expr.rs:829:9 [opt]
frame #69: 0x000100a95bb0 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprMatch$GT$::parse::h1ff6afd9ecea7f46(input=) at expr.rs:2350:24 [opt]
frame #70: 0x000100a52160 `syn::parse::ParseBuffer::parse::h2334be4fa706c19f(self=0x0000000177215fe0) at parse.rs:466:9 [opt]
frame #71: 0x000100a52154 `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1260:31 [opt]
frame #72: 0x000100a8d228 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x0000000177215fe0) at expr.rs:891:9 [opt]
frame #73: 0x000100a8d220 `syn::stmt::parsing::stmt_expr::h95834f2229d821e9(input=0x0000000177215fe0, allow_nosemi=(__0 = true), attrs=Vec @ 0x0000000177215a50) at stmt.rs:339:21 [opt]
frame #74: 0x000100a8c7b4 `syn::stmt::parsing::parse_stmt::h83bee592433198de(input=0x0000000177215fe0, allow_nosemi=(__0 = true)) at stmt.rs:262:13 [opt]
frame #75: 0x000100abfc4c `syn::stmt::parsing::_$LT$impl$u20$syn..stmt..Block$GT$::parse_within::h274ba139e2cd8d35(input=) at stmt.rs:160:28 [opt]
frame #76: 0x000100a979d8 `syn::parse::ParseBuffer::call::h6f4746d1b03313be(self=0x0000000177215fe0, function=) at parse.rs:506:9 [opt]
frame #77: 0x000100a979cc `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprBlock$GT$::parse::h88f314481c78322e(input=0x0000000177216910) at expr.rs:2862:33 [opt]
frame #78: 0x000100a52378 `syn::parse::ParseBuffer::parse::h49018e8ac92277eb(self=0x0000000177216910) at parse.rs:466:9 [opt]
frame #79: 0x000100a5236c `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1268:31 [opt]
frame #80: 0x000100a98538 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x0000000177216910) at expr.rs:891:9 [opt]
frame #81: 0x000100a9852c `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..Arm$GT$::parse::h813388a49c3e6446(input=) at expr.rs:3016:32 [opt]
frame #82: 0x000100a95dfc `syn::parse::ParseBuffer::call::h72a48f48372db5e0(self=, function=) at parse.rs:506:9 [opt]
frame #83: 0x000100a95df0 `syn::expr::parsing::_$LT$impl$u20$syn..expr..Arm$GT$::parse_multiple::hfbd825a8cd189a1c(input=0x0000000177216910) at expr.rs:2991:33 [opt]
frame #84: 0x000100a95d70 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprMatch$GT$::parse::h1ff6afd9ecea7f46(input=) at expr.rs:2356:24 [opt]
frame #85: 0x000100a52160 `syn::parse::ParseBuffer::parse::h2334be4fa706c19f(self=0x00000001772176a0) at parse.rs:466:9 [opt]
frame #86: 0x000100a52154 `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1260:31 [opt]
frame #87: 0x000100a8d228 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x00000001772176a0) at expr.rs:891:9 [opt]
frame #88: 0x000100a8d220 `syn::stmt::parsing::stmt_expr::h95834f2229d821e9(input=0x00000001772176a0, allow_nosemi=(__0 = true), attrs=Vec @ 0x0000000177217110) at stmt.rs:339:21 [opt]
frame #89: 0x000100a8c7b4 `syn::stmt::parsing::parse_stmt::h83bee592433198de(input=0x00000001772176a0, allow_nosemi=(__0 = true)) at stmt.rs:262:13 [opt]
frame #90: 0x000100abfc4c `syn::stmt::parsing::_$LT$impl$u20$syn..stmt..Block$GT$::parse_within::h274ba139e2cd8d35(input=) at stmt.rs:160:28 [opt]
frame #91: 0x000100a979d8 `syn::parse::ParseBuffer::call::h6f4746d1b03313be(self=0x00000001772176a0, function=) at parse.rs:506:9 [opt]
frame #92: 0x000100a979cc `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprBlock$GT$::parse::h88f314481c78322e(input=0x0000000177217fd0) at expr.rs:2862:33 [opt]
frame #93: 0x000100a52378 `syn::parse::ParseBuffer::parse::h49018e8ac92277eb(self=0x0000000177217fd0) at parse.rs:466:9 [opt]
frame #94: 0x000100a5236c `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1268:31 [opt]
frame #95: 0x000100a98538 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x0000000177217fd0) at expr.rs:891:9 [opt]
frame #96: 0x000100a9852c `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..Arm$GT$::parse::h813388a49c3e6446(input=) at expr.rs:3016:32 [opt]
frame #97: 0x000100a95dfc `syn::parse::ParseBuffer::call::h72a48f48372db5e0(self=, function=) at parse.rs:506:9 [opt]
frame #98: 0x000100a95df0 `syn::expr::parsing::_$LT$impl$u20$syn..expr..Arm$GT$::parse_multiple::hfbd825a8cd189a1c(input=0x0000000177217fd0) at expr.rs:2991:33 [opt]
frame #99: 0x000100a95d70 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprMatch$GT$::parse::h1ff6afd9ecea7f46(input=) at expr.rs:2356:24 [opt]
frame #100: 0x000100a52160 `syn::parse::ParseBuffer::parse::h2334be4fa706c19f(self=0x0000000177218d60) at parse.rs:466:9 [opt]
frame #101: 0x000100a52154 `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1260:31 [opt]
frame #102: 0x000100a8d228 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x0000000177218d60) at expr.rs:891:9 [opt]
frame #103: 0x000100a8d220 `syn::stmt::parsing::stmt_expr::h95834f2229d821e9(input=0x0000000177218d60, allow_nosemi=(__0 = true), attrs=Vec @ 0x00000001772187d0) at stmt.rs:339:21 [opt]
frame #104: 0x000100a8c7b4 `syn::stmt::parsing::parse_stmt::h83bee592433198de(input=0x0000000177218d60, allow_nosemi=(__0 = true)) at stmt.rs:262:13 [opt]
frame #105: 0x000100abfc4c `syn::stmt::parsing::_$LT$impl$u20$syn..stmt..Block$GT$::parse_within::h274ba139e2cd8d35(input=) at stmt.rs:160:28 [opt]
frame #106: 0x000100a979d8 `syn::parse::ParseBuffer::call::h6f4746d1b03313be(self=0x0000000177218d60, function=) at parse.rs:506:9 [opt]
frame #107: 0x000100a979cc `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprBlock$GT$::parse::h88f314481c78322e(input=0x0000000177219690) at expr.rs:2862:33 [opt]
frame #108: 0x000100a52378 `syn::parse::ParseBuffer::parse::h49018e8ac92277eb(self=0x0000000177219690) at parse.rs:466:9 [opt]
frame #109: 0x000100a5236c `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1268:31 [opt]
frame #110: 0x000100a98538 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x0000000177219690) at expr.rs:891:9 [opt]
frame #111: 0x000100a9852c `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..Arm$GT$::parse::h813388a49c3e6446(input=) at expr.rs:3016:32 [opt]
frame #112: 0x000100a95dfc `syn::parse::ParseBuffer::call::h72a48f48372db5e0(self=, function=) at parse.rs:506:9 [opt]
frame #113: 0x000100a95df0 `syn::expr::parsing::_$LT$impl$u20$syn..expr..Arm$GT$::parse_multiple::hfbd825a8cd189a1c(input=0x0000000177219690) at expr.rs:2991:33 [opt]
frame #114: 0x000100a95d70 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprMatch$GT$::parse::h1ff6afd9ecea7f46(input=) at expr.rs:2356:24 [opt]
frame #115: 0x000100a52160 `syn::parse::ParseBuffer::parse::h2334be4fa706c19f(self=0x000000017721a420) at parse.rs:466:9 [opt]
frame #116: 0x000100a52154 `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1260:31 [opt]
frame #117: 0x000100a8d228 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x000000017721a420) at expr.rs:891:9 [opt]
frame #118: 0x000100a8d220 `syn::stmt::parsing::stmt_expr::h95834f2229d821e9(input=0x000000017721a420, allow_nosemi=(__0 = true), attrs=Vec @ 0x0000000177219e90) at stmt.rs:339:21 [opt]
frame #119: 0x000100a8c7b4 `syn::stmt::parsing::parse_stmt::h83bee592433198de(input=0x000000017721a420, allow_nosemi=(__0 = true)) at stmt.rs:262:13 [opt]
frame #120: 0x000100abfc4c `syn::stmt::parsing::_$LT$impl$u20$syn..stmt..Block$GT$::parse_within::h274ba139e2cd8d35(input=) at stmt.rs:160:28 [opt]
frame #121: 0x000100a979d8 `syn::parse::ParseBuffer::call::h6f4746d1b03313be(self=0x000000017721a420, function=) at parse.rs:506:9 [opt]
frame #122: 0x000100a979cc `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprBlock$GT$::parse::h88f314481c78322e(input=0x000000017721ad50) at expr.rs:2862:33 [opt]
frame #123: 0x000100a52378 `syn::parse::ParseBuffer::parse::h49018e8ac92277eb(self=0x000000017721ad50) at parse.rs:466:9 [opt]
frame #124: 0x000100a5236c `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1268:31 [opt]
frame #125: 0x000100a98538 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x000000017721ad50) at expr.rs:891:9 [opt]
frame #126: 0x000100a9852c `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..Arm$GT$::parse::h813388a49c3e6446(input=) at expr.rs:3016:32 [opt]
frame #127: 0x000100a95dfc `syn::parse::ParseBuffer::call::h72a48f48372db5e0(self=, function=) at parse.rs:506:9 [opt]
frame #128: 0x000100a95df0 `syn::expr::parsing::_$LT$impl$u20$syn..expr..Arm$GT$::parse_multiple::hfbd825a8cd189a1c(input=0x000000017721ad50) at expr.rs:2991:33 [opt]
frame #129: 0x000100a95d70 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprMatch$GT$::parse::h1ff6afd9ecea7f46(input=) at expr.rs:2356:24 [opt]
frame #130: 0x000100a52160 `syn::parse::ParseBuffer::parse::h2334be4fa706c19f(self=0x000000017721bae0) at parse.rs:466:9 [opt]
frame #131: 0x000100a52154 `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1260:31 [opt]
frame #132: 0x000100a8d228 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x000000017721bae0) at expr.rs:891:9 [opt]
frame #133: 0x000100a8d220 `syn::stmt::parsing::stmt_expr::h95834f2229d821e9(input=0x000000017721bae0, allow_nosemi=(__0 = true), attrs=Vec @ 0x000000017721b550) at stmt.rs:339:21 [opt]
frame #134: 0x000100a8c7b4 `syn::stmt::parsing::parse_stmt::h83bee592433198de(input=0x000000017721bae0, allow_nosemi=(__0 = true)) at stmt.rs:262:13 [opt]
frame #135: 0x000100abfc4c `syn::stmt::parsing::_$LT$impl$u20$syn..stmt..Block$GT$::parse_within::h274ba139e2cd8d35(input=) at stmt.rs:160:28 [opt]
frame #136: 0x000100a979d8 `syn::parse::ParseBuffer::call::h6f4746d1b03313be(self=0x000000017721bae0, function=) at parse.rs:506:9 [opt]
frame #137: 0x000100a979cc `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprBlock$GT$::parse::h88f314481c78322e(input=0x000000017721c410) at expr.rs:2862:33 [opt]
frame #138: 0x000100a52378 `syn::parse::ParseBuffer::parse::h49018e8ac92277eb(self=0x000000017721c410) at parse.rs:466:9 [opt]
frame #139: 0x000100a5236c `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1268:31 [opt]
frame #140: 0x000100a98538 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x000000017721c410) at expr.rs:891:9 [opt]
frame #141: 0x000100a9852c `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..Arm$GT$::parse::h813388a49c3e6446(input=) at expr.rs:3016:32 [opt]
frame #142: 0x000100a95dfc `syn::parse::ParseBuffer::call::h72a48f48372db5e0(self=, function=) at parse.rs:506:9 [opt]
frame #143: 0x000100a95df0 `syn::expr::parsing::_$LT$impl$u20$syn..expr..Arm$GT$::parse_multiple::hfbd825a8cd189a1c(input=0x000000017721c410) at expr.rs:2991:33 [opt]
frame #144: 0x000100a95d70 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprMatch$GT$::parse::h1ff6afd9ecea7f46(input=) at expr.rs:2356:24 [opt]
frame #145: 0x000100a52160 `syn::parse::ParseBuffer::parse::h2334be4fa706c19f(self=0x000000017721d1a0) at parse.rs:466:9 [opt]
frame #146: 0x000100a52154 `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1260:31 [opt]
frame #147: 0x000100a8d228 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x000000017721d1a0) at expr.rs:891:9 [opt]
frame #148: 0x000100a8d220 `syn::stmt::parsing::stmt_expr::h95834f2229d821e9(input=0x000000017721d1a0, allow_nosemi=(__0 = true), attrs=Vec @ 0x000000017721cc10) at stmt.rs:339:21 [opt]
frame #149: 0x000100a8c7b4 `syn::stmt::parsing::parse_stmt::h83bee592433198de(input=0x000000017721d1a0, allow_nosemi=(__0 = true)) at stmt.rs:262:13 [opt]
frame #150: 0x000100abfc4c `syn::stmt::parsing::_$LT$impl$u20$syn..stmt..Block$GT$::parse_within::h274ba139e2cd8d35(input=) at stmt.rs:160:28 [opt]
frame #151: 0x000100a979d8 `syn::parse::ParseBuffer::call::h6f4746d1b03313be(self=0x000000017721d1a0, function=) at parse.rs:506:9 [opt]
frame #152: 0x000100a979cc `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprBlock$GT$::parse::h88f314481c78322e(input=0x000000017721dad0) at expr.rs:2862:33 [opt]
frame #153: 0x000100a52378 `syn::parse::ParseBuffer::parse::h49018e8ac92277eb(self=0x000000017721dad0) at parse.rs:466:9 [opt]
frame #154: 0x000100a5236c `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1268:31 [opt]
frame #155: 0x000100a98538 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x000000017721dad0) at expr.rs:891:9 [opt]
frame #156: 0x000100a9852c `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..Arm$GT$::parse::h813388a49c3e6446(input=) at expr.rs:3016:32 [opt]
frame #157: 0x000100a95dfc `syn::parse::ParseBuffer::call::h72a48f48372db5e0(self=, function=) at parse.rs:506:9 [opt]
frame #158: 0x000100a95df0 `syn::expr::parsing::_$LT$impl$u20$syn..expr..Arm$GT$::parse_multiple::hfbd825a8cd189a1c(input=0x000000017721dad0) at expr.rs:2991:33 [opt]
frame #159: 0x000100a95d70 `syn::expr::parsing::_$LT$impl$u20$syn..parse..Parse$u20$for$u20$syn..expr..ExprMatch$GT$::parse::h1ff6afd9ecea7f46(input=) at expr.rs:2356:24 [opt]
frame #160: 0x000100a52160 `syn::parse::ParseBuffer::parse::h2334be4fa706c19f(self=0x000000017721e860) at parse.rs:466:9 [opt]
frame #161: 0x000100a52154 `syn::expr::parsing::parse_with_earlier_boundary_rule::hc027c6a116544c85(input=) at expr.rs:1260:31 [opt]
frame #162: 0x000100a8d228 `syn::expr::Expr::parse_with_earlier_boundary_rule::hd27a80d372a66876(input=0x000000017721e860) at expr.rs:891:9 [opt]
...
frame #5319: 0x000100a22e74 `syn::parse::Parser::parse_str::hd7836776d293135a(self=, s=) at parse.rs:1268:14 [opt]
```

I don't expect `syn` to be able to succesfully parse it, but it would be nice to have recursion limit to at least abort gracefully.