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20 hours ago •
roc-lang
roc-lang
Compiler bug when running reverse polish notation calculator
This bug could be issued already, but the compiler told me to file a new issue, so I will :)
I translated the RPN calculator from learnyouahaskell to roc. It is not the most performant or idiomatic translation, but it was a first try. Here is the code:
app "main"
packages { pf: "examples/interactive/cli-platform/main.roc" }
imports [pf.Stdout, pf.Stdin, pf.Task.{ Task, await }]
provides [main] to pf
main : Task {} [] [Write [Stdout], Read [Stdin]]
main =
Task.forever
(
_ <- await (Stdout.line "enter an expression:")
line <- await Stdin.line
line |> solveRpn |> Num.toStr |> Stdout.line
)
solveRpn : Str -> F64
solveRpn = \s -> s
|> Str.split " "
|> List.walk [] step
|> List.first
|> Result.withDefault 0
step : List F64, Str -> List F64
step = \stack, input ->
binOp : List F64, (F64, F64 -> F64) -> List F64
binOp = \s, f ->
y = s |> List.last |> Result.withDefault 0
x = s |> List.dropLast |> List.last |> Result.withDefault 0
s |> List.dropLast |> List.dropLast |> List.append (f x y)
when input is
"+" -> binOp stack Num.add
"-" -> binOp stack Num.sub
"*" -> binOp stack Num.mul
"/" -> binOp stack Num.div
s -> stack |> List.append (s |> Str.toF64 |> Result.withDefault 0)
After running RUST_BACKTRACE=full roc run, I get the following output:
🔨 Rebuilding host...
An internal compiler expectation was broken.
This is definitely a compiler bug.
Please file an issue here: https://github.com/roc-lang/roc/issues/new/choose
thread 'main' panicked at 'Undefined Symbol in relocation, (+6936, Relocation { kind: Relative, encoding: Generic, size: +20, target: Symbol(SymbolIndex(+248)), addend: +fffffffffffffffc, implicit_addend: false }): Ok(Symbol { name: "", address: +0, size: +0, kind: Section, section: Section(SectionIndex(+9)), scope: Compilation, weak: false, flags: Elf { st_info: +3, st_other: +0 } })', crates/linker/src/lib.rs:2708:25
stack backtrace:
0: 0x55e774aaf106 - std::backtrace_rs::backtrace::libunwind::trace::h22893a5306c091b4
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
1: 0x55e774aaf106 - std::backtrace_rs::backtrace::trace_unsynchronized::h29c3bc6f9e91819d
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
2: 0x55e774aaf106 - std::sys_common::backtrace::_print_fmt::he497d8a0ec903793
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/sys_common/backtrace.rs:66:5
3: 0x55e774aaf106 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h9c2a9d2774d81873
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/sys_common/backtrace.rs:45:22
4: 0x55e773f8c52c - core::fmt::write::hba4337c43d992f49
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/core/src/fmt/mod.rs:1194:17
5: 0x55e774aaa50f - std::io::Write::write_fmt::heb73de6e02cfabed
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/io/mod.rs:1655:15
6: 0x55e774ab0cf5 - std::sys_common::backtrace::_print::h63c8b24acdd8e8ce
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/sys_common/backtrace.rs:48:5
7: 0x55e774ab0cf5 - std::sys_common::backtrace::print::h426700d6240cdcc2
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/sys_common/backtrace.rs:35:9
8: 0x55e774ab0cf5 - std::panicking::default_hook::{{closure}}::hc9a76eed0b18f82b
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:295:22
9: 0x55e774ab0a6d - std::panicking::default_hook::h2e88d02087fae196
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:314:9
10: 0x55e774ab11d5 - std::panicking::rust_panic_with_hook::habfdcc2e90f9fd4c
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:698:17
11: 0x55e774ab10e4 - std::panicking::begin_panic_handler::{{closure}}::he054b2a83a51d2cd
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:588:13
12: 0x55e774aaf634 - std::sys_common::backtrace::__rust_end_short_backtrace::ha48b94ab49b30915
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/sys_common/backtrace.rs:138:18
13: 0x55e774ab0e3d - rust_begin_unwind
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:584:5
14: 0x55e773dd49b3 - core::panicking::panic_fmt::h366d3a309ae17c94
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/core/src/panicking.rs:143:14
15: 0x55e7746279ea - roc_linker::surgery_elf::h29c5dc23e9abb58c
16: 0x55e77461ca96 - roc_linker::surgery::hff07d7f6f7d52b4a
17: 0x55e774610083 - roc_linker::link_preprocessed_host::h3809fe0eed793818
18: 0x55e7742fbaeb - roc_cli::build::build_file::ha61b316ffe2aafac
19: 0x55e77430a656 - roc_cli::build::haddea3af519b4977
20: 0x55e77416d31e - roc::main::hdd05643fe19e55ff
21: 0x55e77416a8d3 - std::sys_common::backtrace::__rust_begin_short_backtrace::hb1a2ee42dbb3fc9f
22: 0x55e77416a8f1 - std::rt::lang_start::{{closure}}::h7b8d975ac0de2248
23: 0x55e774aa39d2 - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once::had4f69b3aefb47a8
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/core/src/ops/function.rs:259:13
24: 0x55e774aa39d2 - std::panicking::try::do_call::hf2ad5355fcafe775
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:492:40
25: 0x55e774aa39d2 - std::panicking::try::h0a63ac363423e61e
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:456:19
26: 0x55e774aa39d2 - std::panic::catch_unwind::h18088edcecb8693a
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panic.rs:137:14
27: 0x55e774aa39d2 - std::rt::lang_start_internal::{{closure}}::ha7dad166dc711761
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/rt.rs:128:48
28: 0x55e774aa39d2 - std::panicking::try::do_call::hda0c61bf3a57d6e6
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:492:40
29: 0x55e774aa39d2 - std::panicking::try::hbc940e68560040a9
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:456:19
30: 0x55e774aa39d2 - std::panic::catch_unwind::haed0df2aeb3fa368
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panic.rs:137:14
31: 0x55e774aa39d2 - std::rt::lang_start_internal::h9c06694362b5b80c
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/rt.rs:128:20
32: 0x55e774171192 - main
33: 0x7f97794e6237 - __libc_start_call_main
34: 0x7f97794e62f5 - __libc_start_main_impl
35: 0x55e773ef2bc1 - _start
at /build/glibc-2.34/csu/../sysdeps/x86_64/start.S:116
36: 0x0 - <unknown>
Running roc check does not give any errors, Running roc build gives the same error.
Running roc format gives this error:
thread 'main' panicked at 'not yet implemented: Format string literal: PlainLine("+")', crates/compiler/fmt/src/pattern.rs:150:17
stack backtrace:
0: 0x556a8a224106 - std::backtrace_rs::backtrace::libunwind::trace::h22893a5306c091b4
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
1: 0x556a8a224106 - std::backtrace_rs::backtrace::trace_unsynchronized::h29c3bc6f9e91819d
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
2: 0x556a8a224106 - std::sys_common::backtrace::_print_fmt::he497d8a0ec903793
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/sys_common/backtrace.rs:66:5
3: 0x556a8a224106 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h9c2a9d2774d81873
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/sys_common/backtrace.rs:45:22
4: 0x556a8970152c - core::fmt::write::hba4337c43d992f49
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/core/src/fmt/mod.rs:1194:17
5: 0x556a8a21f50f - std::io::Write::write_fmt::heb73de6e02cfabed
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/io/mod.rs:1655:15
6: 0x556a8a225cf5 - std::sys_common::backtrace::_print::h63c8b24acdd8e8ce
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/sys_common/backtrace.rs:48:5
7: 0x556a8a225cf5 - std::sys_common::backtrace::print::h426700d6240cdcc2
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/sys_common/backtrace.rs:35:9
8: 0x556a8a225cf5 - std::panicking::default_hook::{{closure}}::hc9a76eed0b18f82b
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:295:22
9: 0x556a8a225a6d - std::panicking::default_hook::h2e88d02087fae196
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:314:9
10: 0x556a8a2261d5 - std::panicking::rust_panic_with_hook::habfdcc2e90f9fd4c
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:698:17
11: 0x556a8a2260e4 - std::panicking::begin_panic_handler::{{closure}}::he054b2a83a51d2cd
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:588:13
12: 0x556a8a224634 - std::sys_common::backtrace::__rust_end_short_backtrace::ha48b94ab49b30915
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/sys_common/backtrace.rs:138:18
13: 0x556a8a225e3d - rust_begin_unwind
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:584:5
14: 0x556a895499b3 - core::panicking::panic_fmt::h366d3a309ae17c94
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/core/src/panicking.rs:143:14
15: 0x556a89c45521 - roc_fmt::pattern::<impl roc_fmt::annotation::Formattable for roc_parse::ast::Pattern>::format_with_options::h1267d8b68931ea8a
16: 0x556a89c3c994 - roc_fmt::expr::<impl roc_fmt::annotation::Formattable for roc_parse::ast::Expr>::format_with_options::hc71663cc72938a41
17: 0x556a89c375d8 - roc_fmt::def::<impl roc_fmt::annotation::Formattable for roc_parse::ast::Defs>::format_with_options::h7a40ae520ab70470
18: 0x556a89a73fe9 - roc_cli::format::format::hab4acaed20fdc19b
19: 0x556a898e3f3d - roc::main::hdd05643fe19e55ff
20: 0x556a898df8d3 - std::sys_common::backtrace::__rust_begin_short_backtrace::hb1a2ee42dbb3fc9f
21: 0x556a898df8f1 - std::rt::lang_start::{{closure}}::h7b8d975ac0de2248
22: 0x556a8a2189d2 - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once::had4f69b3aefb47a8
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/core/src/ops/function.rs:259:13
23: 0x556a8a2189d2 - std::panicking::try::do_call::hf2ad5355fcafe775
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:492:40
24: 0x556a8a2189d2 - std::panicking::try::h0a63ac363423e61e
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:456:19
25: 0x556a8a2189d2 - std::panic::catch_unwind::h18088edcecb8693a
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panic.rs:137:14
26: 0x556a8a2189d2 - std::rt::lang_start_internal::{{closure}}::ha7dad166dc711761
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/rt.rs:128:48
27: 0x556a8a2189d2 - std::panicking::try::do_call::hda0c61bf3a57d6e6
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:492:40
28: 0x556a8a2189d2 - std::panicking::try::hbc940e68560040a9
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panicking.rs:456:19
29: 0x556a8a2189d2 - std::panic::catch_unwind::haed0df2aeb3fa368
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/panic.rs:137:14
30: 0x556a8a2189d2 - std::rt::lang_start_internal::h9c06694362b5b80c
at /rustc/fe5b13d681f25ee6474be29d748c65adcd91f69e/library/std/src/rt.rs:128:20
31: 0x556a898e6192 - main
32: 0x7f1868040237 - __libc_start_call_main
33: 0x7f18680402f5 - __libc_start_main_impl
34: 0x556a89667bc1 - _start
at /build/glibc-2.34/csu/../sysdeps/x86_64/start.S:116
35: 0x0 - <unknown>
I understand the language is new, and there are still a lot of bugs needed to be fixed. I just hope this issue can help someone fix one bug!
The format and run panics are likely separate bugs. Can you try passing --linker=legacy to roc run and see if that helps?
It works with the --linker=legacy flag. The compile time is much longer now though. Thanks for the quick response.
I don't have access to my x86 machine for a few days, but will look into this once I do.
I did some digging. The relocation in question is
[crates/linker/src/lib.rs:2788] &rel = (
26934,
Relocation {
kind: Relative,
encoding: Generic,
size: 32,
target: Symbol(
SymbolIndex(
587,
),
),
addend: -4,
implicit_addend: false,
},
)
That symbol is
[crates/linker/src/lib.rs:2788] app_obj.symbol_by_index(index) = Ok(
Symbol {
name: "",
address: 0,
size: 0,
kind: Section,
section: Section(
SectionIndex(
9,
),
),
scope: Compilation,
weak: false,
flags: Elf {
st_info: 3,
st_other: 0,
},
},
)
The symbol name is empty, and that means we can't find it in our hashmap of functions which we know how to relocate.
Looking at the symbol table:
583: 0000000000001d6c 18 OBJECT LOCAL DEFAULT 8 __unnamed_432
584: 0000000000001d7e 17 OBJECT LOCAL DEFAULT 8 __unnamed_433
585: 0000000000001d8f 18 OBJECT LOCAL DEFAULT 8 __unnamed_434
586: 0000000000001da1 18 OBJECT LOCAL DEFAULT 8 __unnamed_435
587: 0000000000000000 0 SECTION LOCAL DEFAULT 9
588: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND roc_alloc
589: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND memcpy
590: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND memset
591: 0000000000003140 486 FUNC WEAK DEFAULT 2 __muloti4
Our symbol 587 is of kind SECTION, which is odd. It is in secton 9, which is
Section Headers:
[Nr] Name Type Address Off Size ES Flg Lk Inf Al
[ 0] NULL 0000000000000000 000000 000000 00 0 0 0
[ 1] .strtab STRTAB 0000000000000000 01ce50 00395a 00 0 0 1
[ 2] .text PROGBITS 0000000000000000 000040 00c3b8 00 AX 0 0 16
[ 3] .rela.text RELA 0000000000000000 018440 0014b8 18 14 2 8
[ 4] .rodata.cst16 PROGBITS 0000000000000000 00c400 000100 10 AM 0 0 16
[ 5] .rodata.cst8 PROGBITS 0000000000000000 00c500 0000a0 08 AM 0 0 8
[ 6] .rodata PROGBITS 0000000000000000 00c5a0 003448 00 A 0 0 8
[ 7] .rela.rodata RELA 0000000000000000 0198f8 0001f8 18 14 6 8
[ 8] .rodata.str1.1 PROGBITS 0000000000000000 00f9e8 001dd8 01 AMS 0 0 1
[ 9] .data.rel.ro PROGBITS 0000000000000000 0117c0 002880 00 WA 0 0 8
[10] .rela.data.rel.ro RELA 0000000000000000 019af0 002880 18 14 9 8
This is where my (current) knowledge stops.
So this definitely seems to be the same root issue as #3609. The fix would theoretically be what is mentioned here: https://github.com/roc-lang/roc/issues/3609#issuecomment-1193179430.
In the case the cause is specifically Num.toStr on floats. If you remove that function and just replace it with something silly like (\x -> if x > 0 then "+" else "-"), it will compile with the surgical linker.
What this really means is that the zig builtin creates a constant pointer to constant data. The surgical linker can not yet deal with constant pointers. They need to be converted to a relocation that will happen at run time. Before run time, we don't know the correct address space to setup pointers correctly. Theoretically, we could change the zig builtin in some way to fix this, but really the root issue needs to be addressed.
Anything nested and constant will use section like .data.rel.ro and we currently don't have code to deal with relocations for that.