# Issue with compiling and compiler recursion

**URL:** <https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893>\
**Category:** Help & Support\
**Created:** [June 27, 2019, 12:33am UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893 "2019-06-27T00:33:24Z")\
**Posts on this page:** 17\
**Page:** 1

<div class="post-metadata">

**Author:** ![stakach](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/stakach/32/58_2.png) [@stakach](https://forum.crystal-lang.org/u/stakach)\
**Post date:** [June 27, 2019, 12:33am UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/1 "2019-06-27T00:33:24Z")

</div>

Wondering if anyone can help me with an issue I’m having where I’m hitting a complexity limit.

```
Stack overflow (e.g., infinite or very deep recursion)
[0x10c756057] *CallStack::print_backtrace:Int32 +39
[0x10c6a7a20] __crystal_sigfault_handler +96
[0x7fff68526b5d] _sigtramp +29
[0x10c0450ce] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2302
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
...
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
...
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c584dc8] *Crystal::MainVisitor#expand<Crystal::StringInterpolation>:Bool +1608
[0x10c0466f6] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +7974
[0x10c4ab1b8] *Crystal::MainVisitor#type_assign<Crystal::Var+, Crystal::ASTNode+, Crystal::Assign, Nil>:(Crystal::MetaVar | Nil) +40
[0x10c4aa1f3] *Crystal::MainVisitor#visit<Crystal::Assign>:Bool +83
[0x10c044fdc] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2060
[0x10c04768b] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +11963
[0x10c699a04] *Crystal::Call#instantiate<Crystal::Matches, Crystal::Type+, Nil, Bool>:Array(Crystal::Def+) +6708
[0x10c694bdf] *Crystal::Call#lookup_matches_in_type<Crystal::Type+, Array(Crystal::Type+), (Array(Crystal::NamedArgumentType) | Nil), Nil, String, Bool, Bool, Bool>:Array(Crystal::Def+) +6463
[0x10c69b43a] *Crystal::Call#lookup_matches_in:with_literals<Crystal::Type+, Array(Crystal::Type+), (Array(Crystal::NamedArgumentType) | Nil), Bool>:Array(Crystal::Def+) +154
[0x10c60e040] *Crystal::Call#lookup_matches:with_literals<Bool>:Array(Crystal::Def+) +2240
[0x10be29217] *Crystal::Call#recalculate:Nil +2503
[0x10c0cf8b3] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +6819
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0cecd4] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +3780
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c584dc8] *Crystal::MainVisitor#expand<Crystal::StringInterpolation>:Bool +1608
[0x10c0466f6] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +7974
[0x10c0ce165] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +853
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c4ab1b8] *Crystal::MainVisitor#type_assign<Crystal::Var+, Crystal::ASTNode+, Crystal::Assign, Nil>:(Crystal::MetaVar | Nil) +40
[0x10c4aa1f3] *Crystal::MainVisitor#visit<Crystal::Assign>:Bool +83
[0x10c044fdc] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2060
[0x10c04768b] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +11963
[0x10c699a04] *Crystal::Call#instantiate<Crystal::Matches, Crystal::Type+, Nil, Bool>:Array(Crystal::Def+) +6708
[0x10c694bdf] *Crystal::Call#lookup_matches_in_type<Crystal::Type+, Array(Crystal::Type+), (Array(Crystal::NamedArgumentType) | Nil), Nil, String, Bool, Bool, Bool>:Array(Crystal::Def+) +6463
[0x10c69b43a] *Crystal::Call#lookup_matches_in:with_literals<Crystal::Type+, Array(Crystal::Type+), (Array(Crystal::NamedArgumentType) | Nil), Bool>:Array(Crystal::Def+) +154
[0x10c60e040] *Crystal::Call#lookup_matches:with_literals<Bool>:Array(Crystal::Def+) +2240
[0x10be29217] *Crystal::Call#recalculate:Nil +2503
[0x10c0cf8b3] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +6819
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c0cecd4] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +3780
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c04768b] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +11963
[0x10c680414] *Crystal::Call#match_block_arg<Crystal::Match>:Tuple(Array(Crystal::Var+) | Nil, Crystal::Type+ | Nil) +5812
[0x10c698195] *Crystal::Call#instantiate<Crystal::Matches, Crystal::Type+, Nil, Bool>:Array(Crystal::Def+) +453
[0x10c694bdf] *Crystal::Call#lookup_matches_in_type<Crystal::Type+, Array(Crystal::Type+), (Array(Crystal::NamedArgumentType) | Nil), Nil, String, Bool, Bool, Bool>:Array(Crystal::Def+) +6463
[0x10c69b43a] *Crystal::Call#lookup_matches_in:with_literals<Crystal::Type+, Array(Crystal::Type+), (Array(Crystal::NamedArgumentType) | Nil), Bool>:Array(Crystal::Def+) +154
[0x10c60e040] *Crystal::Call#lookup_matches:with_literals<Bool>:Array(Crystal::Def+) +2240
[0x10be29217] *Crystal::Call#recalculate:Nil +2503
[0x10c0cf8b3] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +6819
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c04768b] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +11963
[0x10c4a857c] *Crystal::MainVisitor#visit<Crystal::Block>:(Bool | Nil) +2780
[0x10c4acb6a] *Crystal::MainVisitor#visit<Crystal::Yield>:Bool +1530
[0x10c045156] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2438
[0x10c04768b] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +11963
[0x10c699a04] *Crystal::Call#instantiate<Crystal::Matches, Crystal::Type+, Nil, Bool>:Array(Crystal::Def+) +6708
[0x10c694bdf] *Crystal::Call#lookup_matches_in_type<Crystal::Type+, Array(Crystal::Type+), (Array(Crystal::NamedArgumentType) | Nil), Nil, String, Bool, Bool, Bool>:Array(Crystal::Def+) +6463
[0x10c69b43a] *Crystal::Call#lookup_matches_in:with_literals<Crystal::Type+, Array(Crystal::Type+), (Array(Crystal::NamedArgumentType) | Nil), Bool>:Array(Crystal::Def+) +154
[0x10c60e040] *Crystal::Call#lookup_matches:with_literals<Bool>:Array(Crystal::Def+) +2240
[0x10be29217] *Crystal::Call#recalculate:Nil +2503
[0x10c0cf8b3] *Crystal::MainVisitor#visit<Crystal::Call>:Bool +6819
[0x10c0450d2] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +2306
[0x10c04768b] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::MainVisitor>:Nil +11963
[0x10c2e3df1] *Crystal::Program#visit_main<Crystal::ASTNode+, Crystal::MainVisitor, Bool, Bool>:Crystal::ASTNode+ +129
[0x10c1ecba1] *Crystal::Program#semantic<Crystal::ASTNode+, Bool>:Crystal::ASTNode+ +10769
[0x10c6c1117] *Crystal::Compiler#compile<Array(Crystal::Compiler::Source), String>:Crystal::Compiler::Result +71
[0x10c6aa622] *Crystal::Command#run:(Bool | Crystal::Compiler::Result | Nil) +1090
[0x10be01b7f] __crystal_main +14095

```

This happens when I add one too many functions to the code I’m working on. You can easily replicate this on your own device by:

1. requires a local running instance of `redis-server`
2. clone: [https://github.com/aca-labs/crystal-engine-drivers](https://github.com/aca-labs/crystal-engine-drivers)
3. run: `shards update`
4. run: `crystal run ./src/app.cr`
5. browse to: [http://localhost:3000/#/aca\_drivers/drivers%2Fhelvar%2Fnet.cr?filter=](http://localhost:3000/#/aca_drivers/drivers%2Fhelvar%2Fnet.cr?filter=)
6. click `run`

This will compile and run a spec against a driver (we build commercial building automation systems and this is a development tool we built for writing drivers in crystal) - the `Helvar::Net` driver is the one triggering this behaviour

 ![image](https://canada1.discourse-cdn.com/flex036/uploads/crystal_lang/original/1X/6806b49bf3213f19a47262dcf0ef0821b0e19a20.png)

The build will probably succeed if you just clone the repository as I limited the number of functions being generated to prevent this compiling issue. But if you uncomment some of these lines the issue will occur

![image](https://canada1.discourse-cdn.com/flex036/uploads/crystal_lang/original/1X/98a64d6b35f6d30db7d5c5f65ce7974a2bd2d206.png)

This might be something @asterite would have some experience with - also I am happy to delve deep into the compiler internals if this is something that can be converted from a recursive algorithm to a dynamic one.

Not a super pressing issue at the moment as I don’t need all the functions but would be good to resolve or even understand what is triggering the behaviour.

---

<div class="post-metadata">

**Author:** ![stakach](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/stakach/32/58_2.png) [@stakach](https://forum.crystal-lang.org/u/stakach)\
**Post date:** [June 27, 2019, 1:00am UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/2 "2019-06-27T01:00:45Z")

</div>

A slightly different backtrace on the same driver

```
Stack overflow (e.g., infinite or very deep recursion)
[0x1057c3057] *CallStack::print_backtrace:Int32 +39
[0x105714a20] __crystal_sigfault_handler +96
[0x7fff68526b5d] _sigtramp +29
[0x1053c76e4] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11108
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
...
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053fdd6f] *Crystal::CodeGenVisitor#visit<Crystal::Assign>:(Bool | Nil) +335
[0x1053c52f1] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +1905
[0x1053c5389] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +2057
[0x1053dc605] *Crystal::CodeGenVisitor#codegen_fun<String, Crystal::Def+, Crystal::Type+, Bool, Crystal::CodeGenVisitor::ModuleInfo, Bool, Bool>:LLVM::Function +4757
[0x1053f16ad] *Crystal::CodeGenVisitor#target_def_fun<Crystal::Def+, Crystal::Type+>:LLVM::Function +2445
[0x1053e9a90] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5616
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efeb4] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +1092
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efad3] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +99
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053fdd6f] *Crystal::CodeGenVisitor#visit<Crystal::Assign>:(Bool | Nil) +335
[0x1053c52f1] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +1905
[0x1053c5389] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +2057
[0x1053dc605] *Crystal::CodeGenVisitor#codegen_fun<String, Crystal::Def+, Crystal::Type+, Bool, Crystal::CodeGenVisitor::ModuleInfo, Bool, Bool>:LLVM::Function +4757
[0x1053f16ad] *Crystal::CodeGenVisitor#target_def_fun<Crystal::Def+, Crystal::Type+>:LLVM::Function +2445
[0x1053e9a90] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5616
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053efeb4] *Crystal::CodeGenVisitor#prepare_call_args_non_external<Crystal::Call, Crystal::Def+, Crystal::Type+>:Tuple(Array(LLVM::Value), Bool) +1092
[0x1053e9909] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5225
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053c5389] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +2057
[0x1053dc605] *Crystal::CodeGenVisitor#codegen_fun<String, Crystal::Def+, Crystal::Type+, Bool, Crystal::CodeGenVisitor::ModuleInfo, Bool, Bool>:LLVM::Function +4757
[0x1053c5e68] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +4840
[0x1053e9978] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +5336
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053c5389] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +2057
[0x1053ca918] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +23960
[0x1053c5389] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +2057
[0x1053ea1f2] *Crystal::CodeGenVisitor#visit<Crystal::Call>:Bool +7506
[0x1053c76e8] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +11112
[0x1053c5389] *Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil +2057
[0x10538d898] *Crystal::Compiler#codegen<Crystal::Program, Crystal::ASTNode+, Array(Crystal::Compiler::Source), String>:(Tuple(Array(Crystal::Compiler::CompilationUnit), Array(String)) | Nil) +760
[0x10572e147] *Crystal::Compiler#compile<Array(Crystal::Compiler::Source), String>:Crystal::Compiler::Result +119
[0x105717622] *Crystal::Command#run:(Bool | Crystal::Compiler::Result | Nil) +1090
[0x104e6eb7f] __crystal_main +14095
[0x104e73448] main +56
```

---

<div class="post-metadata">

**Author:** ![asterite](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/asterite/32/60_2.png) [@asterite](https://forum.crystal-lang.org/u/asterite)\
**Post date:** [June 27, 2019, 1:35am UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/3 "2019-06-27T01:35:35Z")

</div>

Is there a way to reproduce this by calling `crystal some_file.cr`? Otherwise I’m not sure how to instruct that UI to use a different `crystal` executable which will have the debug info I need to find out why it’s crashing.

---

<div class="post-metadata">

**Author:** ![stakach](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/stakach/32/58_2.png) [@stakach](https://forum.crystal-lang.org/u/stakach)\
**Post date:** [June 27, 2019, 2:16am UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/4 "2019-06-27T02:16:09Z")

</div>

Yeah for sure:

```
cd crystal-engine-drivers
export COMPILE_DRIVER=drivers/helvar/net.cr
crystal build -o helvar_net src/build.cr

```

The driver code is required dynamically using the ENV var  
Thanks for having a look!

---

<div class="post-metadata">

**Author:** ![asterite](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/asterite/32/60_2.png) [@asterite](https://forum.crystal-lang.org/u/asterite)\
**Post date:** [June 27, 2019, 12:42pm UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/5 "2019-06-27T12:42:44Z")

</div>

I debugged it a bit and it seems ` __build_helpers__ ` is doing something that’s generating a lot of code or I don’t know. The code is too complex and Crystal can’t handle it because the way Crystal works is it will type a call, and when there’s a call inside that it will type that call and so on. There’s a limit to that: the stack size. So apparently your code is generating code and more code and eventually it consumes the entire stack.

I won’t be able to help here.

My advice is to try to avoid macros at all cost and only use them for simple stuff. Traversing type hierarchies, listing methods, etc., is too complex for my taste and will probably give the compiler a bad time.

(plus I never really imagined Crystal being used in that way, I was aiming for a simpler language)

---

<div class="post-metadata">

**Author:** ![asterite](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/asterite/32/60_2.png) [@asterite](https://forum.crystal-lang.org/u/asterite)\
**Post date:** [June 27, 2019, 12:47pm UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/6 "2019-06-27T12:47:47Z")

</div>

In fact, I would gladly remove all the type introspection features of the macro language and just leave it to a bare minimum which is to process text, arrays and hashes. I believe introspecting such things and using them for code generations usually leads to code that is more complex than alternative solutions.

---

<div class="post-metadata">

**Author:** ![asterite](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/asterite/32/60_2.png) [@asterite](https://forum.crystal-lang.org/u/asterite)\
**Post date:** [June 27, 2019, 12:49pm UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/7 "2019-06-27T12:49:06Z")

</div>

Many of Crystal features exist because at one point we thought “Could this be done? Yes, cool!” without actually thinking about use cases or how it would affect compilation times or even the mess of the resulting code. So I would really like to remove many of those things.

---

<div class="post-metadata">

**Author:** ![stakach](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/stakach/32/58_2.png) [@stakach](https://forum.crystal-lang.org/u/stakach)\
**Post date:** [June 27, 2019, 1:24pm UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/8 "2019-06-27T13:24:09Z")

</div>

Thanks for your help - I’ll look to simplify it.  
The macro system is super powerful and really useful - we’re using it there to generate a public method dispatch and metadata about the driver.

It would be really annoying to have to code that by hand.

---

<div class="post-metadata">

**Author:** ![stakach](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/stakach/32/58_2.png) [@stakach](https://forum.crystal-lang.org/u/stakach)\
**Post date:** [June 28, 2019, 10:00am UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/9 "2019-06-28T10:00:04Z")

</div>

Solved the issue!  
This rubbish looking code was causing the issue:

```
  # provide introspection into available functions
  @@functions : String?
  def self.functions : String
    functions = @@functions
    return functions if functions

      list = %({
      {% for method in methods %}
        {% index = 0 %}
        {% args = [] of Crystal::Macros::Arg %}
        {% for arg in method.args %}
          {% if !method.splat_index || index < method.splat_index %}
            {% args << arg %}
          {% end %}
          {% index = index + 1 %}
        {% end %}

        {{method.name.stringify}}: {
          {% for arg in args %}
            {% if !arg.restriction.is_a?(Union) && arg.restriction.resolve < ::Enum %}
              {% if arg.default_value.is_a?(Nop) %}
                {{arg.name.stringify}}: ["String"],
              {% else %}
                {{arg.name.stringify}}: ["String", "#{{{arg.default_value}}.to_s.to_json}"],
              {% end %}
            {% else %}
              {% if arg.default_value.is_a?(Nop) %}
                {{arg.name.stringify}}: [{{arg.restriction.stringify}}],
              {% else %}
                {{arg.name.stringify}}: [{{arg.restriction.stringify}}, "#{{{arg.default_value}}.to_json}"],
              {% end %}
            {% end %}
          {% end %}
        },
      {% end %}})

    # Remove whitespace, remove all ',' followed by a '}'
    @@functions = list.gsub(/\s/, "").gsub(",}", "}")
  end

```

replaced it with a string builder and everything works wonderfully now!

```
  # provide introspection into available functions
  @@functions : String?
  def self.functions : String
    functions = @@functions
    return functions if functions

    list = String.build do |str|
      str << "{"
      {% for method in methods %}
        {% index = 0 %}
        {% args = [] of Crystal::Macros::Arg %}
        {% for arg in method.args %}
          {% if !method.splat_index || index < method.splat_index %}
            {% args << arg %}
          {% end %}
          {% index = index + 1 %}
        {% end %}

        str << '"'
        str << {{method.name.stringify}}
        str << %(": {)
          {% for arg in args %}
            str << '"'
            str << {{arg.name.stringify}}

            {% if !arg.restriction.is_a?(Union) && arg.restriction.resolve < ::Enum %}
              {% if arg.default_value.is_a?(Nop) %}
                str << %(": ["String"],)
              {% else %}
                str << %(": ["String", ")
                str << {{arg.default_value}}.to_s.to_json
                str << %("],)
              {% end %}
            {% else %}
              str << %(": [")
              str << {{arg.restriction.stringify}}
              {% if !arg.default_value.is_a?(Nop) %}
                str << %(", ")
                str << {{arg.default_value}}.to_json
              {% end %}
              str << %("],)
            {% end %}
          {% end %}
        str << "},"
      {% end %}
      str << "}"
    end

    # Remove whitespace, remove all ',' followed by a '}'
    @@functions = funcs = list.gsub(/\s/, "").gsub(",}", "}")
    funcs
  end

```

Thanks for the advice @asterite I made a whole lot of other improvements too however this was the only thing that actually prevented the compilation.

---

<div class="post-metadata">

**Author:** ![asterite](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/asterite/32/60_2.png) [@asterite](https://forum.crystal-lang.org/u/asterite)\
**Post date:** [June 28, 2019, 11:37am UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/10 "2019-06-28T11:37:37Z")

</div>

Nice! I’m happy that it worked!

I should have mentioned, in my stack trace I printed the calls causing the segfault and it was dying at something like:

```auto
((((((((((((((((((((((((((((((((((((((((String::Builder.new(...

```

I thought it could have been a deeply nested string building (via nested interpolations) but I didn’t browse the code that much to understand it.

I’ll try to find a way to reproduce that in a smaller code and think about ways to fix it, I’m not sure it’s possible.

---

<div class="post-metadata">

**Author:** ![stakach](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/stakach/32/58_2.png) [@stakach](https://forum.crystal-lang.org/u/stakach)\
**Post date:** [June 28, 2019, 12:03pm UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/11 "2019-06-28T12:03:26Z")

</div>

Yeah, it was super weird. Literally the last bit of code I played around with as it doesn’t interact with anything. So I’m very much of the opinion that it was probably me.  
In the end what I thought were the much more complex operations were working fine.

Out of interest, how would one go about debugging the compiler like that?  
Any online resources or links to a guide would be awesome. I’m sure this won’t be the last time I push the boundaries of what is possible

---

<div class="post-metadata">

**Author:** ![asterite](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/asterite/32/60_2.png) [@asterite](https://forum.crystal-lang.org/u/asterite)\
**Post date:** [June 28, 2019, 12:21pm UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/12 "2019-06-28T12:21:42Z")

</div>

So, what I did was:

1. Get the compiler’s source code (well, I already have that)
2. The trace was pointing to `Crystal::MainVisitor#visit<Crystal::Call>:Bool`. That’s the method where a call is typed (or prepared to be typed). I went to that method and added this line: `p! node, node.location` to see the trace of calls being typed.
3. Then I compile the compiler with `make clean crystal`
4. Finally, I use the compiled compiler with the problematic program. You just need to call `bin/crystal` and then the program, though from the problematic program’s path, so in my case it’s `/Users/asterite/Projects/crystal/bin/crystal`. Because I don’t want to type that all the type I have `alias ccrystal="/Users/asterite/Projects/crystal/bin/crystal"` in my bash profile.

And that’s it!

For stuff that I can reduce to simpler code I usually add a compiler spec, which involves other steps. But anyone can modify the compiler, compile it and then use it on any other program with some changes.

---

<div class="post-metadata">

**Author:** ![asterite](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/asterite/32/60_2.png) [@asterite](https://forum.crystal-lang.org/u/asterite)\
**Post date:** [June 28, 2019, 12:29pm UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/13 "2019-06-28T12:29:15Z")

</div>

So, I wrote this Crystal program:

```crystal
# foo.cr
times = 3000
puts(String.build do |io|
  io << "puts "
  times.times do
    io << %("a\#{)
  end
  io << 1
  times.times do
    io << %(}")
  end
end)

```

then I do:

```auto
crystal foo.cr > bar.cr

```

and then:

```auto
crystal bar.cr

```

and with that I get the stack overflow.

But we can run it with Ruby too!

```auto
ruby bar.cr

```

I get:

```auto
$ ruby bar.cr
bar.cr:1: memory exhausted
...a#{"a#{"a#{"a#{"a#{"a#{"a#{"a#{"a#{"a#{"a#{"a#{"a#{"a#{"a#{"...

```

I even get that with `times = 1500` in Ruby, but with that number Crystal works fine.

So I guess in your case it was a really deep nested interpolation.

I don’t think there’s nothing we can do to improve this.

---

<div class="post-metadata">

**Author:** ![asterite](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/asterite/32/60_2.png) [@asterite](https://forum.crystal-lang.org/u/asterite)\
**Post date:** [June 28, 2019, 12:43pm UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/14 "2019-06-28T12:43:29Z")

</div>

By the way, I was surprised to see that the total number of Crystal lines of code in the repo, including `lib`, is about 20K. And for me the initial compilation takes about 7 seconds, but subsequent compilations take 2 seconds. It’s acceptable, I think!

---

<div class="post-metadata">

**Author:** ![stakach](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/stakach/32/58_2.png) [@stakach](https://forum.crystal-lang.org/u/stakach)\
**Post date:** [June 28, 2019, 2:43pm UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/15 "2019-06-28T14:43:42Z")

</div>

Awesome! Thank you so much for the explanation!  
The deeply nested interpolation was definitely a mistake on my part 😌

I find the compile times to be very good - really blows my mind how good the language is. I am so much more productive than I have been on Ruby. 99% of the time, when something compiles, it works first go and I often find myself breaking tests deliberately to make certain that they are running.

Thus far we’ve migrated everything but our Authentication service to Crystal and should have the Crystal version released by August.  
You can see an overview of the project here: [https://docs.google.com/document/d/1fT7GSghFxovsQkLimmthc28xnWAac9d8ojIH56MhusU/edit?usp=sharing](https://docs.google.com/document/d/1fT7GSghFxovsQkLimmthc28xnWAac9d8ojIH56MhusU/edit?usp=sharing)

The system we’re building is a distributed building automation platform - the ruby version had hot loading, but was fairly monolithic - the crystal version compiles drivers and launches a process for each type of hardware (one process might control thousands of LCD displays across an organisation for example)  
The driver compiling and process launching aspect on the servers is dynamic, driven by the database and coordinated by services written in Crystal.

The whole thing is open source so I might make an announcement once it’s production ready

---

<div class="post-metadata">

**Author:** ![girng](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/girng/32/127_2.png) [@girng](https://forum.crystal-lang.org/u/girng)\
**Post date:** [June 29, 2019, 5:34am UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/16 "2019-06-29T05:34:09Z")

</div>

Yeah, that’s quite nice. I still don’t understand why people complained about slow compile times.

I complain about weird stuff too, so I guess it makes sense.

---

<div class="post-metadata">

**Author:** ![stakach](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.crystal-lang.org/stakach/32/58_2.png) [@stakach](https://forum.crystal-lang.org/u/stakach)\
**Post date:** [June 29, 2019, 8:52am UTC](https://forum.crystal-lang.org/t/issue-with-compiling-and-compiler-recursion/893/17 "2019-06-29T08:52:50Z")

</div>

Yeah, given the compile + startup time of running the app above takes roughly the same time as launching a rails app, I am as productive as I’ve ever been